Bis-σ-(phenyl)-tetrakis-μ-(capralactamato)dirhodium(III), formed by oxidative reactions of dirhodium(II) carboxamidates with arylboronic acids promoted by copper(II), exists in two non-interconvertable conformations. In these conformational isomers the caprolactamate ligands are oriented around dirhodium(III) as a propeller with apparent C4 symmetry and in a biplanar array. Cyclic voltammetry and spectroelectrochemistry as well as Raman and resonance Raman spectroscopy of the conformationally distinct Rh2 6+ carboxamidates have been obtained in order to explore the origin of their non-interconversion. Differences in their vibrational spectra occur only in the low wavenumber spectral region, but there is a 250 mV difference in oxidation potential between conformational isomers consistent with a substantial difference ground state energies. Notably, spectroelectrochemical data show that oxidation does not result in isomerization.

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Keywords Carboxamidate, Electrochemistry, Raman spectroscopy, Rhodium
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Journal Inorganica Chimica Acta
Angelone, D. (Davide), Draksharapu, A. (Apparao), Browne, W.R. (Wesley R.), Choudhuri, M.M.R., Crutchley, R, Xu, X. (Xichen), … Doyle, M.P. (Michael P.). (2014). Dinuclear compounds without a metal-metal bond. Dirhodium(III,III) carboxamidates. Inorganica Chimica Acta, 424, 235–240. doi:10.1016/j.ica.2014.09.006