Triply-bonded indium=phosphorus molecules: theoretical designs and characterization

Abstract

The effect of substitution on the potential energy surfaces of triple-bonded RIn=PR (R = F, OH, H, CH3, SiH3, NHC, SiMe(SitBu3)2 and SiiPrDis2) species was investigated, using the density functional theory (i.e., M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B97-D3/LANL2DZ+dp). The theoretical results suggest all of the triple-bonded RIn=PR molecules prefer to adopt a bent form with an angle (∠In-P-R) of about 90°. Present theoretical evidence suggests only the bulkier substituents, in particular for the strong donating groups (such as the NHC group), can greatly stabilize the In=P triple bond. In addition, bonding analyses demonstrate the bonding character of such triple-bonded RIn=PR compounds should be represented as . That is to say, the In=P triple bond contains one traditional σ bond, one traditional π bond, and one donor-acceptor π bond. As a consequence, the theoretical findings strongly suggest the In=P triple bond in acetylene analogues (RIn=PR) should be very weak.