Electron paramagnetic resonance and electron nuclear double resonance investigation of the diradical bis(α-iminopyridinato)zinc complex

Maurice Van Gastel, Connie C. Lu, Karl Wieghardt, Wolfgang Lubitz

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The neutral complex Zn(L·)2 and its monocationic analogue [ZnL(L·) · THF]1+ have been previously reported to contain two and one monoanionic R-iminopyridinate(1-) π radical ligands, respectively [Lu, C.C.; Bill, E.; Weyhermüller, T.; Bothe, E.; Wieghardt, K. J. Am. Chem. Soc. 2008, 130, 3181-3197] (L represents the neutral R-iminopyridine form and THF is tetrahydrofuran). The electronic structures of these complexes have now been studied by Electron Paramagnetic Resonance (EPR) and Electron Nuclear Double Resonance (ENDOR) spectroscopy in conjunction with density-functional theory (DFT) calculations. The ENDOR spectra of the triplet Zn(L·)2 are characteristic of a localized diradical: these two ligand radicals exhibit dipolar exchange interactions, but no superexchange mechanism is operative, which would be consistent with its nearly tetrahedral coordination geometry. The monocationic species [ZnL(L·) · THF]1+ (S ) 1/2) has also been investigated by pulse EPR spectroscopy using large interpulse separations. It is shown that no radical hopping takes places on the time scale of the EPR experiment. The results obtained here, in particular the lack of asymmetry in the charge distribution between the two ligands in the triplet state, may be relevant for a better understanding of the electronic structure of naturally occurring diradicals and triplet states.

Original languageEnglish (US)
Pages (from-to)2626-2632
Number of pages7
JournalInorganic Chemistry
Volume48
Issue number6
DOIs
StatePublished - Mar 16 2009

Fingerprint Dive into the research topics of 'Electron paramagnetic resonance and electron nuclear double resonance investigation of the diradical bis(α-iminopyridinato)zinc complex'. Together they form a unique fingerprint.

  • Cite this