| Abstract
| - The theoretical studies on a series of isoelectronic complexes M(bpy)3n+ (M = Re, Os, and Ir; n = 1, 2, and3, respectively) are carried out with DFT method at B3LYP/LanL2DZ level. The electronic structures andrelated chemical properties of complexes M(bpy)3n+, in particular, the regularities of the center ionic effectson the spectral properties, the chemical stabilities, and the atomic net charge populations, have been investigated.The results show that, for the complexes Re(bpy)31+ and Os(bpy)32+, the main components of HOMO andNHOMO come from d orbitals of the center ion, but for the LUMO and NLUMO, the main componentscome from p orbitals of the atoms C and N in ligands. Therefore, the ground bands and the next groundbands of their electronic spectra are designed as a typical spectrum band of the singlet metal-to-ligand chargetransfer (1MLCT). Whereas for the complex Ir(bpy)33+, whether HOMO and NHOMO or LUMO and NLUMO,their main components come from the p orbitals of C and N in ligands, so the ground band and the nextground band of its electronic spectra are designed as a typical band of the singlet ligand-to-ligand transition(1Lπ−π*). With increase of the atomic number of the center atom M, the energy interval between HOMOand LUMO increases, the wavelength of the corresponding spectrum decreases, and the chemical stability ofthe complex increases. In addition, for three complexes, there are more negative charge populations on C6 inthe ligands, and then C6 can be expected as an active site in electrophilic reactions. The computational resultscan be better used to explain some experimental phenomena and regularities.
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