Slow Magnetic Relaxation and Charge-Transfer in Cyano-Bridged Coordination Clusters Incorporating [Re(CN)7]3−/4−

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• 作者：Joseph M. Zadrozny ; Danna E. Freedman ; David M. Jenkins ; T. David Harris ; Anthony T. Iavarone ; Corine Mathonire ; Rodolphe Clrac ; Jeffrey R. Long
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：October 4, 2010
• 年：2010
• 卷：49
• 期：19
• 页码：8886-8896
• 全文大小：1023K
• 年卷期：v.49,no.19(October 4, 2010)
• ISSN：1520-510X

文摘

Treatment of the cyanometalate building unit [Re(CN)₇]³⁻ with [(PY5Me₂)M(MeCN)]²⁺ (M = Co, Ni, Cu) affords a series of pentanuclear clusters of formulas [(PY5Me₂)₄M₄Re(CN)₇]⁵⁺ (M = Co, Ni, Cu) and [(PY5Me₂)₄Cu₄Re(CN)₇]⁴⁺. Single crystal X-ray diffraction analyses of the clusters reveal a star-like structure in which four [(PY5Me₂)M]²⁺ moieties are linked to a central [Re(CN)₇]³⁻ unit via bridging cyanide ligands. An intramolecular Co^II → Re^IV charge-transfer accompanies the formation of the Co^II₄Re^IV cluster, giving a Co^II₃Co^IIIRe^III species. Spectroelectrochemical methods and irradiation experiments are used to characterize the metal−metal charge-transfer bands of this compound. A rhenium-based thermally induced one-electron reduction is observed for the Cu^II₄Re^IV cluster to give a Cu^II₄Re^III complex; however, this reduction may be forestalled at low temperature. Finally, magnetic measurements reveal intracluster ferromagnetic exchange coupling, strong uniaxial magnetic anisotropy, and slow magnetic relaxation in the Ni^II₄Re^IV and Cu^II₄Re^IV clusters.