The UV-vis absorption spectra of the title complex Ni(mnt)(phen) in twelve solvents and its fluorescence emission spectra in four solvents were reported in this paper. The molecular geometry and electronic structure for the complex in the gas phase were studied by using the PM3 method of the MOT and B3LYP method of the DFT. The observed spectra were explained by the CI calculations of multi-configurations from the ZINDO/S method of the MOT. The result shows that the gaseous molecule of the complex is of a planar structure with the symmetry belonging to point group C_2v, and its ground state is the spin triplet state. The coordination bonds Ni—N and Ni—S are typically covalent bond, and the feedback effect of the 3d electrons of nickel atom is respectably obvious. The absorption and emission bands of the complex at visible region are originated from the charge transfer transitions from ligand phen to the other ligand mnt^2－ (LL'CT), and the absorption bands at ultraviolet region are from π→π* transitions of the ligands.

Key words: nickel complex of dithiolate and 1,10-phenanthroline, electronic absorption and emission spectra, intramolecular charge transfer transition, multiconfiguration CI calculation