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In this work, we present a systematic computational investigation of the phosphine oxide reduction by using a set of phosphine oxides and silanes. While previous studies consider the substituent effect of the phosphine oxide, few theoretical studies have addressed the silane influence over the reaction. For this reason, free energy barriers for the hydrogen transfer step were calculated and analyzed using the distortion–interaction model and natural bond orbital (NBO) theory. Our analysis of R 3 SiH silanes indicated that the highly acidic silanes Cl 3 SiH and (OCN) 3 SiH readily reduce Ph 3 PO. Further analysis revealed that Ph 2 RSiH derivatives (RCl, OCN) also exhibit low activation barriers. NBO analysis showed that the presence of a small electronegative substituent directly bonded to silicon (e.g., Cl, OH) enhances donation from the oxygen lone pair, n(O), into the σ*(SiH) and σ*(SiR) orbitals. This stabilizes the interaction energy and as a result lowers the computed energy barrier. These findings provide a unified electronic framework for phosphine oxide reduction and offer practical design principles for efficient silane reagents.
Lugo‐Fuentes et al. (Mon,) studied this question.