The diimine compound 1-[(2',3',4',5'-tetraphenylbiphenyl-4-yl)methyl]-2-(pyridin-2-yl)-1H-benzo[d]imidazole (Ph6PyMz) has been designed and synthesized in order to prepare [Cu(Ph6PyMz)(DPEphos)]BF4 {DPEphos = bis[2-(diphenylphosphanyl)phenyl] ether} and [RePh6PyMz(CO)3Br]. The molecular structures of [Cu(Ph6PyMz)(DPEphos)]BF4 and [RePh6PyMz(CO)3Br] were determined by single-crystal X-ray diffraction and IR spectroscopy, and their properties were systematically studied by thermal-stability analyses, photophysical analyses, and electrochemistry. It was found that [Cu(Ph6PyMz)(DPEphos)]BF4 and [RePh6PyMz(CO)3Br] mainly give triplet-ligand-to-ligand charge-transfer transition emission in CH2Cl2 solution and pure triplet-metal-to-ligand charge-transfer transition emission in the solid state. The different photophysical behaviors of [Cu(Ph6PyMz)(DPEphos)]BF4 and [RePh6PyMz(CO)3Br] in different states has been attributed to solvent effects and their higher freedom in CH2Cl2 solution. The energy levels of the highest-occupied and lowest-unoccupied molecular orbitals were measured to be 5.76 and 3.11 eV for [Cu(Ph6PyMz)(DPEphos)]BF4 and 5.69 and 3.42 eV for [RePh6PyMz(CO)3Br], respectively. Finally, the ground-state geometrical structures and the UV/Vis absorption spectra in CH2Cl2 solution were theoretically simulated for [Cu(Ph6PyMz)(DPEphos)]BF4 and [RePh6PyMz(CO)3Br].