Exploring the (H2C=PH2)+:N-Base Potential Surfaces: Complexes Stabilized by Pnicogen, Hydrogen, and Tetrel Bonds

Ab initio MP2/aug′-cc-pVTZ calculations have been carried out to determine the structures, binding energies, and bonding properties of complexes involving the cation (HC=PH) and a set of sp-hybridized nitrogen bases including NCCH, NP, NCCl, NCH, NCF, NCCN, and N. On each (HC=PH):N-base surface, four types of unique equilibrium structures exist: a complex with a P⋯N pnicogen bond formed through the π system of (HC=PH) (ZB-π); a complex with a P⋯N pnicogen bond formed through the σ system of (HC=PH) (ZB-σ); a hydrogen-bonded complex with a P-H⋯N hydrogen bond (HB); and a tetrel-bonded complex with a C⋯N bond (TB). Binding energies of complexes stabilized by the same type of intermolecular interaction decrease in the order NCCH > NP > NCCl > NCH > NCF > NCCN > N. For a given base, binding energies decrease in the order ZB-π > HB > ZB-σ > TB, except for a reversal of HB and ZB-σ with the weakest base N. Binding energies of ZB-π, HB, and ZB-σ complexes increase exponentially as the corresponding P-N distance decreases, but the correlation is not as good between the binding energies of TB complexes and the intermolecular C-N distance. Charge-transfer energies stabilize all complexes and also exhibit an exponential dependence on the corresponding intermolecular distances. EOM-CCSD spin-spin coupling constants J(P-N) for ZB-π and ZB-σ complexes, and J(P-N) for HB complexes increase quadratically as the corresponding P-N distance decreases. Values of J(C-N) for TB are small and show little dependence on the C-N distance. J(P-H) values for the hydrogen-bonded P-H bond in HB complexes correlate with the corresponding P-H distance, whereas values of J(P-H) for the non-hydrogen-bonded P-H correlate with the P-N distance.This work was carried out with financial support from the Ministerio de Economía y Competitividad (Project No. CTQ2012-35513-C02-02) and Comunidad Autónoma de Madrid (Project FOTOCARBON, ref S2013/MIT-2841). Thanks are also given to the Ohio Supercomputer Center and CTI (CSIC) for their continued computational supportPeer Reviewe