Selective Reduction of CO₂ to a Formate Equivalent with Heterobimetallic Gold‐ ‐ ‐Copper Hydride Complexes

Abstract

A series of heterobimetallic complexes containing three-center, two-electron Au-H-Cu bonds have been prepared from addition of a parent gold hydride to a bent d copper(I) fragment. These highly unusual heterobimetallic complexes represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu-H-Cu and M-H-M moieties (M=Cu, Ag). The well-defined heterobimetallic hydride complexes act as precatalysts for the conversion of CO into HCO Bpin with HBpin as the reductant. The selectivity of the heterobimetallic complexes for the catalytic production of a formate equivalent surpasses that of the parent monomeric Group 11 complexes.

A Dicopper Platform that Stabilizes the Formation of Pentanuclear Coinage Metal Hydride Complexes

“…In addition, it was found that mixtures of 3 and 5 are stable under an atmosphere of CO 2 for at least 4 days. These results are in contrast to those of Sadighi, Tanase and others who found that related copper hydrides undergo rapid insertion with CO 2 . This comparison suggested that if CO 2 insertion to form a putative formate complex is thermodynamically uphill, then the elimination of CO 2 from the corresponding formate should be favorable.…”

Reactivities of Interstitial Hydrides in a Cu11 Template: En Route to Bimetallic Clusters

“…[7,12] In sharp contrast, M-H-M' fragments are frequently observed in metal hydrides,d epicting donoracceptor relationships. [15] Surprisingly,s uch hydride-bridged, heterometallic clusters were predominantly formed via the coordinating ability of surface hydrides.N ever have interstitial hydrides behaving as Lewis bases been observed in heterometallic clusters,t othe best of our knowledge.…”

Hydride Transfer to Gold: Yes or No? Exploring the Unexpected Versatility of Au⋅⋅⋅H−M Bonding in Heterobimetallic Dihydrides

“…[27] More recent studies revealed that these species might turn into interesting catalytic systems; for example, Crimmin reported that heterobimetallic copper-gold hydrides can hydroborate CO2 in the presence of pinacolborane in high selectivity to give formate derivatives. [28] From a mechanistic point of view, Au-H-M moieties can be seen as a situation where the hydride transfer is arrested in an intermediate stage. [29] One of the aspects that seems key for the stabilization of gold heterobimetallic hydrides is the ability of gold to interact with the second metal and form a donor-acceptor complex.…”