Migration of the proton in the strong O—H...O hydrogen bond in urea–phosphoric acid (1/1)

The structure of urea–phosphoric acid is reported at a large number of temperatures in the range 150–335 K from neutron diffraction data collected using a novel multiple single-crystal data collection method. The work focuses on the behaviour of the H atom involved in the short strong O—H...O hydrogen bond in this material. The position of this atom is shown to vary significantly, by around 0.035  Å, as a function of temperature, becoming effectively centred at the highest temperatures studied. This result, only accessible due to the accurate determination of H-atom parameters by neutron diffraction, has implications for the potential governing the hydrogen bond.

Computing details

Program(s) used to refine structure: GSAS (Larsen & von Dreele, 1994) for 150K, 250K, 290K, 295K, 300K, 305K, 310K, 315K, 320K, 330K, 335K; GSAS (Larsen and von Dreele, 1994) for 280K. For all compounds, molecular graphics: ORTEP (Johnson, 1994).

Figures

(150K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.817 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.420 Å	Cell parameters from 25 reflections
b = 7.421 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.939 Å	T = 150 K
V = 1155.6 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	1037 independent reflections
Radiation source: ISIS spallation source	1037 reflections with > 3σ(I)
None monochromator	Rint = 0.079
time–of–flight LAUE diffraction scans	h = 0→28
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→14
Tmin = 0.36, Tmax = 0.78	l = 0^→15
2327 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.103	(Δ/σ)max < 0.001
wR(F^2) = 0.185	Δρmax = 2.00 e Å^−3
S = 1.20	Δρmin = −1.77 e Å^−3
1037 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.141 _diffrn_reflns_sin(theta)/lambda_max 0.82

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3105 (3)	0.2805 (4)	0.3099 (4)	1.02
O1	0.3403 (3)	0.0912 (4)	0.3626 (4)	1.65
O2	0.2774 (3)	0.3863 (4)	0.4390 (3)	1.42
O3	0.2454 (3)	0.2511 (4)	0.1951 (4)	1.63
O4	0.3788 (3)	0.3679 (4)	0.2390 (4)	1.60
O5	0.4475 (3)	0.6350 (4)	0.3095 (4)	1.56
N1	0.50886 (18)	0.7837 (3)	0.4934 (3)	1.72
N2	0.39745 (17)	0.6335 (3)	0.5437 (3)	1.82
C1	0.4507 (2)	0.6836 (3)	0.4485 (3)	1.12
H1	0.2975 (5)	0.0116 (7)	0.3918 (7)	2.56
H11	0.5531 (6)	0.8116 (8)	0.4212 (8)	3.07
H12	0.5115 (6)	0.8248 (10)	0.5992 (9)	3.61
H21	0.3528 (6)	0.5570 (9)	0.5103 (9)	3.20
H22	0.3989 (6)	0.6723 (9)	0.6503 (7)	3.48
H3	0.2598 (5)	0.1989 (7)	0.0949 (6)	2.36
H4	0.4091 (5)	0.5092 (8)	0.2807 (7)	2.78

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.008 (3)	0.0109 (13)	0.0115 (14)	−0.0018 (13)	0.0005 (15)	−0.0022 (14)
O1	0.009 (3)	0.0172 (14)	0.0223 (17)	0.0025 (15)	−0.0025 (16)	−0.0011 (13)
O2	0.016 (3)	0.0124 (13)	0.0128 (13)	−0.0003 (13)	0.0009 (15)	−0.0029 (12)
O3	0.009 (3)	0.0250 (16)	0.0142 (13)	−0.0014 (14)	−0.0022 (15)	−0.0015 (14)
O4	0.016 (3)	0.0173 (13)	0.0152 (15)	−0.0013 (15)	0.0019 (14)	−0.0012 (12)
O5	0.018 (3)	0.0155 (13)	0.0137 (14)	−0.0049 (14)	0.0020 (15)	0.0013 (12)
N1	0.017 (2)	0.0178 (8)	0.0172 (10)	−0.0045 (10)	0.0016 (11)	−0.0028 (8)
N2	0.013 (2)	0.0234 (10)	0.0184 (10)	−0.0051 (10)	0.0037 (10)	−0.0042 (9)
C1	0.010 (2)	0.0105 (10)	0.0126 (12)	−0.0004 (10)	0.0000 (11)	0.0002 (10)
H1	0.033 (7)	0.017 (2)	0.029 (4)	0.004 (3)	0.002 (3)	−0.004 (2)
H11	0.025 (7)	0.032 (3)	0.035 (4)	−0.003 (3)	0.001 (4)	0.000 (3)
H12	0.031 (8)	0.044 (4)	0.035 (4)	0.001 (4)	−0.002 (4)	−0.014 (3)
H21	0.021 (7)	0.033 (3)	0.040 (4)	−0.006 (3)	0.003 (4)	−0.006 (3)
H22	0.036 (8)	0.047 (4)	0.022 (3)	−0.014 (4)	−0.001 (3)	−0.010 (3)
H3	0.034 (6)	0.018 (3)	0.018 (3)	0.001 (3)	0.005 (3)	−0.001 (2)
H4	0.028 (7)	0.033 (3)	0.025 (3)	0.001 (3)	0.001 (3)	0.002 (3)

Geometric parameters (Å, º)

P1—O1	1.571 (5)	O5—H4	1.178 (8)
P1—O2	1.510 (5)	N1—C1	1.319 (4)
P1—O3	1.544 (6)	N1—H11	1.026 (10)
P1—O4	1.496 (6)	N1—H12	0.995 (8)
O1—H1	0.985 (10)	N2—C1	1.313 (4)
O3—H3	1.008 (7)	N2—H21	1.009 (9)
O4—H4	1.231 (8)	N2—H22	0.996 (7)
O5—C1	1.294 (4)
O1—P1—O2	111.2 (3)	C1—N1—H11	119.9 (5)
O1—P1—O3	108.4 (3)	C1—N1—H12	119.9 (7)
O1—P1—O4	104.6 (3)	H11—N1—H12	120.1 (8)
O2—P1—O3	107.6 (3)	C1—N2—H21	120.9 (5)
O2—P1—O4	113.7 (3)	C1—N2—H22	121.4 (6)
O3—P1—O4	111.4 (3)	H21—N2—H22	117.7 (7)
P1—O1—H1	111.4 (5)	O5—C1—N1	118.8 (3)
P1—O3—H3	117.5 (6)	O5—C1—N2	120.9 (3)
P1—O4—H4	125.6 (5)	N1—C1—N2	120.3 (3)
C1—O5—H4	117.1 (4)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.985 (10)	1.658 (9)	2.642 (6)
O3—H3···O2^ii	1.008 (7)	1.561 (7)	2.568 (5)
O5—H4···O4	1.178 (8)	1.231 (8)	2.400 (5)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(250K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.794 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.549 Å	Cell parameters from 25 reflections
b = 7.446 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.959 Å	T = 250 K
V = 1170.6 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	782 independent reflections
Radiation source: ISIS spallation source	782 reflections with > 3σ(I)
None monochromator	Rint = 0.066
time–of–flight LAUE diffraction scans	h = 0→26
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→15
1798 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.093	(Δ/σ)max < 0.001
wR(F^2) = 0.171	Δρmax = 1.11 e Å^−3
S = 1.18	Δρmin = −1.37 e Å^−3
782 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.141 _diffrn_reflns_sin(theta)/lambda_max 0.66

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3109 (3)	0.2798 (4)	0.3095 (4)	1.80
O1	0.3394 (3)	0.0913 (6)	0.3618 (5)	2.69
O2	0.2775 (3)	0.3860 (4)	0.4381 (4)	2.17
O3	0.2466 (3)	0.2497 (5)	0.1954 (5)	2.69
O4	0.3790 (3)	0.3656 (5)	0.2403 (4)	2.64
O5	0.4469 (3)	0.6331 (4)	0.3106 (4)	2.40
N1	0.5074 (2)	0.7839 (3)	0.4916 (3)	2.67
N2	0.3968 (2)	0.6352 (4)	0.5421 (3)	2.77
C1	0.4497 (2)	0.6835 (4)	0.4483 (4)	1.80
H1	0.2979 (6)	0.0121 (9)	0.3916 (9)	3.50
H11	0.5527 (7)	0.8119 (9)	0.4217 (10)	4.66
H12	0.5135 (7)	0.8252 (10)	0.5982 (8)	4.97
H21	0.3563 (7)	0.5559 (12)	0.5111 (10)	5.02
H22	0.3987 (7)	0.6719 (11)	0.6479 (8)	5.54
H3	0.2608 (6)	0.1963 (9)	0.0964 (8)	3.62
H4	0.4088 (6)	0.5081 (10)	0.2809 (8)	4.00

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.020 (4)	0.0175 (17)	0.0156 (17)	−0.0037 (17)	−0.0010 (18)	−0.0044 (16)
O1	0.020 (4)	0.0271 (19)	0.030 (2)	0.004 (2)	−0.002 (2)	0.0004 (18)
O2	0.029 (4)	0.0200 (16)	0.0177 (17)	−0.0005 (17)	0.0042 (19)	−0.0011 (15)
O3	0.018 (4)	0.037 (2)	0.0251 (18)	0.0011 (18)	−0.0063 (18)	−0.0043 (19)
O4	0.026 (4)	0.028 (2)	0.0223 (19)	−0.0039 (19)	0.0061 (19)	0.0008 (15)
O5	0.027 (4)	0.0223 (18)	0.0219 (19)	−0.0045 (17)	0.0006 (18)	0.0005 (16)
N1	0.024 (3)	0.0289 (12)	0.0262 (13)	−0.0075 (13)	0.0027 (13)	−0.0066 (11)
N2	0.021 (3)	0.0345 (15)	0.0275 (14)	−0.0078 (13)	0.0057 (12)	−0.0043 (11)
C1	0.014 (3)	0.0197 (14)	0.0212 (16)	0.0000 (14)	0.0005 (14)	−0.0002 (12)
H1	0.041 (8)	0.022 (3)	0.045 (4)	0.008 (3)	0.001 (4)	−0.003 (3)
H11	0.043 (9)	0.042 (4)	0.046 (5)	−0.010 (4)	0.006 (4)	−0.004 (4)
H12	0.067 (10)	0.045 (4)	0.030 (4)	−0.003 (5)	−0.011 (4)	−0.013 (3)
H21	0.045 (10)	0.050 (5)	0.055 (6)	−0.024 (5)	0.008 (5)	−0.017 (4)
H22	0.061 (10)	0.068 (5)	0.032 (4)	−0.021 (5)	0.000 (4)	−0.026 (4)
H3	0.050 (8)	0.029 (3)	0.035 (4)	−0.005 (3)	0.007 (4)	−0.003 (3)
H4	0.027 (8)	0.050 (5)	0.038 (4)	0.002 (4)	0.006 (4)	−0.001 (3)

Geometric parameters (Å, º)

P1—O1	1.562 (5)	O5—H4	1.176 (10)
P1—O2	1.516 (5)	N1—C1	1.317 (5)
P1—O3	1.539 (6)	N1—H11	1.032 (12)
P1—O4	1.490 (7)	N1—H12	1.009 (8)
O1—H1	0.974 (12)	N2—C1	1.302 (5)
O3—H3	1.003 (9)	N2—H21	0.965 (11)
O4—H4	1.237 (9)	N2—H22	0.988 (8)
O5—C1	1.290 (5)
O1—P1—O2	111.4 (3)	C1—N1—H11	121.8 (5)
O1—P1—O3	107.6 (3)	C1—N1—H12	122.2 (7)
O1—P1—O4	104.7 (4)	H11—N1—H12	115.5 (9)
O2—P1—O3	107.3 (4)	C1—N2—H21	120.6 (6)
O2—P1—O4	113.8 (3)	C1—N2—H22	121.3 (7)
O3—P1—O4	112.0 (3)	H21—N2—H22	118.0 (9)
P1—O1—H1	112.9 (6)	O5—C1—N1	118.4 (4)
P1—O3—H3	117.6 (8)	O5—C1—N2	120.6 (4)
P1—O4—H4	125.7 (5)	N1—C1—N2	121.0 (3)
C1—O5—H4	117.9 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.974 (12)	1.676 (11)	2.648 (7)
O3—H3···O2^ii	1.003 (9)	1.573 (8)	2.575 (6)
O5—H4···O4	1.176 (10)	1.237 (9)	2.405 (6)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(280K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.788 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.576 Å	Cell parameters from 25 reflections
b = 7.456 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.963 Å	T = 280 K
V = 1174.4 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	705 independent reflections
Radiation source: ISIS spallation source	705 reflections with > 3σ(I)
None monochromator	Rint = 0.087
time–of–flight LAUE diffraction scans	h = 0→23
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→14
Tmin = 0.36, Tmax = 0.78	l = 0^→15
2087 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.121	(Δ/σ)max < 0.001
wR(F^2) = 0.191	Δρmax = 1.34 e Å^−3
S = 1.29	Δρmin = −1.35 e Å^−3
705 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.56

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.62

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3117 (4)	0.2790 (6)	0.3104 (5)	2.26
O1	0.3401 (4)	0.0910 (7)	0.3626 (7)	3.16
O2	0.2782 (4)	0.3855 (6)	0.4374 (5)	2.51
O3	0.2460 (4)	0.2507 (7)	0.1960 (6)	2.62
O4	0.3781 (4)	0.3656 (6)	0.2395 (5)	2.97
O5	0.4467 (4)	0.6336 (5)	0.3096 (5)	2.97
N1	0.5081 (3)	0.7832 (4)	0.4925 (5)	3.29
N2	0.3968 (3)	0.6356 (5)	0.5419 (4)	3.32
C1	0.4491 (4)	0.6856 (5)	0.4473 (5)	2.46
H1	0.2973 (7)	0.0082 (12)	0.3895 (10)	3.06
H11	0.5538 (8)	0.8112 (11)	0.4207 (13)	3.84
H12	0.5101 (9)	0.8279 (16)	0.5952 (16)	5.79
H21	0.3553 (8)	0.5560 (15)	0.5145 (12)	4.63
H22	0.4005 (9)	0.6814 (15)	0.6492 (12)	5.36
H3	0.2619 (9)	0.1941 (12)	0.0955 (9)	5.04
H4	0.4068 (8)	0.5072 (11)	0.2853 (10)	4.03

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.030 (6)	0.020 (3)	0.016 (3)	−0.007 (3)	−0.005 (3)	−0.002 (2)
O1	0.020 (7)	0.021 (3)	0.044 (4)	0.004 (3)	−0.001 (3)	0.004 (3)
O2	0.022 (6)	0.022 (3)	0.027 (3)	−0.002 (3)	0.005 (3)	−0.001 (2)
O3	0.010 (6)	0.036 (3)	0.033 (3)	0.004 (3)	0.000 (3)	−0.006 (3)
O4	0.034 (6)	0.025 (3)	0.028 (3)	−0.008 (3)	0.002 (3)	−0.005 (2)
O5	0.036 (6)	0.024 (3)	0.026 (3)	−0.008 (3)	0.004 (3)	0.002 (2)
N1	0.030 (5)	0.0288 (17)	0.036 (2)	−0.005 (2)	−0.006 (2)	−0.0035 (18)
N2	0.022 (5)	0.041 (2)	0.030 (2)	−0.008 (2)	0.005 (2)	−0.0056 (18)
C1	0.025 (5)	0.022 (2)	0.021 (2)	0.001 (2)	−0.003 (2)	−0.0012 (18)
H1	0.034 (12)	0.028 (5)	0.035 (5)	−0.005 (5)	−0.007 (6)	0.003 (4)
H11	0.018 (13)	0.037 (6)	0.067 (10)	−0.004 (5)	−0.009 (9)	−0.003 (6)
H12	0.020 (15)	0.072 (9)	0.079 (9)	−0.007 (7)	−0.004 (9)	−0.027 (7)
H21	0.022 (13)	0.058 (7)	0.071 (9)	−0.018 (7)	0.014 (9)	−0.025 (6)
H22	0.039 (14)	0.077 (8)	0.042 (7)	−0.011 (7)	0.005 (8)	−0.025 (6)
H3	0.064 (14)	0.037 (6)	0.032 (5)	0.002 (6)	−0.001 (7)	−0.001 (4)
H4	0.036 (14)	0.038 (6)	0.036 (5)	0.002 (5)	0.011 (6)	−0.003 (4)

Geometric parameters (Å, º)

P1—O1	1.560 (8)	O5—H4	1.195 (12)
P1—O2	1.507 (7)	N1—C1	1.329 (7)
P1—O3	1.558 (9)	N1—H11	1.051 (17)
P1—O4	1.477 (9)	N1—H12	0.979 (16)
O1—H1	1.003 (14)	N2—C1	1.306 (7)
O3—H3	1.032 (12)	N2—H21	0.972 (13)
O4—H4	1.240 (11)	N2—H22	1.022 (11)
O5—C1	1.294 (6)
O1—P1—O2	111.8 (4)	C1—N1—H11	121.2 (6)
O1—P1—O3	108.2 (4)	C1—N1—H12	120.2 (11)
O1—P1—O4	105.6 (5)	H11—N1—H12	118.6 (12)
O2—P1—O3	106.2 (5)	C1—N2—H21	122.6 (7)
O2—P1—O4	113.8 (4)	C1—N2—H22	118.1 (9)
O3—P1—O4	111.2 (4)	H21—N2—H22	119.4 (11)
P1—O1—H1	112.7 (7)	O5—C1—N1	118.7 (5)
P1—O3—H3	115.4 (10)	O5—C1—N2	120.7 (5)
P1—O4—H4	123.4 (7)	N1—C1—N2	120.5 (4)
C1—O5—H4	115.5 (6)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	1.003 (14)	1.668 (12)	2.669 (10)
O3—H3···O2^ii	1.032 (12)	1.563 (10)	2.593 (6)
O5—H4···O4	1.195 (12)	1.240 (11)	2.417 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(290K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.785 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.589 Å	Cell parameters from 25 reflections
b = 7.458 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.967 Å	T = 290 K
V = 1176.3 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	686 independent reflections
Radiation source: ISIS spallation source	686 reflections with > 3σ(I)
None monochromator	Rint = 0.071
time–of–flight LAUE diffraction scans	h = 0→30
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→14
2010 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.097	(Δ/σ)max = 0.004
wR(F^2) = 0.159	Δρmax = 1.22 e Å^−3
S = 1.22	Δρmin = −1.18 e Å^−3
686 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.148 _diffrn_reflns_sin(theta)/lambda_max 0.60

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3115 (3)	0.2803 (5)	0.3094 (4)	2.31
O1	0.3397 (4)	0.0906 (7)	0.3622 (6)	3.24
O2	0.2776 (3)	0.3845 (5)	0.4373 (4)	2.38
O3	0.2467 (3)	0.2509 (6)	0.1942 (5)	3.11
O4	0.3789 (3)	0.3669 (5)	0.2392 (4)	3.07
O5	0.4470 (3)	0.6328 (5)	0.3102 (4)	3.08
N1	0.5079 (3)	0.7831 (4)	0.4918 (4)	3.48
N2	0.3968 (2)	0.6355 (4)	0.5419 (3)	3.40
C1	0.4496 (3)	0.6847 (4)	0.4477 (4)	2.23
H1	0.2992 (7)	0.0110 (11)	0.3899 (9)	3.98
H11	0.5509 (8)	0.8113 (10)	0.4206 (11)	4.65
H12	0.5105 (7)	0.8254 (12)	0.5965 (10)	5.43
H21	0.3529 (8)	0.5583 (13)	0.5138 (11)	5.72
H22	0.3953 (8)	0.6751 (13)	0.6450 (9)	6.70
H3	0.2609 (6)	0.1955 (10)	0.0928 (8)	4.34
H4	0.4084 (7)	0.5082 (11)	0.2816 (9)	4.57

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.029 (5)	0.021 (2)	0.0183 (19)	−0.007 (2)	−0.002 (2)	−0.0030 (19)
O1	0.020 (5)	0.032 (3)	0.046 (3)	0.006 (2)	−0.002 (3)	−0.004 (2)
O2	0.024 (4)	0.026 (2)	0.0211 (19)	−0.005 (2)	0.006 (2)	−0.0027 (16)
O3	0.030 (5)	0.040 (3)	0.0251 (19)	−0.001 (2)	−0.009 (2)	−0.005 (2)
O4	0.031 (5)	0.034 (3)	0.028 (2)	−0.006 (2)	0.005 (2)	−0.0032 (18)
O5	0.042 (5)	0.029 (2)	0.0212 (19)	−0.012 (2)	0.006 (2)	−0.0015 (18)
N1	0.032 (4)	0.0351 (14)	0.0374 (16)	−0.0086 (16)	−0.0020 (17)	−0.0092 (14)
N2	0.024 (4)	0.0443 (18)	0.0331 (16)	−0.0100 (16)	0.0065 (15)	−0.0069 (15)
C1	0.016 (4)	0.0257 (16)	0.0247 (17)	0.0013 (17)	0.0031 (17)	−0.0005 (14)
H1	0.046 (11)	0.032 (4)	0.046 (5)	0.018 (4)	−0.007 (5)	−0.002 (4)
H11	0.052 (11)	0.037 (4)	0.052 (6)	−0.010 (4)	0.001 (5)	−0.008 (4)
H12	0.055 (11)	0.058 (5)	0.045 (5)	−0.003 (5)	−0.002 (5)	−0.012 (4)
H21	0.054 (13)	0.058 (5)	0.069 (7)	−0.019 (6)	0.011 (6)	−0.030 (5)
H22	0.082 (14)	0.083 (7)	0.036 (5)	−0.018 (7)	0.001 (5)	−0.021 (5)
H3	0.051 (10)	0.043 (4)	0.037 (4)	−0.001 (4)	0.010 (4)	−0.000 (3)
H4	0.037 (10)	0.051 (5)	0.048 (5)	0.002 (4)	0.014 (4)	−0.006 (4)

Geometric parameters (Å, º)

P1—O1	1.572 (7)	O5—H4	1.179 (11)
P1—O2	1.509 (6)	N1—C1	1.321 (6)
P1—O3	1.553 (7)	N1—H11	1.012 (15)
P1—O4	1.490 (7)	N1—H12	0.992 (11)
O1—H1	0.960 (16)	N2—C1	1.308 (5)
O3—H3	1.030 (10)	N2—H21	0.996 (14)
O4—H4	1.235 (10)	N2—H22	0.971 (9)
O5—C1	1.293 (5)
O1—P1—O2	111.1 (3)	C1—N1—H11	120.4 (5)
O1—P1—O3	107.8 (3)	C1—N1—H12	119.8 (8)
O1—P1—O4	105.4 (5)	H11—N1—H12	119.7 (10)
O2—P1—O3	106.8 (5)	C1—N2—H21	123.3 (6)
O2—P1—O4	114.3 (3)	C1—N2—H22	123.4 (9)
O3—P1—O4	111.3 (4)	H21—N2—H22	113.3 (10)
P1—O1—H1	113.6 (6)	O5—C1—N1	118.6 (4)
P1—O3—H3	117.7 (8)	O5—C1—N2	120.4 (4)
P1—O4—H4	125.1 (6)	N1—C1—N2	120.9 (4)
C1—O5—H4	117.6 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.960 (16)	1.702 (13)	2.659 (8)
O3—H3···O2^ii	1.030 (10)	1.545 (8)	2.573 (5)
O5—H4···O4	1.179 (11)	1.235 (10)	2.403 (6)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(295K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.784 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.595 Å	Cell parameters from 25 reflections
b = 7.460 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.968 Å	T = 295 K
V = 1177.1 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	677 independent reflections
Radiation source: ISIS spallation source	677 reflections with > 3σ(I)
None monochromator	Rint = 0.074
time–of–flight LAUE diffraction scans	h = 0→27
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→14
1928 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.094	(Δ/σ)max < 0.001
wR(F^2) = 0.163	Δρmax = 1.05 e Å^−3
S = 1.25	Δρmin = −1.09 e Å^−3
677 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.59

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.59

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3114 (3)	0.2796 (5)	0.3093 (5)	2.16
O1	0.3399 (4)	0.0915 (7)	0.3606 (6)	3.47
O2	0.2772 (3)	0.3842 (5)	0.4363 (4)	2.48
O3	0.2465 (4)	0.2506 (7)	0.1943 (5)	3.17
O4	0.3786 (3)	0.3666 (5)	0.2380 (5)	2.95
O5	0.4471 (4)	0.6342 (5)	0.3104 (5)	3.08
N1	0.5082 (3)	0.7829 (4)	0.4914 (4)	3.35
N2	0.3969 (3)	0.6369 (4)	0.5419 (3)	3.42
C1	0.4493 (3)	0.6847 (4)	0.4476 (4)	2.19
H1	0.2991 (6)	0.0090 (11)	0.3943 (9)	3.70
H11	0.5522 (8)	0.8140 (10)	0.4188 (11)	4.85
H12	0.5111 (8)	0.8250 (13)	0.5981 (11)	5.74
H21	0.3542 (9)	0.5604 (14)	0.5163 (12)	6.24
H22	0.3966 (8)	0.6731 (12)	0.6443 (10)	6.35
H3	0.2616 (7)	0.1980 (11)	0.0941 (9)	4.46
H4	0.4085 (7)	0.5094 (11)	0.2819 (9)	4.71

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.027 (5)	0.019 (2)	0.017 (2)	−0.005 (2)	0.001 (2)	−0.003 (2)
O1	0.031 (6)	0.031 (3)	0.043 (3)	0.005 (3)	−0.004 (3)	0.001 (2)
O2	0.033 (5)	0.023 (2)	0.020 (2)	−0.002 (2)	0.004 (2)	0.0000 (18)
O3	0.020 (5)	0.046 (3)	0.029 (2)	0.004 (2)	−0.007 (2)	−0.008 (2)
O4	0.023 (5)	0.032 (3)	0.030 (2)	−0.003 (2)	0.008 (2)	−0.0041 (19)
O5	0.038 (5)	0.031 (2)	0.025 (2)	−0.012 (2)	0.001 (2)	0.000 (2)
N1	0.030 (4)	0.0356 (15)	0.0349 (17)	−0.0093 (16)	0.0009 (17)	−0.0089 (14)
N2	0.026 (3)	0.0443 (19)	0.0322 (15)	−0.0082 (17)	0.0082 (16)	−0.0036 (16)
C1	0.019 (4)	0.0253 (17)	0.0216 (18)	0.0033 (17)	−0.0003 (17)	0.0002 (15)
H1	0.034 (11)	0.034 (4)	0.045 (5)	0.002 (4)	0.001 (4)	0.004 (4)
H11	0.050 (11)	0.040 (4)	0.050 (6)	−0.012 (5)	−0.005 (5)	−0.004 (4)
H12	0.066 (13)	0.062 (6)	0.045 (5)	−0.011 (6)	−0.003 (5)	−0.008 (4)
H21	0.052 (14)	0.053 (5)	0.083 (8)	−0.023 (6)	−0.003 (6)	−0.027 (5)
H22	0.079 (13)	0.066 (6)	0.038 (5)	−0.024 (6)	−0.006 (6)	−0.014 (5)
H3	0.058 (11)	0.042 (5)	0.038 (5)	−0.001 (5)	0.003 (5)	−0.001 (4)
H4	0.047 (11)	0.051 (5)	0.040 (5)	−0.007 (5)	0.012 (4)	−0.005 (4)

Geometric parameters (Å, º)

P1—O1	1.560 (6)	O5—H4	1.180 (11)
P1—O2	1.506 (6)	N1—C1	1.328 (6)
P1—O3	1.554 (8)	N1—H11	1.038 (15)
P1—O4	1.493 (7)	N1—H12	1.009 (11)
O1—H1	0.994 (14)	N2—C1	1.301 (6)
O3—H3	1.016 (11)	N2—H21	0.971 (14)
O4—H4	1.252 (10)	N2—H22	0.958 (10)
O5—C1	1.287 (5)
O1—P1—O2	111.8 (4)	C1—N1—H11	121.4 (6)
O1—P1—O3	107.9 (4)	C1—N1—H12	119.4 (9)
O1—P1—O4	105.2 (5)	H11—N1—H12	119.2 (10)
O2—P1—O3	106.3 (5)	C1—N2—H21	123.8 (7)
O2—P1—O4	114.5 (3)	C1—N2—H22	123.3 (9)
O3—P1—O4	111.0 (4)	H21—N2—H22	112.8 (10)
P1—O1—H1	114.4 (7)	O5—C1—N1	117.9 (4)
P1—O3—H3	116.7 (9)	O5—C1—N2	121.2 (4)
P1—O4—H4	124.6 (6)	N1—C1—N2	120.8 (4)
C1—O5—H4	117.1 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.994 (14)	1.677 (12)	2.665 (9)
O3—H3···O2^ii	1.016 (11)	1.566 (9)	2.580 (6)
O5—H4···O4	1.180 (11)	1.252 (10)	2.420 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(300K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.783 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.601 Å	Cell parameters from 25 reflections
b = 7.461 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.968 Å	T = 300 K
V = 1177.7 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	649 independent reflections
Radiation source: ISIS spallation source	649 reflections with > 3σ(I)
None monochromator	Rint = 0.064
time–of–flight LAUE diffraction scans	h = 0→23
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→14
Tmin = 0.36, Tmax = 0.78	l = 0^→12
1858 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.090	(Δ/σ)max < 0.001
wR(F^2) = 0.154	Δρmax = 0.88 e Å^−3
S = 1.21	Δρmin = −0.96 e Å^−3
649 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.148 _diffrn_reflns_sin(theta)/lambda_max 0.57

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3119 (3)	0.2799 (5)	0.3104 (4)	2.20
O1	0.3393 (4)	0.0913 (7)	0.3611 (6)	3.49
O2	0.2775 (3)	0.3846 (5)	0.4380 (4)	2.73
O3	0.2466 (3)	0.2505 (7)	0.1936 (5)	3.43
O4	0.3785 (3)	0.3661 (5)	0.2386 (5)	3.20
O5	0.4471 (3)	0.6338 (5)	0.3110 (5)	3.10
N1	0.5070 (3)	0.7839 (4)	0.4917 (4)	3.51
N2	0.3966 (3)	0.6378 (5)	0.5418 (4)	3.72
C1	0.4489 (3)	0.6846 (4)	0.4478 (4)	2.48
H1	0.2987 (6)	0.0104 (10)	0.3901 (8)	3.68
H11	0.5501 (8)	0.8115 (10)	0.4185 (11)	5.11
H12	0.5113 (7)	0.8220 (12)	0.5970 (11)	5.40
H21	0.3540 (8)	0.5606 (14)	0.5129 (11)	5.68
H22	0.3951 (8)	0.6743 (13)	0.6428 (11)	6.81
H3	0.2599 (7)	0.1971 (10)	0.0928 (9)	4.37
H4	0.4089 (7)	0.5064 (11)	0.2819 (8)	4.42

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.030 (5)	0.020 (2)	0.0155 (17)	−0.005 (2)	−0.003 (2)	−0.0027 (19)
O1	0.026 (5)	0.032 (2)	0.046 (3)	0.004 (2)	−0.006 (3)	0.003 (2)
O2	0.036 (5)	0.025 (2)	0.021 (2)	−0.003 (2)	0.005 (2)	−0.0039 (17)
O3	0.029 (6)	0.046 (3)	0.029 (2)	−0.001 (2)	−0.007 (2)	−0.007 (2)
O4	0.030 (5)	0.034 (2)	0.033 (2)	−0.006 (3)	0.007 (2)	−0.0048 (19)
O5	0.040 (5)	0.029 (2)	0.0227 (19)	−0.012 (2)	0.007 (2)	0.000 (2)
N1	0.032 (4)	0.0347 (14)	0.0354 (16)	−0.0082 (16)	0.0012 (17)	−0.0078 (13)
N2	0.029 (4)	0.0469 (19)	0.0350 (16)	−0.0108 (17)	0.0071 (17)	−0.0055 (16)
C1	0.023 (4)	0.0261 (17)	0.0251 (19)	0.0016 (17)	0.0030 (18)	0.0013 (15)
H1	0.042 (10)	0.029 (4)	0.037 (4)	0.005 (4)	0.002 (4)	0.002 (3)
H11	0.051 (12)	0.044 (4)	0.056 (6)	−0.007 (5)	0.005 (5)	−0.003 (4)
H12	0.055 (12)	0.063 (6)	0.047 (5)	−0.004 (5)	−0.007 (5)	−0.007 (4)
H21	0.046 (12)	0.067 (6)	0.060 (6)	−0.023 (6)	0.003 (5)	−0.026 (5)
H22	0.080 (14)	0.077 (6)	0.044 (5)	−0.029 (6)	0.012 (6)	−0.021 (5)
H3	0.052 (10)	0.040 (4)	0.039 (5)	−0.007 (4)	0.000 (4)	0.000 (3)
H4	0.043 (10)	0.052 (5)	0.034 (4)	−0.004 (4)	0.013 (4)	−0.007 (4)

Geometric parameters (Å, º)

P1—O1	1.556 (7)	O5—H4	1.193 (11)
P1—O2	1.512 (6)	N1—C1	1.323 (6)
P1—O3	1.570 (7)	N1—H11	1.023 (14)
P1—O4	1.485 (7)	N1—H12	0.989 (12)
O1—H1	0.971 (14)	N2—C1	1.297 (6)
O3—H3	1.016 (10)	N2—H21	0.980 (15)
O4—H4	1.238 (10)	N2—H22	0.946 (11)
O5—C1	1.285 (5)
O1—P1—O2	111.7 (3)	C1—N1—H11	119.6 (6)
O1—P1—O3	107.2 (4)	C1—N1—H12	120.3 (9)
O1—P1—O4	105.8 (5)	H11—N1—H12	119.9 (10)
O2—P1—O3	106.5 (5)	C1—N2—H21	121.9 (7)
O2—P1—O4	114.9 (3)	C1—N2—H22	124.4 (9)
O3—P1—O4	110.5 (4)	H21—N2—H22	113.7 (10)
P1—O1—H1	114.4 (6)	O5—C1—N1	117.9 (4)
P1—O3—H3	118.7 (9)	O5—C1—N2	121.6 (5)
P1—O4—H4	124.8 (5)	N1—C1—N2	120.4 (4)
C1—O5—H4	117.2 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.971 (14)	1.693 (12)	2.661 (8)
O3—H3···O2^ii	1.016 (10)	1.547 (9)	2.562 (6)
O5—H4···O4	1.193 (11)	1.238 (10)	2.422 (6)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(305K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.782 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.608 Å	Cell parameters from 25 reflections
b = 7.462 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.970 Å	T = 305 K
V = 1178.4 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	645 independent reflections
Radiation source: ISIS spallation source	645 reflections with > 3σ(I)
None monochromator	Rint = 0.066
time–of–flight LAUE diffraction scans	h = 0→23
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→14
1817 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.099	(Δ/σ)max < 0.001
wR(F^2) = 0.165	Δρmax = 1.19 e Å^−3
S = 1.29	Δρmin = −1.07 e Å^−3
645 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.57

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3122 (4)	0.2806 (5)	0.3101 (5)	2.12
O1	0.3397 (5)	0.0898 (8)	0.3612 (6)	3.60
O2	0.2770 (3)	0.3848 (5)	0.4372 (4)	2.74
O3	0.2470 (3)	0.2506 (7)	0.1940 (5)	3.22
O4	0.3785 (4)	0.3659 (6)	0.2391 (5)	3.00
O5	0.4469 (4)	0.6340 (5)	0.3110 (5)	3.11
N1	0.5083 (3)	0.7824 (4)	0.4908 (4)	3.41
N2	0.3963 (3)	0.6386 (5)	0.5415 (4)	3.69
C1	0.4493 (3)	0.6855 (4)	0.4485 (4)	2.39
H1	0.2994 (7)	0.0106 (12)	0.3918 (10)	3.88
H11	0.5512 (9)	0.8112 (12)	0.4241 (14)	5.36
H12	0.5088 (9)	0.8220 (14)	0.5968 (11)	6.53
H21	0.3528 (9)	0.5621 (15)	0.5126 (13)	7.13
H22	0.3971 (9)	0.6763 (14)	0.6430 (11)	7.17
H3	0.2618 (8)	0.1999 (11)	0.0909 (11)	4.92
H4	0.4090 (7)	0.5053 (10)	0.2818 (8)	4.19

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.024 (5)	0.021 (2)	0.017 (2)	−0.004 (2)	0.000 (2)	0.000 (2)
O1	0.032 (6)	0.032 (3)	0.042 (3)	0.011 (3)	−0.007 (3)	−0.004 (2)
O2	0.036 (5)	0.025 (2)	0.020 (2)	−0.003 (2)	0.005 (2)	−0.0047 (19)
O3	0.022 (5)	0.048 (3)	0.027 (2)	0.000 (2)	−0.006 (3)	−0.007 (2)
O4	0.028 (6)	0.031 (3)	0.033 (3)	−0.006 (3)	0.004 (2)	−0.004 (2)
O5	0.042 (5)	0.030 (2)	0.022 (2)	−0.011 (3)	0.004 (2)	−0.002 (2)
N1	0.031 (4)	0.0352 (16)	0.0362 (18)	−0.0068 (18)	0.0011 (19)	−0.0078 (15)
N2	0.026 (4)	0.048 (2)	0.0372 (17)	−0.0094 (18)	0.0077 (18)	−0.0039 (17)
C1	0.025 (4)	0.0244 (18)	0.0221 (19)	0.0017 (19)	0.0003 (19)	−0.0004 (16)
H1	0.038 (12)	0.034 (4)	0.045 (5)	0.012 (4)	−0.002 (5)	−0.002 (4)
H11	0.045 (13)	0.044 (5)	0.070 (8)	0.004 (5)	−0.005 (6)	−0.006 (5)
H12	0.091 (15)	0.065 (6)	0.043 (6)	−0.010 (6)	−0.006 (6)	−0.019 (5)
H21	0.064 (16)	0.064 (7)	0.081 (9)	−0.038 (7)	0.010 (7)	−0.035 (6)
H22	0.103 (16)	0.077 (7)	0.036 (5)	−0.027 (8)	0.004 (6)	−0.031 (5)
H3	0.051 (12)	0.042 (5)	0.052 (6)	−0.001 (5)	−0.006 (5)	−0.001 (4)
H4	0.048 (11)	0.045 (5)	0.032 (4)	−0.003 (5)	0.013 (4)	0.001 (4)

Geometric parameters (Å, º)

P1—O1	1.572 (7)	O5—H4	1.199 (11)
P1—O2	1.513 (6)	N1—C1	1.321 (7)
P1—O3	1.567 (8)	N1—H11	0.99 (2)
P1—O4	1.474 (8)	N1—H12	0.995 (12)
O1—H1	0.964 (17)	N2—C1	1.299 (6)
O3—H3	1.033 (13)	N2—H21	0.990 (15)
O4—H4	1.231 (10)	N2—H22	0.953 (11)
O5—C1	1.293 (5)
O1—P1—O2	111.8 (4)	C1—N1—H11	123.1 (7)
O1—P1—O3	106.8 (4)	C1—N1—H12	116.3 (10)
O1—P1—O4	105.9 (5)	H11—N1—H12	120.5 (12)
O2—P1—O3	105.9 (5)	C1—N2—H21	122.9 (7)
O2—P1—O4	115.3 (4)	C1—N2—H22	121.6 (10)
O3—P1—O4	110.8 (4)	H21—N2—H22	115.5 (12)
P1—O1—H1	114.3 (7)	O5—C1—N1	117.6 (5)
P1—O3—H3	117.6 (9)	O5—C1—N2	120.6 (5)
P1—O4—H4	125.1 (6)	N1—C1—N2	121.8 (4)
C1—O5—H4	117.7 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.964 (17)	1.690 (14)	2.651 (10)
O3—H3···O2^ii	1.033 (13)	1.540 (11)	2.570 (6)
O5—H4···O4	1.199 (11)	1.231 (10)	2.422 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(310K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.781 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.614 Å	Cell parameters from 25 reflections
b = 7.463 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.971 Å	T = 310 K
V = 1179.1 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	636 independent reflections
Radiation source: ISIS spallation source	636 reflections with > 3σ(I)
None monochromator	Rint = 0.066
time–of–flight LAUE diffraction scans	h = 0→26
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→11
1804 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.101	(Δ/σ)max < 0.001
wR(F^2) = 0.167	Δρmax = 1.14 e Å^−3
S = 1.23	Δρmin = −1.19 e Å^−3
636 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.59

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.55

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3126 (4)	0.2801 (5)	0.3091 (5)	2.01
O1	0.3397 (4)	0.0893 (7)	0.3602 (6)	3.35
O2	0.2771 (4)	0.3842 (5)	0.4375 (5)	2.77
O3	0.2466 (4)	0.2501 (7)	0.1942 (6)	3.31
O4	0.3784 (4)	0.3646 (6)	0.2399 (5)	3.13
O5	0.4472 (4)	0.6336 (5)	0.3111 (5)	3.04
N1	0.5080 (3)	0.7819 (5)	0.4905 (4)	3.51
N2	0.3970 (3)	0.6376 (5)	0.5414 (4)	3.85
C1	0.4491 (3)	0.6853 (5)	0.4486 (4)	2.23
H1	0.2988 (7)	0.0101 (12)	0.3931 (10)	4.03
H11	0.5511 (9)	0.8132 (12)	0.4217 (15)	5.77
H12	0.5102 (8)	0.8241 (14)	0.5970 (11)	6.27
H21	0.3540 (9)	0.5616 (15)	0.5131 (13)	6.65
H22	0.3957 (9)	0.6759 (14)	0.6457 (12)	7.03
H3	0.2614 (7)	0.1997 (12)	0.0921 (11)	4.86
H4	0.4085 (7)	0.5059 (11)	0.2822 (10)	4.46

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.020 (5)	0.021 (2)	0.018 (2)	−0.002 (2)	0.003 (2)	0.002 (2)
O1	0.027 (6)	0.030 (3)	0.041 (3)	0.004 (3)	−0.005 (3)	−0.001 (2)
O2	0.034 (5)	0.024 (2)	0.026 (3)	−0.002 (2)	0.001 (3)	−0.005 (2)
O3	0.022 (5)	0.047 (3)	0.032 (2)	0.002 (2)	−0.007 (3)	−0.007 (2)
O4	0.033 (6)	0.031 (3)	0.029 (3)	−0.004 (3)	0.004 (3)	−0.004 (2)
O5	0.039 (5)	0.028 (2)	0.026 (2)	−0.010 (2)	0.001 (2)	−0.002 (2)
N1	0.035 (4)	0.0363 (16)	0.0329 (18)	−0.0087 (18)	0.0005 (18)	−0.0095 (15)
N2	0.028 (4)	0.049 (2)	0.0386 (19)	−0.0101 (19)	0.0082 (19)	−0.0033 (18)
C1	0.018 (4)	0.0258 (19)	0.0232 (19)	0.0024 (18)	0.0006 (19)	0.0000 (16)
H1	0.052 (12)	0.033 (4)	0.032 (4)	0.013 (5)	−0.001 (5)	0.000 (4)
H11	0.049 (13)	0.048 (5)	0.071 (8)	−0.004 (6)	−0.006 (6)	−0.011 (6)
H12	0.091 (15)	0.068 (7)	0.034 (5)	−0.007 (7)	−0.005 (5)	−0.010 (5)
H21	0.072 (16)	0.055 (6)	0.073 (8)	−0.030 (7)	−0.001 (7)	−0.029 (5)
H22	0.099 (16)	0.074 (7)	0.036 (5)	−0.023 (7)	0.008 (6)	−0.032 (5)
H3	0.045 (12)	0.050 (6)	0.052 (6)	−0.001 (5)	−0.004 (5)	0.001 (5)
H4	0.036 (11)	0.048 (5)	0.046 (5)	−0.001 (5)	0.013 (4)	−0.003 (4)

Geometric parameters (Å, º)

P1—O1	1.570 (7)	O5—H4	1.201 (11)
P1—O2	1.524 (6)	N1—C1	1.319 (7)
P1—O3	1.569 (8)	N1—H11	1.01 (2)
P1—O4	1.459 (8)	N1—H12	1.007 (12)
O1—H1	0.977 (17)	N2—C1	1.289 (6)
O3—H3	1.024 (14)	N2—H21	0.980 (16)
O4—H4	1.239 (10)	N2—H22	0.979 (11)
O5—C1	1.293 (6)
O1—P1—O2	111.5 (4)	C1—N1—H11	123.1 (7)
O1—P1—O3	106.7 (4)	C1—N1—H12	118.1 (10)
O1—P1—O4	105.9 (5)	H11—N1—H12	118.8 (11)
O2—P1—O3	105.4 (5)	C1—N2—H21	122.9 (8)
O2—P1—O4	115.3 (4)	C1—N2—H22	123.6 (10)
O3—P1—O4	111.8 (4)	H21—N2—H22	113.5 (11)
P1—O1—H1	114.4 (7)	O5—C1—N1	117.1 (5)
P1—O3—H3	116.9 (10)	O5—C1—N2	121.1 (5)
P1—O4—H4	125.2 (6)	N1—C1—N2	121.8 (4)
C1—O5—H4	117.2 (6)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.977 (17)	1.682 (14)	2.656 (9)
O3—H3···O2^ii	1.024 (14)	1.546 (11)	2.568 (7)
O5—H4···O4	1.201 (11)	1.239 (10)	2.431 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(315K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.780 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.621 Å	Cell parameters from 25 reflections
b = 7.463 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.972 Å	T = 315 K
V = 1179.7 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	617 independent reflections
Radiation source: ISIS spallation source	617 reflections with > 3σ(I)
None monochromator	Rint = 0.069
time–of–flight LAUE diffraction scans	h = 0→22
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→11
Tmin = 0.36, Tmax = 0.78	l = 0^→11
1756 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.102	(Δ/σ)max < 0.001
wR(F^2) = 0.166	Δρmax = 1.03 e Å^−3
S = 1.27	Δρmin = −1.06 e Å^−3
617 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.55

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3120 (4)	0.2792 (5)	0.3100 (5)	2.42
O1	0.3407 (5)	0.0926 (7)	0.3596 (6)	3.86
O2	0.2779 (4)	0.3841 (5)	0.4370 (5)	2.74
O3	0.2471 (4)	0.2501 (7)	0.1939 (6)	3.30
O4	0.3783 (4)	0.3652 (6)	0.2393 (5)	3.10
O5	0.4473 (4)	0.6338 (5)	0.3117 (5)	3.20
N1	0.5082 (3)	0.7835 (5)	0.4917 (5)	3.84
N2	0.3962 (3)	0.6378 (5)	0.5405 (4)	3.87
C1	0.4497 (3)	0.6860 (5)	0.4477 (4)	2.50
H1	0.2987 (6)	0.0089 (11)	0.3934 (9)	3.82
H11	0.5520 (10)	0.8148 (12)	0.4211 (14)	5.94
H12	0.5082 (7)	0.8203 (14)	0.5968 (12)	5.23
H21	0.3540 (9)	0.5612 (15)	0.5138 (12)	6.12
H22	0.3947 (8)	0.6761 (13)	0.6452 (12)	6.46
H3	0.2615 (8)	0.1975 (12)	0.0905 (11)	5.65
H4	0.4083 (8)	0.5041 (11)	0.2802 (8)	4.95

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.034 (6)	0.025 (3)	0.012 (2)	−0.005 (3)	0.000 (2)	0.000 (2)
O1	0.041 (7)	0.031 (3)	0.044 (4)	0.007 (3)	−0.008 (3)	−0.000 (3)
O2	0.027 (5)	0.029 (2)	0.027 (2)	−0.000 (2)	0.004 (3)	−0.008 (2)
O3	0.022 (6)	0.048 (3)	0.029 (2)	0.004 (3)	−0.005 (3)	−0.011 (3)
O4	0.018 (6)	0.036 (3)	0.035 (3)	−0.007 (3)	0.003 (3)	−0.004 (2)
O5	0.037 (5)	0.030 (3)	0.028 (2)	−0.013 (3)	0.011 (3)	0.002 (2)
N1	0.038 (5)	0.0352 (16)	0.041 (2)	−0.0074 (19)	0.002 (2)	−0.0079 (17)
N2	0.033 (4)	0.050 (2)	0.0339 (18)	−0.012 (2)	0.0080 (19)	−0.0047 (18)
C1	0.022 (4)	0.0264 (19)	0.024 (2)	0.005 (2)	0.005 (2)	0.0045 (17)
H1	0.057 (12)	0.028 (4)	0.039 (5)	−0.003 (5)	0.006 (5)	0.006 (4)
H11	0.063 (14)	0.040 (5)	0.078 (9)	0.000 (6)	−0.003 (7)	0.000 (6)
H12	0.054 (13)	0.068 (7)	0.042 (6)	−0.005 (6)	−0.003 (5)	−0.010 (5)
H21	0.072 (17)	0.061 (6)	0.062 (8)	−0.023 (7)	−0.005 (6)	−0.021 (6)
H22	0.071 (14)	0.071 (6)	0.050 (6)	−0.019 (7)	−0.008 (6)	−0.022 (6)
H3	0.065 (13)	0.046 (6)	0.057 (7)	−0.001 (5)	−0.012 (6)	−0.001 (5)
H4	0.059 (12)	0.052 (5)	0.033 (4)	−0.007 (6)	0.014 (5)	0.000 (4)

Geometric parameters (Å, º)

P1—O1	1.547 (7)	O5—H4	1.221 (11)
P1—O2	1.507 (6)	N1—C1	1.323 (7)
P1—O3	1.562 (8)	N1—H11	1.03 (2)
P1—O4	1.477 (8)	N1—H12	0.982 (14)
O1—H1	1.014 (15)	N2—C1	1.307 (6)
O3—H3	1.038 (13)	N2—H21	0.969 (16)
O4—H4	1.219 (11)	N2—H22	0.982 (12)
O5—C1	1.282 (6)
O1—P1—O2	112.4 (4)	C1—N1—H11	121.8 (7)
O1—P1—O3	107.8 (4)	C1—N1—H12	116.1 (9)
O1—P1—O4	104.8 (5)	H11—N1—H12	122.0 (11)
O2—P1—O3	106.5 (5)	C1—N2—H21	124.0 (7)
O2—P1—O4	114.4 (4)	C1—N2—H22	123.3 (10)
O3—P1—O4	110.7 (4)	H21—N2—H22	112.7 (11)
P1—O1—H1	113.7 (7)	O5—C1—N1	118.4 (5)
P1—O3—H3	118.0 (10)	O5—C1—N2	120.0 (5)
P1—O4—H4	125.7 (6)	N1—C1—N2	121.5 (4)
C1—O5—H4	118.6 (5)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	1.014 (15)	1.686 (12)	2.696 (9)
O3—H3···O2^ii	1.038 (13)	1.534 (11)	2.571 (7)
O5—H4···O4	1.221 (11)	1.219 (11)	2.433 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(320K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.778 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.629 Å	Cell parameters from 25 reflections
b = 7.465 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.974 Å	T = 320 K
V = 1180.9 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	594 independent reflections
Radiation source: ISIS spallation source	594 reflections with > 3σ(I)
None monochromator	Rint = 0.070
time–of–flight LAUE diffraction scans	h = 0→19
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→12
Tmin = 0.36, Tmax = 0.78	l = 0^→11
1694 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.103	(Δ/σ)max < 0.001
wR(F^2) = 0.161	Δρmax = 0.97 e Å^−3
S = 1.28	Δρmin = −0.97 e Å^−3
594 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.59

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.54

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3127 (4)	0.2799 (5)	0.3096 (5)	2.45
O1	0.3405 (5)	0.0927 (8)	0.3604 (7)	4.23
O2	0.2779 (4)	0.3841 (5)	0.4378 (5)	3.07
O3	0.2471 (4)	0.2510 (8)	0.1931 (6)	3.54
O4	0.3789 (4)	0.3650 (6)	0.2394 (5)	3.13
O5	0.4474 (4)	0.6327 (5)	0.3124 (5)	3.37
N1	0.5080 (3)	0.7836 (5)	0.4903 (5)	3.70
N2	0.3966 (3)	0.6393 (5)	0.5416 (4)	3.81
C1	0.4490 (3)	0.6855 (5)	0.4482 (5)	2.50
H1	0.2986 (7)	0.0076 (12)	0.3919 (9)	3.83
H11	0.5495 (11)	0.8109 (12)	0.4215 (15)	5.91
H12	0.5068 (8)	0.8236 (13)	0.5984 (11)	5.65
H21	0.3540 (9)	0.5610 (16)	0.5126 (12)	6.14
H22	0.3934 (10)	0.6756 (14)	0.6454 (13)	7.61
H3	0.2618 (8)	0.1990 (12)	0.0924 (13)	5.25
H4	0.4079 (8)	0.5054 (11)	0.2801 (9)	4.54

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.036 (6)	0.023 (3)	0.016 (2)	−0.007 (3)	−0.001 (3)	−0.003 (2)
O1	0.040 (8)	0.037 (3)	0.052 (4)	0.010 (3)	−0.008 (4)	0.002 (3)
O2	0.039 (6)	0.027 (3)	0.026 (3)	−0.003 (2)	0.010 (3)	−0.005 (2)
O3	0.021 (6)	0.051 (3)	0.035 (3)	0.001 (3)	−0.007 (3)	−0.007 (3)
O4	0.022 (6)	0.039 (3)	0.033 (3)	−0.005 (3)	0.002 (3)	−0.005 (2)
O5	0.045 (6)	0.031 (3)	0.025 (3)	−0.013 (3)	0.005 (3)	−0.003 (2)
N1	0.042 (4)	0.0344 (17)	0.0355 (19)	−0.007 (2)	−0.001 (2)	−0.0103 (15)
N2	0.030 (4)	0.048 (2)	0.0368 (19)	−0.0128 (19)	0.008 (2)	−0.0064 (18)
C1	0.022 (5)	0.0258 (19)	0.026 (2)	0.004 (2)	0.001 (2)	0.0010 (17)
H1	0.043 (11)	0.033 (4)	0.037 (5)	0.004 (5)	0.000 (5)	0.005 (4)
H11	0.071 (14)	0.041 (5)	0.064 (8)	0.001 (6)	−0.002 (7)	−0.001 (5)
H12	0.067 (13)	0.066 (6)	0.038 (5)	−0.010 (6)	−0.007 (5)	−0.011 (5)
H21	0.046 (15)	0.068 (7)	0.073 (8)	−0.035 (7)	−0.004 (7)	−0.021 (6)
H22	0.093 (17)	0.076 (7)	0.049 (6)	−0.015 (7)	0.001 (7)	−0.016 (6)
H3	0.043 (13)	0.043 (5)	0.068 (8)	−0.006 (5)	−0.008 (6)	0.005 (5)
H4	0.053 (11)	0.044 (5)	0.038 (5)	−0.002 (5)	0.019 (5)	−0.003 (4)

Geometric parameters (Å, º)

P1—O1	1.549 (7)	O5—H4	1.214 (12)
P1—O2	1.519 (7)	N1—C1	1.326 (7)
P1—O3	1.574 (9)	N1—H11	0.98 (2)
P1—O4	1.471 (8)	N1—H12	1.015 (12)
O1—H1	1.015 (17)	N2—C1	1.295 (7)
O3—H3	1.016 (16)	N2—H21	0.986 (15)
O4—H4	1.222 (11)	N2—H22	0.972 (13)
O5—C1	1.281 (6)
O1—P1—O2	111.5 (4)	C1—N1—H11	121.4 (8)
O1—P1—O3	107.7 (4)	C1—N1—H12	114.8 (10)
O1—P1—O4	105.4 (5)	H11—N1—H12	123.8 (12)
O2—P1—O3	106.0 (5)	C1—N2—H21	122.0 (8)
O2—P1—O4	115.1 (4)	C1—N2—H22	126.0 (11)
O3—P1—O4	111.0 (4)	H21—N2—H22	111.9 (12)
P1—O1—H1	114.6 (7)	O5—C1—N1	117.3 (5)
P1—O3—H3	117.1 (11)	O5—C1—N2	121.2 (5)
P1—O4—H4	125.0 (6)	N1—C1—N2	121.5 (4)
C1—O5—H4	118.8 (6)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	1.015 (17)	1.684 (13)	2.695 (10)
O3—H3···O2^ii	1.016 (16)	1.546 (13)	2.561 (7)
O5—H4···O4	1.214 (12)	1.222 (11)	2.425 (8)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(330K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.776 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.639 Å	Cell parameters from 25 reflections
b = 7.466 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.975 Å	T = 330 K
V = 1181.9 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	606 independent reflections
Radiation source: ISIS spallation source	606 reflections with > 3σ(I)
None monochromator	Rint = 0.075
time–of–flight LAUE diffraction scans	h = 0→22
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→13
Tmin = 0.36, Tmax = 0.78	l = 0^→12
1661 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.101	(Δ/σ)max < 0.001
wR(F^2) = 0.163	Δρmax = 0.92 e Å^−3
S = 1.29	Δρmin = −0.97 e Å^−3
606 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.60

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.54

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3117 (4)	0.2795 (5)	0.3091 (5)	2.54
O1	0.3393 (4)	0.0921 (8)	0.3605 (6)	3.76
O2	0.2783 (3)	0.3848 (5)	0.4361 (5)	2.67
O3	0.2479 (4)	0.2506 (7)	0.1923 (6)	3.52
O4	0.3790 (4)	0.3650 (7)	0.2403 (5)	3.73
O5	0.4471 (4)	0.6333 (5)	0.3100 (5)	3.56
N1	0.5072 (4)	0.7839 (5)	0.4915 (5)	4.21
N2	0.3964 (3)	0.6387 (5)	0.5417 (4)	4.17
C1	0.4495 (3)	0.6852 (5)	0.4470 (5)	3.00
H1	0.2977 (8)	0.0102 (13)	0.3911 (10)	4.92
H11	0.5514 (11)	0.8096 (13)	0.4211 (16)	6.54
H12	0.5103 (8)	0.8222 (14)	0.5986 (12)	5.97
H21	0.3536 (10)	0.5616 (17)	0.5142 (13)	6.58
H22	0.3955 (8)	0.6767 (14)	0.6442 (12)	6.70
H3	0.2616 (7)	0.1959 (11)	0.0940 (9)	4.73
H4	0.4079 (8)	0.5061 (13)	0.2789 (10)	6.03

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.037 (5)	0.023 (3)	0.0154 (19)	−0.008 (2)	0.000 (2)	0.001 (2)
O1	0.030 (6)	0.037 (3)	0.045 (3)	0.009 (3)	−0.010 (3)	0.001 (3)
O2	0.019 (5)	0.028 (2)	0.031 (2)	−0.004 (2)	0.004 (2)	−0.002 (2)
O3	0.019 (5)	0.051 (3)	0.034 (2)	0.002 (2)	−0.009 (3)	−0.004 (2)
O4	0.033 (6)	0.045 (3)	0.033 (3)	−0.009 (3)	0.007 (3)	−0.001 (2)
O5	0.051 (6)	0.029 (3)	0.028 (2)	−0.010 (3)	0.007 (3)	−0.002 (2)
N1	0.045 (4)	0.0413 (17)	0.0397 (19)	−0.010 (2)	−0.002 (2)	−0.0131 (17)
N2	0.035 (4)	0.051 (2)	0.0384 (18)	−0.007 (2)	0.006 (2)	−0.0064 (18)
C1	0.032 (5)	0.029 (2)	0.027 (2)	0.002 (2)	−0.001 (2)	−0.0008 (17)
H1	0.066 (13)	0.035 (5)	0.046 (5)	0.008 (5)	−0.004 (5)	−0.002 (4)
H11	0.073 (15)	0.047 (5)	0.078 (8)	−0.016 (6)	−0.011 (7)	−0.005 (6)
H12	0.048 (12)	0.075 (7)	0.056 (6)	0.000 (6)	−0.006 (5)	−0.026 (5)
H21	0.049 (15)	0.071 (7)	0.074 (8)	−0.024 (7)	0.008 (7)	−0.020 (6)
H22	0.069 (14)	0.080 (7)	0.050 (6)	−0.014 (7)	0.003 (6)	−0.020 (6)
H3	0.055 (11)	0.048 (5)	0.039 (5)	−0.007 (5)	0.000 (5)	−0.002 (4)
H4	0.079 (14)	0.053 (6)	0.044 (5)	−0.004 (6)	0.018 (5)	−0.007 (4)

Geometric parameters (Å, º)

P1—O1	1.552 (7)	O5—H4	1.208 (13)
P1—O2	1.505 (7)	N1—C1	1.317 (7)
P1—O3	1.552 (8)	N1—H11	1.02 (2)
P1—O4	1.482 (8)	N1—H12	1.004 (13)
O1—H1	0.994 (18)	N2—C1	1.312 (7)
O3—H3	1.002 (12)	N2—H21	0.982 (19)
O4—H4	1.221 (12)	N2—H22	0.963 (12)
O5—C1	1.290 (6)
O1—P1—O2	111.6 (4)	C1—N1—H11	120.4 (7)
O1—P1—O3	107.6 (4)	C1—N1—H12	119.4 (10)
O1—P1—O4	105.1 (5)	H11—N1—H12	119.8 (11)
O2—P1—O3	107.5 (5)	C1—N2—H21	122.9 (8)
O2—P1—O4	113.8 (4)	C1—N2—H22	123.6 (10)
O3—P1—O4	111.0 (4)	H21—N2—H22	113.6 (11)
P1—O1—H1	113.9 (7)	O5—C1—N1	118.8 (5)
P1—O3—H3	118.5 (10)	O5—C1—N2	120.9 (5)
P1—O4—H4	126.0 (7)	N1—C1—N2	120.2 (4)
C1—O5—H4	118.4 (6)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	0.994 (18)	1.685 (14)	2.676 (10)
O3—H3···O2^ii	1.002 (12)	1.567 (10)	2.568 (7)
O5—H4···O4	1.208 (13)	1.221 (12)	2.419 (8)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.

(335K) Urea-phosphoric acid 1:1 complex

Crystal data

CH7N2O5P	F(000) = 26.58
Mr = 158.0	Dx = 1.775 Mg m^−3
Orthorhombic, Pbca	Neutron radiation, λ = 0.5-5.0 Å
a = 17.648 Å	Cell parameters from 25 reflections
b = 7.467 Å	µ = 1.96, at 1 Angstrom mm^−1
c = 8.976 Å	T = 335 K
V = 1182.8 Å^3	Irregular prisms, colourless
Z = 8	3.0 × 2.5 × 1.5 mm

Data collection

SXD diffractometer	553 independent reflections
Radiation source: ISIS spallation source	553 reflections with > 3σ(I)
None monochromator	Rint = 0.084
time–of–flight LAUE diffraction scans	h = 0→21
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 1.00 + 0.96 * lambda [cm^-1]	k = 0^→13
Tmin = 0.36, Tmax = 0.78	l = 0^→11
1395 measured reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	Calculated w = 1/[σ^2(Fo^2)]
R[F^2 > 2σ(F^2)] = 0.101	(Δ/σ)max < 0.001
wR(F^2) = 0.163	Δρmax = 0.93 e Å^−3
S = 1.26	Δρmin = −0.92 e Å^−3
553 reflections	Extinction correction: Becker-Coppens Lorentzian model
145 parameters	Extinction coefficient: 8.410
0 restraints

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.23 _cell_measurement_sin(theta)/lambda_max 0.57

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

Refinement. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.140 _diffrn_reflns_sin(theta)/lambda_max 0.53

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P1	0.3124 (4)	0.2813 (7)	0.3082 (6)	2.40
O1	0.3392 (5)	0.0928 (10)	0.3599 (6)	3.64
O2	0.2783 (4)	0.3840 (6)	0.4381 (5)	3.38
O3	0.2460 (4)	0.2497 (8)	0.1922 (7)	3.48
O4	0.3788 (4)	0.3639 (8)	0.2402 (6)	4.02
O5	0.4458 (5)	0.6350 (7)	0.3112 (6)	4.29
N1	0.5080 (4)	0.7844 (6)	0.4923 (5)	4.22
N2	0.3956 (4)	0.6397 (6)	0.5407 (4)	4.23
C1	0.4498 (4)	0.6853 (6)	0.4479 (5)	3.26
H1	0.2976 (9)	0.0064 (15)	0.3897 (12)	5.03
H11	0.5548 (11)	0.8095 (16)	0.424 (2)	6.56
H12	0.5101 (9)	0.8197 (15)	0.5986 (12)	6.57
H21	0.3533 (10)	0.561 (2)	0.5149 (15)	6.91
H22	0.3992 (9)	0.6661 (14)	0.6500 (12)	6.87
H3	0.2619 (8)	0.2018 (15)	0.0945 (12)	4.94
H4	0.4077 (8)	0.5039 (13)	0.2831 (10)	4.66

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.020 (6)	0.032 (3)	0.019 (2)	−0.005 (3)	−0.002 (3)	−0.001 (2)
O1	0.027 (6)	0.040 (4)	0.042 (3)	0.011 (4)	−0.002 (3)	0.006 (3)
O2	0.036 (6)	0.028 (3)	0.037 (3)	0.007 (3)	−0.000 (3)	−0.001 (2)
O3	0.017 (6)	0.048 (4)	0.041 (3)	−0.007 (3)	−0.004 (3)	−0.006 (3)
O4	0.038 (7)	0.042 (4)	0.037 (3)	−0.012 (4)	0.008 (3)	−0.001 (3)
O5	0.062 (8)	0.032 (4)	0.035 (3)	−0.003 (4)	0.007 (3)	−0.001 (3)
N1	0.052 (5)	0.041 (2)	0.034 (2)	−0.004 (3)	−0.003 (2)	−0.0106 (18)
N2	0.036 (5)	0.048 (3)	0.040 (2)	−0.008 (3)	0.007 (2)	−0.008 (2)
C1	0.033 (6)	0.034 (3)	0.033 (3)	0.006 (3)	−0.001 (3)	0.0031 (19)
H1	0.060 (14)	0.032 (6)	0.058 (6)	0.003 (6)	−0.015 (6)	−0.002 (5)
H11	0.024 (14)	0.049 (7)	0.113 (12)	−0.010 (8)	−0.010 (8)	0.001 (7)
H12	0.088 (15)	0.075 (8)	0.035 (5)	−0.020 (8)	−0.013 (6)	−0.022 (5)
H21	0.056 (18)	0.082 (9)	0.078 (9)	−0.042 (10)	0.007 (8)	−0.011 (7)
H22	0.065 (15)	0.083 (9)	0.057 (7)	−0.020 (8)	0.007 (7)	−0.031 (6)
H3	0.031 (12)	0.066 (8)	0.056 (7)	0.005 (7)	−0.008 (6)	−0.002 (5)
H4	0.045 (13)	0.043 (6)	0.048 (6)	−0.003 (6)	0.005 (5)	−0.004 (4)

Geometric parameters (Å, º)

P1—O1	1.556 (9)	O5—H4	1.214 (15)
P1—O2	1.520 (8)	N1—C1	1.326 (9)
P1—O3	1.585 (9)	N1—H11	1.05 (2)
P1—O4	1.458 (9)	N1—H12	0.991 (12)
O1—H1	1.01 (2)	N2—C1	1.314 (8)
O3—H3	0.988 (16)	N2—H21	0.98 (2)
O4—H4	1.226 (13)	N2—H22	1.003 (12)
O5—C1	1.285 (7)
O1—P1—O2	110.3 (4)	C1—N1—H11	122.4 (8)
O1—P1—O3	106.6 (5)	C1—N1—H12	117.9 (11)
O1—P1—O4	105.3 (6)	H11—N1—H12	119.0 (13)
O2—P1—O3	106.7 (6)	C1—N2—H21	124.2 (9)
O2—P1—O4	115.2 (5)	C1—N2—H22	121.6 (12)
O3—P1—O4	112.5 (5)	H21—N2—H22	113.5 (12)
P1—O1—H1	115.8 (8)	O5—C1—N1	119.6 (6)
P1—O3—H3	115.2 (11)	O5—C1—N2	119.3 (6)
P1—O4—H4	124.3 (7)	N1—C1—N2	121.1 (5)
C1—O5—H4	117.7 (7)

Hydrogen-bond geometry (Å)

D—H···A	D—H	H···A	D···A
O1—H1···O2^i	1.01 (2)	1.679 (17)	2.687 (12)
O3—H3···O2^ii	0.988 (16)	1.570 (12)	2.554 (8)
O5—H4···O4	1.214 (15)	1.226 (13)	2.430 (9)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) x, −y+1/2, z−1/2.