Synthesis, Structures and Coordination Chemistry of Singly Bridged Phosphane‐Boranes with Coordinately Unsaturated Platinum Group Metals

Abstract

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)2BBN}2Cl] (13).

A comparison of the coordination behaviour of R2PCH2BMe2 (R = Me vs. Ph) ambiphilic ligands with late transition metals

“…The electron rich metal centre and trans -influence of the phosphine donor presumably also contribute. For comparison, bulkier R 2 PCH 2 CH 2 BC 8 H 14 (R = Ph 5 or 2-furyl; 36 BC 8 H 14 = 9-borabicyclononyl) ligands formed trans -[RhCl(CO)(R 2 PCH 2 CH 2 BC 8 H 14 ) 2 ] complexes in which either one borane (R = Ph; Cl–B = 2.353(3) Å) or neither borane (R = 2-furyl) interacts with the chloride co-ligand in the solid state. By contrast, the less sterically-hindered but more rigid Me 2 PCMeCMeBMe 2 ligand afforded trans -[RhCl(CO)(Me 2 PCMeCMeBMe 2 ) 2 ] featuring two Rh–BR 3 interactions (Rh–B = 2.94(3) and 2.97(4) Å).…”

“…The electron rich metal centre and trans-influence of the phosphine donor presumably also contribute. For comparison, bulkier R 2 PCH 2 CH 2 BC 8 H 14 (R = Ph 5 or 2-furyl; 36 37 Formation of a rhodium-borane interaction in 7 is presumably disfavoured by the short linker between the phosphine and the borane of Ph 2 PCH 2 BMe 2 , which would result in a strained 4-membered Rh-P-C-B ring.…”

Direct Allylic Amination of Allylic Alcohol Catalyzed by Palladium Complex Bearing Phosphine–Borane Ligand

“…The synthesis, structure analysis, and reactivity of various transition-metal complexes bearing monophosphine–boranes and monophosphine–borates , as ligands have been reported by many groups. Some of these phosphine–borane complexes are useful for the catalytic reaction. , Pd-catalyzed Suzuki–Miyaura coupling and Rh-catalyzed hydroformylation using phosphine–borane ligands were reported by Bourissou and co-workers.…”