Iron Lanthanide Phosphonate Clusters: {Fe6Ln6P6} Wells鈥擠awson-like Structures with D3d Symmetry

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• 作者：Eufemio Moreno Pineda ; Floriana Tuna ; Yan-Zhen Zheng ; Simon J. Teat ; Richard E. P. Winpenny ; J眉rgen Schnack ; Eric J. L. McInnes
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：March 17, 2014
• 年：2014
• 卷：53
• 期：6
• 页码：3032-3038
• 全文大小：397K
• 年卷期：v.53,no.6(March 17, 2014)
• ISSN：1520-510X

文摘

Reaction of [Fe₃(渭₃-O)(O₂C^tBu)₆(HO₂C^tBu)₃](O₂C^tBu) and [Ln₂(O₂C^tBu)₆(HO₂C^tBu)₆] (Ln = lanthanide) with three different phosphonic acids produce a family of highly symmetrical {Fe₆Ln₆P₆} clusters with general formula [Fe₆Ln₆(渭₃-O)₂(CO₃)(O₃PR)₆(O₂C^tBu)₁₈], where R = methyl 1, phenyl 2, or n-hexyl 3. All the clusters present an analogous metal frame to the previously reported {Ni₆Ln₆P₆} both being related to the well-known Wells鈥揇awson ion from polyoxometallate chemistry. These highly symmetrical clusters have, or approximate very closely to, D_3d point symmetry. Both Fe^III and Gd^III ions are magnetically isotropic and could thus exhibit promising magnetocaloric properties; hence we investigated the {Fe₆Gd₆P₆} compounds accordingly. Modeling the magnetic data of [Fe₆Gd₆(渭₃-O)₂(CO₃)(O₃PPh)₆(O₂C^tBu)₁₈] by the finite-temperature Lanczos method gave a strong antiferromagnetic Fe路路路Fe interaction (J_Fe鈥揊e = 鈭?0 cm^鈥?) and very weak Gd路路路Gd and Gd路路路Fe exchange interactions (|J| < 0.1 cm^鈥?). The strong antiferromagnetic Fe路路路Fe interaction could account for the relatively smaller 鈭捨?i>S_m value observed, compared against the {Ni₆Gd₆P₆} analogues.