Ammonium 1-ammonio­ethane-1,1-diylbis(hydrogenphospho­nate) dihydrate

The title compound, NH₄⁺·C₂H₈NO₆P₂⁻·2H₂O, was obtained by the reaction between 1-amino­ethane-1,1-diyldiphospho­nic acid and ammonium hydroxide (1:1) in an aqueous solution. The asymmetric unit contains one anion with two H atoms transferred from the phospho­nic acid groups to the amino group of the anion and to an ammonia mol­ecule, giving an ammonium cation. The structure displays N—H...O and O—H...O hydrogen bonding, which creates a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.033
• wR factor = 0.074
• Data-to-parameter ratio = 11.8

checkCIF/PLATON results

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PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?

Alert level G
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   1 ALERT level G = General alerts; check

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S1. Comment

The organic diphosphonic acids are potentially very powerful chelating agents used in metal extractions and are tested by the pharmaceutical industry for use as efficient drugs preventing calcification and inhibiting bone resorption (Tromelin et al., 1986, Matczak-Jon & Videnova-Adrabinska, 2005). Diphosphonic acids are used in the treatment of Paget disease, osteoporosis and tumoral osteolysis (Szabo et al., 2002). The asymmetric unit of title compound (Fig. 1) contains one molecule, which exists as anion with two protons transferred from the phosphonic group to the amino group and from another phosphonic group to ammonium cation. In the crystal structure of the title compound the phosphorus atom displays a slightly distorted tetrahedral geometry provided by three oxygen atoms and one carbon atom (Bruckmann et al. (1999); Olive et al. (2000); Coiro et al. (1989)). Bond lengths and angles have normal values (Allen et al., 1987). One ammonium cation and two solvent water molecules are present in asymetric unit. The structure is stabilized by three-dimensional O–H···O and N–H···O hydrogen bonds network (Table 1, Fig.2).

Related literature

Diphosphonic acids are efficient drugs for the prevention of calcification and the inhibition bone resorption (Tromelin et al., 1986, Matczak-Jon & Videnova-Adrabinska, 2005) and are used in the treatment of Pagets disease, osteoporosis and tumoral osteolysis (Szabo et al., 2002). For related structures, see: Bruckmann et al. (1999); Olive et al. (2000); Coiro et al. (1989). For bond-length data, see: Allen et al. (1987).

S2. Experimental

The title compound was obtained by the reaction of 1-aminoethane-1,1-diyldiphosphonic acid and ammonium hydroxide (1:1) in the aqueous solution. The solution was left at room temperature. Colourless crystals of the title compound were obtained after 1 day staying.

S3. Refinement

All H atoms bonded to O and N atoms were located in a difference map. Other H atoms bonded to C were positioned geometrically and refined using a riding model with C–H = 0.98 Å for CH₃ with U_iso(H) = 1.5Ueq(C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures

	Fig. 1. The asymmetric unit of title compound with the atom numbering scheme. The displacement ellipsoids are shown at 50% probability level. H atoms are presented as a small spheres of arbitrary radius.
	Fig. 2. Crystal packing of title compound, projection along b axis. Dashed lines indicate hydrogen bonds.

Ammonium 1-ammonioethane-1,1-diylbis(hydrogenphosphonate) dihydtare

Crystal data

H4N^+·C2H8NO6P2^−·2H2O	F(000) = 544
Mr = 258.11	Dx = 1.659 Mg m^−3
Monoclinic, P21/c	Melting point: 511 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 8.8922 (3) Å	Cell parameters from 4102 reflections
b = 6.9390 (3) Å	θ = 2.4–26.4°
c = 18.9576 (8) Å	µ = 0.45 mm^−1
β = 117.957 (2)°	T = 173 K
V = 1033.23 (7) Å^3	Needle, colourless
Z = 4	0.23 × 0.19 × 0.09 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	2126 independent reflections
Radiation source: Fine-focus sealed tube	1710 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.057
ϕ and ω scans	θmax = 26.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −11→11
Tmin = 0.906, Tmax = 0.963	k = −8→8
14152 measured reflections	l = −23→23

Refinement

Refinement on F^2	Primary atom site location: Direct
Least-squares matrix: Full	Secondary atom site location: Difmap
R[F^2 > 2σ(F^2)] = 0.033	Hydrogen site location: Geom
wR(F^2) = 0.074	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0326P)^2 + 0.4969P] where P = (Fo^2 + 2Fc^2)/3
2126 reflections	(Δ/σ)max = 0.001
180 parameters	Δρmax = 0.50 e Å^−3
2 restraints	Δρmin = −0.42 e Å^−3

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
P1	0.45684 (7)	0.78215 (7)	0.83905 (3)	0.00967 (14)
P2	0.75545 (7)	0.49061 (7)	0.90274 (3)	0.00998 (14)
C1	0.6842 (3)	0.7385 (3)	0.86839 (12)	0.0102 (4)
C2	0.7977 (3)	0.8851 (3)	0.93146 (13)	0.0151 (5)
H2A	0.9172	0.8604	0.9460	0.023*
H2B	0.7816	0.8730	0.9790	0.023*
H2C	0.7668	1.0157	0.9097	0.023*
N1	0.7091 (2)	0.7652 (3)	0.79539 (11)	0.0110 (4)
N2	0.4118 (3)	0.2940 (3)	0.92879 (12)	0.0156 (4)
O1	0.41873 (18)	0.6941 (2)	0.90108 (8)	0.0136 (3)
O2	0.42601 (18)	0.99358 (19)	0.82470 (8)	0.0138 (3)
O3	0.35764 (18)	0.6661 (2)	0.75879 (9)	0.0118 (3)
O4	0.61946 (17)	0.3541 (2)	0.84970 (8)	0.0127 (3)
O5	0.92422 (18)	0.4672 (2)	0.90282 (8)	0.0137 (3)
O6	0.7742 (2)	0.4803 (2)	0.98869 (9)	0.0142 (3)
H3O	0.366 (3)	0.724 (4)	0.7255 (16)	0.033 (8)*
H6O	0.873 (4)	0.492 (4)	1.0228 (18)	0.044 (9)*
H11N	0.653 (3)	0.669 (4)	0.7568 (15)	0.022 (6)*
H12N	0.822 (3)	0.761 (3)	0.8110 (14)	0.016 (6)*
H13N	0.672 (3)	0.878 (4)	0.7751 (14)	0.019 (7)*
H21N	0.303 (4)	0.265 (4)	0.9075 (17)	0.036 (8)*
H22N	0.453 (3)	0.222 (4)	0.9061 (16)	0.028 (8)*
H23N	0.418 (3)	0.422 (5)	0.9160 (17)	0.039 (8)*
H24N	0.463 (3)	0.275 (3)	0.9819 (15)	0.013 (6)*
O7	0.0562 (2)	0.2189 (3)	0.83327 (12)	0.0225 (4)
O8	−0.0558 (2)	0.3200 (3)	0.67241 (11)	0.0235 (4)
H71O	0.019 (4)	0.249 (4)	0.786 (2)	0.042 (9)*
H72O	0.004 (3)	0.278 (4)	0.8504 (16)	0.025 (8)*
H81O	−0.145 (3)	0.279 (4)	0.6455 (15)	0.034 (9)*
H82O	−0.064 (4)	0.431 (3)	0.668 (2)	0.063 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0092 (3)	0.0081 (3)	0.0112 (3)	0.0005 (2)	0.0044 (2)	0.0006 (2)
P2	0.0099 (3)	0.0091 (3)	0.0099 (3)	0.0006 (2)	0.0038 (2)	0.0007 (2)
C1	0.0101 (10)	0.0095 (10)	0.0110 (10)	−0.0006 (8)	0.0049 (8)	0.0002 (8)
C2	0.0152 (11)	0.0123 (11)	0.0167 (11)	−0.0028 (9)	0.0065 (9)	−0.0034 (9)
N1	0.0104 (10)	0.0097 (9)	0.0125 (9)	0.0006 (8)	0.0051 (8)	0.0019 (8)
N2	0.0169 (11)	0.0169 (11)	0.0144 (11)	−0.0005 (9)	0.0084 (9)	−0.0014 (8)
O1	0.0138 (8)	0.0141 (8)	0.0144 (8)	0.0004 (6)	0.0078 (6)	0.0025 (6)
O2	0.0155 (8)	0.0104 (7)	0.0152 (7)	0.0010 (6)	0.0069 (6)	0.0004 (6)
O3	0.0130 (8)	0.0103 (7)	0.0108 (7)	−0.0015 (6)	0.0044 (6)	0.0010 (6)
O4	0.0131 (8)	0.0100 (7)	0.0142 (7)	−0.0009 (6)	0.0058 (6)	−0.0007 (6)
O5	0.0117 (8)	0.0144 (8)	0.0141 (7)	0.0018 (6)	0.0052 (6)	−0.0001 (6)
O6	0.0107 (8)	0.0194 (8)	0.0114 (7)	0.0008 (6)	0.0042 (7)	0.0014 (6)
O7	0.0173 (9)	0.0237 (9)	0.0262 (10)	0.0030 (7)	0.0100 (8)	−0.0056 (8)
O8	0.0164 (10)	0.0216 (10)	0.0324 (10)	0.0009 (8)	0.0115 (9)	−0.0013 (8)

Geometric parameters (Å, º)

P1—O2	1.4939 (14)	N1—H11N	0.94 (3)
P1—O1	1.4982 (14)	N1—H12N	0.90 (3)
P1—O3	1.5760 (15)	N1—H13N	0.87 (3)
P1—C1	1.853 (2)	N2—H21N	0.88 (3)
P2—O4	1.4933 (15)	N2—H22N	0.85 (3)
P2—O5	1.5088 (15)	N2—H23N	0.93 (3)
P2—O6	1.5598 (15)	N2—H24N	0.90 (2)
P2—C1	1.843 (2)	O3—H3O	0.78 (3)
C1—N1	1.512 (3)	O6—H6O	0.81 (3)
C1—C2	1.534 (3)	O7—H71O	0.83 (3)
C2—H2A	0.9800	O7—H72O	0.80 (3)
C2—H2B	0.9800	O8—H81O	0.768 (17)
C2—H2C	0.9800	O8—H82O	0.775 (18)
O2—P1—O1	116.99 (8)	H2A—C2—H2B	109.5
O2—P1—O3	110.75 (8)	C1—C2—H2C	109.5
O1—P1—O3	108.61 (9)	H2A—C2—H2C	109.5
O2—P1—C1	107.25 (9)	H2B—C2—H2C	109.5
O1—P1—C1	108.31 (9)	C1—N1—H11N	111.7 (15)
O3—P1—C1	104.13 (9)	C1—N1—H12N	108.2 (15)
O4—P2—O5	115.05 (8)	H11N—N1—H12N	110 (2)
O4—P2—O6	109.31 (8)	C1—N1—H13N	109.0 (15)
O5—P2—O6	112.01 (8)	H11N—N1—H13N	110 (2)
O4—P2—C1	108.55 (9)	H12N—N1—H13N	108 (2)
O5—P2—C1	106.13 (9)	H21N—N2—H22N	106 (3)
O6—P2—C1	105.23 (9)	H21N—N2—H23N	107 (2)
N1—C1—C2	107.87 (16)	H22N—N2—H23N	110 (3)
N1—C1—P2	105.33 (13)	H21N—N2—H24N	110 (2)
C2—C1—P2	110.63 (14)	H22N—N2—H24N	112 (2)
N1—C1—P1	108.22 (14)	H23N—N2—H24N	112 (2)
C2—C1—P1	110.60 (14)	P1—O3—H3O	107 (2)
P2—C1—P1	113.86 (10)	P2—O6—H6O	112 (2)
C1—C2—H2A	109.5	H71O—O7—H72O	108 (3)
C1—C2—H2B	109.5	H81O—O8—H82O	106 (3)
O4—P2—C1—N1	−77.19 (14)	O2—P1—C1—N1	−71.57 (14)
O5—P2—C1—N1	47.00 (15)	O1—P1—C1—N1	161.33 (13)
O6—P2—C1—N1	165.88 (13)	O3—P1—C1—N1	45.86 (15)
O4—P2—C1—C2	166.50 (13)	O2—P1—C1—C2	46.40 (16)
O5—P2—C1—C2	−69.31 (15)	O1—P1—C1—C2	−80.71 (15)
O6—P2—C1—C2	49.58 (16)	O3—P1—C1—C2	163.82 (14)
O4—P2—C1—P1	41.22 (13)	O2—P1—C1—P2	171.69 (10)
O5—P2—C1—P1	165.41 (10)	O1—P1—C1—P2	44.58 (13)
O6—P2—C1—P1	−75.71 (12)	O3—P1—C1—P2	−70.88 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3O···O4^i	0.78 (3)	1.74 (3)	2.523 (2)	179 (3)
O6—H6O···O5^ii	0.81 (3)	1.71 (3)	2.526 (2)	175 (3)
N1—H11N···O2^iii	0.94 (3)	1.83 (3)	2.759 (2)	169 (2)
N1—H12N···O8^i	0.90 (3)	2.00 (3)	2.873 (3)	164 (2)
N1—H13N···O3^i	0.87 (3)	2.08 (3)	2.928 (2)	167 (2)
N2—H21N···O7	0.88 (3)	2.00 (3)	2.860 (3)	165 (3)
N2—H22N···O2^iv	0.85 (3)	2.14 (3)	2.914 (3)	151 (2)
N2—H23N···O1	0.93 (3)	1.91 (3)	2.832 (3)	171 (3)
N2—H24N···O1^v	0.90 (2)	1.97 (3)	2.850 (3)	165 (2)
O7—H71O···O8	0.83 (3)	1.99 (3)	2.817 (3)	177 (3)
O7—H72O···O5^vi	0.80 (3)	1.97 (3)	2.745 (2)	165 (3)
O8—H81O···O1^vii	0.77 (2)	2.24 (2)	2.984 (2)	162 (3)
O8—H82O···O7^viii	0.78 (2)	2.00 (2)	2.770 (3)	173 (4)

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