Abstract
We report the infrared, Raman, and surface-enhanced Raman scattering (SERS) spectra of triruthenium dipyridylamido complexes and of diruthenium mixed nickel metal-string complexes. From the results of analysis on the vibrational modes, we assigned their vibrational frequencies and structures. The infrared band at 323-326 cm -1 is assigned to the Ru 3 asymmetric stretching mode for [Ru 3 (dpa) 4 Cl 2 ] 0-2+ . In these complexes we observed no Raman band corresponding to the Ru 3 symmetric stretching mode although thismode is expected to have substantial Raman intensity. There is no frequency shift in the Ru 3 asymmetric stretching modes for the complexes with varied oxidational states. No splitting in Raman spectra for the pyridyl breathing line indicates similar bonding environment for both pyridyls in dpa - , thus a delocalized structure in the [Ru 3 ] 6-8+ unit is proposed. For Ru 3 (dpa) 4 (CN) 2 complex series, we assign the infrared band at 302 cm -1 to the Ru 3 asymmetric stretching mode and the weak Raman line at 285 cm -1 to the Ru 3 symmetric stretching. Coordination to the strong axial ligand CN - weakens the Ru-Ru bonding. For the diruthenium nickel complex [Ru 2 Ni(dpa) 4 Cl 2 ] 0-1+ , the diruthenium stretching mode ν Ru-Ru is assigned to the intense band at 327 and 333 cm -1 in the Raman spectra for the neutral and oxidized forms, respectively. This implies a strong Ru-Ru metal-metal bonding.