Metallaborane chemistry. Part IV. Molecular and crystal structures of a ten-atom, twentytwo-electron nido-metallacarbaborane: 2,7-Dimethyl-9,9-bis(triethylphosphine)-2,7-dicarba-9-platina-nido-decaborane(7)

The molecular structure of the title compound has been elucidated by single-crystal X-ray diffraction and refined to R 0.036 for 3 185 independent observed reflections. The compound crystallises in a monoclinic cell of dimensions a = 17.23(1), b = 18.86(1), c = 10.093(6) Å, and β = 126.96(4)°, space group P2₁/a The polyhedral geometry approximates to that of a bicapped (B and C) square antiprism, with the metal atom in a CBBPt prism face, adjacent to the boron cap. The platinum-carbon distance [2.83(1₅) Å] is non-bonding and thus the molecule has a nido-structure with an open BCBPt face. Distortions from the expected closo-structure are ascribed to the preferred planar co-ordination of Pt¹¹ and low polyhedral connectivity of carbon.