The chemistry of bridged borylene complexes

The stabilisation of borylenes (BX, X=various ligands) in the sphere of a transition metal was achieved for the first time in the case of bridged borylene complexes of the type [(LxM)2BX]. These compounds are characterised by 2c–2e bonds between metal and boron, thus belonging to the class of transition metal complexes of boron. Over the past 5 years different synthetic approaches were made, yielding the first structurally authentic metal complexes with a bridging BX ligand. Their synthesis, structure and reactivity is the subject of this paper.