Ethane-1,2-diylbis(methyl­phosphinic acid)

In the title compound, C₄H₁₂O₄P₂, there are two crystallographically independent half-mol­ecules in the asymmetric unit, both molecules lying on centres of symmetry. Each mol­ecule is connected on both sides to neighbouring mol­ecules via strong O—H...O hydrogen bonds. The –POOH groups accept and donate one hydrogen bond in interactions with the neighbouring –POOH group of the adjacent mol­ecule, to give one-dimensional chains along [10]. As each phosphinic acid group donates and accepts one hydrogen bond, the connection between the mol­ecules is best described by a ring motif which can be classified by the Etter symbol R₂²(8).

Key indicators

• Single-crystal X-ray study
• T = 290 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.036
• wR factor = 0.079
• Data-to-parameter ratio = 17.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.09 Ratio

Alert level G
PLAT793_ALERT_2_G Check the Absolute Configuration of P1     .....          R
PLAT793_ALERT_2_G Check the Absolute Configuration of P2     .....          R

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound, [HOO(CH₃)P-(CH₂)₂-P(CH₃)OOH, crystallizes in the monoclinic centrosymmetric space group P2₁/c with two crystallographically independent molecules in the asymmetric unit both of them lying on a centre of symmetry. The molecules are connected on both sides to the next molecules via strong O—H···H hydrogen bonds. The bond lengths and angles in the two crystallographic independent molecules are identical within the ranges of their standard uncertainties. As each posphinic acid group donates and accepts one hydrogen bond the motif of this connection between the molecules is best described by an eight-membered ring (Fig.1) which can be classified by the Etter symbol R²₂(8) (Etter et al., 1990). A motif which is well known for acetic acid and its derivatives. Each –POOH group accepts and donates one hydrogen bond to the neighbouring –POOH groups of the next molecules to give a one-dimensional chains along [10–1]. This was surprising to us, as the very similar ethane-1,2-diylbis(phosphinic acid) forms a two-dimensional hydrogen bonded network (Bruckmann et al., 1999).

Related literature

For related literature, see: Bruckmann et al. (1999); Etter et al. (1990); Sicken et al. (2000).

S2. Experimental

The title compound is generally available by methods described in the literature (Sicken et al., 2000). Recrystallization of the raw material from ethanolic solution at room temperature gave block shaped, colourless crystals.

S3. Refinement

After refinement of all non-hydrogen atoms using anisotropic displacement parameters, all H atom positions were obtained from successive difference Fourier synthesis. Atom coordinates as well as individual U_iso values are refined freely for each hydrogen atom.

Computing details

Data collection: R3m/V Software (Siemens, 1989); cell refinement: R3m/V Software (Siemens, 1989); data reduction: R3m/V Software (Siemens, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. : Part of the hydrogen bonded chain of the title structure. (displacement ellipsoids at the 50% probability level, H-atoms drawn with arbitrary radius, ' = -x, 1 - y, 2 - z; '' = 1 - x, 1 - y, 1 - z)

Ethane-1,2-diylbis(methylphosphinic acid)

Crystal data

C4H12O4P2	F(000) = 392
Mr = 186.08	Dx = 1.458 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 37 reflections
a = 6.7761 (18) Å	θ = 5.1–14.3°
b = 18.703 (8) Å	µ = 0.47 mm^−1
c = 6.8401 (15) Å	T = 290 K
β = 102.09 (3)°	Block, colourless
V = 847.7 (5) Å^3	0.40 × 0.35 × 0.30 mm
Z = 4

Data collection

Nicolet/Siemens P21/P3-four-circle diffractometer	Rint = 0.023
Radiation source: fine-focus sealed tube	θmax = 30.0°, θmin = 2.2°
Graphite monochromator	h = 0→9
ω scans	k = −26→26
4847 measured reflections	l = −9→9
2466 independent reflections	3 standard reflections every 100 reflections
1879 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: difference Fourier map
wR(F^2) = 0.079	All H-atom parameters refined
S = 1.01	w = 1/[σ^2(Fo^2) + (0.025P)^2 + 0.41P] where P = (Fo^2 + 2Fc^2)/3
2466 reflections	(Δ/σ)max = 0.003
139 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.34 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 > 2σ(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	0.10537 (7)	0.60187 (2)	0.89929 (7)	0.03542 (12)
O1	0.0298 (2)	0.59213 (9)	0.6716 (2)	0.0477 (3)
H1	0.114 (6)	0.606 (2)	0.586 (6)	0.145 (15)*
O2	0.32968 (19)	0.59006 (8)	0.96702 (19)	0.0455 (3)
C1	0.0385 (5)	0.68801 (12)	0.9733 (4)	0.0563 (6)
H11	0.067 (4)	0.6933 (14)	1.116 (4)	0.070 (8)*
H12	0.106 (5)	0.7222 (17)	0.917 (5)	0.094 (10)*
H13	−0.088 (4)	0.6940 (15)	0.925 (4)	0.075 (9)*
C2	−0.0220 (3)	0.53869 (9)	1.0246 (3)	0.0371 (4)
H21	0.017 (3)	0.5445 (12)	1.163 (3)	0.047 (6)*
H22	−0.157 (3)	0.5475 (12)	0.984 (3)	0.051 (6)*
P2	0.48253 (7)	0.61724 (2)	0.51341 (7)	0.03302 (11)
O3	0.25753 (19)	0.62778 (7)	0.44442 (18)	0.0412 (3)
O4	0.5560 (2)	0.62903 (7)	0.7409 (2)	0.0421 (3)
H4	0.470 (5)	0.6132 (18)	0.826 (5)	0.117 (12)*
C3	0.6086 (4)	0.67852 (12)	0.3826 (4)	0.0501 (5)
H31	0.575 (4)	0.7228 (16)	0.410 (4)	0.078 (8)*
H32	0.565 (4)	0.6729 (14)	0.247 (4)	0.065 (8)*
H33	0.738 (4)	0.6751 (15)	0.426 (4)	0.079 (9)*
C4	0.5508 (3)	0.52908 (9)	0.4481 (3)	0.0343 (3)
H41	0.693 (3)	0.5257 (11)	0.494 (3)	0.042 (5)*
H42	0.513 (3)	0.5270 (11)	0.311 (3)	0.044 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0352 (2)	0.0375 (2)	0.0329 (2)	−0.00097 (17)	0.00569 (17)	0.00385 (18)
O1	0.0359 (7)	0.0712 (10)	0.0338 (7)	−0.0062 (6)	0.0024 (5)	0.0038 (6)
O2	0.0350 (7)	0.0632 (9)	0.0364 (7)	−0.0004 (6)	0.0030 (5)	0.0047 (6)
C1	0.0677 (16)	0.0365 (10)	0.0624 (16)	0.0033 (10)	0.0087 (12)	0.0018 (10)
C2	0.0403 (9)	0.0362 (9)	0.0361 (9)	0.0017 (7)	0.0108 (7)	0.0015 (7)
P2	0.0359 (2)	0.02862 (19)	0.0346 (2)	−0.00337 (16)	0.00759 (17)	0.00217 (17)
O3	0.0379 (7)	0.0472 (7)	0.0371 (7)	0.0038 (5)	0.0047 (5)	0.0049 (5)
O4	0.0374 (7)	0.0493 (8)	0.0378 (7)	−0.0064 (6)	0.0037 (5)	−0.0068 (6)
C3	0.0576 (14)	0.0369 (10)	0.0563 (13)	−0.0105 (9)	0.0133 (11)	0.0095 (9)
C4	0.0380 (9)	0.0299 (8)	0.0357 (9)	−0.0019 (7)	0.0095 (7)	0.0018 (7)

Geometric parameters (Å, º)

P1—O2	1.5096 (14)	P2—O3	1.5115 (14)
P1—O1	1.5452 (15)	P2—O4	1.5468 (14)
P1—C1	1.776 (2)	P2—C3	1.779 (2)
P1—C2	1.7850 (19)	P2—C4	1.7942 (19)
O1—H1	0.94 (4)	O4—H4	0.95 (4)
C1—H11	0.96 (3)	C3—H31	0.89 (3)
C1—H12	0.92 (3)	C3—H32	0.92 (3)
C1—H13	0.86 (3)	C3—H33	0.87 (3)
C2—C2^i	1.529 (3)	C4—C4^ii	1.539 (3)
C2—H21	0.93 (2)	C4—H41	0.95 (2)
C2—H22	0.91 (2)	C4—H42	0.92 (2)
O2—P1—O1	113.08 (8)	O3—P2—O4	112.74 (8)
O2—P1—C1	110.24 (12)	O3—P2—C3	108.55 (11)
O1—P1—C1	110.11 (12)	O4—P2—C3	109.08 (11)
O2—P1—C2	108.23 (9)	O3—P2—C4	109.76 (8)
O1—P1—C2	108.33 (9)	O4—P2—C4	109.63 (8)
C1—P1—C2	106.60 (11)	C3—P2—C4	106.90 (11)
P1—O1—H1	119 (2)	P2—O4—H4	118 (2)
P1—C1—H11	112.0 (16)	P2—C3—H31	108.9 (18)
P1—C1—H12	109.5 (19)	P2—C3—H32	110.5 (16)
H11—C1—H12	110 (2)	H31—C3—H32	106 (2)
P1—C1—H13	107.7 (19)	P2—C3—H33	109.7 (19)
H11—C1—H13	110 (2)	H31—C3—H33	106 (3)
H12—C1—H13	107 (3)	H32—C3—H33	115 (2)
C2^i—C2—P1	112.62 (17)	C4^ii—C4—P2	111.78 (16)
C2^i—C2—H21	107.8 (14)	C4^ii—C4—H41	108.8 (12)
P1—C2—H21	110.3 (13)	P2—C4—H41	106.0 (12)
C2^i—C2—H22	109.4 (15)	C4^ii—C4—H42	112.7 (13)
P1—C2—H22	106.6 (14)	P2—C4—H42	105.1 (13)
H21—C2—H22	110.1 (18)	H41—C4—H42	112.3 (17)
O2—P1—C2—C2^i	−61.3 (2)	O3—P2—C4—C4^ii	−62.1 (2)
O1—P1—C2—C2^i	61.7 (2)	O4—P2—C4—C4^ii	62.3 (2)
C1—P1—C2—C2^i	−179.8 (2)	C3—P2—C4—C4^ii	−179.64 (19)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4···O2	0.95 (4)	1.55 (4)	2.504 (2)	178 (3)
O1—H1···O3	0.94 (4)	1.56 (4)	2.499 (2)	179 (4)