Substituent effect on relative stabilities of the phosphorus and tin multiple bonds

The unimolecular rearrangement of XSnP (X=H, Li, BeH, BH2, CH3, NH2, OH, and F) to SnPX is considered using B3LYP and QCISD calculations. The theoretical findings suggest that the doubly bonded SnPX molecule is intrinsically more stable than the triply bonded XSnP species, regardless of the electronegativity of the substituent X attached. On the other hand, the model calculations predict that only bulky aryl substituents can greatly stabilize XSnP over SnPX due to the steric effect.