Infrared spectra and coordination mode of transition memtal complexes with ligand dicyanodithiolene and bipyridine

The experimental data of intermediate and far infrared of the title complexes M(mnt) (bpy), M=Mn(II), Fe(I), Co(II), Ni(I), Cu(II), Zn(II), have been in detail given from 4 000 to 400 cm^-1 and 500 to 100 cm^-1 in the present work. Normal-Coordinate Analyses (NCA) on these complixes were studied with the molecular symmetry group C_2V and C₂ (approximate with symetry group C_2V). Band assignments for 81 Infrared-and Raman-active viberations was obtained. Combined with DTA-TG and electronic spectra, the coordination mode of the transition memtal complexes with ligand dicyanodithiolene and bipyridine was studied. Compared with the complexes Cu(bpy)Cl₂ the bonds C=C, C=N streching frequences or band strength in complexes MLL′ are decreased in different degrees because of the conjugated feedback-bond M→^πL (mnt^2-). Several bands between 470 and 411 cm^-1 are associated with M-S stretching modes, 384 and 293 cm^-1 are associated with M-N stretching modes. The M-S bond is slightly stronger than the M-N bond.