Copper(I) complexes derived from mono- and diphosphino-boranes: Cu-->B interactions supported by arene coordination.

The monophosphino-boranes o-iPr(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 = iPr) readily react with CuCl to afford the corresponding complexes {[o-iPr(2)P(C(6)H(4))BPh(2)]Cu(mu-Cl)}(2) 2, {[o-iPr(2)P(C(6)H(4))BCy(2)]Cu(mu-Cl)}(2) 4, {[o-Ph(2)P(C(6)H(4))](2)BPh}CuCl 7, and {[o-iPr(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 eta(2)-BC coordination mode adopted by complexes 7 and 8 has been thoroughly analyzed by density-functional theory (DFT) calculations.