“Variable” hyperfine coupling constants

Claxton, T. A.; Oakes, J.

doi:10.1016/0009-2614(67)85045-0

Cited by 5 publications

(1 citation statement)

References 6 publications

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“…The likely explanation for these seemingly contradictory characteristics is the alternating-linewidth effect. [133][134][135] The asymmetry observed for the 14 N coupling arises from breaking the π-conjugation at one of the M−N−C−C−N chelate rings upon reduction, which alters the coupling at the C−N versus the C═N nitrogen nuclei. These spectra indicate that the arrangement of these bonds is rapidly interchanging due to electron transfer between the metal sites, resulting in out-of-phase modulation of the hyperfine splittings.…”

Section: Resultsmentioning

confidence: 99%

Unusually Strong Long-range Electronic Coupling Across Redox-Active Bridges in M3+/M4+ Mixed-Valence Complexes of Group 4 Congeners

Bell

DeYonker

Moore

et al. 2021

Preprint

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Homobimetallic complexes of Group 4 metals, supported by the redox-active tetrakis(imino)pyracene (TIP) ligand were synthesized and isolated. The formation of these complexes resulted in LUMOs having significantly lower energies than the free ligand and the respective metal salts, MCl4 (M = Ti, Zr, Hf), whereby all three complexes were readily reduced by one electron using the mild reductant, Cp*2Fe (E0 = -0.59 V). Spectroscopic characterization and quantum chemical analyses of the reduced species revealed that the resulting complexes are delocalized, borderline Class II-III (Ti) and Class III (Zr, Hf) mixed valence complexes. All three complexes display surprisingly strong long-range electronic coupling between the metal centers, as M to M distances, rAB, are nearly 12 Å. The coupling strengths of Zr and Hf were significantly stronger than those observed for the Ti complex, suggesting that better orbital overlap between the ligand and 4d or 5d metal centers helps to relieve the instability of the 3+ oxidation state via delocalization.

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Section: Resultsmentioning

confidence: 99%