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 Rh26+ 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.
Bibliographical noteFunding Information:
The European Research Council (StG, No. 279549, DA, WRB) and Funding from the Ministry of Education, Culture and Science (Gravity program 024.001.035, WRB) are acknowledged for financial support. MPD thanks the US National Science Foundation ( CHE1212446 ) for their support of this research.
© 2014 Elsevier B.V. All rights reserved.
- Raman spectroscopy