Collect. Czech. Chem. Commun. 1996, 61, 1767-1772

Electron Spin Resonance Super-Hyperfine Splitting Study of Polycrystalline Niobocene and Vanadocene Dichlorides

Jana Holubová, Zdeněk Černošek and Ivan Pavlík

Department of General and Inorganic Chemistry, University of Pardubice, 532 10 Pardubice, Czech Republic


The electron spin resonance (ESR) spectra of niobocene and vanadocene dichlorides were studied on the title compounds prepared as magnetically diluted species in polycrystalline form. The resolved super-hyperfine splitting of anisotropic ESR spectra of both studied compounds was firstly observed. Computer simulation confirmed that this super-hyperfine splitting is due to interaction of unpaired electron with nuclear spin of two chlorine ligands. Average value of super-hyperfine coupling constant is 13.3 MHz for niobocene dichloride. For vanadocene dichloride, it is estimated to be in the range of 6-10 MHz. It corresponds approximately to 10% delocalization of metal unpaired electron spin density onto chlorine ligands in case of niobocene dichloride and to 4-7% delocalization in case of vanadocene dichloride.

Keywords: Electron spin resonance; Organometallic compounds; Hyperfine interaction.