Abstract
The electronic and redox properties of the title polyanions have been calculated by means of density functional theory (DFT). These were unrestricted open-shell systems with electronic configuration of d(I) of V. In this behalf, energies and compositions of alpha-LUMO, beta-LUMO, alpha-HOMO, and beta-HOMO were also analyzed. First of all, electronic and redox properties of vanadosilicate [Si8V14O50](12-) (system 1) were calculated and then Si-IV was substituted with Ge-IV, P-V, and As-V for further investigations of systems 2, 3, and 4, respectively. The substitution greatly modifies the electronic properties as alpha-LUMOs are quite different in all the studied systems. The alpha-LUMO is mainly composed of V and O in system 1, V and Ge in system 2, V and O in system 3, and As, O, and V in system 4. The alpha HOMO-LUMO energy gaps are greatly reduced in systems 2, 3, and 4 as compared with system 1. The system 4 [As8V14O50](4-) has minimal value of total bonding energy, whereas system 2 [Ge8V14O50](12-) has maximal, so energetically system 4 is more favourable than the others. After the first reduction, alpha-LUMO in [Si8V14O50](14-) is made up of V and Si, beta-LUMO in [Ge8V14O50](13-) is concentrated on V and Ge, beta-LUMO in [P8V14O50](5-) is composed of V only, whereas beta-LUMO in [As8V14O50](5-) is delocalized over V, O, and As with almost the same contribution of all three atoms.