Mono- and Di-chloro-bridged Discrete Dimers and Trimers and Mono-Chloro-Bridged 1D-Coordination Polymer of Copper(II). Magneto-structural Studies †‡

The synthesis, structural characterization, and magnetic properties of three copper(II) complexes, a mono-chloro-bridged [Cu2II(L6)2(μ-Cl)(Cl)(CuIICl4)] (1) and a dichloro-bridged [CuII2(L7)2(μ-Cl)2][ClO4]2 (3) discrete trimers and dimers, and a mono-chloro-bridged 1D-coordination polymer [CuII(L6)(μ-Cl)][ClO4]·CH3CN (2), are reported. Molecular structures were authenticated by X-ray crystallography. Temperature-dependent magnetic measurements carried out on powdered samples of 1–3 indicated a very weak antiferromagnetic exchange-coupling within the {CuII(μ-Cl)CuII(μ-Cl)CuIICl3}+ units in 1 [Curie-Weiss plot: θ = –0.19(1) K and g = 2.07(1)], a ferromagnetic behavior within {CuII(μ-Cl)2CuII}2+ units in 3 [Ĥ = –JS1·S2: J = +6.0(1) cm–1, D (zero-field splitting parameter) = 4.5(2) cm–1, and g = 2.11], and a weak intrachain antiferromagnetic behavior due to {CuII(μ-Cl)CuII}3+ units in 2 [single-chain polymer: J = –0.20(1) cm–1 and g = 2.11]. The square-pyramidal stereochemistry of the central copper(II) atoms in 1–3 was identified by their absorption spectral properties in acetontrile. An attempt was made to rationalize the observed magneto-structural behavior.

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