@Article{PhysChemChemPhys_7_85, author = {C. Gouverd and F. Biaso and L. Cataldo and T. Berclaz and M. Geoffroy and E. Levillain and N. Avarvari and M. Fourmigu{\'e} and F.X. Sauvage and C. Wartelle}, title = {{Tetrathiafulvalene-phosphine-based iron and ruthenium carbonyl complexes: Electrochemical and EPR studies}}, journal= {Phys. Chem. Chem. Phys.}, ISSN = {1463-9076}, volume= {7}, pages = {85-93}, url = {http://www.rsc.org/publishing/journals/CP/article.asp?doi=b409958c}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref00583.pdf}, doi= {10.1039/b409958c}, abstract = {{The radical cation of the redox active ligand 3,4-dimethyl-3\',4\'-bis-(diphenylphosphino)-tetrathiafulvalene ( P2) has been chemically and electrochemically generated and studied by EPR spectroscopy. Consistent with DFT calculations, the observed hyperfine structure (septet due to the two methyl groups) indicates a strong delocalization of the unpaired electron on the central S$_2$C=CS$_2$ part of the tetrathiafulvalene (TTF) moiety and zero spin densities on the phosphine groups. In contrast with the ruthenium(0) carbonyl complexes of P2 whose one-electron oxidation directly leads to decomplexation and produces P2$^{•}$$^{+}$, one-electron oxidation of [Fe( P2)(CO)$_3$] gives rise to the metal-centered oxidation species [Fe$^{(I)}$( P2)(CO)$_3$], characterized by a coupling with two $^{31}$P nuclei and a rather large {\em g}-anisotropy. The stability of this complex is however modest and, after some minutes, the species resulting from the scission of a P{\frac{ }{ }}Fe bond is detected. Moreover, in presence of free ligand, [Fe$^{(I)}$( P2)(CO)$_3$] reacts to give the complex [Fe$^{(I)}$( P2)$_2$(CO)] containing two TTF fragments. The two-electron oxidation of [Fe( P2)(CO)$_3$] leads to decomplexation and to the P2$^{•}$$^{+}$ spectrum. Besides EPR spectroscopy, cyclic voltammetry as well as FTIR spectroelectrochemistry are used in order to explain the behaviour of [Fe( P2)(CO)$_3$] upon oxidation. This behaviour notably differs from that of the Ru(0) counterpart. This difference is tentatively rationalized on the basis of structural arguments.}}, year = {2005} }