Cobalt Clusters with Cubane-Type Topologies Based on Trivacant Polyoxometalate Ligands

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• 作者：Yan Duan ; Juan M. Clemente-Juan ; Carlos Giménez-Saiz ; Eugenio Coronado
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：January 19, 2016
• 年：2016
• 卷：55
• 期：2
• 页码：925-938
• 全文大小：747K
• ISSN：1520-510X

文摘

Four novel cobalt-substituted polyoxometalates having cobalt cores exhibiting cubane or dicubane topologies have been synthesized and characterized by IR, elemental analysis, electrochemistry, UV–vis spectroscopy, X-ray single-crystal analysis, and magnetic studies. The tetracobalt(II)-substituted polyoxometalate [Co₄(OH)₃(H₂O)₆(PW₉O₃₄)]^4– (1) consists of a trilacunary [B-α-PW₉O₃₄]^9– unit which accommodates a cubane-like {Co^II₄O₄} core. In the heptacobalt(II,III)-containing polyoxometalates [Co₇(OH)₆(H₂O)₆(PW₉O₃₄)₂]^9– (2), [Co₇(OH)₆(H₂O)₄(PW₉O₃₄)₂]_n^9n– (3), and [Co₇(OH)₆(H₂O)₆(P₂W₁₅O₅₆)₂]^15– (4), dicubane-like {Co^II₆Co^IIIO₈} cores are encapsulated between two heptadentate [B-α-PW₉O₃₄]^9– (in 2 and 3) or [α-P₂W₁₅O₅₆]^15– (in 4) ligands. While 1, 2, and 4 are discrete polyoxometalates, 3 exhibits a polymeric, chain-like structure that results from the condensation of polyoxoanions of type 2. The magnetic properties of these complexes have been fitted according to an anisotropic exchange model in the low-temperature regime and discussed on the basis of ferromagnetic interactions between Co²⁺ ions with angles Co–L–Co (L = O, OH) close to orthogonality and weakly antiferromagnetic interactions between Co²⁺ ions connected through central diamagnetic Co³⁺ ion. Moreover, we will show the interest of the unique spin structures provided by these cubane and dicubane cobalt topologies in molecular spintronics (molecular spins addressed though an electric field) and quantum computing (spin qu-gates).