Skeletal structures of hexa-organo substituted triatomics R3XYZR3: A rationalisation using the second-order Jahn—Teller effect

In compounds of type R₃XYZR₃ (R  phenyl, methyl, benzyl; X, Z  Al, Si, P, Ge, Sn; Y  C, N, O, F) linearity of the XYZ skeleton is predicted by the second-order Jahn—Teller effect in those examples where the valence orbitals of X and Z are much less tightly bound than those of Y. When the X and Z orbitals are bound more tightly than those of Y, the XYZ skeleton is predicted to be non linear at Y. The effects of varying R, X and Z, and the contribution of π-interactions are discussed.