Ferromagnetic nanoscale electron correlation promoted by organic spin-dependent delocalization.

Journal of the American Chemical Society
Martin L. KirkJunghyun Lee

Abstract

We describe the electronic structure and the origin of ferromagnetic exchange coupling in two new metal complexes, NN-SQ-Co(III)(py)(2)Cat-NN (1) and NN-Ph-SQ-Co(III)(py)(2)Cat-Ph-NN (2) (NN = nitronylnitroxide radical, Ph = 1,4-phenylene, SQ = S = (1)/(2) semiquinone radical, Cat = S = 0 catecholate, and py = pyridine). Near-IR electronic absorption spectroscopy for 1 and 2 reveals a low-energy optical band that has been assigned as a Psi(u) --> Psi(g) transition involving bonding and antibonding linear combinations of delocalized dioxolene (SQ/Cat) valence frontier molecular orbitals. The ferromagnetic exchange interaction in 1 is so strong that only the high-spin quartet state (S(T) = (3)/(2)) is thermally populated at temperatures up to 300 K. The temperature-dependent magnetic susceptibility data for 2 reveals that an excited state spin doublet (S(T) = (1)/(2)) is populated at higher temperatures, indicating that the phenylene spacer modulates the magnitude of the magnetic exchange. The valence delocalization within the dioxolene dyad of 2 results in ferromagnetic alignment of two localized NN radicals separated by over 22 A. The ferromagnetic exchange in 1 and 2 results from a spin-dependent delocalization (double exchang...Continue Reading

References

May 12, 2000·Chemistry : a European Journal·S F Nelsen
Dec 26, 2001·Chemical Reviews·K D DemadisT J Meyer
Feb 6, 2003·Journal of the American Chemical Society·David A ShultzJeff W Kampf
Aug 3, 2005·Inorganic Chemistry·Peter H DinolfoJoseph T Hupp
Feb 1, 2007·Journal of the American Chemical Society·Martin L KirkCandice L Brannen
Apr 19, 2007·Chemistry : a European Journal·Frédéric BiasoNarcis Avarvari

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Citations

May 21, 2010·Journal of the American Chemical Society·Kelly G MatzMartin L Kirk
Sep 17, 2015·Journal of the American Chemical Society·Alexandra I GaudetteT David Harris
Dec 21, 2016·The Journal of Physical Chemistry. a·Torben SteenbockCarmen Herrmann
Apr 14, 2018·Dalton Transactions : an International Journal of Inorganic Chemistry·David J R BrookBruce C Noll
Jul 23, 2013·Chemistry : a European Journal·Jesús Ferrando-SoriaEmilio Pardo
Oct 4, 2017·Chemical Science·Martin L KirkLukasz Wojtas
Nov 30, 2019·The Journal of Chemical Physics·Benjamin W SteinMartin L Kirk

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