Copper(I) Complexes derived from Mono- and Diphosphino-Boranes: Cu→B Interactions Supported by Arene Coordination

The monophosphino-boranes o - i Pr 2 P(C 6 H 4 )BR 2 ( 1: R = Ph and 3: R = Cy) and diphosphino-boranes [ o -R 2 P(C 6 H 4 )] 2 BPh ( 5: R = Ph and 6: R = i Pr) readily react with CuCl to afford the corresponding complexes {[ o - i Pr 2 P(C 6 H 4 )BPh 2 ]Cu(μ-Cl)} 2 2, {[ o - i Pr 2 P(C 6 H 4 )BCy 2 ]Cu(μ-Cl)} 2 4, {[ o -Ph 2 P(C 6 H 4 )] 2 BPh}CuCl 7, and {[ o - i Pr 2 P(C 6 H 4 )] 2 BPh}CuCl 8 . The presence of Cu→B interactions supported by arene coordination within complexes 2, 7, and 8 has been unambiguously evidenced by NMR spectroscopy and X-ray diffraction studies. The unique η 2 -BC coordination mode adopted by complexes 7 and 8 has been thoroughly analyzed by density-functional theory (DFT) calculations.