Dual Activation of H 2 and CO 2 by a Pincer‐Type Ni–Zn Heterobimetallic Complex
Krishnendu Dey, Matthias Borowski, Gregor Schnakenburg, Connie C. LuABSTRACT
Various Ni‐based metalloenzymes employ synergistic heterometallic cooperativity where a Ni center and a second metal ion cofacilitate small‐molecule conversion. Inspired by these biological systems, synthetic model complexes have been developed that exploit bimetallic cooperativity to achieve analogous reactivity. In this work, we report a bimetallic Ni−Zn complex comprising a pincer‐type diamido‐diaminodiphosphine ligand, in which a weakly Lewis acidic Zn(II) center stabilizes a T‐shaped Ni(0) site. Subsequent reactivity with H 2 led to the isolation of a rare Ni dihydride complex, which dynamically interconverts between Zn( μ ‐H)Ni(H) and trans ‐Ni(H) 2 motifs via rotational rocking about the P−Ni−P axis. The Ni dihydride complex is a competent alkene hydrogenation catalyst (5 mol% loading, 70°C, 2 bar H 2 ) for terminal olefins. Also, the Ni dihydride inserts CO 2 to give a rare Ni hydrido formate. This product further reacts with a second equivalent of CO 2 through a carboxylate shift mechanism that unveils a nucleophilic Zn(II) amide group that inserts CO 2 to give carbamate. Collectively, our experimental and computational results highlight the role of Zn(II) as a weakly Lewis acidic partner, which promotes the dual activation of H 2 and CO 2 by a single Ni center in the absence of any external base.