Determination of the valence state of diruthenium moiety using redox reactions and surface-enhanced Raman scattering: Application in heterometal extended metal-atom chain diruthenium nickel complexes
Journal
Journal of Physical Chemistry C
Journal Volume
120
Journal Issue
36
Pages
20297-20302
Date Issued
2016
Author(s)
Wu, B.-H.
Lin, J.-Y.
Ho, K.-Y.
Huang, M.-J.
Hua, S.-A.
Cheng, M.-C.
Yang, Y.-W.
Chen, I.-C.
Abstract
Redox reaction was photoinduced on metal nanoparticle (NP) with diruthenium complexes absorbing on the surface. Surface enhanced Raman scattering (SERS) was employed to detect the vibrational wavenumber of the Ru-Ru stretching mode νRu-Ru,str. During reaction, the local environment remains roughly unaltered; the variation of bonding strength of Ru-Ru related to its valence state can be measured. The heterometal extended metal atom chain (EMAC) complexes diruthenium nickel dipyridylamide [Ru2Ni(dpa)4Cl2]0,1+ (dpa = dipyridylamide) display the Raman νRu-Ru,str at 327 (broad) and 333 cm-1 in solid form for the neutral and oxidized complexes, respectively, but red-shift to 312 cm-1 on gold NP substrate and to 328 cm-1 on AgNP. According to the oxidation potentials from voltammogram, and the Raman shifts obtained for the model complex Ru2(OAc)4Cl we assign the diruthenium core with charge +5/+4 and +6, respectively for the neutral and oxidized diruthenium nickel dipyridylamide in solid form. On substrate AuNP the hot electrons produced to fill in the antibonding orbital, the Ru24+ π∗4 core with weak Ru-Ru bonding was formed and on AgNP the oxidized complex was reduced to neutral form. For pentanuclear EMAC [Ni-Ru2-Ni2(tpda)4(NCS)2] (tpda = tripyridyldiamide) νRu-Ru,str is at 337 cm-1 and SERS band peaked at 328 cm-1. We assign the Ru26+ core in solid and reduction by NPs to form Ru25+.
SDGs
Type
journal article