화학공학소재연구정보센터
Inorganic Chemistry, Vol.56, No.23, 14671-14681, 2017
E-H (E = B, Si, C) Bond Activation by Tuning Structural and Electronic Properties of Phosphenium Cations
In this work, strategic enhancement of electrophilicity of phosphenium cations for the purpose of small-molecule activation was described. Our synthetic methodology for generation of novel two-coordinate phosphorus(III)-based compounds [{C6H4(MeN)(2)C}(2)C center dot PR](2+) ([2a](2+), R = (NPr2)-Pr-i; [2b](2+), R = Ph) was based on the exceptional electron-donating properties of the carbodicarbene ligand (CDC). The effects of P-centered substituent exchange and increase in the overall positive charge on small substrate activation were comparatively determined by incorporating the bis(amino)phosphenium ion [((Pr2N)-Pr-i)(2)P](+) ([1](+)) in this study. Implemented structural and electronic modifications of phosphenium salts were computationally verified and subsequently confirmed by isolation and characterization of the corresponding E-H (E = B, Si, C) bond activation products. While both phosphenium mono- and dications oxidatively inserted/cleaved the B-H bond of Lewis base stabilized boranes, the increased electrophilicity of doubly charged species also afforded the activation of significantly less hydridic Si-H and C-H bonds. The preference of [2a](2+) and [2b](2+) to abstract the hydride rather than to insert into the corresponding bond of silanes, as well as the formation of the carbodicarbene-stabilized parent phosphenium ion [{C6H4(MeN)(2)C}(2)C center dot PH2](+) ([2 center dot PH2](+)) were experimentally validated.