A second triclinic polymorph of (1-ammonio-1-phosphono-eth-yl)phospho-nate.

The asymmetric unit of the second polymorph of the title compound, C(2)H(9)NO(6)P(2), contains one mol-ecule existing as a zwitterion. The N atom of the ammonio group is protonated and one of the phospho-nic acid groups is deprotonated. Bond lengths and angles are similar in both polymorphs. Besides the differences in cell parameters, the most significant structural difference between this structure and that of the first polymorph [Dudko, Bon, Kozachkova, Tsarik & Pekhno (2008 ▶), Ukr. Khim. Zh.74, 104-106] is the presence of strong symmetric hydrogen bonds between neighbouring phospho-nate groups. H atoms involved in these hydrogen bonds are located at inversion centres and O⋯O distances are observed in the range 2.458 (5)-2.523 (5) Å. These bonds and additional O-H⋯O and N-H⋯O hydrogen bonds inter-link the mol-ecules, giving a three-dimensional supromolecular network.

Related literature

For the original polymorph, see: Dudko et al. (2008 ▶). For similar bis­phospho­nates, see: Fernández et al. (2003 ▶); Li et al. (2009 ▶). For general background on the usage of organic diphospho­nic acids as chelating agents in metal extraction and as drugs to prevent calcification and inhibit bone resorption, see: Matczak-Jon & Videnova-Adrabinska (2005 ▶); Matkovskaya et al. (2001 ▶). For examples of symmetrical O—H⋯O hydrogen bonds, see Catti & Ferraris (1976 ▶); Meot-Ner (2005 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C2H9NO6P2

M = 205.04

Triclinic,

a = 5.5674 (11) Å

b = 5.9023 (12) Å

c = 11.385 (2) Å

α = 82.334 (10)°

β = 82.145 (9)°

γ = 78.148 (10)°

V = 360.56 (12) Å3

Z = 2

Mo Kα radiation

μ = 0.59 mm−1

T = 296 K

0.56 × 0.16 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2007 ▶) T min = 0.734, T max = 0.949

4331 measured reflections

1401 independent reflections

861 reflections with I > 2σ(I)

R int = 0.058

Refinement

R[F 2 > 2σ(F 2)] = 0.049

wR(F 2) = 0.122

S = 1.06

1401 reflections

116 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.45 e Å−3

Δρmin = −0.43 e Å−3

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811022239/im2293sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811022239/im2293Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811022239/im2293Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C2H9NO6P2	Z = 2
Mr = 205.04	F(000) = 212
Triclinic, P1	Dx = 1.889 Mg m−3
Hall symbol: -P 1	Melting point: 551 K
a = 5.5674 (11) Å	Mo Kα radiation, λ = 0.71073 Å
b = 5.9023 (12) Å	Cell parameters from 1315 reflections
c = 11.385 (2) Å	θ = 3.6–25.3°
α = 82.334 (10)°	µ = 0.59 mm−1
β = 82.145 (9)°	T = 296 K
γ = 78.148 (10)°	Needle, colourless
V = 360.56 (12) Å3	0.56 × 0.16 × 0.09 mm

Bruker APEXII CCD diffractometer	1401 independent reflections
Radiation source: fine-focus sealed tube	861 reflections with I > 2σ(I)
graphite	Rint = 0.058
φ and ω scans	θmax = 26.0°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2007)	h = −6→6
Tmin = 0.734, Tmax = 0.949	k = −7→7
4331 measured reflections	l = −12→14

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.122	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ2(Fo2) + (0.0387P)2 + 0.6717P] where P = (Fo2 + 2Fc2)/3
1401 reflections	(Δ/σ)max < 0.001
116 parameters	Δρmax = 0.45 e Å−3
0 restraints	Δρmin = −0.43 e Å−3

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.

	x	y	z	Uiso*/Ueq
P1	0.4512 (2)	−0.0726 (2)	0.18108 (11)	0.0243 (4)
P2	0.2798 (2)	0.2733 (2)	0.36756 (11)	0.0266 (4)
O1	0.3269 (6)	−0.1949 (6)	0.1024 (3)	0.0327 (9)
H1O	0.337 (11)	−0.133 (11)	0.034 (5)	0.049*
O2	0.6470 (5)	0.0492 (6)	0.1152 (3)	0.0337 (9)
O3	0.5438 (7)	−0.2366 (6)	0.2838 (4)	0.0475 (11)
H3O	0.531 (12)	−0.379 (12)	0.301 (6)	0.071*
O4	0.5260 (5)	0.3445 (5)	0.3268 (3)	0.0236 (8)
O5	0.2923 (6)	0.0865 (7)	0.4724 (3)	0.0344 (9)
H5O	0.5000	0.0000	0.5000	0.052*
O6	0.0723 (6)	0.4792 (7)	0.3914 (3)	0.0421 (10)
H6O	0.0000	0.5000	0.5000	0.063*
N1	−0.0104 (8)	0.0192 (9)	0.2928 (4)	0.0287 (11)
H1A	−0.086 (10)	−0.025 (9)	0.237 (5)	0.043*
H1B	−0.151 (10)	0.102 (10)	0.316 (5)	0.043*
H1C	0.030 (10)	−0.091 (10)	0.342 (5)	0.043*
C1	0.1979 (8)	0.1433 (8)	0.2439 (4)	0.0195 (10)
C2	0.1069 (9)	0.3297 (8)	0.1441 (4)	0.0278 (12)
H2A	0.0827	0.2556	0.0776	0.042*
H2B	0.2276	0.4265	0.1191	0.042*
H2C	−0.0464	0.4235	0.1730	0.042*

	U11	U22	U33	U12	U13	U23
P1	0.0236 (7)	0.0195 (7)	0.0316 (7)	−0.0033 (5)	−0.0072 (6)	−0.0066 (6)
P2	0.0204 (7)	0.0387 (9)	0.0230 (7)	−0.0080 (6)	−0.0030 (5)	−0.0074 (6)
O1	0.038 (2)	0.028 (2)	0.037 (2)	−0.0124 (17)	−0.0077 (18)	−0.0095 (17)
O2	0.0203 (18)	0.045 (2)	0.042 (2)	−0.0155 (16)	0.0069 (16)	−0.0208 (18)
O3	0.065 (3)	0.016 (2)	0.068 (3)	−0.0036 (19)	−0.042 (2)	0.002 (2)
O4	0.0182 (16)	0.0200 (18)	0.0344 (19)	−0.0022 (13)	−0.0056 (14)	−0.0091 (15)
O5	0.0272 (19)	0.055 (2)	0.0241 (18)	−0.0172 (17)	−0.0077 (15)	0.0035 (17)
O6	0.0231 (19)	0.067 (3)	0.034 (2)	0.0124 (18)	−0.0057 (16)	−0.0270 (19)
N1	0.017 (2)	0.036 (3)	0.033 (3)	−0.009 (2)	−0.006 (2)	0.005 (2)
C1	0.016 (2)	0.022 (3)	0.022 (2)	−0.0064 (19)	−0.0040 (19)	0.000 (2)
C2	0.031 (3)	0.023 (3)	0.027 (3)	0.000 (2)	−0.007 (2)	−0.001 (2)

P1—O2	1.490 (3)	O5—H5O	1.229 (0)
P1—O3	1.493 (4)	O6—H6O	1.261 (0)
P1—O1	1.533 (4)	N1—C1	1.502 (6)
P1—C1	1.831 (5)	N1—H1A	0.90 (6)
P2—O4	1.510 (3)	N1—H1B	0.86 (6)
P2—O5	1.512 (4)	N1—H1C	0.82 (6)
P2—O6	1.520 (3)	C1—C2	1.534 (6)
P2—C1	1.840 (4)	C2—H2A	0.9600
O1—H1O	0.81 (6)	C2—H2B	0.9600
O3—H3O	0.85 (7)	C2—H2C	0.9600
O2—P1—O3	111.7 (2)	C1—N1—H1B	118 (4)
O2—P1—O1	114.3 (2)	H1A—N1—H1B	87 (4)
O3—P1—O1	110.8 (2)	C1—N1—H1C	113 (4)
O2—P1—C1	109.0 (2)	H1A—N1—H1C	110 (5)
O3—P1—C1	106.5 (2)	H1B—N1—H1C	111 (6)
O1—P1—C1	103.86 (19)	N1—C1—C2	107.8 (4)
O4—P2—O5	112.46 (18)	N1—C1—P1	107.2 (3)
O4—P2—O6	112.8 (2)	C2—C1—P1	109.4 (3)
O5—P2—O6	111.7 (2)	N1—C1—P2	107.4 (3)
O4—P2—C1	107.07 (18)	C2—C1—P2	111.7 (3)
O5—P2—C1	106.2 (2)	P1—C1—P2	113.1 (2)
O6—P2—C1	105.98 (19)	C1—C2—H2A	109.5
P1—O1—H1O	110 (4)	C1—C2—H2B	109.5
P1—O3—H3O	128 (4)	H2A—C2—H2B	109.5
P2—O5—H5O	115.9 (0)	C1—C2—H2C	109.5
P2—O6—H6O	115.1 (0)	H2A—C2—H2C	109.5
C1—N1—H1A	115 (3)	H2B—C2—H2C	109.5
O2—P1—C1—N1	171.5 (3)	O4—P2—C1—N1	166.1 (3)
O3—P1—C1—N1	−67.9 (3)	O5—P2—C1—N1	45.8 (3)
O1—P1—C1—N1	49.2 (3)	O6—P2—C1—N1	−73.2 (4)
O2—P1—C1—C2	54.9 (4)	O4—P2—C1—C2	−76.0 (3)
O3—P1—C1—C2	175.5 (3)	O5—P2—C1—C2	163.7 (3)
O1—P1—C1—C2	−67.4 (3)	O6—P2—C1—C2	44.7 (4)
O2—P1—C1—P2	−70.3 (3)	O4—P2—C1—P1	48.0 (3)
O3—P1—C1—P2	50.3 (3)	O5—P2—C1—P1	−72.4 (3)
O1—P1—C1—P2	167.4 (2)	O6—P2—C1—P1	168.7 (2)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O2i	0.81 (6)	1.70 (6)	2.507 (5)	170 (6)
O3—H3O···O4ii	0.85 (7)	1.63 (7)	2.475 (5)	175 (7)
O5—H5O···O5iii	1.23 (1)	1.23 (1)	2.458 (5)	180 (0)
O6—H6O···O6iv	1.26 (1)	1.26 (1)	2.523 (6)	180.(1)
N1—H1A···O2v	0.90 (6)	2.11 (6)	2.929 (6)	150 (5)
N1—H1B···O4v	0.86 (6)	2.06 (6)	2.896 (5)	165 (5)
N1—H1C···O6ii	0.82 (6)	2.50 (6)	3.196 (6)	145 (5)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O2i	0.81 (6)	1.70 (6)	2.507 (5)	170 (6)
O3—H3O⋯O4ii	0.85 (7)	1.63 (7)	2.475 (5)	175 (7)
O5—H5O⋯O5iii	1.23 (1)	1.23 (1)	2.458 (5)	180 (0)
O6—H6O⋯O6iv	1.26 (1)	1.26 (1)	2.523 (6)	180 (1)
N1—H1A⋯O2v	0.90 (6)	2.11 (6)	2.929 (6)	150 (5)
N1—H1B⋯O4v	0.86 (6)	2.06 (6)	2.896 (5)	165 (5)
N1—H1C⋯O6ii	0.82 (6)	2.50 (6)	3.196 (6)	145 (5)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) .