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Two polymorphs of bis(2-carbamoylguanidinium) fluorophosphonate dihydrate, 2C
2H
7N
4O
+·FO
3P
2-·2H
2O, are presented. Polymorph (I), crystallizing in the space group
Pnma, is slightly less densely packed than polymorph (II), which crystallizes in
Pbca. In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered over two positions, in contrast with its H atoms. The hydrogen-bond patterns in both polymorphs share similar features. There are O-H
O and N-H
O hydrogen bonds in both structures. The water molecules donate their H atoms to the O atoms of the fluorophosphonates exclusively. The water molecules and the fluorophosphonates participate in the formation of
R44(10) graph-set motifs. These motifs extend along the
a axis in each structure. The water molecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N-H
O hydrogen bonds. The water molecules are significant building elements in the formation of a three-dimensional hydrogen-bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen-bond networks of (I) and (II). The N-H
O and O-H
O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N-H
O hydrogen bonds are shorter than the shortest O-H
O hydrogen bonds, which is an unusual feature. The properties of the hydrogen-bond network in (II) can be related to an unusually long P-O bond length for an unhydrogenated fluorophosphonate anion that is present in this structure. In both structures, the N-H
F interactions are far weaker than the N-H
O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).
Supporting information
CCDC references: 867021; 867022
The title compounds were prepared by neutralization of stoichiometric amounts
of solutions of guanylurea hydroxide and H2PO3F. Guanylurea hydroxide was
prepared from hydrochloride hemihydrate (1.18 g) by an exchange reaction on
Anex. This solution was then concentrated using a vacuum rotatory evaporator.
Guanylurea chloride hemihydrate was prepared by acid hydrolysis of
cyanoguanidine. A dilute aqueous solution (100 ml of water to every 0.1 mol of
cyanoguanidine) of equimolar ratios of cyanoguanidine (99%, Sigma–Aldrich)
and hydrochloric acid (p.a., Lachema) was gradually heated. After about 45 min, when the reaction mixture started boiling, the originally colourless
mixture suddenly became grey and cloudy for a while and then an exothermic
process occurred. This reaction was accompanied by very intense boiling of the
reaction mixture. The heating was immediately interrupted and the reaction
mixture placed on a cold magnetic stirrer while it was still boiling due to
the exothermic reaction, and the mixture was stirred for another 15 min.
The liquid, which in the meantime had turned colourless again, was heated at
boiling point for 2 h. The excess water was then evaporated under vacuum and a
white crystalline product was filtered off. This was purified by
recrystallization from water and characterized by powder X-ray diffraction.
The powder diffraction pattern was found to be identical to the structure with
CSD refcode JODZOR (Scoponi et al., 1991). The IR spectrum was
also
recorded, in order to exclude the possibility of contamination of the product
by cyanoguanidine. The IR spectrum was in accordance with that obtained by
Scoponi et al. (1991), whereas the intense doublet of the CN-
group
typical for cyanoguanidine was absent.
A solution of H2PO3F was prepared from a solution of (NH4)2PO3F.H2O
passed through a column of Catex. (NH4)2PO3F.H2O was prepared
according to the method described by Schülke & Kayser (1991) and the
raw
material of (NH4)2PO3F.H2O prepared by this method was recrystallized
in order to remove (NH4)H2PO4 contamination. The volume of the eluted
solution of H2PO3F was about 50 ml for the cases of (I) and (II). The
solutions were placed in an evacuated desiccator over P4O10. Crystals
appeared within about 10 d. The crystals of (I) and (II) were placed in
special glass capillaries because they seemed to be hygroscopic.
The synthesis used 0.59 g (NH4)2PO3F.H2O and 0.936 g of guanylurea
hydroxide. Each polymorph was prepared in a different batch.
All H atoms were discernible in difference electron-density maps for both
structures. The applied constraints and restraints were as similar as possible
for the refinement of each structure. The N—H distances for primary and
secondary amine H atoms were constrained to 0.86 and 0.89 Å, respectively,
with Uiso(H) = 1.2Ueq(N). The water O—H distances were
restrained to 0.820 (1) Å, and the interatomic angles in the water molecules
were restrained to 107.90 (1)° (this value was retrieved from the CSD), with
Uiso(H) = 1.5Ueq(O). Additionally, in the case of (I) the
displacement parameters of the disordered water O atoms OW and
OW' were constrained to be equal; these water O atoms were refined
anisotropically.
For both compounds, data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: PLATON (Spek, 2009) and DIAMOND (Brandenburg, 2010); software used to prepare material for publication: JANA2006 (Petříček et al., 2006).
(I) Bis(2-carbamoylguanidinium) fluorophosphonate
top
Crystal data top
2(C2H7N4O+)·FO3P2−·2H2O | F(000) = 712 |
Mr = 340.2 | Dx = 1.574 Mg m−3 |
Orthorhombic, Pnma | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2ac 2n | Cell parameters from 12987 reflections |
a = 12.2788 (1) Å | θ = 3.6–66.9° |
b = 17.4866 (2) Å | µ = 2.30 mm−1 |
c = 6.6851 (1) Å | T = 120 K |
V = 1435.39 (3) Å3 | Block, colourless |
Z = 4 | 0.51 × 0.34 × 0.24 mm |
Data collection top
Oxford Xcalibur Gemini Ultra diffractometer | 1326 independent reflections |
Radiation source: Enhance Ultra (Cu) X-ray Source | 1219 reflections with I > 3σ(I) |
Mirror monochromator | Rint = 0.050 |
Detector resolution: 10.3784 pixels mm-1 | θmax = 67.1°, θmin = 5.1° |
ω scans | h = −14→14 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | k = −20→20 |
Tmin = 0.444, Tmax = 0.580 | l = −7→7 |
20298 measured reflections | |
Refinement top
Refinement on F2 | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.034 | Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0004I2] |
wR(F2) = 0.086 | (Δ/σ)max = 0.042 |
S = 2.93 | Δρmax = 0.31 e Å−3 |
1326 reflections | Δρmin = −0.36 e Å−3 |
110 parameters | Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974) |
5 restraints | Extinction coefficient: 2000 (300) |
36 constraints | |
Crystal data top
2(C2H7N4O+)·FO3P2−·2H2O | V = 1435.39 (3) Å3 |
Mr = 340.2 | Z = 4 |
Orthorhombic, Pnma | Cu Kα radiation |
a = 12.2788 (1) Å | µ = 2.30 mm−1 |
b = 17.4866 (2) Å | T = 120 K |
c = 6.6851 (1) Å | 0.51 × 0.34 × 0.24 mm |
Data collection top
Oxford Xcalibur Gemini Ultra diffractometer | 1326 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | 1219 reflections with I > 3σ(I) |
Tmin = 0.444, Tmax = 0.580 | Rint = 0.050 |
20298 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.034 | 5 restraints |
wR(F2) = 0.086 | H atoms treated by a mixture of independent and constrained refinement |
S = 2.93 | Δρmax = 0.31 e Å−3 |
1326 reflections | Δρmin = −0.36 e Å−3 |
110 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
P1 | 0.79564 (4) | 0.25 | 0.64167 (9) | 0.01375 (18) | |
F1 | 0.69594 (10) | 0.25 | 0.4892 (2) | 0.0242 (4) | |
O1 | 0.74310 (12) | 0.25 | 0.8461 (2) | 0.0184 (5) | |
O2 | 0.85611 (8) | 0.17715 (5) | 0.59359 (18) | 0.0186 (3) | |
O3 | 0.88034 (8) | 0.02675 (6) | 1.21935 (18) | 0.0203 (3) | |
C1 | 0.86096 (11) | 0.07693 (8) | 1.09535 (18) | 0.0165 (5) | |
N1 | 0.84118 (12) | 0.14962 (8) | 1.14404 (18) | 0.0236 (4) | |
H1N1 | 0.853384 | 0.165343 | 1.263852 | 0.0283* | |
H2N1 | 0.816224 | 0.180743 | 1.055605 | 0.0283* | |
N2 | 0.86000 (10) | 0.06207 (7) | 0.8909 (2) | 0.0165 (4) | |
H1N2 | 0.850937 | 0.101651 | 0.808841 | 0.0198* | |
C2 | 0.87185 (11) | −0.00828 (6) | 0.8065 (2) | 0.0162 (5) | |
N3 | 0.87779 (11) | −0.07068 (5) | 0.9178 (2) | 0.0197 (4) | |
H1N3 | 0.881549 | −0.114893 | 0.861882 | 0.0236* | |
H2N3 | 0.877899 | −0.067047 | 1.046109 | 0.0236* | |
N4 | 0.87500 (10) | −0.01219 (6) | 0.61146 (19) | 0.0200 (4) | |
H1N4 | 0.881167 | −0.05585 | 0.553335 | 0.024* | |
H2N4 | 0.870909 | 0.028901 | 0.541168 | 0.024* | |
OW | 0.5761 (2) | 0.14236 (16) | 0.8878 (5) | 0.0349 (8) | 0.5 |
OW' | 0.5734 (2) | 0.15990 (15) | 1.0159 (5) | 0.0349 (8) | 0.5 |
H1OW | 0.51922 (19) | 0.1500 (12) | 0.9490 (13) | 0.0523* | |
H2OW | 0.6235 (8) | 0.1691 (10) | 0.9383 (12) | 0.0523* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
P1 | 0.0175 (3) | 0.0113 (3) | 0.0124 (4) | 0 | −0.0002 (2) | 0 |
F1 | 0.0259 (6) | 0.0248 (6) | 0.0219 (9) | 0 | −0.0083 (5) | 0 |
O1 | 0.0218 (7) | 0.0182 (7) | 0.0152 (10) | 0 | 0.0030 (6) | 0 |
O2 | 0.0245 (5) | 0.0127 (5) | 0.0185 (7) | 0.0022 (4) | 0.0025 (4) | −0.0004 (4) |
O3 | 0.0259 (5) | 0.0215 (5) | 0.0134 (7) | 0.0031 (4) | −0.0003 (5) | 0.0032 (4) |
C1 | 0.0168 (7) | 0.0172 (7) | 0.0154 (10) | −0.0005 (5) | −0.0002 (6) | 0.0005 (6) |
N1 | 0.0386 (8) | 0.0177 (6) | 0.0145 (9) | 0.0040 (5) | −0.0027 (6) | −0.0020 (5) |
N2 | 0.0229 (6) | 0.0134 (6) | 0.0132 (8) | 0.0007 (4) | −0.0005 (5) | 0.0024 (5) |
C2 | 0.0134 (6) | 0.0188 (7) | 0.0164 (11) | −0.0004 (5) | 0.0004 (6) | 0.0003 (6) |
N3 | 0.0265 (6) | 0.0137 (6) | 0.0188 (9) | 0.0007 (4) | 0.0014 (6) | 0.0009 (5) |
N4 | 0.0237 (6) | 0.0205 (6) | 0.0160 (10) | 0.0005 (5) | 0.0005 (5) | −0.0015 (5) |
OW | 0.0208 (7) | 0.0273 (11) | 0.056 (2) | −0.0029 (7) | −0.0023 (13) | 0.0156 (12) |
OW' | 0.0208 (7) | 0.0273 (11) | 0.056 (2) | −0.0029 (7) | −0.0023 (13) | 0.0156 (12) |
Geometric parameters (Å, º) top
P1—F1 | 1.5931 (15) | C2—N3 | 1.3226 (16) |
P1—O1 | 1.5112 (17) | C2—N4 | 1.3065 (19) |
P1—O2 | 1.5092 (10) | N3—H1N3 | 0.86 |
P1—O2i | 1.5092 (10) | N3—H2N3 | 0.86 |
O3—C1 | 1.2303 (17) | N4—H1N4 | 0.86 |
C1—N1 | 1.3344 (19) | N4—H2N4 | 0.86 |
C1—N2 | 1.3915 (18) | OW—OW' | 0.910 (5) |
N1—H1N1 | 0.86 | OW—H1OW | 0.820 (6) |
N1—H2N1 | 0.86 | OW—H2OW | 0.820 (13) |
N2—H1N2 | 0.89 | OW'—H1OW | 0.821 (7) |
N2—C2 | 1.3611 (16) | OW'—H2OW | 0.821 (10) |
| | | |
F1—P1—O1 | 104.52 (8) | C1—N2—C2 | 125.08 (12) |
F1—P1—O2 | 103.99 (5) | H1N2—N2—C2 | 117.4581 |
F1—P1—O2i | 103.99 (5) | N2—C2—N3 | 121.24 (13) |
O1—P1—O2 | 113.74 (5) | N2—C2—N4 | 117.64 (11) |
O1—P1—O2i | 113.74 (5) | N3—C2—N4 | 121.11 (11) |
O2—P1—O2i | 115.16 (6) | C2—N3—H1N3 | 119.9998 |
O3—C1—N1 | 123.38 (12) | C2—N3—H2N3 | 119.9994 |
O3—C1—N2 | 122.03 (13) | H1N3—N3—H2N3 | 120.0009 |
N1—C1—N2 | 114.58 (12) | C2—N4—H1N4 | 119.9999 |
C1—N1—H1N1 | 120 | C2—N4—H2N4 | 120.0003 |
C1—N1—H2N1 | 120.0003 | H1N4—N4—H2N4 | 119.9998 |
H1N1—N1—H2N1 | 119.9997 | H1OW—OW—H2OW | 107.9 (13) |
C1—N2—H1N2 | 117.459 | H1OW—OW'—H2OW | 107.8 (9) |
Symmetry code: (i) x, −y+1/2, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O2ii | 0.86 | 2.21 | 3.0491 (17) | 164 |
N1—H2N1···O1 | 0.86 | 2.06 | 2.9152 (18) | 175 |
N2—H1N2···O2 | 0.89 | 1.95 | 2.8286 (17) | 167 |
N3—H1N3···F1iii | 0.86 | 2.69 | 3.2984 (10) | 129 |
N3—H1N3···OW′iv | 0.86 | 2.50 | 3.164 (4) | 134 |
N3—H2N3···O3 | 0.86 | 2.01 | 2.6395 (17) | 129 |
N3—H2N3···OWiii | 0.86 | 2.70 | 3.430 (4) | 144 |
N4—H1N4···OWiv | 0.86 | 1.95 | 2.789 (3) | 166 |
N4—H1N4···OW′iv | 0.86 | 1.92 | 2.735 (3) | 158 |
N4—H2N4···O2 | 0.86 | 2.62 | 3.3211 (14) | 139 |
N4—H2N4···O3v | 0.86 | 2.15 | 2.7091 (17) | 122 |
OW—H1OW···O2vi | 0.820 (6) | 2.078 (5) | 2.771 (3) | 142.1 (8) |
OW′—H1OW···O2vi | 0.821 (7) | 2.078 (5) | 2.783 (3) | 143.9 (15) |
OW—H2OW···O1 | 0.820 (13) | 2.130 (14) | 2.798 (3) | 138.6 (9) |
OW′—H2OW···O1 | 0.821 (10) | 2.130 (14) | 2.848 (3) | 146.1 (15) |
Symmetry codes: (ii) x, y, z+1; (iii) −x+3/2, −y, z+1/2; (iv) −x+3/2, −y, z−1/2; (v) x, y, z−1; (vi) x−1/2, y, −z+3/2. |
(II) Bis(2-carbamoylguanidinium) fluorophosphonate
top
Crystal data top
2(C2H7N4O+)·FO3P2−·2H2O | F(000) = 1424 |
Mr = 340.2 | Dx = 1.587 Mg m−3 |
Orthorhombic, Pbca | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 1710 reflections |
a = 6.5362 (3) Å | θ = 3.1–62.4° |
b = 16.6485 (6) Å | µ = 2.32 mm−1 |
c = 26.1629 (15) Å | T = 120 K |
V = 2847.0 (2) Å3 | Plate, colourless |
Z = 8 | 0.43 × 0.14 × 0.04 mm |
Data collection top
Oxford Xcalibur Gemini Ultra diffractometer | 2210 independent reflections |
Radiation source: X-ray tube | 968 reflections with I > 3σ(I) |
Mirror monochromator | Rint = 0.110 |
Detector resolution: 10.3784 pixels mm-1 | θmax = 62.3°, θmin = 5.3° |
ω scans | h = −7→4 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | k = −18→16 |
Tmin = 0.718, Tmax = 0.908 | l = −29→27 |
7251 measured reflections | |
Refinement top
Refinement on F2 | 60 constraints |
R[F2 > 2σ(F2)] = 0.070 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.193 | Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0004I2] |
S = 1.43 | (Δ/σ)max = 0.036 |
2210 reflections | Δρmax = 0.84 e Å−3 |
202 parameters | Δρmin = −0.60 e Å−3 |
6 restraints | |
Crystal data top
2(C2H7N4O+)·FO3P2−·2H2O | V = 2847.0 (2) Å3 |
Mr = 340.2 | Z = 8 |
Orthorhombic, Pbca | Cu Kα radiation |
a = 6.5362 (3) Å | µ = 2.32 mm−1 |
b = 16.6485 (6) Å | T = 120 K |
c = 26.1629 (15) Å | 0.43 × 0.14 × 0.04 mm |
Data collection top
Oxford Xcalibur Gemini Ultra diffractometer | 2210 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | 968 reflections with I > 3σ(I) |
Tmin = 0.718, Tmax = 0.908 | Rint = 0.110 |
7251 measured reflections | θmax = 62.3° |
Refinement top
R[F2 > 2σ(F2)] = 0.070 | 6 restraints |
wR(F2) = 0.193 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.43 | Δρmax = 0.84 e Å−3 |
2210 reflections | Δρmin = −0.60 e Å−3 |
202 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
P1 | 0.2388 (4) | 0.28849 (10) | 0.36710 (7) | 0.0273 (7) | |
F1 | 0.2556 (8) | 0.3407 (2) | 0.41754 (16) | 0.0393 (16) | |
O1 | 0.3413 (9) | 0.2109 (3) | 0.3806 (2) | 0.0355 (19) | |
O2 | 0.3468 (9) | 0.3371 (3) | 0.3271 (2) | 0.042 (2) | |
O3 | 0.0079 (9) | 0.2824 (3) | 0.3579 (2) | 0.041 (2) | |
O41 | 0.3459 (9) | 0.0964 (3) | 0.2048 (2) | 0.037 (2) | |
C11 | 0.3645 (13) | 0.1390 (4) | 0.2425 (2) | 0.030 (3) | |
N11 | 0.4141 (13) | 0.2160 (3) | 0.2420 (2) | 0.041 (3) | |
H1N11 | 0.409457 | 0.243501 | 0.269815 | 0.0495* | |
H2N11 | 0.450919 | 0.238523 | 0.213921 | 0.0495* | |
N21 | 0.3370 (10) | 0.1082 (3) | 0.2924 (2) | 0.033 (2) | |
H1N21 | 0.353245 | 0.142259 | 0.318245 | 0.0396* | |
C21 | 0.2874 (12) | 0.0305 (3) | 0.3043 (3) | 0.027 (3) | |
N31 | 0.2686 (12) | −0.0249 (2) | 0.2686 (2) | 0.030 (2) | |
H1N31 | 0.29433 | −0.013236 | 0.2372 | 0.0359* | |
H2N31 | 0.230506 | −0.072733 | 0.27662 | 0.0359* | |
N41 | 0.2655 (12) | 0.0129 (2) | 0.3526 (2) | 0.034 (2) | |
H1N41 | 0.290971 | 0.048551 | 0.375515 | 0.0407* | |
H2N41 | 0.225479 | −0.034254 | 0.361468 | 0.0407* | |
O42 | 0.7714 (10) | 0.4622 (3) | 0.54348 (18) | 0.0330 (19) | |
C12 | 0.7595 (14) | 0.4166 (4) | 0.5063 (2) | 0.028 (3) | |
N12 | 0.7614 (15) | 0.3370 (3) | 0.51053 (19) | 0.038 (2) | |
H1N12 | 0.76991 | 0.307551 | 0.483597 | 0.0457* | |
H2N12 | 0.75401 | 0.314917 | 0.540199 | 0.0457* | |
N22 | 0.7449 (11) | 0.4462 (3) | 0.4570 (2) | 0.031 (2) | |
H1N22 | 0.738916 | 0.410468 | 0.431762 | 0.0372* | |
C22 | 0.7387 (14) | 0.5266 (2) | 0.4434 (3) | 0.027 (3) | |
N32 | 0.7288 (13) | 0.5428 (2) | 0.3948 (2) | 0.035 (2) | |
H1N32 | 0.739588 | 0.504719 | 0.372681 | 0.0417* | |
H2N32 | 0.711459 | 0.591473 | 0.3847 | 0.0417* | |
N42 | 0.7349 (14) | 0.5822 (2) | 0.4789 (2) | 0.034 (2) | |
H1N42 | 0.75366 | 0.569386 | 0.510346 | 0.0412* | |
H2N42 | 0.713532 | 0.631507 | 0.470617 | 0.0412* | |
OW1 | 0.7273 (9) | 0.2291 (3) | 0.4235 (2) | 0.035 (2) | |
H1W1 | 0.818 (7) | 0.231 (5) | 0.402 (2) | 0.0527* | |
H2W1 | 0.623 (6) | 0.247 (5) | 0.411 (3) | 0.0527* | |
OW2 | 0.7287 (10) | 0.3986 (3) | 0.3421 (3) | 0.045 (2) | |
H2W2 | 0.828 (7) | 0.369 (4) | 0.343 (4) | 0.0681* | |
H1W2 | 0.626 (6) | 0.371 (4) | 0.339 (4) | 0.0681* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
P1 | 0.0422 (15) | 0.0162 (8) | 0.0236 (10) | −0.0014 (11) | −0.0012 (11) | −0.0019 (7) |
F1 | 0.052 (3) | 0.032 (2) | 0.034 (3) | 0.006 (2) | −0.004 (3) | −0.0104 (18) |
O1 | 0.057 (4) | 0.015 (2) | 0.034 (3) | 0.001 (3) | −0.001 (3) | 0.000 (2) |
O2 | 0.060 (4) | 0.024 (3) | 0.041 (4) | 0.001 (3) | 0.002 (3) | 0.012 (2) |
O3 | 0.036 (4) | 0.040 (3) | 0.047 (4) | −0.002 (3) | −0.009 (3) | 0.001 (3) |
O41 | 0.061 (5) | 0.023 (3) | 0.028 (3) | −0.001 (3) | 0.002 (3) | −0.004 (2) |
C11 | 0.034 (6) | 0.030 (4) | 0.027 (5) | 0.004 (4) | −0.003 (4) | 0.000 (3) |
N11 | 0.057 (6) | 0.026 (4) | 0.040 (5) | −0.007 (4) | 0.014 (5) | 0.004 (3) |
N21 | 0.050 (5) | 0.023 (3) | 0.026 (4) | 0.004 (3) | −0.001 (4) | −0.006 (3) |
C21 | 0.028 (6) | 0.023 (4) | 0.030 (5) | 0.002 (4) | −0.003 (4) | −0.001 (3) |
N31 | 0.045 (5) | 0.019 (3) | 0.026 (3) | −0.003 (4) | 0.001 (4) | −0.003 (2) |
N41 | 0.052 (5) | 0.024 (3) | 0.026 (4) | 0.006 (4) | −0.004 (4) | −0.001 (3) |
O42 | 0.051 (4) | 0.025 (3) | 0.023 (3) | −0.002 (3) | −0.003 (3) | −0.001 (2) |
C12 | 0.036 (6) | 0.027 (4) | 0.022 (4) | −0.001 (4) | −0.004 (4) | 0.002 (3) |
N12 | 0.066 (5) | 0.017 (3) | 0.032 (4) | 0.003 (4) | −0.004 (5) | −0.001 (2) |
N22 | 0.054 (5) | 0.020 (3) | 0.019 (3) | −0.011 (4) | 0.000 (4) | −0.005 (2) |
C22 | 0.027 (5) | 0.025 (4) | 0.031 (4) | −0.010 (4) | 0.005 (5) | −0.003 (3) |
N32 | 0.055 (5) | 0.029 (3) | 0.020 (4) | 0.000 (4) | 0.003 (4) | 0.001 (3) |
N42 | 0.062 (5) | 0.018 (3) | 0.023 (3) | 0.000 (4) | 0.004 (4) | −0.001 (2) |
OW1 | 0.040 (4) | 0.031 (3) | 0.035 (3) | 0.002 (3) | −0.005 (3) | 0.006 (2) |
OW2 | 0.050 (4) | 0.022 (3) | 0.064 (4) | 0.002 (3) | −0.003 (5) | −0.001 (3) |
Geometric parameters (Å, º) top
P1—F1 | 1.584 (4) | O42—C12 | 1.237 (7) |
P1—O1 | 1.497 (5) | C12—N12 | 1.330 (8) |
P1—O2 | 1.499 (6) | C12—N22 | 1.385 (8) |
P1—O3 | 1.531 (6) | N12—H1N12 | 0.86 |
O41—C11 | 1.222 (8) | N12—H2N12 | 0.86 |
C11—N11 | 1.322 (9) | N22—H1N22 | 0.89 |
C11—N21 | 1.413 (9) | N22—C22 | 1.385 (7) |
N11—H1N11 | 0.86 | C22—N32 | 1.303 (9) |
N11—H2N11 | 0.86 | C22—N42 | 1.310 (7) |
H1N11—H2N11 | 1.4896 | N32—H1N32 | 0.86 |
N21—H1N21 | 0.89 | N32—H2N32 | 0.86 |
N21—C21 | 1.370 (7) | N42—H1N42 | 0.86 |
C21—N31 | 1.320 (8) | N42—H2N42 | 0.86 |
C21—N41 | 1.304 (9) | OW1—H1W1 | 0.82 (5) |
N31—H1N31 | 0.86 | OW1—H2W1 | 0.82 (5) |
N31—H2N31 | 0.86 | H1W1—H2W1 | 1.33 (7) |
N41—H1N41 | 0.86 | OW2—H2W2 | 0.82 (5) |
N41—H2N41 | 0.86 | OW2—H1W2 | 0.82 (5) |
| | | |
F1—P1—O1 | 104.2 (3) | C21—N41—H1N41 | 120.0003 |
F1—P1—O2 | 104.6 (3) | C21—N41—H2N41 | 119.9999 |
F1—P1—O3 | 103.6 (3) | H1N41—N41—H2N41 | 119.9997 |
O1—P1—O2 | 114.8 (3) | O42—C12—N12 | 123.1 (5) |
O1—P1—O3 | 114.9 (3) | O42—C12—N22 | 121.2 (6) |
O2—P1—O3 | 113.0 (3) | N12—C12—N22 | 115.7 (5) |
P1—O3—H1W1i | 125.3 (16) | C12—N12—H1N12 | 120.0005 |
P1—O3—H2W2i | 126.2 (16) | C12—N12—H2N12 | 120 |
H1W1i—O3—H2W2i | 93 (3) | H1N12—N12—H2N12 | 119.9995 |
O41—C11—N11 | 125.4 (6) | C12—N22—H1N22 | 117.0683 |
O41—C11—N21 | 121.5 (6) | C12—N22—C22 | 125.9 (5) |
N11—C11—N21 | 113.1 (6) | H1N22—N22—C22 | 117.0671 |
C11—N11—H1N11 | 119.9996 | N22—C22—N32 | 116.8 (5) |
C11—N11—H2N11 | 120.0009 | N22—C22—N42 | 120.1 (6) |
H1N11—N11—H2N11 | 119.9995 | N32—C22—N42 | 123.0 (4) |
C11—N21—H1N21 | 117.1361 | H2N32—C22—H1N42 | 122.8835 |
C11—N21—C21 | 125.7 (6) | C22—N32—H1N32 | 120 |
H1N21—N21—C21 | 117.1355 | C22—N32—H2N32 | 120 |
N21—C21—N31 | 121.3 (6) | H1N32—N32—H2N32 | 120 |
N21—C21—N41 | 117.3 (5) | C22—N42—H1N42 | 120.0006 |
N31—C21—N41 | 121.3 (5) | C22—N42—H2N42 | 119.9993 |
C21—N31—H1N31 | 119.9998 | H1N42—N42—H2N42 | 120.0001 |
C21—N31—H2N31 | 119.9996 | H1W1—OW1—H2W1 | 108 (6) |
H1N31—N31—H2N31 | 120.0006 | H2W2—OW2—H1W2 | 108 (5) |
Symmetry code: (i) x−1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H1N11···O2 | 0.86 | 2.20 | 3.036 (8) | 164 |
N11—H2N11···O3ii | 0.86 | 2.05 | 2.904 (8) | 172 |
N21—H1N21···O1 | 0.89 | 1.99 | 2.873 (8) | 170 |
N31—H1N31···O41 | 0.86 | 2.04 | 2.668 (7) | 129 |
N31—H1N31···C11 | 0.86 | 2.58 | 2.882 (8) | 102 |
N31—H1N31···OW2iii | 0.86 | 2.55 | 3.164 (9) | 129 |
N31—H2N31···O2iv | 0.86 | 2.06 | 2.862 (7) | 154 |
N41—H1N41···O1 | 0.86 | 2.73 | 3.413 (6) | 138 |
N41—H1N41···O42v | 0.86 | 2.13 | 2.751 (7) | 129 |
N41—H2N41···F1iv | 0.86 | 2.55 | 3.337 (6) | 152 |
N41—H2N41···O2iv | 0.86 | 2.37 | 3.091 (7) | 142 |
N12—H1N12···OW1 | 0.86 | 2.06 | 2.908 (7) | 168 |
N12—H2N12···O1vi | 0.86 | 2.19 | 3.004 (7) | 157 |
N22—H1N22···OW2 | 0.89 | 2.35 | 3.109 (9) | 143 |
N32—H1N32···OW2 | 0.86 | 1.94 | 2.766 (7) | 161 |
N32—H2N32···O41vii | 0.86 | 2.37 | 2.796 (8) | 111 |
N32—H2N32···OW1viii | 0.86 | 2.54 | 3.205 (7) | 135 |
N42—H1N42···F1ix | 0.86 | 2.41 | 3.000 (7) | 126 |
N42—H1N42···O42 | 0.86 | 1.99 | 2.629 (7) | 130 |
N42—H2N42···OW1viii | 0.86 | 2.08 | 2.852 (7) | 150 |
OW1—H1W1···O3x | 0.82 (5) | 1.89 (6) | 2.665 (8) | 156 (8) |
OW1—H2W1···O1 | 0.82 (5) | 2.09 (5) | 2.778 (8) | 141 (7) |
OW2—H2W2···O3x | 0.82 (5) | 1.89 (6) | 2.692 (8) | 164 (8) |
OW2—H1W2···O2 | 0.82 (5) | 1.94 (5) | 2.727 (9) | 162 (6) |
Symmetry codes: (ii) x+1/2, y, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1/2, y−1/2, z; (v) x−1/2, −y+1/2, −z+1; (vi) x+1/2, −y+1/2, −z+1; (vii) −x+1, y+1/2, −z+1/2; (viii) −x+3/2, y+1/2, z; (ix) −x+1, −y+1, −z+1; (x) x+1, y, z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | 2(C2H7N4O+)·FO3P2−·2H2O | 2(C2H7N4O+)·FO3P2−·2H2O |
Mr | 340.2 | 340.2 |
Crystal system, space group | Orthorhombic, Pnma | Orthorhombic, Pbca |
Temperature (K) | 120 | 120 |
a, b, c (Å) | 12.2788 (1), 17.4866 (2), 6.6851 (1) | 6.5362 (3), 16.6485 (6), 26.1629 (15) |
V (Å3) | 1435.39 (3) | 2847.0 (2) |
Z | 4 | 8 |
Radiation type | Cu Kα | Cu Kα |
µ (mm−1) | 2.30 | 2.32 |
Crystal size (mm) | 0.51 × 0.34 × 0.24 | 0.43 × 0.14 × 0.04 |
|
Data collection |
Diffractometer | Oxford Xcalibur Gemini Ultra diffractometer | Oxford Xcalibur Gemini Ultra diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) |
Tmin, Tmax | 0.444, 0.580 | 0.718, 0.908 |
No. of measured, independent and observed [I > 3σ(I)] reflections | 20298, 1326, 1219 | 7251, 2210, 968 |
Rint | 0.050 | 0.110 |
θmax (°) | 67.1 | 62.3 |
(sin θ/λ)max (Å−1) | 0.597 | 0.574 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.086, 2.93 | 0.070, 0.193, 1.43 |
No. of reflections | 1326 | 2210 |
No. of parameters | 110 | 202 |
No. of restraints | 5 | 6 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.31, −0.36 | 0.84, −0.60 |
Selected bond lengths (Å) for (I) topP1—F1 | 1.5931 (15) | P1—O2 | 1.5092 (10) |
P1—O1 | 1.5112 (17) | P1—O2i | 1.5092 (10) |
Symmetry code: (i) x, −y+1/2, z. |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O2ii | 0.86 | 2.21 | 3.0491 (17) | 164 |
N1—H2N1···O1 | 0.86 | 2.06 | 2.9152 (18) | 175 |
N2—H1N2···O2 | 0.89 | 1.95 | 2.8286 (17) | 167 |
N3—H1N3···F1iii | 0.86 | 2.69 | 3.2984 (10) | 129 |
N3—H1N3···OW'iv | 0.86 | 2.50 | 3.164 (4) | 134 |
N3—H2N3···O3 | 0.86 | 2.01 | 2.6395 (17) | 129 |
N3—H2N3···OWiii | 0.86 | 2.70 | 3.430 (4) | 144 |
N4—H1N4···OWiv | 0.86 | 1.95 | 2.789 (3) | 166 |
N4—H1N4···OW'iv | 0.86 | 1.92 | 2.735 (3) | 158 |
N4—H2N4···O2 | 0.86 | 2.62 | 3.3211 (14) | 139 |
N4—H2N4···O3v | 0.86 | 2.15 | 2.7091 (17) | 122 |
OW—H1OW···O2vi | 0.820 (6) | 2.078 (5) | 2.771 (3) | 142.1 (8) |
OW'—H1OW···O2vi | 0.821 (7) | 2.078 (5) | 2.783 (3) | 143.9 (15) |
OW—H2OW···O1 | 0.820 (13) | 2.130 (14) | 2.798 (3) | 138.6 (9) |
OW'—H2OW···O1 | 0.821 (10) | 2.130 (14) | 2.848 (3) | 146.1 (15) |
Symmetry codes: (ii) x, y, z+1; (iii) −x+3/2, −y, z+1/2; (iv) −x+3/2, −y, z−1/2; (v) x, y, z−1; (vi) x−1/2, y, −z+3/2. |
Selected bond lengths (Å) for (II) topP1—F1 | 1.584 (4) | P1—O2 | 1.499 (6) |
P1—O1 | 1.497 (5) | P1—O3 | 1.531 (6) |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H1N11···O2 | 0.86 | 2.20 | 3.036 (8) | 164 |
N11—H2N11···O3i | 0.86 | 2.05 | 2.904 (8) | 172 |
N21—H1N21···O1 | 0.89 | 1.99 | 2.873 (8) | 170 |
N31—H1N31···O41 | 0.86 | 2.04 | 2.668 (7) | 129 |
N31—H1N31···C11 | 0.86 | 2.58 | 2.882 (8) | 102 |
N31—H1N31···OW2ii | 0.86 | 2.55 | 3.164 (9) | 129 |
N31—H2N31···O2iii | 0.86 | 2.06 | 2.862 (7) | 154 |
N41—H1N41···O42iv | 0.86 | 2.13 | 2.751 (7) | 129 |
N41—H2N41···F1iii | 0.86 | 2.55 | 3.337 (6) | 152 |
N41—H2N41···O2iii | 0.86 | 2.37 | 3.091 (7) | 142 |
N12—H1N12···OW1 | 0.86 | 2.06 | 2.908 (7) | 168 |
N12—H2N12···O1v | 0.86 | 2.19 | 3.004 (7) | 157 |
N22—H1N22···OW2 | 0.89 | 2.35 | 3.109 (9) | 143 |
N32—H1N32···OW2 | 0.86 | 1.94 | 2.766 (7) | 161 |
N32—H2N32···OW1vi | 0.86 | 2.54 | 3.205 (7) | 135 |
N42—H1N42···F1vii | 0.86 | 2.41 | 3.000 (7) | 126 |
N42—H1N42···O42 | 0.86 | 1.99 | 2.629 (7) | 130 |
N42—H2N42···OW1vi | 0.86 | 2.08 | 2.852 (7) | 150 |
OW1—H1W1···O3viii | 0.82 (5) | 1.89 (6) | 2.665 (8) | 156 (8) |
OW1—H2W1···O1 | 0.82 (5) | 2.09 (5) | 2.778 (8) | 141 (7) |
OW2—H2W2···O3viii | 0.82 (5) | 1.89 (6) | 2.692 (8) | 164 (8) |
OW2—H1W2···O2 | 0.82 (5) | 1.94 (5) | 2.727 (9) | 162 (6) |
Symmetry codes: (i) x+1/2, y, −z+1/2; (ii) −x+1, y−1/2, −z+1/2; (iii) −x+1/2, y−1/2, z; (iv) x−1/2, −y+1/2, −z+1; (v) x+1/2, −y+1/2, −z+1; (vi) −x+3/2, y+1/2, z; (vii) −x+1, −y+1, −z+1; (viii) x+1, y, z. |
Comparison of the equivalent isotropic displacement parameters
Ueq (Å2) of the non-H atoms in the two polymorphs, (I) and (II) top | (I) | (II), cation 1 | (II), cation 2 |
Atom | | | |
P1 | 0.01375 (18) | 0.0273 (7) | |
O1 | 0.0184 (5) | 0.0355 (19) | |
O2 | 0.0186 (3) | 0.042 (2) | |
O2/O3 | 0.0186 (3) | 0.041 (2) | |
F1 | 0.0242 (4) | 0.0393 (16) | |
O3/O41/O42 | 0.0203 (3) | 0.037 (2) | 0.0330 (19) |
C1/C11/C12 | 0.0165 (5) | 0.030 (3) | 0.028 (3) |
N1/N11/N12 | 0.0236 (4) | 0.041 (3) | 0.038 (2) |
N2/N21/N22 | 0.0165 (4) | 0.033 (2) | 0.031 (2) |
C2/C21/C22 | 0.0162 (5) | 0.027 (3) | 0.027 (3) |
N3/N31/N32 | 0.0197 (4) | 0.030 (2) | 0.035 (2) |
N4/N41/N42 | 0.0200 (4) | 0.034 (2) | 0.034 (2) |
OW/OW1/OW2 | 0.0349 (8) | 0.035 (2) | 0.045 (2) |
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Interest in the synthesis of the title structures was aroused by the preparation and structure determination of a series of mixed crystals of 2-carbamoylguanidinium hydrogen fluorophosphonate and 2-carbamoylguanidinium hydrogen phosphite (Fábry et al., 2012a). Pure 2-carbamoylguanidinium hydrogen phosphite (Fridrichová, Němec, Císařová & Němec, 2010) shows interesting physical properties (Fridrichová , Němec, Císařová & Chvostová, 2010; Kroupa & Fridrichová, 2011), namely spontaneous non-collinear second-harmonic generation of light. This property of second-harmonic generation is related to the constitutent cation, which shows significant hyperpolarizability (Fridrichová, Němec, Císařová & Němec, 2010). Therefore, we were interested in the preparation of crystals with different cation–anion molar ratios of 2-carbamoylguanidinium and fluorophosphonate than in the above-mentioned structures (Fábry et al., 2012a). The suggested ratios included the cation–anion molar ratio 2:1 which was expected to yield a structure with a nonhydrogenated fluorophosphonate. Two such structures have now been prepared and their structures are reported below.
Bis(2-carbamoylguanidinium) fluorophosphonate dihydrate crystallizes in space group Pnma to give polymorph (I). It also crystallizes in space group Pbca to give polymorph (II), which has a doubled unit-cell volume and is slightly more densely packed; the volume ratio per formula unit is 0.9917 compared with (I). In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered in contrast with its H atoms. This means that two slightly different hydrogen-bond patterns co-exist in the same structure.
The molecules (Figs. 1 and 2) are linked together by water–fluorophosphonate O—H···O hydrogen bonds and N—H···O hydrogen bonds (Tables 1 and 2) in both structures. Fluorine – as is usual (Dunitz & Taylor, 1997) – avoids participation in strong hydrogen bonds, though there is, for example, a relatively short N41—H1N41···F1 interaction in (II) (Table 2). The oxo groups [atoms O3 in (I) and O41 and O42 in (II)] participate in intra- and intermolecular N—H···O hydrogen bonds with quite acute angles (Tables 1 and 2).
The water–fluorophosphonate O—H···O hydrogen bonds result in the same R44(10) graph-set motif (Etter et al., 1990) in both structures (Figs. 3 and 4). These interactions contribute significantly to the formation of a three-dimensional hydrogen-bond network in each structure. However, there is an important difference between the two polymorphs in this respect. In (I), the 2-carbamoylguanidinium cations and fluorophosphonate anions form ribbons parallel to the a axis (Fig. 5), while the water molecules are indispensable for the construction of a three-dimensional hydrogen-bond network by linking these ribbons together. On the other hand, in (II) only the 2-carbamoylguanidinium cations and fluorophosphonate anions are needed to form a three-dimensional hydrogen-bond network (Fig. 6), although the water molecules reinforce the three-dimensional hydrogen-bond network (Table 2) significantly in this structure.
There is another important difference between the hydrogen-bond networks in (I) and (II), related to the strengths of the water–fluorophosphonate O—H···O hydrogen bonds in (I) and (II) (Tables 1 and 2). These hydrogen bonds are weaker in (I); the H···O distances are about 0.2 Å longer in (I) than those in (II). On the other hand, the N—H···O hydrogen bonds in (I) are shorter than the water–fluorophosphonate O—H···O hydrogen bonds in (I). The latter feature is quite unusual; a search of the Cambridge Structural Database (CSD, Version 5.32 with addenda from April 1 2011; Allen, 2002) for structures in which both O—H···O and N—H···O hydrogen bonds were simultaneously present yielded for O—H···O mean O—H and H···O values of 0.797 (1) and 1.990 (3) Å, respectively, while for N—H···O, the retrieved values were 0.897 (1) Å for N—H and 2.133 (2) Å for H···O. The search was carried out on organic structures only, with R < 0.05, without any error or disorder, and excluding polymeric and ionic structures.
In addition, the water–fluorophosphonate O—H···O angles in (I) are more acute than in (II). This is a manifestation of weaker hydrogen bonds (Jeffrey, 1995) of this type in (I) than in (II). This also seems to be related to the fact that the anion is situated in a special position in (I). Hence, only two symmetry-independent fluorophosphonate O atoms can be involved in the water–fluorophosphonate O—H···O hydrogen bonds, in contrast with (II), where there are three independent fluorophosphonate O atoms participating in this interaction. Moreover, since there is only one independent water molecule in (I), but two in general positions in (II), the molecules in the latter structure can better adjust in order to optimize their interactions.
The ability of the water molecules to interact with their neighbouring molecules is also manifested by the number of N—H···O(water) hydrogen bonds. While the disordered water O atoms in (I) are acceptors of just one amine H atom, in (II) one of the water O atoms (OW2) accepts one H atom and the second (OW1) accepts two.
A plot of P—F versus longest P—O distance in the fluorophosphonate anion was shown in the article by Fábry et al. (2012a), showing that the P—F distance is inversely proportional to the longest P—O distance in the anion. Therefore, this distance is quite sensitive to the hydrogenation of the fluorophosphonate because the P—O bond length of the hydroxyl group is larger than those of the remaining O atoms. Therefore, the fluorophosphonates and hydrogen fluorophosphonates can be readily distinguished. The distances within the anions for (I) and (II) are given in Tables 3 and 4, respectively.
In (II), the P—O and P—F distances are unusual because P1—O2 is quite long for a structure where the fluorophosphonate is not hydrogenated. The P1—F1 distance is correspondingly shortened. Hence, (II) is situated on the boundary between hydrogenated and unhydrogenated fluorophosphonates. This peculiarity of (II) seems to be related to the hydrogen-bond network in which the fluorophosphonate is involved. Atom O2 is hydrogen-bonded more strongly to neighbouring molecules than atoms O1 and O3. Atom O2 is also an acceptor of the strongest hydrogen bonds stemming from two water molecules [OW2—H2W2···O2 and OW1—H1W1···O2i; symmetry code: (i) x + 1, y, z] and of another strong N—H···O2 hydrogen bond [Desiraju & Steiner, 1999; N11—H2N11···O2ii; symmetry code: (ii) x + 1/2, y, -z + 1/2]. These O—H···O and N—H···O angles lie in the range 156–172°, which is typical for rather strong hydrogen bonds. A similar influence of the hydrogen bonds on P—O(acceptor) distances, and concomitantly on P—F distances, has recently been found in tris(guanylurea)(1+) hydrogen fluorophosphonate fluorophosphonate monohydrate (Fábry et al., 2012b). On the other hand, the P—O distances are quite short and the P—F distance quite long in (I).
Comparison of the hydrogen-bond distances pertinent to the bonding of the fluorophosphonates in (I) and (II) shows that the fluorophosphonate is less firmly bound in (I).
The χ2 indices for the best planes through the non-H atoms of the cations are 19477.0, 36.29 and 84.29 for (I), the first cation in (II) and the second cation in (II), respectively. [The first and second cations in (II) contain atoms O41 and O42, respectively.] This is an enormous contrast, indicating that the cation in (I) is quite strained. The largest deviation from the best plane through the cationic non-H atoms in (I) is for atom N3, which is situated 0.12 (3) Å from this plane. In the case of the cations in (II), the atoms with the largest deviations from the best planes through the non-H atoms are N31 and N42, which are 0.031 (9) and 0.055 (10) Å from their respective best planes. The χ2 indices in the related structures of 2-carbamoylguanidinium hydrogen fluorophosphonate and 2-carbamoylguanidinium hydrogen phosphite are 1139.577 (Fábry et al., 2012a) and 6515.041 (Fridrichová, Němec, Císařová & Němec, 2010; Fábry et al., 2012a), respectively. It is also of interest that the equivalent isotropic displacement parameters of the non-H atoms in (I) are lower than those in (II) (Table 5).
The above-mentioned facts [the disorder of the water O atoms, the features of the O—H···O and N—H···O hydrogen bonds, the position of the anions on special and general positions in (I) and (II), respectively] indicate that (II) seems to be thermodynamically more stable than (I), even though the molecules in (II) are only slightly more densely packed than those in (I).
The existence of two polymorphs indicates complexity is present in solutions of 2-carbamoylguanidinium:fluorophosphonate in a molar ratio of 2:1. Our experiments have shown reproducibility for the preparations of 2-carbamoylguanidinium hydrogen fluorophosphonate (Fábry et al., 2012a) but difficult reproducibility for different solutions. Another prepared compound was tris(guanylurea)(1+) hydrogen fluorophosphonate fluorophosphonate monohydrate (Fábry et al., 2012b).