Enhanced Hydrogen Dissociation on Bi-metallic Half-Sandwiched Complex: A DFT study

Abstract

Hydrogen dissociation is an important reaction in the development of clean and sustainable energy technologies, and catalysts capable of reacting with molecular hydrogen effectively are needed to overcome the rising level of environmental pollution and traditional energy sources depletion. Clean and renewable energy sources, including hydrogen, are the potential solutions to these issues that receive more and more attention. This work has employed the simulations of the density functional theory to examine the adsorption and dissociation characteristics of hydrogen on 𝜂6-C6H6 bimetallic half-sandwiched complexes. The thermodynamic stability of all the complexes is confirmed by the calculated interaction energies, and results in negative interactions between the metals and the ligands and between the metals. Interaction energy of maximum value (-3.98 eV) occurred in FeCr(η⁶-C6H6). Electronic structure calculations of frontier molecular orbitals (FMO) and natural bond orbital (NBO) simulations show that there is a significant redistribution of charge across the bimetallic structure with profound effects of metal-metal cooperation on catalytic activity. Interaction region indicator (IRI) studies elucidated the nature of bonding contacts by showing that there were shared or partially covalent bonds in the catalytic systems.. Hydrogen adsorption and dissociation pathways is studied for all optimized complexes. Among all optimized complexes, FeMn(η⁶-C₆H₆) has an extraordinarily low activation barrier (0.18 eV), indicating greater catalytic efficiency for hydrogen dissociation. The increased activity is governed by effective charge transfer from the bimetallic centers to the antibonding orbitals of hydrogen, resulting in considerable H–H bond weakening. The pivotal insights gained from this study enhance our understanding about the stability, electronic properties and hydrogen dissociation reaction of bimetallic half sandwiched complexes.