Metallaborane reaction chemistry. Part 10. Phenylacetylene incorporation via [4,4-(PMe2Ph)2-arachno-4-PtCB8H12] in a ‘converse’ metalladicarbaborane synthesis of [7,7-(PMe2Ph)2-isonido-7,6,8-PtC2B6H7-6-Ph]

Reaction between PhCtriple bond; length of mdashCH and [4,4-(PMe2Ph)2-arachno-4-PtB8H12] (1) gives carbons-apart [7,7-(PMe2Ph)2-isonido-7,6,8-PtC2B6H7-6-Ph] (2), in a ‘converse’ synthesis of a metallacarbaborane, viz. in a synthesis by addition of carbon centres into a pre-formed metallaborane, rather than by metal-centre addition to a pre-formed carbaborane. The long B(3)–B(4) diagonal distance of 2.541(8) Å in the quadrilateral open face is one of the longest so far observed in a metallanonaborane-type compound, and results principally from a restricted orbital contribution of the {Pt(PMe2Ph)2} centre to the {PtC2B6} cluster bonding system.