Ab initio study of the isomerism, structure, and stability of Li[XMY2] molecules and Li[XM'Y2]+ ions (M=C, Si; M'=N, P; X=F, Cl, H; Y=O, S)

Ab initio calculations of the surfaces of potential energy for the valent-isoelectronic (with Nval=24 and 18) trigonal dioxo-dithiohydrate and halide anions of the XMY2-=XCO2-, XSiO2-, XCS2-, XSiS2- type and their lithium salts Li[XMY2], the related series of the neutral molecules XMY2=XNO2, XPO2, XNS2 and XPS2, their ion-molecular complexes Li[XMY2]+, X=F, Cl, H; Y=O, S were performed. The calculations were carried out using GAUSSIAN-98 program. The effort to assess the structural parameters as valence, so non-valence isomers, their comparative energies, the oscillation spectra (for the identification by IR spectroscopy) was taken. The potential barriers dividing isomers, mutual transitions between them were estimated and their dependence from the nature of cation and substituents X and Y was traced