New Family of Thiocyanate-Bridged Re(IV)-SCN-M(II) (M = Ni, Co, Fe, and Mn) Heterobimetallic Compounds: Synthesis, Crystal Structure, and Magnetic Properties

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• 作者：Ricardo Gonz谩lez ; Alvaro Acosta ; Ra煤l Chiozzone ; Carlos Kremer ; Donatella Armentano ; Giovanni De Munno ; Miguel Julve ; Francesc Lloret ; Juan Faus
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：May 21, 2012
• 年：2012
• 卷：51
• 期：10
• 页码：5737-5747
• 全文大小：458K
• 年卷期：v.51,no.10(May 21, 2012)
• ISSN：1520-510X

文摘

The heterobimetallic complexes of formula [(Me₂phen)₂M(渭-NCS)Re(NCS)₅]路CH₃CN [Me₂phen = 2,9-dimethyl-1,10-phenanthroline and M = Ni (1), Co (2), Fe (3), and Mn (4)] have been prepared, and their crystal structures have been determined by X-ray diffraction on single crystals. Compounds 1鈥?b>4 crystallize in the monoclinic C2/c space group, and their structure consists of neutral [(Me₂phen)₂M(渭-NCS)Re(NCS)₅] heterodinuclear units with a Re-SCN-M bridge. Each Re(IV) ion in this series is six-coordinated with one sulfur and five nitrogen atoms from six thiocyanate groups building a somewhat distorted octahedral environment, whereas the M(II) metal ions are five-coordinated with four nitrogen atoms from two bidentate Me₂phen molecules and a nitrogen atom from the bridging thiocyanate describing distorted trigonal bipyramidal surroundings. The values of the Re路路路M separation through the thiocyanate bridge in 1鈥?b>4 vary in the range 5.903(1)鈥?.117(3) 脜. The magnetic properties of 1鈥?b>4 as well as those of the parent mononuclear Re(IV) compounds (NBu₄)₂[Re(NCS)₆] (A1) (NBu₄⁺ = tetra-n-butylammonium cation) and [Zn(NO₃)(Me₂phen)₂]₂[Re(NCS)₅(SCN)] (A2) were investigated in the temperature range 1.9鈥?00 K. Weak antiferromagnetic interactions between the Re(IV) and M(II) ions across the bridging thiocyanate were found in 1鈥?b>4 [J = 鈭?.3 (1), 鈭?.4 (2), 鈭?.8 (3), and 鈭?.2 cm^鈥? (4), the Hamiltonian being defined as 膜 = 鈥?i>J艤_Re路艤_M]. The magnetic behavior of A2 is that of a magnetically diluted Re(IV) complex with a large and positive value of the zero-field splitting for the ground level (D_Re = +37.0 cm^鈥?). In the case of A1, although its magnetic behavior is similar to that of A2 in the high-temperature range (D_Re being +19.0 cm^鈥?), it exhibits a weak ferromagnetism below 3.0 K with a canting angle of 1.3掳.