Computational\nInsights into the Effect of Ligands\nand Transition-Metal Centers on the Mechanism and Regioselectivity\nof Hydrosilylation of Alkenes

Development\nof sustainable synthetic methods for the\nhydrosilylation\nof alkenes, catalyzed by 3d transition metals, offers a promising\nalternative to traditional noble metal catalysts. This study presents\na computational mechanistic investigation into the hydrosilylation\nof alkenes, focusing on the role of ligands and metal centers in modulating\nthe reaction’s mechanism and regioselectivity. The ligand’s\nelectronic and steric properties were found to modulate the regioselectivity\nfor cobalt catalysts, with phosphine ligand (xantphos) promoting higher\nlinear selectivity compared to nitrogen-based ligand (<sup>mes</sup>PDI). The energy decomposition analysis reveals that the xantphos\nligand favors linear products due to stronger electrostatic and orbital\ninteractions despite increased steric repulsion. The metal center\nalso plays a crucial role, with cobalt catalysts favoring the modified\nChalk–Harrod mechanism for branched product formation in the\npresence of <i>PNN</i> ligand (<sup><i>i</i>Pr</sup>P<sup>C</sup>NN<sup>Me</sup>), due to lower activation barriers in\nalkene insertion. Beneficial electrostatic and orbital interactions\npredominate, rendering the alkene insertion transition state for cobalt\nmore favorable compared to that for iron. This work provides a comprehensive\nunderstanding of how ligand and metal center effects can be harnessed\nto control regioselectivity in hydrosilylation reactions.