Synthesis and Coordination of a Bisphosphine-[NHC-borane] Compound: A Ligand Framework for Bimetallic Structure Featuring a Boron-Bridging Moiety.

We report herein the synthesis of a bisphosphine-[NHC-BH 3 ] compound and its coordination toward gold. The ligand is shown to support a bimetallic structure bisphosphine-[NHC-BH 3 ](AuCl) 2 . The abstraction of one chloride from the gold metal center triggers the activation of a BH 3 fragment, leading to the reductive elimination of H 2 and the formation of a dicationic Au 4 2+ complex featuring Au centers at the +0.5 oxidation state, via a (μ-H)Au 2 intermediate, characterized in situ at 183 K. The reactivity of Au 4 with thiophenol led to the reoxidation of the gold metal centers to a (μ-S(Ph))Au 2 complex. In the different complexes, borane fragment was shown to bridge the Au 2 core via weak interaction with [BH], [BCl], and [BH 2 ] moieties.