Synthesis, structures and coordination chemistry of singly bridged phosphane-boranes with coordinately unsaturated platinum group metals

A range of singly bridged phosphane-boranes (PBs) have been investigated as potential ligands for basic transition metals. The PBs Ph2PC(Ph)=C(R)BR2 (R = Bu 1, Ph 2, Et 3), based on a rigid cis-ethylene bridges, have been prepared, improving upon limited literature precedent. All three compounds have been comprehensively characterised for the first time, including by X-ray diffraction studies. Significant intramolecular P→B association is apparent in each case, which serves to preclude their engagement as ligands. In contrast, the more flexible PBs R2P(CH2)2BBN (R = Fu 5, Ph 6) readily coordinate to the platinum group metals Pt, Pd and Rh. These complexes have been fully characterised, including an X-ray diffraction study of [Rh(CO){Fu2P(CH2)2-BBN}2Cl] (13)