Copper-Ligand Cooperativity in H$_2$ Activation Enables the Synthesis of Copper Hydride Complexes

Copper(I) complexes of a new participative triphosphane ligand (2 H) have been prepared and structurally characterized, in particular [Cu(2 H)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(2 H)(HBEt3)]. Their formation evidences transient formation of [Cu(2 H)H] formed by hydrogenolysis of the Cu-N bond of [Cu(2)]2. [Cu(2 H)(HBEt3)] behaves like a hydride complex and inserts CO2 to yield the formate product [Cu(2 H)(O2CH)]. QTAIM analysis of the Cu-H-BEt3 interaction indicates a hydride complex stabilized by the Lewis acid BEt3