Molecular and crystal structure of 3,3-bis(triethylphosphine)-1,2-di-carba-3-platinadodecaborane(11), and molecular-orbital analysis of the ‘slip’ distortion in carbametallaboranes

Abstract

Crystals of the title compound are monoclinic, space group P2₁/n with unit-cell dimensions a= 9.375(4), b= 15.985(3), c= 16.033(7)Å, and β= 93.56(5)°. The structure has been solved using 6 068 observed reflections recorded at ca. 215 K on a four-circle diffractometer, and refined by least squares to R 0.047. The geometry of the cage is that of a highly distorted icosahedron in which the platin urn atom ‘slips’ towards B (8) and the metalbonded face ‘folds’ across B(4)… B(7). Molecular-orbital calculations based on the extended- Hückel approximation have accounted for the ‘slip’ and ‘fold’ distortions observed in this and related Carbametallaboranes.