INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
artículos
Título:
All-trans-[CIRuII(py)(4)(NC)Ru-II(py)(4)(CN)Ru-II(py)(4)(NO)](PF6)(4): A Redox-Active 2-Donor/1-Acceptor System Based on the Electrophilic {RuNO}(6) Motif
Autor/es:
DE CANDIA, A. G. SINGH, P. KAIM, W. SLEP, L. D
Revista:
INORGANIC CHEMISTRY
Editorial:
ACS
Referencias:
Año: 2009 vol. 48 p. 565 - 565
ISSN:
0020-1669
Resumen:
The new linear homotrinuclear compound trans-[CIRuII(py)(4)(NC)Ru-II(py)(4)(CN)Ru-II(py)(4)(NO)](PF6)(4) was prepared by reaction between the nitro complex trans-[(NC)Ru-II(py)(4)(CN)Ru-II(py)(4)(NO2)](+) and the solvento complex obtained by reaction between [CIRuII(py)(4)(NO)](3+) and N-3(-) in acetone. The trans-[ClRuII(py)(4) (NC)Ru-II(py)(4)(CN)Ru-II(py)(4)(NO)](4+) ion (I) has been characterized by H-1 NMR and IR spectroscopy (nu(NO) = 1919 cm(-1)). This species displays intense electronic absorptions in the visible region which can be assigned to donor-acceptor charge-transfer transitions (DACT) involving {RuNO}(6)-centered acceptor orbitals and donor orbitals located on the two different neighboring metal centers at ca. 6.7 and 12.6 angstrom distance from the metal in the {RuNO}(6) fragment. Addition of OH- to I generated the nitro complex with a second-order rate constant of (12.5 +/- 0.2) x 10(3) M-1 s(-1) (25 degrees C). Cyclic voltammetry experiments complemented by spectroelectrochemistry in the UV-vis-NIR region reveal that I can be reversibly reduced at 0.49 or 0.20 V vs AgCl/Ag for acetonitrile and water, respectively, and oxidized at 0.71 or 0.57 V vs AgCl/Ag. The spectroscopic and spectroelectrochemical information (UV-vis-NIR, X-band EPR) supplemented with electronic structure computation (DFT) reveals that the one-electron reduction is centered on the nitrosyl moiety to yield a {RUNO}(7) species, while oxidation occurs on the chlororuthenium side of the molecule. Both processes yield significant changes of the electronic spectra which are discussed in parallel with the electronic structure picture as obtained by DFT.