Monomeric phosphinoboranes: the role of the B- and P-substituents for PB multiple bonding

The influence of the boron substituents on the structures of the first fully characterized monomeric diphosphinoboranes [(2,4,6-Me3C6H2)2P]B–X (X = OEt, Br) has been established; especially for X = Br, P–B multiple bonding may be clearly inferred from the molecular structure.