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

The monophosphino-boranes o-iPr2P(C6H4)BR2 (1: R = Ph and 3: R = Cy) and diphosphino-boranes [o-R2P(C6H4)]2BPh (5: R = Ph and 6: R = iPr) readily react with CuCl to afford the corresponding complexes {[o-iPr2P(C6H4)BPh2]Cu(μ-Cl)}2 2, {[o-iPr2P(C6H4)BCy2]Cu(μ-Cl)}2 4, {[o-Ph2P(C6H4)]2BPh}CuCl 7, and {[o-iPr2P(C6H4)]2BPh}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 η2-BC coordination mode adopted by complexes 7 and 8 has been thoroughly analyzed by density-functional theory (DFT) calculations.