Journal article
Ligand substituent effect observed for ytterbocene 4'-cyano-2,2':6',2' '-terpyridine
Inorganic chemistry, Vol.44(16), pp.5911-5920
08/08/2005
Handle:
https://hdl.handle.net/2376/105524
PMID: 16060647
Abstract
A new N-heterocyclic complex of ytterbocene (Cp(2)Yb(II), Cp = C(5)Me(5)) has been prepared by the addition of 4'-cyano-2,2':6',2' '-terpyridine (tpyCN) to Cp(2)Yb(II)(OEt(2)) in toluene to give a dark blue species designated as Cp(2)Yb(tpyCN). The effect of the electron-withdrawing group (-CN) on the redox potentials of the charge-transfer form of this complex [in which an electron is transferred from the f(14) metal center to the lowest unoccupied (pi) molecular orbital of the tpyCN ligand to give a 4f(13)-pi(1) electronic configuration] has been quantified by cyclic voltammetry. The tpyCN ligand stabilizes this configuration by 60 mV more than that in the unsubstituted tpy ligand complex and by 110 mV more than that in the unsubstituted bpy ligand complex. Magnetic susceptibility measurements corroborate the enhanced stabilization of the 4f(13)-pi(1) configuration by the substituted terpyridyl ligand complex. Furthermore, the temperature dependence of the magnetic data is most consistent with a thermally induced valence tautomeric equilibrium between this paramagnetic 4f(13)-pi(1) form that dominates near room temperature and the diamagnetic 4f(14)-pi(0) form that dominates at low temperature. Differing coordination modes for the tpyCN ligand to the ytterbocene center have also been confirmed by isolation and X-ray crystallographic characterization of complexes binding through either the cyano nitrogen of tpyCN or the three terpyridyl nitrogen atoms of tpyCN.
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Details
- Title
- Ligand substituent effect observed for ytterbocene 4'-cyano-2,2':6',2' '-terpyridine
- Creators
- Jacqueline M Veauthier - Chemistry, Theoretical, and Materials Science and Technology Divisions, Los Alamos National Laboratory, New Mexico 87545, USAEric J SchelterChristopher J KuehlAurora E ClarkBrian L ScottDavid E MorrisRichard L MartinJ D ThompsonJaqueline L KiplingerKevin D John
- Publication Details
- Inorganic chemistry, Vol.44(16), pp.5911-5920
- Academic Unit
- Chemistry, Department of
- Publisher
- United States
- Identifiers
- 99900546859201842
- Language
- English
- Resource Type
- Journal article