10-VERTEX POLYHEDRAL MONOCARBABORANE CHEMISTRY - THE NOVEL HIGH-YIELD FORMATION OF THE 10-VERTEX CLOSO COMPOUND [6-(PME2PH)-CLOSO-1-CB9H9] FROM THE THERMOLYSIS OF [8,8-(PME2PH)2-NIDO-8,7-PTCB9H11]

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourless air-stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P2(1)/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, beta = 97.860(7)-degrees and Z = 8, and the structure has been refined to R(R(w)) = 0.045(0.051) for 3 281 observed reflections with F(o) > 2.0sigma(F(o)). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.