A novel tetranucleate nickel (II)-based molecular catalytic system: Beneath visible light, highly effective and selective for CO2-to-CO transformation

Abstract

Two kinds of easily synthesized, novel and excellent performance nickel(II)-based catalysts Ni4 [Ni4Cl8(tmphen)4(H2O)2] (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline) and Ni-dmphen [NiCl2(4,7-dmphen)2] (dmphen = 4,7-dimethyl-1,10-phenanthroline) were obtained. Under visible light, a high turnover number of CO (TONCO) was achieved with 6258.3 (95.2% selectivity) corresponding to Ni4, and the TONCO is 4037.9 (94.5% selectivity) for Ni-dmphen. A mechanism containing a four-stage proton-coupled electron transfer process was sketched by conjoint analysis using High-Resolution Mass Spectrometry (HRMS) and Density Functional Theory (DFT) calculations.