High-frequency EPR and structural data as complementary information on stable radical complexes containing the semi-reduced azo function
✍ Scribed by Biprajit Sarkar; Stephanie Frantz; Sayak Roy; Monika Sieger; Carole Duboc; Gert Denninger; Hans-Jürgen Kümmerer; Wolfgang Kaim
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 241 KB
- Volume
- 890
- Category
- Article
- ISSN
- 0022-2860
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✦ Synopsis
Dinuclear metal compounds [(L n M)(l-BL ÅÀ )(ML n )] k involving radical anions of bridging ligands BL such as 2,2 0 -azobispyridine or 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine and coordinated inorganic or organometallic complex fragments ML n containing copper(I), rhenium(I), ruthenium(II), osmium(II), rhodium(III) or iridium(III) have been investigated in frozen solutions using high field EPR spectroscopy at W band (95 GHz) or higher frequencies. The generally small but still rather variable anisotropy of the g factor shows typical patterns reflecting the specific metal/ligand interactions, the competition between bridging and ancillary ligands for spin density, and the spin-orbit coupling constants of the metals. The EPR data are thus shown to specify the structural data as obtained from X-ray crystallography for a standard series of diphosphinocopper(I) complexes involving the radical ligands indicated. The (RNNR) ÅÀ group can be placed next to the related superoxide (OO) ÅÀ as a paramagnetic ligand with specific geometrical and electronic structure.