Electronic structures and related properties of complexes M(bpy)(3)(n+)(M = Re, Os, and Ir; n = 1, 2, and 3, respectively)

The theoretical studies on a series of isoelectronic complexes M(bPY)(3)(n) (M = Re, Os, and Ir; n = 1, 2, and 3, respectively) are carried out with DFT method at B3LYP/LanL2DZ level. The electronic structures and related ch emical properties of complexes M(bpy)(3)(n+), in particular, the regulariti es of the center ionic effects on the spectral properties, the chemical sta bilities, and the atomic net charge populations, have been investigated. Th e results show that, for the complexes Re(bpy)(3)(1+) and Os(bpy)(3)(2+), t he main components of HOMO and NHOMO come from d orbitals of the center ion , but for the LUMO and NLUMO, the main components come from p orbitals of t he atoms C and N in ligands. Therefore, the ground bands and the next groun d bands of their electronic spectra are designed as a typical spectrum band of the singlet metal-to-ligand charge transfer ((MLCT)-M-1). Whereas for t he complex Ir(bpy)(3)(3+), whether HOMO and NHOMO or LUMO and NLUMO, their main components come from the p orbitals of C and N in ligands, so the grou nd band and the next ground band of its electronic spectra are designed as a typical band of the singlet ligand-to-ligand transition (L-1 pi-pi*). Wit h increase of the atomic number of the center atom M, the energy interval b etween HOMO and LUMO increases, the wavelength of the corresponding spectru m decreases, and the chemical stability of the complex increases. In additi on, for three complexes, there are more negative charge populations on C6 i n the ligands, and then C6 can be expected as an active site in electrophil ic reactions. The computational results can be better used to explain some experimental phenomena and regularities.