Substitution, cooperative, and solvent effects on π pnicogen bonds in the FH(2)P and FH(2)As complexes.

Ab initio calculations have been carried out to study the substitution effect on the π pnicogen bond in ZH(2)P-C(2)HM (Z = H, H(3)C, NC, F; M = H, CH(3), Li) dimer, cooperative effect of the π pnicogen bond and hydrogen bond in XH-FH(2)Y-C(2)H(4) (X = HO, NC, F; Y = P and As) trimer, and solvent effect on the π pnicogen bond in FH(2)P-C(2)H(2), FH(2)P-C(2)H(4), FH(2)As-C(2)H(2), and FH(2)As-C(2)H(4) dimers. The interaction energy of π pnicogen bond increases in magnitude from -1.51 kcal mol(-1) in H(3)P-C(2)H(2) dimer to -7.53 kcal mol(-1) in FH(2)P-C(2)HLi dimer at the MP2/aug-cc-pVTZ level. The π pnicogen bond is enhanced by 12-30 % due to the presence of hydrogen bond in the trimer. The π pnicogen bond is also enhanced in solvents. The natural bond orbital analysis and symmetry adapted perturbation theory (SAPT) were used to unveil the source of substitution, cooperative, and solvent effects.