American Chemical Society
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Three p-tert-Butylthiacalix[4]arene-Supported Cobalt Compounds Obtained in One Pot Involving In Situ Formation of N6H2 Ligand

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journal contribution
posted on 2010-09-06, 00:00 authored by Yanfeng Bi, Wuping Liao, Guancheng Xu, Ruiping Deng, Meiyan Wang, Zhijian Wu, Song Gao, Hongjie Zhang
Three p-tert-butylthiacalix[4]arene (H4TC4A)-supported CoII compounds, [Co4(TC4A)(N3)4(N6H2)(CH3OH)](CH3OH)2 (1), [Co8(TC4A)2(N3)2(N6H2)2(CH3COO)4(CH3OH)4](OH)2(CH3OH)4 (2), and [Co10(TC4A)4(N3)4](CH3OH)4 (3), have been solvothermally obtained in one pot and structurally characterized by single-crystal X-ray diffraction analyses, powder XRD, and IR spectroscopy. This work presents the first one-dimensional (1) cobalt cluster for the calixarene complexes and another two octanuclear (2) or decanuclear (3) cobalt clusters. In the structures of compounds 1 and 2, a novel N6H2 ligand formed by the in situ (2 + 3) cycloaddition of two azides was observed. Density functional theory (DFT) calculations give the heat of formation (2N3 + 2H+ → N6H2) and decomposition energy (N6H2 → 3N2 + H2) of 677.47 and 124.85 kcal/mol, respectively. Furthermore, an intergradation was determined at the B3LYP/6-311++g(d,p) level for the formation of the N6H2 ligand. In addition, one TC4A ligand of a sandwich unit adopts a cone conformation, while the other adopts a pinched cone conformation in 3. The magnetic properties of these three compounds were influenced mainly by the orbital contributions of the distorted octahedral CoII ions.