Symmetric hydrogen bonding in dimethyl­ammonium hydrogen diphenyl­diphospho­nate

In the title compound, C₂H₈N⁺·C₁₂H₁₁O₅P₂⁻, pairs of hydrogen diphenyl­diphospho­nate anions form dimers across a twofold axis, with two symmetric O...H...O hydrogen bonds [O...O = 2.406 (3) and 2.418 (3) Å]. The 12-membered ring thus formed has crystallographic 2 and quasi-222 symmetry. Cations on either side of the ring form N—H...O hydrogen bonds to the four extraannular O atoms, with N...O distances of 2.765 (2) and 2.748 (3) Å.

S1. Comment

As part of our interest in preparing and characterizing bridging methylene phosphine complexes, the title compound was isolated during the synthesis of Ph(H)PCH₂P(H)Ph by Stelzer's reaction (Langhans & Stelzer, 1987), during which the order of addition of dimethylformamide and water was reversed.

The chemically significant species, [(CH₃)₂NH₂]₂[(C₆H₅)₂P₂O₅H]₂, (I), consists of two hydrogen diphenyldiphosphonate anions fused into a P₄O₆H₂ ring by two short hydrogen bonds (Fig. 1 and Table 2), both apparently symmetric, with their H atoms centrally located on a twofold axis. While we cannot rule out the possibility that these hydrogen bonds involve disordered H atoms, with half-occupied sites slightly off the twofold axis, difference maps (see Fig. 2) show no elongation of the density along the O···O lines. The O—H distances are quite long, approximately 1.2 Å. Steiner & Saenger (1994), by examining O—H···O hydrogen-bonded structures determined from low-T neutron-diffraction data, noted a smooth lengthening of the O—H distances in the donors with a shortening of the O···O distance. Although their data set contained no instances of hydrogen bonds across symmetry elements, they found a minimum O···O distance of ca 2.39 Å, with equal O—H and H···O distances at that distance. Thus, the symmetric hydrogen bonds observed in (I) are in accordance with the findings of Steiner & Saenger (1994). In (I), the P1—O3 and P2—O5 distances (Table 1) to O atoms involved in the symmetric hydrogen bonds are intermediate in length between the P═O distance, 1.506 (2) Å, and P—OH distances, 1.536 (2) and 1.554 (2) Å, in benzenephosphonic acid (Mahmoudkhani & Langer, 2002).

The four remaining O atoms, viz. O2, O4 and their symmetry equivalents, accept hydrogen bonds from two cations on either side of the plane. The P═ O distances are typical of double bonds (Corbridge, 1974).

The structure of the same dimerized anion has been reported at 213 K, with a complex palladium cation (Kingsley et al., 2001), but with asymmetric ordered hydrogen bonds [O···O = 2.424 (3) Å]. That dimer lies on an inversion center rather than a twofold axis, so that symmetry does not require either disorder of the H-atom positions or a symmetric hydrogen bond. In the presence of Pd, uncertainties in H-atom positions are rather large; the reported O—H distance is 1.02 (6) Å and the H···O distance is 1.43 (6) Å. Thus, the deviation of the H-atom position from the O···O mid-point is of marginal statistical significance, and that hydrogen bond may approach the apparently symmetric one observed in the title compound.

S2. Experimental

Phenyl phosphine (19.75 g, 0.180 mol) was added to CH₂Cl₂ (7.63 g, 0.090 mol) with stirring in an ice-cooled Schlenk flask. To this mixture was added degassed water (150 ml). Dimethylformamide (56 ml) was syringed into the mixture and the solution turned cloudy. Degassed 56% KOH solution (27 ml) was added slowly by canula over a period of 20 min, and stirring was continued for 10 h. The reaction mixture separated into two layers, and the organic layer was extracted three times with pentane (50 ml). The pentane was removed by distillation, and the remaining residue was separated by fractional distillation, yielding the starting material, phenyl phosphine. The second fraction, collected at 307 K, was the title compound, and shiny white crystals formed by sublimation.

S3. Refinement

N– and O-bound H atoms were individually refined, except that the U_iso(H) values for the former were set at 1.2U_eq(N). All C-bound H atoms were placed in calculated positions with C—H distances of 0.93 Å [please check; these distances are not given in the CIF] and U_iso(H) values of 1.2 or 1.5 times U_eq(C), and thereafter treated as riding. A torsional parameter was refined for each methyl group.

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The structure of (I), showing the atomic numbering scheme and displacement ellipsoids at the 50% probability level.
	Fig. 2. Fourier difference maps showing the two symmetric hydrogen bonds. The peak heights at the H-atom positions are approximately 1 e Å^−3.

dimethylammonium hydrogen diphenyldiphosphonate

Crystal data

C2H8N^+·C12H11O5P2^−	Dx = 1.369 Mg m^−3
Mr = 343.24	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41cd	Cell parameters from 5490 reflections
Hall symbol: I 4bw -2c	θ = 2.5–32.5°
a = 13.110 (3) Å	µ = 0.28 mm^−1
c = 38.751 (8) Å	T = 102 K
V = 6660 (3) Å^3	Fragment, colorless
Z = 16	0.33 × 0.30 × 0.18 mm
F(000) = 2880

Data collection

Nonius KappaCCD (with Oxford Cryostream) diffractometer	5654 independent reflections
Radiation source: fine-focus sealed tube	4268 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
ω scans with κ offsets	θmax = 32.6°, θmin = 3.1°
Absorption correction: multi-scan HKL SCALEPACK (Otwinowski & Minor 1997)	h = −19→19
Tmin = 0.887, Tmax = 0.951	k = −14→14
33359 measured reflections	l = −57→56

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.095	w = 1/[σ^2(Fo^2) + (0.0434P)^2 + 1.9071P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.001
5654 reflections	Δρmax = 0.33 e Å^−3
212 parameters	Δρmin = −0.31 e Å^−3
1 restraint	Absolute structure: Flack (1983), 2590 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.21 (8)

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
P1	0.52537 (4)	0.67758 (4)	0.249946 (11)	0.01640 (11)
P2	0.45614 (4)	0.67403 (4)	0.320250 (11)	0.01822 (11)
O1	0.48821 (11)	0.73281 (9)	0.28514 (4)	0.0209 (3)
O2	0.63740 (11)	0.66309 (11)	0.24934 (4)	0.0221 (3)
O3	0.45930 (11)	0.58222 (11)	0.24646 (4)	0.0214 (3)
H3O	0.5000	0.5000	0.2462 (13)	0.052 (12)*
O4	0.34640 (11)	0.64784 (11)	0.32035 (4)	0.0238 (3)
O5	0.53197 (11)	0.58649 (11)	0.32417 (4)	0.0225 (3)
H5O	0.5000	0.5000	0.3225 (14)	0.063 (13)*
C1	0.48281 (16)	0.76549 (16)	0.21795 (5)	0.0173 (4)
C2	0.54905 (17)	0.79951 (17)	0.19240 (5)	0.0268 (5)
H2	0.6197	0.7838	0.1936	0.032*
C3	0.5109 (2)	0.85702 (19)	0.16494 (6)	0.0360 (6)
H3	0.5556	0.8797	0.1472	0.043*
C4	0.4086 (2)	0.8810 (2)	0.16339 (6)	0.0391 (6)
H4	0.3830	0.9190	0.1444	0.047*
C5	0.3431 (2)	0.85021 (19)	0.18920 (6)	0.0335 (5)
H5	0.2732	0.8691	0.1884	0.040*
C6	0.37934 (16)	0.79167 (17)	0.21639 (5)	0.0240 (4)
H6	0.3340	0.7693	0.2339	0.029*
C7	0.48755 (17)	0.76661 (15)	0.35222 (5)	0.0207 (4)
C8	0.41877 (17)	0.78648 (17)	0.37900 (5)	0.0247 (4)
H8	0.3519	0.7586	0.3783	0.030*
C9	0.4485 (2)	0.84715 (18)	0.40669 (6)	0.0321 (6)
H9	0.4022	0.8604	0.4250	0.039*
C10	0.5459 (2)	0.88815 (18)	0.40747 (6)	0.0323 (6)
H10	0.5668	0.9280	0.4267	0.039*
C11	0.6129 (2)	0.87149 (17)	0.38045 (6)	0.0307 (5)
H11	0.6785	0.9023	0.3808	0.037*
C12	0.58478 (18)	0.81019 (16)	0.35295 (5)	0.0247 (5)
H12	0.6314	0.7978	0.3347	0.030*
N1A	0.74007 (13)	0.50925 (16)	0.28364 (6)	0.0242 (3)
H1N	0.701 (2)	0.554 (2)	0.2727 (7)	0.029*
H2N	0.702 (2)	0.465 (2)	0.2948 (6)	0.029*
C1A	0.8031 (2)	0.4524 (2)	0.25843 (6)	0.0375 (6)
H1A1	0.8415	0.3990	0.2704	0.056*
H1A2	0.8507	0.4994	0.2472	0.056*
H1A3	0.7587	0.4212	0.2410	0.056*
C2A	0.7989 (2)	0.5673 (2)	0.30947 (7)	0.0391 (6)
H2A1	0.8406	0.6188	0.2978	0.059*
H2A2	0.8433	0.5206	0.3223	0.059*
H2A3	0.7518	0.6010	0.3255	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0185 (3)	0.0146 (3)	0.0161 (2)	0.00160 (18)	−0.0011 (2)	−0.00010 (19)
P2	0.0237 (3)	0.0143 (3)	0.0166 (2)	0.00020 (19)	−0.00092 (19)	0.00039 (19)
O1	0.0323 (8)	0.0144 (6)	0.0161 (5)	0.0019 (6)	0.0015 (6)	0.0007 (6)
O2	0.0181 (7)	0.0233 (8)	0.0251 (7)	0.0017 (6)	−0.0029 (6)	0.0045 (6)
O3	0.0214 (8)	0.0143 (8)	0.0285 (8)	0.0004 (5)	−0.0008 (6)	−0.0015 (6)
O4	0.0243 (8)	0.0206 (8)	0.0265 (7)	−0.0007 (6)	−0.0002 (6)	−0.0047 (6)
O5	0.0258 (8)	0.0141 (7)	0.0277 (8)	−0.0001 (5)	−0.0028 (6)	0.0020 (6)
C1	0.0215 (11)	0.0139 (10)	0.0164 (9)	0.0021 (7)	−0.0032 (7)	−0.0015 (7)
C2	0.0270 (12)	0.0252 (13)	0.0281 (11)	0.0054 (9)	0.0033 (9)	0.0036 (8)
C3	0.0518 (18)	0.0322 (14)	0.0241 (11)	0.0062 (11)	0.0055 (10)	0.0107 (10)
C4	0.0552 (19)	0.0296 (14)	0.0324 (13)	0.0069 (12)	−0.0143 (11)	0.0097 (10)
C5	0.0329 (14)	0.0292 (13)	0.0386 (12)	0.0073 (9)	−0.0160 (10)	−0.0020 (10)
C6	0.0207 (11)	0.0209 (11)	0.0304 (11)	0.0003 (8)	−0.0029 (8)	−0.0015 (8)
C7	0.0284 (12)	0.0152 (10)	0.0185 (9)	0.0022 (8)	−0.0043 (8)	0.0015 (7)
C8	0.0298 (12)	0.0200 (11)	0.0242 (10)	0.0040 (8)	−0.0028 (8)	−0.0009 (8)
C9	0.0486 (16)	0.0264 (13)	0.0214 (10)	0.0145 (11)	−0.0024 (9)	−0.0026 (9)
C10	0.0510 (17)	0.0194 (12)	0.0266 (11)	0.0077 (10)	−0.0163 (10)	−0.0051 (9)
C11	0.0389 (14)	0.0191 (12)	0.0342 (12)	−0.0030 (9)	−0.0152 (10)	0.0039 (9)
C12	0.0339 (13)	0.0194 (11)	0.0208 (9)	−0.0012 (8)	−0.0045 (8)	0.0049 (8)
N1A	0.0206 (9)	0.0191 (10)	0.0328 (8)	−0.0015 (7)	−0.0039 (9)	0.0075 (7)
C1A	0.0374 (15)	0.0314 (15)	0.0437 (14)	0.0055 (11)	0.0083 (11)	0.0069 (10)
C2A	0.0406 (16)	0.0328 (15)	0.0439 (13)	−0.0097 (11)	−0.0187 (11)	0.0087 (11)

Geometric parameters (Å, º)

P1—O2	1.4811 (15)	C7—C12	1.397 (3)
P1—O3	1.5269 (16)	C7—C8	1.399 (3)
P1—O1	1.6190 (16)	C8—C9	1.391 (3)
P1—C1	1.782 (2)	C8—H8	0.9500
P2—O4	1.4791 (16)	C9—C10	1.385 (4)
P2—O5	1.5260 (15)	C9—H9	0.9500
P2—O1	1.6193 (17)	C10—C11	1.384 (4)
P2—C7	1.782 (2)	C10—H10	0.9500
O3—H3O	1.2028 (15)	C11—C12	1.385 (3)
O5—H5O	1.211 (3)	C11—H11	0.9500
C1—C2	1.390 (3)	C12—H12	0.9500
C1—C6	1.401 (3)	N1A—C2A	1.475 (3)
C2—C3	1.397 (3)	N1A—C1A	1.481 (3)
C2—H2	0.9500	N1A—H1N	0.89 (3)
C3—C4	1.379 (4)	N1A—H2N	0.88 (3)
C3—H3	0.9500	C1A—H1A1	0.9800
C4—C5	1.378 (4)	C1A—H1A2	0.9800
C4—H4	0.9500	C1A—H1A3	0.9800
C5—C6	1.387 (3)	C2A—H2A1	0.9800
C5—H5	0.9500	C2A—H2A2	0.9800
C6—H6	0.9500	C2A—H2A3	0.9800
O2—P1—O3	117.14 (8)	C12—C7—P2	120.22 (17)
O2—P1—O1	111.66 (9)	C8—C7—P2	119.56 (17)
O3—P1—O1	105.66 (8)	C9—C8—C7	119.8 (2)
O2—P1—C1	112.48 (9)	C9—C8—H8	120.1
O3—P1—C1	106.88 (9)	C7—C8—H8	120.1
O1—P1—C1	101.69 (8)	C10—C9—C8	119.8 (2)
O4—P2—O5	117.31 (8)	C10—C9—H9	120.1
O4—P2—O1	111.43 (9)	C8—C9—H9	120.1
O5—P2—O1	105.81 (8)	C11—C10—C9	120.5 (2)
O4—P2—C7	112.39 (10)	C11—C10—H10	119.8
O5—P2—C7	107.00 (9)	C9—C10—H10	119.8
O1—P2—C7	101.54 (9)	C10—C11—C12	120.3 (2)
P1—O1—P2	124.96 (8)	C10—C11—H11	119.8
H3O—O3—P1	118.9 (3)	C12—C11—H11	119.8
H5O—O5—P2	118.3 (4)	C11—C12—C7	119.7 (2)
P2—O5—H5O	118.3 (4)	C11—C12—H12	120.1
C2—C1—C6	119.71 (19)	C7—C12—H12	120.1
C2—C1—P1	120.48 (16)	C2A—N1A—C1A	114.59 (19)
C6—C1—P1	119.45 (15)	C2A—N1A—H1N	106.7 (17)
C1—C2—C3	119.5 (2)	C1A—N1A—H1N	109.9 (16)
C1—C2—H2	120.3	C2A—N1A—H2N	107.5 (16)
C3—C2—H2	120.3	C1A—N1A—H2N	107.8 (17)
C4—C3—C2	120.3 (2)	H1N—N1A—H2N	110 (2)
C4—C3—H3	119.8	N1A—C1A—H1A1	109.5
C2—C3—H3	119.8	N1A—C1A—H1A2	109.5
C5—C4—C3	120.5 (2)	H1A1—C1A—H1A2	109.5
C5—C4—H4	119.8	N1A—C1A—H1A3	109.5
C3—C4—H4	119.8	H1A1—C1A—H1A3	109.5
C4—C5—C6	120.0 (2)	H1A2—C1A—H1A3	109.5
C4—C5—H5	120.0	N1A—C2A—H2A1	109.5
C6—C5—H5	120.0	N1A—C2A—H2A2	109.5
C5—C6—C1	120.0 (2)	H2A1—C2A—H2A2	109.5
C5—C6—H6	120.0	N1A—C2A—H2A3	109.5
C1—C6—H6	120.0	H2A1—C2A—H2A3	109.5
C12—C7—C8	119.8 (2)	H2A2—C2A—H2A3	109.5
O2—P1—O1—P2	−89.86 (13)	C4—C5—C6—C1	1.2 (3)
O3—P1—O1—P2	38.52 (13)	C2—C1—C6—C5	0.8 (3)
C1—P1—O1—P2	149.99 (12)	P1—C1—C6—C5	−172.32 (17)
O4—P2—O1—P1	−88.63 (13)	O4—P2—C7—C12	−171.69 (16)
O5—P2—O1—P1	39.93 (13)	O5—P2—C7—C12	58.15 (18)
C7—P2—O1—P1	151.52 (13)	O1—P2—C7—C12	−52.53 (18)
O2—P1—C1—C2	10.3 (2)	O4—P2—C7—C8	15.89 (19)
O3—P1—C1—C2	−119.55 (18)	O5—P2—C7—C8	−114.26 (16)
O1—P1—C1—C2	129.91 (17)	O1—P2—C7—C8	135.06 (16)
O2—P1—C1—C6	−176.58 (16)	C12—C7—C8—C9	−1.8 (3)
O3—P1—C1—C6	53.52 (19)	P2—C7—C8—C9	170.63 (17)
O1—P1—C1—C6	−57.02 (18)	C7—C8—C9—C10	0.5 (3)
C6—C1—C2—C3	−1.8 (3)	C8—C9—C10—C11	1.8 (3)
P1—C1—C2—C3	171.24 (18)	C9—C10—C11—C12	−2.6 (3)
C1—C2—C3—C4	0.8 (4)	C10—C11—C12—C7	1.2 (3)
C2—C3—C4—C5	1.2 (4)	C8—C7—C12—C11	1.0 (3)
C3—C4—C5—C6	−2.2 (4)	P2—C7—C12—C11	−171.42 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3O···O3^i	1.2028 (15)	1.2028 (15)	2.406 (3)	179 (5)
O5—H5O···O5^i	1.211 (3)	1.211 (3)	2.418 (3)	174 (5)
N1A—H1N···O2	0.89 (3)	1.89 (3)	2.765 (2)	170 (3)
N1A—H2N···O4^i	0.88 (3)	1.89 (3)	2.748 (3)	165 (3)

Symmetry code: (i) −x+1, −y+1, z.