A new luminescent compound of Ru(imin)(2)(CN)(2), where imin is 2-(N-methylformimidoyl)pyridine, which has smaller pi electron system than bpy and phen is synthesized. The (1)MLCT absorption maximum of this complex is nearly identical with that of Ru(bpy)(2)(CN)(2) and Ru(phen)(2)(CN)(2), while the emission from the (3)MLCT state of the former is highly red-shifted in comparison with that of the latter. The Stokes shift (Delta E(ST)), which is the energy difference between the (1)MLCT absorption maximum and the emission maximum, of Ru(imin)(2)(CN)(2) in protic and aprotic solvents shows the good correlation with the solvent acceptor number (AN) and the solvent dielectric parameter, respectively, similar to those of Ru(bpy)(2)(CN)(2) and Ru(phen)(2)(CN)(2). However, the solvent dependence of Delta E(ST) of the former is weak compared with that of the latter both in protic and aprotic solvents. DV-X alpha calculations show that (i) the electronic density on CN is less decreased for Ru(imin)(2)(CN)(2) in the MLCT excited states compared with that for the L = bpy and phen analogues and that (ii) the decrease of the dipole moment of Ru(imin)(2)(CN)(2) in the excited state is smaller than that of the others. The weak solvent dependence of Delta E(ST) for Ru(imin)(2)(CN)(2) in protic solvents is considered to come from the small decrease of the electronic density on CN, which makes the solvent reorganization caused from the change of the Lewis acidity of CN smaller. The weak solvent dependence of Ru(imin)(2)(CN)(2) in aprotic media is accounted for by the small dielectric reorganization of the solvents in the excited state due to the small decrease of the dipole moment of this molecule. The large Delta E(ST) of Ru(imin)(2)(CN)(2) comes from the inner-sphere reorganization of the less rigid C=N bond of the methylimine on which the promoted electron is relatively localized in the lowest MLCT states.