Fluoroarene Complexes with Small Bite Angle Bisphosphines: Routes to Amine–Borane and Aminoborylene Complexes

Fluoroarene complexes of the small bite angle bisphosphine Cy 2 PCH 2 PCy 2 (dcpm) have been prepared: [Rh(dcpm)(η 6 ‐1,2‐F 2 C 6 H 4 )][Al{OC(CF 3 ) 3 } 4 ] and [Rh(dcpm)(η 6 ‐1,2,3‐F 3 C 6 H 3 )][Al{OC(CF 3 ) 3 } 4 ]. These complexes act as precursors to a previously inaccessible σ‐amine–borane complex [Rh(dcpm)(η 2 ‐H 3 B · NMe 3 )][Al{OC(CF 3 ) 3 } 4 ] of a small bite‐angle phosphine. This complex is a poor catalyst for the dehydrocoupling of H 3 B · NMe 2 H. Instead, formation of the bridging borylene complex [{RhH(µ‐dcpm)} 2 (µ‐H)(µ‐BNMe 2 )][Al{OC(CF 3 ) 3 } 4 ] occurs, which has been studied by NMR, mass spectrometry, crystallographic and DFT techniques. This represents a new route to bridging borylene complexes.