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• 作者：Floriant Doungmene^a ; Pablo A. Aparicio^b ; Joseline Ntienoue^c ; Charyle S. Ayingone Mezui^c ; Pedro de Oliveira^a ; Xavier Ló ; pez^b ; ^{javier.lopez@urv.cat" class="auth_mail} ; Israë ; l M. Mbomekallé ; ^a ; ^c ; ^{israel.mbomekalle@u-psud.fr" class="auth_mail}
• 关键词：Polyoxometalates ; Electrochemistry ; DFT calculations
• 刊名：Electrochimica Acta
• 出版年：10 April, 2014
• 年：2014
• 卷：125
• 期：Complete
• 页码：674-682
• 全文大小：1948 K

文摘

An innovative study on the electrochemical behaviour of mixed d metal-iron containing Wells-Dawson sandwich-type complexes [(FeOH₂)₂M₂(X₂W₁₅O₅₆)₂]^{14鈭?/sup> and [(MOH₂)₂Fe₂(X₂W₁₅O₅₆)₂]14鈭?/sup> (with M = CrIII, MnII, MnIII, CoII, NiII, CuII or ZnII and X = PV or AsV) was carried out. These complexes have a four-centre equatorial metal cluster constituted of two Fe atoms and two atoms of another metal. The FeIII centres are either in an external position, [(FeOH₂)₂M₂], or in an internal position, [M₂(OH₂)₂Fe₂]. Experimental methods (cyclic voltammetry and controlled potential coulometry) and theoretical calculations (density functional theory) allowed us to determine and analyse the redox potential values associated with the reduction of the FeIII centres in these species. The influence of the position of the FeIII centres, the nature of the metal centre M and the electron density distribution in the tetranuclear cluster (either [(FeOH₂)₂M₂] or [(MOH₂)₂Fe₂]) have been studied and rationalised in order to account for the observed behaviours. The data suggest that the most stable isomers are those where FeIII centres are internally-located, [(MOH₂)₂Fe₂]. Consequently, their reduction is more difficult than those having externally-located FeIII isomers, [(FeOH₂)₂M₂]. Some experimental results revealed a few exceptions to this rule which have not been rationalised yet.}