American Chemical Society
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Structural Transformation from a Discrete CuII4 Cluster to Two Extended CuII4 + CuII1 Chain-Based Three-Dimensional Frameworks by Changing the Spacer Functionality: Synthesis, Crystal Structures, and Magnetic Properties

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journal contribution
posted on 2016-02-21, 18:31 authored by En-Cui Yang, Bo Ding, Zhong-Yi Liu, You-Li Yang, Xiao-Jun Zhao
Three unique [Cu43-OH)2]6+ core-based magnetic complexes, [Cu4(amtrz)23-OH)2(nb)6]·2H2O (1), {[Cu5(H2O)6(trz)23-OH)2(btc)2]·0.6H2O}n (2), and {[Cu5(H2O)2(Htrz)23-OH)2(btec)2]·0.125H2O}n (3) (amtrz = 4-amino-1,2,4-triazole, Htrz = 1,2,4-triazole, Hnb = 4-nitrobenzoic acid, H3btc = 1,2,3-benzenetricarboxylic acid, and H4btec = 1,2,4,5-benzenetetracarboxylic acid), were synthesized by varying the spacer functionality of the mixed ligands. Significantly resulting from the cooperative cocoordination of the metal ions with polytopic triazolyl and carboxylate groups, a structural transformation from a discrete CuII4 cluster for 1 to two alternate CuII4 + CuII1 chain-based three-dimensional frameworks for 2 and 3 was achieved. Moreover, the connectivity manner of the structural subunits in 2 and 3 depends strongly on the number and position of the carboxylate group attached on the phenyl backbone. The nearest-neighbor interactions within the CuII4 cluster and between CuII4 cluster and CuII1 core mediated by the mixed short bridges were quantitatively calculated and compared based on the established magneto-structural relationships. Strong antiferromagnetic coupling interactions up to −206(4) cm–1 were observed in the isolated CuII4 cluster due to the favorable spatial orientation of the mixed multiple heterobridges toward the spin carriers.