10-VERTEX METALLABORANE CLUSTERS - ACTION AS A B-FRAME SUPPORT FOR HETEROBIMETALLIC SPECIES - [7,7-(PME3)2-9,9,9-H(PPH3)(PH2P-ORTHO-C6H4)-NIDO-7,9-PTIRB9H10-4] AND RELATED-COMPOUNDS

Reaction of the nido ten-vertex iridaborane [sym-6,6,6-H(PPh3)(PPh2-ortho-C6H4)-nido-6-IrBH12-5] (1) or its uncyclized analogue 2 with KH followed by cis-[PtCl2(PMe3)2] yields the orange-red air-stable complex [7,7-(PMe3)2-9,9,9-H(PPh3)(Ph2P-ortho-C6H4)-nido-7,9-PtIrB9H10-4] (3) or the corresponding acyclic analogue (4). Compound 3 has been characterized by multi-element NMR spectroscopy and by X-ray crystallography. It crystallizes in the monoclinic space group C2/c with a = 4072.1(8), b = 1509.2(4), c = 1912.9(4) pm, beta = 110.63(2)-degrees, Z = 8, and the structure (R = 0.047 from 5641 reflections) is that of an eleven-vertex nido-dimetallaundecaborane with non-adjacent metal atoms in its open face, and has similarities to the structures of related nido-mono-metallaundecaboranes. During the course of the reaction the starting compounds 1 and 2 are shown to undergo a cluster rearrangement that may also play a role in many hitherto ostensibly disparate ten-vertex cluster reactions.