CRYSTAL AND MOLECULAR STRUCTURE OF PHOSPHORUS TRIFLUORIDE-TRIS(DIFLUOROBORYL)BORANE B4F6.PF3

The crystal structure of phosphorus trifluoride-tris(difluorobory 1)borane, B4F6.PF3, has been determined by an X-ray diffraction study of single-crystal specimens. The orthorhombic unit cell, space group Pniiia, with a = 13.893 ± 0.005 Å, b = 10.578 ± 0.005 Å, and c = 6.075 ± 0.005 Å, contains four formula units. The calculated density is 1.82 g/cm3. The structure was solved by statistical methods and refined by full-matrix least squares to a conventional R of 9.3% for 703 data collected by counter methods (6.7% for the 603 nonzero data). The molecule consists of a central boron atom, tetrahedrally bonded to three BF2 groups and the PF3 group in such a way that the molecule has approximately 3m (C3v) point symmetry, one mirror of which is required by the crystal symmetry. Distances found (uncorrected for thermal motion) are: B-F, 1.305 Å; B-B, 1.68 Å; B-P, 1.82o Å; P-F, 1.51 Å (all ± 0.015 Å). © 1969, American Chemical Society. All rights reserved.