Ab initio structure determination of triphenyl phosphite by powder synchrotron X-ray diffraction

The crystal structure of the glass-forming molecular liquid triphenyl phosphite [TPP, P(OC₆H₅)₃, six torsional degrees of freedom] has been solved ab initio at 110 K from powder synchrotron X-ray diffraction data by real-space methods (simulated annealing) followed by rigid-body Rietveld refinements. The symmetry is trigonal, with a rhombohedral lattice, space group . The associated hexagonal cell, which is a sixfold multiple of the previously published less-symmetric monoclinic cell [Hédoux et al. (1999). Phys. Rev. B, 60, 9390–9395], is unusually large [V = 7075.7 (4) ų, Z = 18] and displays a noteworthy platelet-like shape [a = 37.766 (1) and c = 5.7286 (2) Å]. The TPP molecule does not exhibit the ideal C₃ symmetric propeller shape, its conformation being on the contrary almost mirror-symmetric, with the pseudo-mirror plane passing through the P—O1 bond and two carbon atoms in para position with respect to the O1 atom. The hitherto unknown topological features of crystalline TPP, including unusual intermolecular weak C—H...O hydrogen-bonding networks, are presented and discussed in the scope of the `glacial state' problem.

Computing details

Data collection: NICE; cell refinement: JANA2000; program(s) used to solve structure: DASH; program(s) used to refine structure: JANA2000; molecular graphics: CAMERON; software used to prepare material for publication: JANA2000.

Figures

triphenyl phosphite

Crystal data

C18H15O3P	F(000) = 2916
Mr = 310.27	Dx = 1.311 Mg m^−3
Trigonal, R3	Synchrotron radiation, λ = 0.850871 Å
a = 37.766 (1) Å	µ = 0.25 mm^−1
c = 5.7286 (2) Å	T = 110 K
V = 7075.7 (4) Å^3	colourless
Z = 18	cylinder, 5 × 1 mm

Data collection

ESRF beamline BM16 diffractometer	Scan method: continuous
Radiation source: synchrotron, ESRF beamline BM16	Absorption correction: for a cylinder mounted on the ϕ axis ?
Si 111 monochromator	Tmin = ?, Tmax = ?
Specimen mounting: glass capillary	2θmin = 1.500°, 2θmax = 45.000°, 2θstep = 0.004°
Data collection mode: transmission

Refinement

Refinement on Inet	66 parameters
Least-squares matrix: full	6 restraints
Rp = 0.047	4 constraints
Rwp = 0.059	Only H-atom displacement parameters refined
Rexp = 0.046	Weighting scheme based on measured s.u.'s
χ^2 = 2.690	(Δ/σ)max = 0.006
14485 data points	Background function: Chebyshev polynomial
Profile function: pseudo-Voigt

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
P	0.23853 (15)	0.07191 (17)	0.0648 (8)	0.029 (3)
O3	0.19150 (18)	0.0520 (2)	0.1450 (15)	0.030 (4)*
O1	0.2558 (3)	0.1203 (2)	0.0715 (16)	0.043 (4)*
O2	0.2521 (2)	0.0641 (3)	0.3153 (11)	0.027 (4)*
C11	0.24871 (12)	0.14104 (11)	0.2530 (8)	0.011 (2)*
C12	0.21488 (12)	0.14655 (11)	0.2382 (8)	0.011 (2)*
C13	0.20707 (12)	0.16697 (11)	0.4162 (8)	0.011 (2)*
C14	0.23309 (12)	0.18176 (11)	0.6088 (8)	0.011 (2)*
C15	0.26682 (12)	0.17625 (11)	0.6236 (8)	0.011 (2)*
C16	0.27463 (12)	0.15584 (11)	0.4457 (8)	0.011 (2)*
H12	0.19624 (12)	0.13588 (11)	0.1002 (8)	0.052 (11)*
H13	0.18288 (12)	0.17098 (11)	0.4057 (8)	0.052 (11)*
H14	0.22754 (12)	0.19637 (11)	0.7367 (8)	0.052 (11)*
H15	0.28542 (12)	0.18694 (11)	0.7618 (8)	0.052 (11)*
H16	0.29881 (12)	0.15181 (11)	0.4564 (8)	0.052 (11)*
C21	0.28958 (16)	0.06614 (9)	0.3528 (8)	0.010 (2)*
C22	0.32218 (16)	0.08403 (9)	0.1962 (8)	0.010 (2)*
C23	0.35729 (16)	0.08131 (9)	0.2360 (8)	0.010 (2)*
C24	0.35961 (16)	0.06081 (9)	0.4323 (8)	0.010 (2)*
C25	0.32701 (16)	0.04293 (9)	0.5890 (8)	0.010 (2)*
C26	0.29200 (16)	0.04564 (9)	0.5492 (8)	0.010 (2)*
H22	0.32038 (16)	0.09877 (9)	0.0558 (8)	0.052 (11)*
H23	0.38072 (16)	0.09401 (9)	0.1240 (8)	0.052 (11)*
H24	0.38474 (16)	0.05894 (9)	0.4609 (8)	0.052 (11)*
H25	0.32874 (16)	0.02818 (9)	0.7297 (8)	0.052 (11)*
H26	0.26862 (16)	0.03289 (9)	0.6615 (8)	0.052 (11)*
C31	0.16122 (10)	0.04118 (13)	−0.0293 (7)	0.013 (2)*
C32	0.12334 (10)	0.00751 (13)	0.0257 (7)	0.013 (2)*
C33	0.09050 (10)	−0.00500 (13)	−0.1271 (7)	0.013 (2)*
C34	0.09545 (10)	0.01626 (13)	−0.3348 (7)	0.013 (2)*
C35	0.13333 (10)	0.05003 (13)	−0.3898 (7)	0.013 (2)*
C36	0.16627 (10)	0.06244 (13)	−0.2371 (7)	0.013 (2)*
H32	0.11971 (10)	−0.00768 (13)	0.1749 (7)	0.052 (11)*
H33	0.06339 (10)	−0.02924 (13)	−0.0878 (7)	0.052 (11)*
H34	0.07185 (10)	0.00729 (13)	−0.4442 (7)	0.052 (11)*
H35	0.13688 (10)	0.06532 (13)	−0.5385 (7)	0.052 (11)*
H36	0.19347 (10)	0.08656 (13)	−0.2765 (7)	0.052 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P	0.023 (4)	0.047 (5)	0.027 (3)	0.026 (4)	0.011 (3)	0.009 (4)

Geometric parameters (Å, º)

O3—P	1.611 (8)	O1—C15^iii	3.216 (10)
O3—O1	2.542 (9)	O1—C15	3.709 (10)
O3—O2	2.315 (13)	O1—C16^iii	3.769 (10)
O3—C11	3.015 (8)	O1—C16	2.439 (10)
O3—C12	3.265 (10)	O1—C21	3.319 (12)
O3—C14^i	3.990 (11)	O1—C22	3.479 (13)
O3—C16	3.986 (7)	O1—C31	3.369 (8)
O3—C21	3.667 (10)	O1—C36	3.456 (9)
O3—C31	1.416 (8)	O2—P	1.601 (10)
O3—C32	2.365 (6)	O2—O3	2.315 (13)
O3—C33	3.661 (7)	O2—O1	2.487 (14)
O3—C35	3.748 (9)	O2—C11	2.995 (14)
O3—C35^ii	3.431 (9)	O2—C13^i	3.941 (9)
O3—C36	2.496 (10)	O2—C14^i	3.829 (11)
O3—C36^ii	3.738 (10)	O2—C16	3.216 (12)
O1—P	1.605 (9)	O2—C21	1.394 (13)
O1—O3	2.542 (9)	O2—C22	2.457 (12)
O1—O2	2.487 (14)	O2—C23	3.717 (13)
O1—C11	1.406 (11)	O2—C25	3.654 (13)
O1—C12	2.411 (13)	O2—C26	2.365 (13)
O1—C13	3.692 (12)	O2—C31	3.669 (10)
O1—C14^iii	3.891 (11)
O2—P—O1	101.8 (5)	O1—C11—C16	121.2 (6)
O2—P—O3	92.2 (5)	O1—C11—C12	118.8 (5)
O1—P—O3	104.5 (6)	O2—C21—C26	116.1 (5)
C11—O1—P	124.8 (6)	O2—C21—C22	123.6 (5)
C21—O2—P	122.5 (6)	O3—C31—C32	114.6 (4)
C31—O3—P	118.5 (6)	O3—C31—C36	125.3 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15···O1^ii	1.00	2.814 (9)	3.216 (10)	104.7 (3)
C35—H35···O3^iii	1.00	2.97 (1)	3.431 (9)	109.0 (3)

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