Hemisphere and Distance-Dependent Steric Analysis of PNN Iron Pincer Complexes Using SambVca 2.1 and Its Influence on Alkene Hydrosilylation

A series of PNN iron pincer complexes was synthesized and structurally characterized by X-ray and computational analysis. Using the optimized structures obtained by density functional theory calculations, the steric parameters of the ligands, based on the percent buried volume (%VBur), were evaluated using SambVca 2.1. Subsequently, the catalytic performance, including product selectivity and alkene hydrosilylation conversion, were examined and the relationship with %VBur values was determined. The product selectivity was found to positively correlate with the %VBur values of the hemisphere, including the location of the reaction site in the inner sphere (<6.0 Å). In contrast, the reaction conversion showed a negative correlation with the steric parameters of the outer sphere. Finally, the steric influence of the inner and outer spheres on catalytic performance was discussed on the basis of the proposed catalytic mechanism.