A monoclinic polymorph of bis(tert-butyl­per­thio­phosphonic) dianhydride

In comparison with the known orthorhombic polymorph oftrans-2,4-di-tert-butyl-2,4-dithioxo-1,3-di­thia-2,4-diphosph­etane, C₈H₁₈P₂S₄, (I) [Shore, Pennington, Noble & Cordes (1988). Phosphorous Sulfur, 39, 153-157], the new crystallographic modification is monoclinic and the corresponding solid density is markedly higher. In both structures, the mol­ecules have 2/m symmetry imposed by space-group symmetry and all corresponding bond lengths and angles are equal within the limits of errors.

S1. Experimental

The title compound, trans-2,4-di-tert-butyl-1,3-dithia-2,4-diphosphetane-2,4-dithione, was prepared during the reaction of tert-butyllithium with pyridine (py) stabilized dithiometaphosphoryl chloride py→ PS₂Cl. Slow dropping of one equivalent of tert-butyllithium into a suspension of py→ PS₂Cl in benzene at 323 K, filtration, evaporation at high vacuum, and recrystallization from toluene produced crystals suitable for X-ray analysis.

Computing details

Data collection: STADI4-1.06 (Stoe & Cie, 1997); cell refinement: STADI4-1.06; data reduction: X-RED1.07 (Stoe & Cie, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

t-butylperthiophosphonic anhydride

Crystal data

C8H18P2S4	F(000) = 320
Mr = 304.40	Dx = 1.422 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
a = 9.7313 (8) Å	Cell parameters from 62 reflections
b = 9.2898 (11) Å	θ = 13.0–17.1°
c = 8.115 (1) Å	µ = 0.86 mm^−1
β = 104.252 (8)°	T = 180 K
V = 711.03 (13) Å^3	Square plate, colorless
Z = 2	0.57 × 0.57 × 0.26 mm

Data collection

Stoe Stadi-4 diffractometer	846 reflections with I > 2σ(I)
Radiation source: fine-focus sealed X-ray tube	Rint = 0.038
Planar graphite monochromator	θmax = 27.6°, θmin = 2.6°
2θ/ω scan, ratio = 1.0, width(ω) = 1.55–1.7°	h = −12→12
Absorption correction: ψ scan (North et al., 1968)	k = −12→12
Tmin = 0.640, Tmax = 0.808	l = −10→10
3495 measured reflections	3 standard reflections every 120 min
876 independent reflections	intensity decay: 4.5%

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)] = 0.025	All H-atom parameters refined
wR(F^2) = 0.064	w = 1/[σ^2(Fo^2) + (0.0387P)^2 + 0.2726P] where P = (Fo^2 + 2Fc^2)/3
S = 1.15	(Δ/σ)max = 0.007
876 reflections	Δρmax = 0.56 e Å^−3
59 parameters	Δρmin = −0.42 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.038 (3)

Special details

Experimental. Recrystallized from toluene. During data collection the crystal was in cold N₂ gas of a cryostream cooler (Oxford Cryosystems, 1992).

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
C1	0.26900 (17)	0.0000	0.7169 (2)	0.0213 (3)
C2	0.3839 (2)	0.0000	0.6188 (2)	0.0316 (4)
H2A	0.340 (3)	0.0000	0.498 (3)	0.041 (7)*
H2B	0.4395 (19)	0.087 (2)	0.642 (2)	0.037 (4)*
C3	0.17746 (16)	0.13571 (17)	0.67561 (18)	0.0340 (3)
H3A	0.140 (2)	0.135 (2)	0.556 (2)	0.046 (5)*
H3B	0.2344 (19)	0.220 (2)	0.710 (2)	0.046 (5)*
H3C	0.103 (2)	0.132 (2)	0.733 (3)	0.050 (5)*
P1	0.34693 (4)	0.0000	0.94995 (5)	0.01647 (16)
S2	0.5000	0.16765 (4)	1.0000	0.01934 (16)
S3	0.20793 (4)	0.0000	1.08369 (5)	0.02503 (16)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0191 (7)	0.0244 (8)	0.0181 (7)	0.000	0.0000 (5)	0.000
C2	0.0287 (9)	0.0455 (12)	0.0207 (8)	0.000	0.0060 (7)	0.000
C3	0.0358 (7)	0.0326 (7)	0.0284 (6)	0.0107 (6)	−0.0019 (5)	0.0039 (5)
P1	0.0127 (2)	0.0172 (2)	0.0189 (2)	0.000	0.00270 (15)	0.000
S2	0.0158 (2)	0.0152 (2)	0.0258 (2)	0.000	0.00289 (15)	0.000
S3	0.0200 (2)	0.0286 (3)	0.0291 (3)	0.000	0.01107 (17)	0.000

Geometric parameters (Å, º)

C1—C2	1.524 (3)	C3—H3B	0.96 (2)
C1—C3^i	1.5324 (18)	C3—H3C	0.96 (2)
C1—C3	1.5324 (18)	P1—S3	1.9314 (6)
C1—P1	1.8561 (16)	P1—S2	2.1240 (4)
C2—H2A	0.96 (3)	P1—S2^ii	2.1240 (4)
C2—H2B	0.962 (18)	S2—P1^ii	2.1240 (4)
C3—H3A	0.951 (18)
C2—C1—C3^i	110.33 (10)	H3A—C3—H3B	110.4 (17)
C2—C1—C3	110.33 (10)	C1—C3—H3C	109.6 (13)
C3^i—C1—C3	110.71 (16)	H3A—C3—H3C	110.8 (16)
C2—C1—P1	111.35 (11)	H3B—C3—H3C	109.7 (17)
C3^i—C1—P1	107.01 (9)	C1—P1—S3	113.92 (6)
C3—C1—P1	107.01 (9)	C1—P1—S2	106.63 (4)
C1—C2—H2A	109.3 (16)	S3—P1—S2	116.601 (16)
C1—C2—H2B	110.3 (10)	C1—P1—S2^ii	106.63 (4)
H2A—C2—H2B	106.6 (12)	S3—P1—S2^ii	116.601 (16)
C1—C3—H3A	106.1 (13)	S2—P1—S2^ii	94.32 (2)
C1—C3—H3B	110.2 (11)	P1—S2—P1^ii	85.68 (2)
C2—C1—P1—S3	180.0	C2—C1—P1—S2^ii	−49.929 (18)
C3^i—C1—P1—S3	−59.36 (10)	C3^i—C1—P1—S2^ii	70.71 (11)
C3—C1—P1—S3	59.36 (10)	C3—C1—P1—S2^ii	−170.57 (9)
C2—C1—P1—S2	49.929 (18)	C1—P1—S2—P1^ii	−108.79 (5)
C3^i—C1—P1—S2	170.57 (9)	S3—P1—S2—P1^ii	122.68 (3)
C3—C1—P1—S2	−70.71 (11)	S2^ii—P1—S2—P1^ii	0.0

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