Experimental and theoretical studies of correlated rotation in tris(ortho-tolyl) derivatives of P, As and Si

Variable temperature NMR studies have established equilibrium constants and/or activation parameters for the exo2↔exo3 equilibrium in the series M(o-tolyl)3(M = P, As), XM (o-tolyl)3(M = P, X = O, S, Se; M = As, X = O, S) and [MeM(o-tolyl)3]n+(n= 0, M = Si; n= 1, M = P, As). The crystal structure of OAs(o-tolyl)3H2O is reported. Molecular mechanics studies of P(o-tolyl)3 reproduce correctly the ground state exo3 conformation and provide an analysis of the lowest energy two-ring flip exchange mechanism.