Computational insights into hydroboration with acyclic α-Borylamido-germylene and stannylene catalysts: Cooperative dual catalysis the key to system efficiency

Abstract

The chemistry of low valent main group compounds has grown as an alternative to the chemistry of less abundant and less green transition metal complexes. It has been found that low valent compounds such as carbenes, silylenes, stannylenes and germylenes are efficient for activating small molecules and for catalysis. However, the reaction mechanism and the factors that affect the rate of reaction are not completely understood. In this computational investigation with density functional theory (DFT), we investigate and demonstrate the efficiency of a new mechanism for the hydroboration of aldehydes by germylenes and stannylenes, in the presence of the common hydroborating agent, pinacolborane, HBpin. This mechanism involves an HBpin molecule as an additional catalyst that cooperates with the germylene or stannylene catalyst to efficiently carry out the hydroboration. This mechanism is first demonstrated to work for experimentally reported systems, and then shown to be efficient for newly proposed germylene and stannylene systems. These new systems are α-Borylamido-germylene ((2,6-iPr2C6H3NBCy2)2Ge(II)) and α-Borylamido-stannylene((2,6-iPr2C6H3NBCy2)2Sn(II)). These new insights will help researchers look into low valent germylene and stannylene chemistry from a new perspective.