R. Watanabe, T. Shimada, Nobumasa Koyama
Nov 28, 2011
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0
Influential Citations
15
Citations
Journal
Polyhedron
Abstract
Abstract The introduction of a relatively bulky alkyl group at 2-position of pyrazine afforded unique μ-pyz complexes, namely, dinuclear [{Cu(hfac)2}2(μ-2-isobutylpyrazine)], trinuclear [{Cu(hfac)2}3(μ-2-isopropylpyrazine)2], and polymeric [Cu(hfac)2(μ-ibupyz)]n (Hhfac stands for 1,1,1,5,5,5-hexafluoropentane-2,4-dione). These compounds have an axial–equatorial dinuclear moiety, which is expected to show ferromagnetic interaction. However, they exhibited practically negligible or very weak antiferromagnetic interaction. This may be due to violation of orthogonality because of the steric hindrance of the isobutyl or isopropyl groups. We analyzed the relationship between the structural deformation parameter defined as the N(eq)⋯N(ax)–Cu angle and the exchange coupling parameter. A critical angle, at which the sign of the magnetic coupling changes from positive to negative, is estimated to be 165(2)°. The present results are reasonably explained in this relation.