IR, Raman, and surface-enhanced Raman spectroscopic study on triruthenium dipyridylamide diruthenium nickel dipyridylamide family: Metal-metal bonding and structures
Journal
Journal of the Chinese Chemical Society
Journal Volume
61
Journal Issue
12
Pages
1289-1296
Date Issued
2014
Author(s)
Abstract
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 this mode 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.
Type
journal article