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 Ph 2 PC(Ph)=C(R)BR 2 (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 R 2 P(CH 2 ) 2 BBN (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){Fu 2 P(CH 2 ) 2 BBN} 2 Cl] ( 13 ).