Heterotetranuclear Oxalato-Bridged ReIV3MII (M = Mn, Fe, Co, Ni, Cu) Complexes: A New Example of a Single-Molecule Magnet (M = Ni)

详细信息    查看全文

• 作者：Jos Martnez-Lillo^† ; ^‡ ; ; Donatella Armentano^‡ ; ; Giovanni De Munno*^‡ ; ; Wolfgang Wernsdorfer ; Juan Modesto Clemente-Juan^R
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：April 6, 2009
• 年：2009
• 卷：48
• 期：7
• 页码：3027-3038
• 全文大小：454K
• 年卷期：v.48,no.7(April 6, 2009)
• ISSN：1520-510X

文摘

The use of the mononuclear species (NBu₄)₂[Re^IVCl₄(ox)] (NBu₄⁺ = tetra-n-butylammonium cation; ox = oxalate dianion) as a ligand toward fully solvated divalent first-row transition-metal ions affords the tetranuclear complexes (NBu₄)₄[{Re^IVCl₄(μ-ox)}₃M^II] with M = Mn (1), Fe (2), Co (3), Ni (4), and Cu (5). Their structure is made up of discrete [{ReCl₄(μ-ox)}₃M]⁴⁻ anions and bulky NBu₄⁺ cations. The complexes 2−5 crystallize in the triclinic system with space group P; 2 and 5 as well as 3 and 4 are isostructural. The Re and M atoms exhibit somewhat distorted ReCl₄O₂ and MO₆ octahedral surroundings, with the oxalate groups adopting the bis-bidentate bridging mode. Magnetic susceptibility measurements on polycrystalline samples of 1−5 in the temperature range 1.9−300 K show the occurrence of intramolecular antiferromagnetic [J = −1.30 cm⁻¹ (1)] and ferromagnetic couplings [J = +1.62 (2), +3.0 (3), +16.3 (4), and +4.64 cm⁻¹ (5)], with the Hamiltonian being defined as H = −J[S_M(S_Re1 + S_Re2 + S_Re3)]. Compound 4 is the first example of an oxalato-bridged heterometallic species that behaves as a single-molecule magnet with a ground-state spin S = ¹¹/₂ and D = −0.8(1) cm⁻¹, as shown by the study of its static and dynamic magnetic properties and a high-frequency electron paramagnetic resonance study on polycrystalline samples together with detailed micro-SQUID measurements on single crystals.