Repozytorium

Cyclic and linear structures constructed by ionic bonds between alkali ion and pinwheel pentanuclear [GdIII(CuIIL)4] core of M [GdIII(CuIIL)4] (M+ = Na+, K+, and Cs+; H3L =N-(4,-methyl-6-oxo-3-azahept-4-enyl)oxamic acid).

Autorzy

Y. Maruno

K. Yabe

H. Hagiwara

Takeshi Fujinami

Naohide Matsumoto

Nazzareno Re

Jerzy Mroziński

Rok wydania

2010

Czasopismo

Bulletin of the Chemical Society of Japan

Numer woluminu

83

Strony

1511-1517

DOI

10.1246/bcsj.20100223

Kolekcja

Naukowa

Język

Angielski

Typ publikacji

Artykuł

Streszczenie

Three copper(II)gadolinium(III) complexes M[Gd(CuL)4] with M+ = Na+, K+, and Cs+ have been synthesized, where H3L denotes N-(4-methyl-6-oxo-3-azahept-4-enyl) oxamic acid. The anionic part [Gd(CuL)4]- assumes a pinwheellike pentanuclear GdCu4 core and the central GdIII ion is coordinated by eight oxygen atoms of four "(CuL)," where each "(CuL)" assumes a square-planar N2O2 coordination geometry and functions as a bidentate chelate ligand to Gd III ion. The sodium and potassium salts assume a one-dimensional (1D) chain structure bridged by Na+ or K+ ions, while the cesium salt assumes a cyclic dimeric structure bridged by Cs+ ions. For the assembly structures, the cation acts as a connector between adjacent [Ln(CuL)4]- cores. The magnetic data demonstrated an intracluster ferromagnetic interaction between GdIII and Cu II ions within a GdCu4 core and an intercluster antiferromagnetic interaction through the cation. The magnetic susceptibilities can be reproduced by the spin Hamiltonian based on the pentanuclear GdCu 4 structure, Ĥ = βH(4gCuSCu + g GdSGd) - 2JSGd(SCu1 + S Cu2 + SCu3 + SCu4). The best-fit parameters are gGd = 2.00, gCu = 2.12, JGd-Cu =+1.11 cm -1, zJ' = -0.065 cm-1, and 0.4% of monomeric Cu II impurity for the Na+ salt,; gGd = 2.00, gCu = 2.13, JGdCu=+ 1.03 cm-1, zJ' = -0.038 cm-1, and 0.2% of monomeric CuII impurity for the K + salt,; and gGd = 2.00, gCu = 2.14, J GdCu=+ 0.67 cm-1, zJ' = -0.025 cm-1, 0.2% of monomeric CuII impurity for the Cs+ salt. The Gd-Cu coupling constant J is very similar in the Na+ and K+ salts (+1.11 and +1.03 cm-1) but is slightly smaller for the Cs + salt (+0.67 cm-1), probably due to the different packing of the GdCu4 clusters in the latter salt (cyclic dimers instead of an infinite chain); (2) the intercluster antiferromagnetic interaction, responsible for the low temperature decrease of XMT, significantly decreases when the ionic radius of the alkali cation increases (Na+ > K+ > Cs+) thus keeping the pentanuclear units further apart.

Adres publiczny

http://dx.doi.org/10.1246/bcsj.20100223

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