Methyl­enebis(phospho­nic difluoride)

The crystal structure of the title compound, CH₂F₄O₂P₂, is characterized by an extensive net of C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](P-C) = 0.002 Å
• R factor = 0.028
• wR factor = 0.075
• Data-to-parameter ratio = 21.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT431_ALERT_2_C Short Inter HL..A Contact  F4     ..  O4      ..       2.97 Ang.
PLAT431_ALERT_2_C Short Inter HL..A Contact  F6     ..  O1      ..       2.90 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2B    ..  O1      ..       2.67 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2B    ..  F4      ..       2.76 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1A    ..  F6      ..       2.71 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           30.52
           From the CIF: _reflns_number_total               3500
           Count of symmetry unique reflns         1828
           Completeness (_total/calc)            191.47%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1672
           Fraction of Friedel pairs measured     0.915
           Are heavy atom types Z>Si present        yes
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 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
   4 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Bis(phosphonates) form an interesting class of hydrolytically stable analogues of pyrophosphate, in which the bridging oxygen atom is replaced by a methylene group or a substituted methylene group. Several members of this class have been employed as therapeutic agents for the treatment of bone disorders such as hypercalcemia of malignancy, osteoporosis, and Paget's disease. Other bis(phosphonates) have been shown to be potent antiparasitic agents or herbicides (Matczak-Jon et al.; 2005, and references cited therein). The corresponding bis(phosphonicdichlorides) such as CH₂(POCl₂)₂ are known since 1961 (Richard et al., 1961; Maier et al., 1965). The crystal structure of CH₂(POCl₂)₂ was determined by Sheldrick (1975). Althoff et al. (1981) first reported the preparation and spectroscopic characterization of the corresponding fluoride, i.e. the title compound methylene-bis(phosphonicdifluoride), CH₂(POF₂)₂. Large, clear, colorless crystals (up to 2 cm in length) originating from the original work published in 1981 were found to be of excellent quality for X-ray diffraction. The crystal structure of the title compound is characterized by an extensive net of C—H···O hydrogen bonds.

Related literature

For related literature, see: Althoff et al. (1981); Maier (1965); Matczak-Jon et al., (2005); Richard et al. (1961); Sheldrick (1975).

S2. Experimental

Large, clear, colorlesss crystals originating from the early work by Althoff et al. (1981) were used in this study.

S3. Refinement

Refinments based on F² (SHELXL97), H atoms are refined in rinding models.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXTL-Plus (Bruker, 1998); molecular graphics: SHELXTL-Plus; software used to prepare material for publication: SHELXTL-Plus.

Figures

	Fig. 1. The molecule of the title compound in the crystal. Thermal ellipsoids represent 50% probability levels.
	Fig. 2. The hydrogen-bonded network of the title compound in the crystal.

Methylenebis(phosphonic difluoride)

Crystal data

CH2F4O2P2	F(000) = 720
Mr = 183.97	Dx = 2.132 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2 c -2 n	Cell parameters from 5368 reflections
a = 16.975 (2) Å	θ = 2.8–30.5°
b = 5.2277 (6) Å	µ = 0.77 mm^−1
c = 12.9176 (14) Å	T = 173 K
V = 1146.3 (2) Å^3	Plate, colourless
Z = 8	0.43 × 0.27 × 0.13 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	3500 independent reflections
Radiation source: fine-focus sealed tube	3205 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
Detector resolution: 8.192 pixels mm^-1	θmax = 30.5°, θmin = 2.4°
ω scans	h = −24→24
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	k = −7→7
Tmin = 0.733, Tmax = 0.907	l = −18→18
18754 measured reflections

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)] = 0.028	H-atom parameters constrained
wR(F^2) = 0.076	w = 1/[σ^2(Fo^2) + (0.0533P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
3500 reflections	Δρmax = 0.57 e Å^−3
163 parameters	Δρmin = −0.54 e Å^−3
1 restraint	Absolute structure: Flack (1983), with 1672 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.03 (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	0.55572 (3)	0.28344 (8)	0.60836 (4)	0.02034 (12)
P2	0.55486 (3)	0.02274 (8)	0.81045 (4)	0.02008 (10)
P4	0.30379 (3)	0.79236 (8)	0.76166 (4)	0.02068 (11)
P3	0.30600 (3)	0.54835 (8)	0.55714 (4)	0.01888 (10)
F2	0.59439 (9)	0.5203 (2)	0.56183 (12)	0.0347 (3)
F3	0.49330 (9)	0.1952 (2)	0.86152 (13)	0.0327 (3)
F7	0.33664 (9)	1.0365 (2)	0.80986 (13)	0.0354 (3)
F5	0.24222 (8)	0.7124 (2)	0.50573 (12)	0.0323 (3)
O3	0.27660 (9)	0.3092 (2)	0.59923 (13)	0.0248 (3)
F4	0.61055 (8)	−0.0141 (2)	0.90233 (10)	0.0296 (3)
O4	0.21851 (10)	0.7812 (3)	0.75682 (15)	0.0288 (4)
O1	0.47055 (10)	0.2938 (3)	0.61383 (15)	0.0299 (4)
O2	0.52357 (10)	−0.2127 (2)	0.76811 (15)	0.0276 (3)
F6	0.36236 (8)	0.5180 (2)	0.46534 (10)	0.0270 (2)
C2	0.35521 (12)	0.7605 (3)	0.64298 (17)	0.0179 (4)
H2A	0.4090	0.6954	0.6568	0.021*
H2B	0.3601	0.9306	0.6099	0.021*
F1	0.58654 (8)	0.0785 (3)	0.53391 (11)	0.0347 (3)
C1	0.60738 (12)	0.2305 (3)	0.72558 (17)	0.0191 (4)
H1A	0.6163	0.3964	0.7606	0.023*
H1B	0.6595	0.1547	0.7099	0.023*
F8	0.34007 (9)	0.5934 (3)	0.83358 (11)	0.0370 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0220 (3)	0.01534 (18)	0.0237 (3)	0.00100 (16)	−0.0022 (2)	0.00045 (16)
P2	0.0230 (2)	0.01312 (17)	0.0241 (2)	−0.00233 (14)	0.00020 (18)	0.00064 (17)
P4	0.0224 (3)	0.01646 (18)	0.0231 (3)	0.00051 (16)	0.0025 (2)	−0.00196 (17)
P3	0.02080 (19)	0.01297 (17)	0.0229 (2)	−0.00030 (15)	−0.00179 (18)	−0.00083 (16)
F2	0.0438 (7)	0.0267 (6)	0.0335 (7)	−0.0073 (5)	−0.0018 (7)	0.0121 (5)
F3	0.0314 (7)	0.0262 (5)	0.0404 (8)	0.0013 (5)	0.0136 (6)	−0.0029 (5)
F7	0.0416 (7)	0.0296 (6)	0.0350 (7)	−0.0071 (5)	0.0048 (6)	−0.0159 (6)
F5	0.0312 (7)	0.0256 (6)	0.0403 (9)	0.0045 (5)	−0.0145 (6)	0.0006 (5)
O3	0.0265 (7)	0.0155 (6)	0.0324 (8)	−0.0045 (5)	−0.0004 (6)	−0.0007 (5)
F4	0.0439 (7)	0.0194 (5)	0.0254 (6)	−0.0008 (5)	−0.0078 (5)	0.0019 (4)
O4	0.0233 (7)	0.0256 (6)	0.0376 (10)	0.0014 (5)	0.0074 (8)	−0.0016 (6)
O1	0.0227 (8)	0.0269 (6)	0.0402 (10)	0.0032 (6)	−0.0066 (8)	−0.0007 (6)
O2	0.0313 (8)	0.0165 (5)	0.0351 (9)	−0.0070 (5)	−0.0029 (7)	−0.0007 (5)
F6	0.0385 (6)	0.0194 (5)	0.0229 (5)	0.0002 (4)	0.0046 (5)	−0.0021 (4)
C2	0.0173 (9)	0.0131 (6)	0.0231 (11)	−0.0013 (5)	0.0017 (8)	−0.0018 (6)
F1	0.0400 (8)	0.0331 (6)	0.0310 (7)	0.0070 (6)	−0.0023 (5)	−0.0132 (5)
C1	0.0167 (9)	0.0146 (6)	0.0258 (12)	−0.0007 (6)	0.0004 (9)	0.0006 (6)
F8	0.0442 (8)	0.0361 (7)	0.0306 (7)	0.0065 (6)	−0.0010 (6)	0.0119 (5)

Geometric parameters (Å, º)

P1—O1	1.4484 (17)	P4—F7	1.5256 (13)
P1—F2	1.5248 (13)	P4—C2	1.772 (2)
P1—F1	1.5320 (14)	P3—O3	1.4518 (14)
P1—C1	1.772 (2)	P3—F6	1.5318 (14)
P2—O2	1.4478 (14)	P3—F5	1.5324 (14)
P2—F4	1.5295 (13)	P3—C2	1.777 (2)
P2—F3	1.5296 (14)	C2—H2A	0.9900
P2—C1	1.782 (2)	C2—H2B	0.9900
P4—O4	1.4501 (17)	C1—H1A	0.9900
P4—F8	1.5244 (14)	C1—H1B	0.9900
O1—P1—F2	114.74 (9)	O3—P3—F6	114.55 (8)
O1—P1—F1	113.44 (9)	O3—P3—F5	113.66 (9)
F2—P1—F1	99.99 (9)	F6—P3—F5	99.42 (8)
O1—P1—C1	117.27 (11)	O3—P3—C2	117.73 (10)
F2—P1—C1	104.52 (9)	F6—P3—C2	104.72 (9)
F1—P1—C1	104.97 (8)	F5—P3—C2	104.67 (8)
O2—P2—F4	114.39 (8)	P4—C2—P3	111.53 (10)
O2—P2—F3	114.41 (9)	P4—C2—H2A	109.3
F4—P2—F3	99.31 (8)	P3—C2—H2A	109.3
O2—P2—C1	117.98 (11)	P4—C2—H2B	109.3
F4—P2—C1	104.18 (9)	P3—C2—H2B	109.3
F3—P2—C1	104.36 (8)	H2A—C2—H2B	108.0
O4—P4—F8	113.70 (9)	P1—C1—P2	111.93 (11)
O4—P4—F7	114.59 (9)	P1—C1—H1A	109.2
F8—P4—F7	100.04 (9)	P2—C1—H1A	109.2
O4—P4—C2	116.78 (11)	P1—C1—H1B	109.2
F8—P4—C2	105.32 (8)	P2—C1—H1B	109.2
F7—P4—C2	104.58 (9)	H1A—C1—H1B	107.9
O4—P4—C2—P3	−34.20 (13)	O1—P1—C1—P2	34.75 (13)
F8—P4—C2—P3	93.04 (12)	F2—P1—C1—P2	163.05 (10)
F7—P4—C2—P3	−162.01 (10)	F1—P1—C1—P2	−92.20 (12)
O3—P3—C2—P4	−44.90 (14)	O2—P2—C1—P1	48.12 (14)
F6—P3—C2—P4	−173.47 (9)	F4—P2—C1—P1	176.18 (9)
F5—P3—C2—P4	82.42 (12)	F3—P2—C1—P1	−80.12 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O1	0.99	2.41	3.151 (2)	131
C2—H2A···O2^i	0.99	2.47	3.286 (3)	140
C2—H2B···O3^i	0.99	2.44	3.214 (2)	135
C2—H2B···O1^i	0.99	2.67	3.428 (2)	134
C2—H2B···F4^ii	0.99	2.76	3.429 (2)	125
C1—H1A···O4^iii	0.99	2.42	3.200 (2)	135
C1—H1A···O2^i	0.99	2.58	3.286 (2)	128
C1—H1A···F6^iv	0.99	2.71	3.404 (3)	128
C1—H1B···O3^v	0.99	2.46	3.310 (3)	144
C1—H1B···O4^v	0.99	2.56	3.298 (2)	131

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