Gold–boron chemistry. Part 2. The interaction of {AuP(C₆H₁₁)₃} bridges with decaboranyl cages: the accurate structure of [5,6-µ-{AuP(C₆H₁₁)₃}-nido-B₁₀H₁₃], and the synthesis and molecular and electronic structures of its conjugate base [5,6,9,10-µ₄-{AuP(C₆H₁₁)₃}-nido-B₁₀H₁₂]^–

Abstract

Analysis of the results of an accurate, low-temperature redetermination of the molecular structure of [5,6-p-{Au~(C6H,l),)-nido-~,oH13] (1 a) implies an interaction, albeit weak, between the bridging gold atom and the B(9)H(9,1 O)B(lO) moiety, and extended Huckel molecular orbital (EHMO) calculations reveal that the nature of this bonding is interaction of the three-centre twoelectron-B (9) H B (1 0) unit with a previously vacant 6sp-hybrid orbital on gold. Mossbauer parameters obtained for ( l a ) are consistent with an sp-hybridised gold([) atom which makes a supplementary weak interaction. Deprotonation of (1 a) or of its P( C6H,Me-2), analogue removes the H(9,I 0) atom, and affords species (2) in which the gold-phosphine unit has slipped from p to