A computational study of pnicogen−hydride interaction in complexes XH2P⋯HBeY

The pnicogen−hydride interaction in the complexes XH2P⋯HBeY (X = F, Cl and Br; Y = H, F, Cl, Br, and CH3) has been studied and characterized using ab initio quantum chemistry methods. P in XH2P and H in HBeY act as Lewis acid and base respectively. Calculation indicates that the interaction between XH2P and HBeY is strong, comparable with typical hydrogen bonds; the calculated binding energies with BSSE correction by MP4(SDQ)/aug-cc-PVTZ vary from the least 13.29 kJ/mol of BrH2P⋅⋅⋅HBeF to the largest 45.63 kJ/mol of FH2P⋅⋅⋅ HBeH. The binding energy increases with the acidity of P and the basicity of HBeY. An electron-withdrawing substituent X will enhance but an electron-withdrawing substituent Y will weaken the pnicogen−hydride interaction. Theory of atoms in molecules, natural bond orbitals and natural resonance theory, molecular electrostatic potential and localized molecular orbital energy decomposition analysis were applied to investigate the pnicogen–hydride bonds. A double-way charge transfers and intermolecular hyperconjugations from Lp(P) to σ∗(HBe) and from σ(HBe) to σ∗(XP) mainly contribute to the stability and bonding of the complexes.