title: New insights into hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds by rhenium(V)-dioxo complexes.
abstract: The hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds catalyzed by high-valent rhenium(V)-dioxo complex ReO2I(PPh3)2 (1) were studied computationally to determine the underlying mechanism. Our calculations revealed that the ionic outer-sphere pathway in which the organic substrate attacks the Si center in an η(1)-silane rhenium adduct to prompt the heterolytic cleavage of the Si-H bond is the most energetically favorable process for rhenium(V)-dioxo complex 1 catalyzed hydrosilylation of imines. The activation energy of the turnover-limiting step was calculated to be 22.8 kcal/mol with phenylmethanimine. This value is energetically more favorable than the [2 + 2] addition pathway by as much as 10.0 kcal/mol. Moreover, the ionic outer-sphere pathway competes with the [2 + 2] addition mechanism for rhenium(V)-dioxo complex 1 catalyzing the hydrosilylation of carbonyl compounds. Furthermore, the electron-donating group on the organic substrates would induce a better activity favoring the ionic outer-sphere mechanistic pathway. These findings highlight the unique features of high-valent transition-metal complexes as Lewis acids in activating the Si-H bond and catalyzing the reduction reactions.
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Provincial Key Laboratory for NSLSCS, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China.
authors.forename: Liangfang
authors.initials: L
authors.lastname: Huang
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Provincial Key Laboratory for NSLSCS, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China.
authors.forename: Wenmin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Provincial Key Laboratory for NSLSCS, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Wei
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Provincial Key Laboratory for NSLSCS, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wei
mesh_terms: D002244:Carbon / Q000737:chemistry*; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*; D012821:Silanes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D012821:Silanes; D012211:Rhenium; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen