Copper–Ligand Cooperativity in H2 Activation Enables the Synthesis of Copper Hydride Complexes

Copper­(I) complexes of a new participative triphosphane ligand (2H) have been prepared and structurally characterized: in particular, [Cu­(2H)­I] and [Cu­(2)]2. Hydrogenation of the latter species afforded the trimetallic hydride species [Cu3(2)2(μ-H)] or, in the presence of BEt3, [Cu­(2H)­(HBEt3)]. Their formation evidences the transient formation of [Cu­(2H)­H] formed by hydrogenolysis of the Cu–N bond of [Cu­(2)]2. [Cu­(2H)­(HBEt3)] behaves like a hydride complex and inserts CO2 to yield the formate product [Cu­(2H)­(O2CH)]. A QTAIM (quantum theory of atoms in molecules) analysis of the Cu–H–BEt3 interaction indicates a hydride complex stabilized by the Lewis acid BEt3.