Charge density distribution in aminomethylphosphonic acid

The experimental charge density distribution in aminomethylphosphonic acid has been determined from X-ray diffraction and its topological features have been analyzed. The results have shown that the P—O bonds are highly polarized, moreover the P—OH bond is weaker than the bonds to unprotonated O atoms. These facts have been confirmed by theoretical density functional theory (DFT) calculations, which have shown that the single, strongly polarized bonds within the phosphonate group are modified by hyperconjugation effects.

Computing details

Data collection: CrysAlis PRO, Oxford Diffraction Ltd., Version 1.171.33.32 (release 27-01-2009 CrysAlis171 .NET) (compiled Jan 27 2009,14:17:37) for pl1absn. Cell refinement: CrysAlis PRO, Oxford Diffraction Ltd., Version 1.171.33.32 (release 27-01-2009 CrysAlis171 .NET) (compiled Jan 27 2009,14:17:37) for pl1absn. Data reduction: CrysAlis PRO, Oxford Diffraction Ltd., Version 1.171.33.32 (release 27-01-2009 CrysAlis171 .NET) (compiled Jan 27 2009,14:17:37) for pl1absn. Program(s) used to solve structure: SHELXS97 (Sheldrick, 1990) for pl1absn. Program(s) used to refine structure: SHELXL97 (Sheldrick, 1997) for pl1absn; Volkov et al., (2006) for pl1rec1, pl1rec2. Molecular graphics: Volkov et al., (2006) for pl1rec1, pl1rec2. Software used to prepare material for publication: Volkov et al., (2006) for pl1rec1, pl1rec2.

aminomethylphosphonic acid (pl1absn)

Crystal data

CH6NO3P	Dx = 1.788 Mg m^−3
Mr = 111.04	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 36516 reflections
a = 8.977 (7) Å	θ = 4.4–75.8°
b = 9.186 (7) Å	µ = 0.53 mm^−1
c = 10.003 (7) Å	T = 85 K
V = 824.9 (11) Å^3	Triangular prism, colourless
Z = 8	0.38 × 0.30 × 0.21 mm
F(000) = 464

Data collection

Goniometer Xcalibur, detector: Onyx diffractometer	8630 independent reflections
Radiation source: fine-focus sealed tube	7006 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 8.1956 pixels mm^-1	θmax = 76.4°, θmin = 3.8°
ω and π scans	h = −23→24
Absorption correction: analytical CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.33.32 (release 27-01-2009 CrysAlis171 .NET) (compiled Jan 27 2009,14:17:37) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by R.C. Clark & J.S. Reid. (Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897)	k = −24→12
Tmin = 0.886, Tmax = 0.942	l = −26→27
80581 measured reflections

Refinement

Refinement on F^2	Primary atom site location: from literature
Least-squares matrix: full	Secondary atom site location: from literature
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: difference Fourier map
wR(F^2) = 0.046	All H-atom parameters refined
S = 2.00	w = 1/[σ^2(Fo^2) + (0.P)^2] where P = (Fo^2 + 2Fc^2)/3
8630 reflections	(Δ/σ)max = 0.005
79 parameters	Δρmax = 0.52 e Å^−3
0 restraints	Δρmin = −0.70 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
P	0.236403 (6)	0.628028 (6)	0.441060 (5)	0.00494 (1)
O1	0.19391 (2)	0.646334 (19)	0.584733 (16)	0.00862 (2)
O2	0.335313 (17)	0.498867 (17)	0.409145 (17)	0.00740 (2)
O3	0.316973 (19)	0.765242 (18)	0.381243 (18)	0.00857 (2)
C	0.06901 (2)	0.60750 (2)	0.34063 (2)	0.00746 (2)
N	0.10764 (2)	0.58701 (2)	0.196965 (18)	0.00746 (2)
H1	0.0115 (7)	0.5243 (7)	0.3684 (6)	0.0157 (15)*
H2	0.0038 (7)	0.6885 (7)	0.3427 (6)	0.0144 (14)*
H3	0.0253 (9)	0.5616 (8)	0.1537 (7)	0.0262 (18)*
H4	0.1742 (8)	0.5213 (8)	0.1856 (7)	0.0195 (16)*
H5	0.1419 (8)	0.6752 (7)	0.1610 (7)	0.0188 (16)*
H6	0.2614 (11)	0.8517 (8)	0.3936 (11)	0.041 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P	0.00562 (1)	0.00449 (1)	0.00471 (1)	0.00004 (1)	0.00003 (1)	−0.00006 (1)
O1	0.01103 (5)	0.00955 (5)	0.00529 (4)	0.00105 (4)	0.00075 (3)	−0.00069 (3)
O2	0.00742 (4)	0.00550 (4)	0.00927 (4)	0.00104 (3)	0.00071 (3)	−0.00028 (3)
O3	0.00886 (4)	0.00553 (4)	0.01131 (5)	−0.00089 (3)	0.00118 (4)	0.00112 (3)
C	0.00633 (5)	0.00940 (6)	0.00664 (5)	−0.00016 (4)	0.00008 (4)	−0.00008 (4)
N	0.00783 (4)	0.00849 (5)	0.00607 (4)	−0.00016 (3)	−0.00064 (3)	−0.00013 (3)

Geometric parameters (Å, º)

P—O1	1.4964 (10)	P—C	1.8173 (11)
P—O2	1.5159 (8)	C—N	1.4903 (10)
P—O3	1.5716 (9)
O1—P—O2	116.074 (12)	O2—P—C	106.66 (4)
O1—P—O3	113.13 (3)	O3—P—C	104.67 (3)
O2—P—O3	106.14 (5)	N—C—P	110.72 (4)
O1—P—C	109.38 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N—H3···O2^i	0.888 (8)	1.906 (8)	2.7854 (17)	170.0 (7)
N—H4···O1^ii	0.857 (7)	2.189 (7)	3.0048 (15)	159.1 (6)
N—H5···O1^iii	0.938 (7)	1.868 (7)	2.8036 (17)	175.2 (7)
O3—H6···O2^iv	0.946 (8)	1.614 (8)	2.5598 (15)	178.0 (11)

Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x+1/2, −y+1, z−1/2; (iii) x, −y+3/2, z−1/2; (iv) −x+1/2, y+1/2, z.

(pl1rec1)

Crystal data

a = Å	α = °
b = Å	β = °
c = Å	γ = °

Data collection

h = →	l = →
k = →

Refinement

Refinement on F	0 restraints
Least-squares matrix: full	w1 = 1/[s^2(Fo)]
R[F^2 > 2σ(F^2)] = 0.013	(Δ/σ)max < 0.001
wR(F^2) = 0.012	Δρmax = 0.31 e Å^−3
S = 1.36	Δρmin = −0.27 e Å^−3
4737 reflections	Extinction correction: Becker-Coppens type 1 Gaussian isotropic, Becker, P.J. & Coppens, P. (1974) Acta Cryst., A30, 129-153.
224 parameters	Extinction coefficient: 0.126 (6)

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

	x	y	z	Uiso*/Ueq
P	0.236397 (4)	0.628033 (4)	0.441050 (4)	0.005
O(1)	0.193913 (19)	0.646295 (19)	0.584765 (16)	0.008
O(2)	0.335345 (16)	0.498864 (17)	0.409113 (16)	0.007
O(3)	0.316956 (18)	0.765323 (18)	0.381207 (18)	0.008
N	0.107631 (18)	0.586992 (19)	0.196986 (16)	0.007
C	0.069003 (17)	0.60750 (2)	0.340601 (16)	0.007
H(1)	0.005206	0.514261	0.376153	0.029 (2)
H(2)	−0.000013	0.704107	0.35355	0.028 (2)
H(3)	0.014025	0.554375	0.145522	0.025 (3)
H(4)	0.18552	0.505988	0.183459	0.021 (2)
H(5)	0.148216	0.683376	0.159016	0.022 (2)
H(6)	0.26066	0.853539	0.390966	0.017 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P	0.005486 (13)	0.004291 (13)	0.004529 (13)	0.000051 (9)	0.000030 (9)	−0.000059 (9)
O(1)	0.01082 (5)	0.00943 (5)	0.00513 (4)	0.00108 (4)	0.00075 (4)	−0.00069 (3)
O(2)	0.00728 (4)	0.00538 (4)	0.00904 (4)	0.00102 (3)	0.00069 (3)	−0.00024 (3)
O(3)	0.00872 (5)	0.00539 (4)	0.01104 (5)	−0.00096 (4)	0.00115 (4)	0.00113 (4)
N	0.00765 (4)	0.00831 (5)	0.00597 (4)	−0.00024 (4)	−0.00061 (3)	−0.00011 (4)
C	0.00611 (4)	0.00934 (5)	0.00663 (5)	−0.00019 (4)	−0.00002 (3)	−0.00009 (4)

Geometric parameters (Å, º)

P—O(1)	1.4967 (2)	N—H(3)	1.0300 (2)
P—O(2)	1.5162 (1)	N—H(4)	1.0300 (2)
P—O(3)	1.5722 (2)	N—H(5)	1.0300 (2)
P—C	1.8175 (2)	C—H(1)	1.0900 (2)
O(3)—H(6)	0.9600 (2)	C—H(2)	1.0900 (2)
O(1)—P—O(2)	116.063 (9)	H(3)—N—H(4)	106.142 (15)
O(1)—P—O(3)	113.141 (10)	H(3)—N—H(5)	110.752 (15)
O(1)—P—C	109.387 (9)	H(4)—N—H(5)	109.417 (15)
O(2)—P—O(3)	106.144 (9)	P—C—H(1)	109.607 (12)
O(2)—P—C	106.660 (8)	P—C—H(2)	108.650 (12)
O(3)—P—C	104.658 (9)	H(1)—C—H(2)	107.597 (13)
P—O(3)—H(6)	113.344 (13)
O(1)—P—O(3)—H(6)	−55.175 (15)	O(2)—P—C—H(2)	−174.443 (14)
O(1)—P—C—H(1)	−58.024 (13)	O(3)—P—C—H(1)	−179.536 (14)
O(1)—P—C—H(2)	59.295 (12)	O(3)—P—C—H(2)	−62.217 (12)
O(2)—P—O(3)—H(6)	176.427 (17)	C—P—O(3)—H(6)	63.833 (14)
O(2)—P—C—H(1)	68.238 (13)

(pl1rec2)

Crystal data

a = Å	α = °
b = Å	β = °
c = Å	γ = °

Data collection

h = →	l = →
k = →

Refinement

Refinement on F	0 restraints
Least-squares matrix: full	w1 = 1/[s^2(Fo)]
R[F^2 > 2σ(F^2)] = 0.013	(Δ/σ)max = 0.034
wR(F^2) = 0.012	Δρmax = 0.29 e Å^−3
S = 1.34	Δρmin = −0.22 e Å^−3
4737 reflections	Extinction correction: Becker-Coppens type 1 Gaussian isotropic, Becker, P.J. & Coppens, P. (1974) Acta Cryst., A30, 129-153.
219 parameters	Extinction coefficient: 0.129 (6)

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

	x	y	z	Uiso*/Ueq
P	0.236396 (4)	0.628033 (4)	0.441050 (4)	0.005
O(1)	0.193911 (17)	0.646298 (17)	0.584738 (15)	0.008
O(2)	0.335332 (15)	0.498876 (15)	0.409118 (14)	0.007
O(3)	0.316986 (16)	0.765308 (16)	0.381217 (16)	0.008
N	0.107636 (17)	0.586997 (18)	0.196983 (15)	0.007
C	0.069014 (17)	0.607508 (19)	0.340616 (16)	0.007
H(1)	0.006356	0.513402	0.37588	0.027 (3)
H(2)	0.001208	0.705313	0.35081	0.030 (3)
H(3)	0.013746	0.553524	0.146406	0.025 (3)
H(4)	0.185418	0.505653	0.184736	0.022 (2)
H(5)	0.146001	0.683544	0.157533	0.022 (3)
H(6)	0.26184	0.854128	0.391624	0.021 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P	0.005476 (13)	0.004277 (13)	0.004519 (13)	0.000044 (9)	0.000025 (9)	−0.000055 (9)
O(1)	0.01081 (4)	0.00937 (4)	0.00513 (4)	0.00107 (3)	0.00075 (3)	−0.00067 (3)
O(2)	0.00726 (4)	0.00533 (4)	0.00904 (4)	0.00102 (3)	0.00069 (3)	−0.00024 (3)
O(3)	0.00870 (4)	0.00531 (4)	0.01109 (5)	−0.00097 (3)	0.00117 (3)	0.00116 (3)
N	0.00763 (4)	0.00827 (5)	0.00594 (4)	−0.00023 (3)	−0.00061 (3)	−0.00012 (3)
C	0.00612 (4)	0.00930 (5)	0.00659 (5)	−0.00019 (3)	0.00001 (3)	−0.00009 (3)

Geometric parameters (Å, º)

P—O(1)	1.4965 (1)	N—H(3)	1.0300 (1)
P—O(2)	1.5161 (1)	N—H(4)	1.0300 (2)
P—O(3)	1.5722 (1)	N—H(5)	1.0300 (2)
P—C	1.8173 (2)	C—H(1)	1.0900 (2)
O(3)—H(6)	0.9600 (1)	C—H(2)	1.0900 (2)
O(1)—P—O(2)	116.065 (8)	H(3)—N—H(4)	106.245 (14)
O(1)—P—O(3)	113.140 (9)	H(3)—N—H(5)	110.028 (14)
O(1)—P—C	109.382 (8)	H(4)—N—H(5)	110.635 (14)
O(2)—P—O(3)	106.135 (8)	P—C—H(1)	109.272 (11)
O(2)—P—C	106.661 (8)	P—C—H(2)	108.935 (11)
O(3)—P—C	104.669 (8)	H(1)—C—H(2)	109.588 (13)
P—O(3)—H(6)	113.773 (12)
O(1)—P—O(3)—H(6)	−54.450 (13)	O(2)—P—C—H(2)	−172.714 (13)
O(1)—P—C—H(1)	−58.674 (12)	O(3)—P—C—H(1)	179.811 (13)
O(1)—P—C—H(2)	61.023 (12)	O(3)—P—C—H(2)	−60.492 (12)
O(2)—P—O(3)—H(6)	177.156 (15)	C—P—O(3)—H(6)	64.558 (13)
O(2)—P—C—H(1)	67.589 (12)