QUT ePrints

Coordination of 2,2'-Bipyridyl and 1,10-Phenanthroline to Substituted Ytterbocenes: An Experimental Investigation of Spin Coupling in Lanthanide Complexes

Schultz, Madeleine, Boncella, James M., Berg, David J., Tilley, T. Don, & Andersen, Richard A. (2002) Coordination of 2,2'-Bipyridyl and 1,10-Phenanthroline to Substituted Ytterbocenes: An Experimental Investigation of Spin Coupling in Lanthanide Complexes. Organometallics, 21(3), pp. 460-472.

View at publisher

Abstract

Addition of 2,2'-bipyridyl to diamagnetic (Me5C5)2Yb(OEt2) gives the brown adduct (Me5C5)2Yb(bipy). The solution 1H NMR and electronic absorption spectra show that the bipyridyl complex is paramagnetic, containing a bipyridyl radical anion, which can also be detected in the solid-state infrared spectrum and by the single-crystal X-ray crystallographic analysis. However, the measured magnetic moment, which varies from less than 1 muB at 5 K to 2.5 muB at 300 K, is higher than expected for (Me5C5)2YbII(bipy0) and less than expected for (Me5C5)2YbIII(bipy-). An electron exchange model for spin coupling between Yb(III), with electron configuration 4f13, and the single unpaired electron in the bipyridyl radical anion is presented, based on comparison with the iodide salt [(Me5C5)2YbIII(bipy0)]+[I]-. Comparing the magnetic susceptibility of (Me5C5)2Yb(phen) with its iodide salt shows similar behavior with phenanthroline as ligand. The extent of paramagnetism and therefore the exchange coupling is changed by the nature of the substituents on the cyclopentadienide rings; electron-withdrawing SiMe3 groups favor Yb(II), while electron-donating alkyl groups stabilize the Yb(III) species. The molecular structures of many of the compounds have been determined in the solid state, and the bond distances and angles are consistent with the interpretation of the magnetism. The ring substituents, and therefore the different magnetic environments about the ytterbium center, also influence the rate of intermolecular exchange of the heterocyclic base ligands in solution; when the ligand is reduced, it exchanges more slowly than in the diamagnetic compounds.

Impact and interest:

100 citations in Web of Science®
Search Google Scholar™

Citation countsare sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

ID Code: 9087
Item Type: Journal Article
Additional Information: This article is freely available from the American Chemical Society website 12 months after the publication date. See links to publisher website in this record.
ISSN: 1520-6041
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > OTHER CHEMICAL SCIENCES (039900) > Organometallic Chemistry (039904)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Copyright Owner: Copyright 2002 American Chemical Society
Deposited On: 20 Aug 2007
Last Modified: 09 Mar 2011 11:58

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page