Metallaborane chemistry. Part VII. The nido-carbaplatinanonaborane. Molecular and crystal structure of nido-3,8-dimethyl-2,2-bis(triethylphosphine)- 3,8-dicarba-2-platinanonaborane(6)

The molecular structure of the title compound has been determined by analysis of single-crystal X-ray diffraction data recorded on a diffractometer. Two independent molecules crystallise in the asymmetric unit of an orthorhombic cell of dimensions a = 18.868(8), b = 17.143(7), and c = 31.07(2) Å; space group Pbca. Least-squares refinement, by use of 4 542 independent observed reflections, has converged to R 0.069 (all atoms save methyl hydrogens included). Geometrically the nine-atom metallacage is based on a tricapped trigonal prism in which the metal lies in a prism face, adjacent to boron and carbon caps. The other low-connectivity position hosts the second cage carbon atom which binds a B₄ unit possessing a non-bonding B(7)⋯B(9) mean separation of 2.435 Å. This produces an open Pt(2)B(7)C(8)B(9) face and classifies the species as a nido-polyhedron.