Concerning the electronic coupling of MoMo quadruple bonds linked by 4,4′-azodibenzoate and comparison with t2g6-Ru(II) centers by 4,4′-azodiphenylcyanamido ligands

Malcolm H. Chisholm, Jason S. D'Acchioli, Christopher M. Hadad, Nathan J. Patmore

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From the reactions between Mo2(O2C tBu)4 and each of terephthalic acid and 4,4′-azodibenzoic acid, the compounds [Mo2(O2C tBu)3]2(μ-O2CC6H 4CO2) (1) and [Mo2(O2C tBu)3]2(μ-O2CC6H 4N2C6H4CO2) (2) have been made and characterized by spectroscopic and electrochemical methods. Their electronic structures have been examined by computations employing density functional theory on model compounds where HCO2 substitutes for tBuCO2. On the basis of these studies, the two Mo 2 units are shown to be only weakly coupled and the mixed-valence ions 1+ and 2+ to be valence-trapped and Class II and I, respectively, on the Robin-Day classification scheme for mixed-valence compounds. These results are compared to t2g6-Ru centers linked by 1,4-dicyanamidobenzene and azo-4,4′-diphenylcyanamido bridges for which the mixed-valence ions [Ru-bridge-Ru]5+ have been previously classified as fully delocalized, Class III [Crutchley et al. Inorg. Chem. 2001, 40, 1189; Inorg. Chem. 2004, 43, 1770], and on the basis of results described herein, it is proposed that the latter complex ion is more likely a mixed-valence organic radical where the bridge is oxidized and not the Ru(2+) centers.

Original languageEnglish
Pages (from-to)11035-11042
Number of pages8
JournalInorganic Chemistry
Issue number26
Publication statusPublished - 1 Dec 2006
Externally publishedYes


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