Theoretical insights into the trends in molecular properties of HCY, HSiY and HGeY molecules where Y = N, P, As.

To obtain insights into the factors that govern the analogy between HCN and its isostructures, HXY where X = C, Si, Ge and Y = N, P, As, the electronic and structural properties of these species in ground, cationic and anionic states at the QCISD, MP2 and B3LYP levels with 6-311++G** basis set and the first exited state with TD-B3LYP method have been presented. The results suggest that there are some correlations between structural and thermodynamic properties of the smallest member of this group (HCN) and heavier congers. The results of computation at these levels also predict the stability of HCAs in the ground state and HCN, HSiN and HGeN in the cationic state from the energetic point of view. Molecular electrostatic potential map inspection shows that in HXN species nucleophilic region positions on N atom but in HXP and HXAs molecules by increasing the size of central atom nucleophilic region shifts from region near X atom toward terminal atom. Finally, the nature of bonds of HXY molecules are systematically studied through atoms in molecules (AIM) and natural bond orbital analyses (NBO).