Theoretical study of the relative stabilities of arsasilenes and arsasilynes

The unimolecular rearrangement of arsasilyne, XSi=As (X = H, Li, Na, BeH, MgH, BH2, AlH2, CH3, SiH3, NH2, PH2, OH, SH, F, Cl), to arsasilene, Si=AsX, is considered using B3LYP and CCSD(T) calculations. The theoretical findings suggest that highly electronegative substitution occurs preferentially at silicon and, thus, strongly stabilizes triply bonded XSi= As, with respect to doubly bonded Si=AsX, both from a thermodynamic and from a kinetic viewpoint.