Facile Insertion of Carbon Dioxide into Cu 2 (μ‐H) Dinuclear Units Supported by Tetraphosphine Ligands

Reactions of meso ‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with Cu I species in the presence of NaBH 4 afforded di‐ and tetranuclear copper hydride complexes, [Cu 2 (μ‐H)(μ‐dpmppm) 2 ]X ( 1 ) and [Cu 4 (μ‐H) 2 (μ 4 ‐H)(μ‐dpmppm) 2 ]X ( 2 ) (X=BF 4 , PF 6 ). Complex 1 undergoes facile insertion of CO 2 (1 atm) at room temperature, leading to a formate‐bridged dicopper complex [Cu 2 (μ‐HCOO)(dpmppm) 2 ]X ( 3 ). The experimental and DFT theoretical studies clearly demonstrate that CO 2 insertion into the Cu 2 (μ‐H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO 2 insertion to give a formate‐bridged complex, [Cu 4 (μ‐HCOO) 3 (dpmppm) 2 ]X, during which the square Cu 4 framework opened up to a linear tetranuclear chain.