Comprehensive Understanding of Bi‐functional Behavior of PNP‐Pincer Complexes Towards the Conversion of CO into Methanol and CO₂: A DFT Approach

Abstract

The conversion mechanisms of CO into methanol through hydrogenation and CO 2 through hydrolysis catalyzed by (PNP) RuH 2 CO (1) pincer complex have been explored employing density functional theory (DFT). For both the reactions, we have identified two pathways. In pathway-I, at first the CO takes part in the reaction by interacting with the Ru-center of pincer complex and after that the H 2 /H 2 O molecule participates in the reaction, whereas in pathway-II, the generation of hydrogenated/hydrolyzed pincer from initial pincer via the assistance of H 2 or H 2 O molecule occurs first, followed by the reaction with CO. In case of hydrogenation, for both the pathways, CO is first converted to HCHO through hydrogenation which further undergoes hydrogenation to form methanol. In pathway-I, the reaction of HCHO with H 2 in presence of dehydrogenated pincer leads to produce methanol, whereas for pathway-II the hydrogenated pincer formed at the beginning of this pathway carries out the aforementioned conversion. Further in presence of methanol, CO is catalytically converted to methyl formate. On the other hand, in case of hydrolysis, the conversion of CO to CO 2 can be achieved in two ways, where 2 nd step, i. e. formic acid to CO 2 via formate ion formation follows similar mechanism for both the pathways. Overall, from our study it is revealed that the Rupincer complex acts as a promising homogeneous catalyst for converting CO to various organic chemical commodities.