Polyhedral metallaphosphaborane chemistry: the preparation, molecular structure, and nuclear magnetic resonance study of [2-Ph-1,1-(PMe2Ph)2-closo-1,2-PtPB10H10], and some related chemistry

Abstract

The reaction of [B₁₀H₁₁PPh]^– with cis-[PtCl₂(PMe₂Ph)₂] in CH₂Cl₂ yields the new closo twelve-vertex species [(PMe₂Ph)₂PtB₁₀H₁₀PPh](43% yield) and small quantities of the known nine-vertex arachno-[(PMe₂Ph)₂PtB₈H₁₂]. Crystals of the yellow, air-stable platinaphosphaborane are triclinic, space group P, with a= 961.8(1), b= 1 077.2(2), c= 1 661.4(2) pm, α= 108.67(1), β= 84.63(1), γ= 115.96(1)°, and Z= 2; the final R factor is 0.0212 for 3 702 observed reflections. Diffraction analysis shows that the cluster structure is based on a PtB₁₀P icosahedron with the platinum and phosphorus atoms occupying adjacent positions. The metal-to-cluster bonding is rotationally fluxional with ΔG^‡₂₇₇ca. 58 kJ mol^–1. Detailed n.m.r. data for [(PMe₂Ph)₂PtB₁₀H₁₀PPh], neutral B₁₀H₁₂PPh, and anionic [B₁₀H₁₁PPh]^– are presented, compared, and briefly discussed. In contrast to the platinum reaction, reaction of [B₁₀H₁₁PPh]^– with [{Rh(η⁵-C₅Me₅)Cl₂}₂] gives the known nido ten-vertex [6-(η⁵-C₅Me₅)-nido-6-RhB₉H₁₃] and two other products identified as the twelve-vertex closo dimetallaphosphaboranes [7-X-1-Ph-2,3-(η⁵-C₅Me₅)-closo-2,3,1 - Rh₂PB₉H₈](X = Cl or H).