The ability of silylenes to bind excess electrons: Electron affinities of SiX2, and SiXY species (X,Y=H,CH3,SiH3,F,Cl,Br)

Abstract

Recently, Ishida and co-workers have isolated silylene radical anions via the one-electron reduction of isolable cyclic dialkylsilylenes, discovering these corresponding radical anions to be relatively stable at low temperatures. Herein we report theoretical predictions of the adiabatic electron affinities (AEA), vertical electron affinities, and vertical detachment energies of a series of methyl, silyl, and halosubstituted silylene compounds. This research utilizes the carefully calibrated DZP++ basis with the combination of the popular nonhybrid and hybrid DFT functionals, BLYP, B3LYP, and BHHLYP. The level of theory employed and the ensemble of species under study confirm the ability of silylenes to bind excess electrons with Si(SiH(3))(2) being the most effective, having a predicted AEA of 1.95 eV. While it is known that methyl substituents have a diminishing effect on the computed electron affinities (EAs), it is shown that fluorine shows an analogous negative effect. Similarly, previous suggestions that Si(CH(3))(2) will not bind an electron appear incorrect, with EA[Si(CH(3))(2)] predicted here to be 0.46 eV.