Structures, energies, bonding, and NMR properties of pnicogen complexes H2XP:NXH2 (X ≥ H, CH3, NH2, OH, F, Cl)

Ab initio calculations have been carried out in a systematic investigation of P···N pnicogen complexes H2XP:NXH2 for X ≥ H, CH3, NH2, OH, F, and Cl, as well as selected complexes with different substituents X bonded to P and N. Binding energies for complexes H2XP:NXH2 range from 8 to 27 kJ mol-1 and increase to 39 kJ mol-1 for H 2FP:N(CH3)H2. Equilibrium structures have a nearly linear A - P - N arrangement, with A being the atom directly bonded to P. Binding energies correlate with intermolecular N - P distances as well as with bonding parameters obtained from AIM and SAPT analyses. Complexation increases 31P chemical shieldings in complexes with binding energies greater than 19 kJ mol-1. One-bond spin - spin coupling constants 1pJ(N - P) across the pnicogen interaction exhibit a quadratic dependence on the N - P distance for complexes H2XP:NXH2, similar to the dependence of 2hJ(X - Y) on the X - Y distance for complexes with X - H···Y hydrogen bonds. However, when the mixed complexes H2XP:NX′H2 are included, the curvature of the trendline changes and the good correlation between 1pJ(N - P) and the N - P distance is lost. © 2011 American Chemical Society.Peer Reviewe