IR,Raman, and Surface‐enhanced Raman Spectroscopic Study on Triruthenium Dipyridylamide Diruthenium Nickel Dipyridylamide Family: Metal‐metal Bonding and Structures |
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| Authors: | Yu‐Chun Chiu Kuan‐Yi Ho a I‐Chia Chen Shao‐An Hua Ming‐Chuan Cheng Shie‐Ming Peng |
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| Affiliation: | 1. Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30013, Republic of China;2. Department of Chemistry, National Taiwan University, No.?1, Sec.?4, Roosevelt Road, Taipei, Taiwan 10617, Republic of China |
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| 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 Ru3 asymmetric stretching mode for Ru3(dpa)4Cl2]0–2+. In these complexes we observed no Raman band corresponding to the Ru3 symmetric stretching mode although this mode is expected to have substantial Raman intensity. There is no frequency shift in the Ru3 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 Ru3]6–8+ unit is proposed. For Ru3(dpa)4(CN)2 complex series, we assign the infrared band at 302 cm?1 to the Ru3 asymmetric stretching mode and the weak Raman line at 285 cm?1 to the Ru3 symmetric stretching. Coordination to the strong axial ligand CN– weakens the Ru‐Ru bonding. For the diruthenium nickel complex Ru2Ni(dpa)4Cl2]0–1+, the diruthenium stretching mode νRu‐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. |
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| Keywords: | Triruthenium dipyridylamido complexes Mixed‐metal string complexes SERS Raman |
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