Ferromagnetic Coupling in 鈥淒ouble-Bridged鈥?Dihydrogenpyrophosphate Complexes of Cobalt(II) and Nickel(II)

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• 作者：Tiffany J. Greenfield ; Amanda E. Hoffman ; Nadia Marino ; Alan G. Goos ; Francesc Lloret ; Miguel Julve ; Robert P. Doyle
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：July 6, 2015
• 年：2015
• 卷：54
• 期：13
• 页码：6537-6546
• 全文大小：625K
• ISSN：1520-510X

文摘

Three isostructural compounds of the formula {[M(bipy)(H₂O)(H₂P₂O₇)]₂路2H₂O} [bipy = 2,2鈥?bipyridine; M = Ni (1), Co (2), Mn (3)] have been isolated from aqueous solutions containing the corresponding metal(II) chloride hydrate with a bipy and sodium pyrophosphate solution in a 1:1:2 molar ratio, and their structures were determined by single-crystal X-ray diffraction. The structures of 1鈥?b>3 consist of neutral aqua(2,2鈥?bipyridine)metal(II) dinuclear units bridged by two dihydrogenpyrophosphate groups adopting a bidentate/monodentate mode. Each metal ion in 1鈥?b>3 is six-coordinate in a distorted octahedral geometry, with the reduced value of the angle subtended by the chelating bipy at the metal ion [79.6(1)掳 (1), 77.32(7)掳 (2), and 72.9(1)掳 (3)] being the main source of this distortion. The values of the intramolecular metal鈥搈etal separation are 5.271(1) 脜 (1), 5.3065(8) 脜 (2), and 5.371(1) 脜 (3). Magnetic susceptibility measurements on polycrystalline samples of 1鈥?b>3 in the temperature range 1.9鈥?00 K shows weak intramolecular ferromagnetic [J = +1.86(2) cm^鈥? (1) and +0.25(1) cm^鈥? (2)] and antiferromagnetic [J = 鈭?.48(1) cm^鈥? (3)] coupling, with the spin Hamiltonian being defined as H = 鈭?i>JS_M1路S_M1a. This rarely observed coordination mode for dihydrogenpyrophosphate leads to ferromagnetic coupling in complexes of nickel(II) or cobalt(II).