Homo and heterometallic rhomb-like Ni₄ and Mn₂Ni₂ complexes

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• 作者：Ritwik Modak ; Yeasin Sikdar ; Senjuti M ; al ; Carlos J. G贸mez-Garc铆a ; Samia Benmansour ; Sudipta Chatterjee ; Sanchita Goswami
• 关键词：Hydroxyl rich ligand ; Defective dicubane core ; XRD analysis ; Homometallic NiII4 ; Heterometallic MnIII2NiII2 ; Antiferromagnetic coupling
• 刊名：Polyhedron
• 出版年：9 March, 2014
• 年：2014
• 卷：70
• 期：Complete
• 页码：155-163
• 全文大小：2011 K

文摘

Two new polynuclear complexes with hydroxyl-rich Schiff base ligand 3-[(2-Hydroxy-benzylidene)-amino]-propane-1,2-diol (H₃L), namely [Ni^II₂(HL)(H₂L)(SCN)]₂路DMF (1) and [Mn^III₂Ni^II₂(HL)₂(L)₂] (2) have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, FTIR, UV-Vis spectroscopy and variable temperature magnetic susceptibility measurements. The X-ray refinements reveal that both compounds present defective rhomb-like dicubane central cores (Ni₄ in 1 and Mn₂Ni₂ in 2). Magnetic susceptibility measurements indicate the presence of overall antiferromagnetic exchange interactions in 1 along the side connected by a N and O atoms (J₁ = 鈭?3.6 cm^鈭?) and along the short diagonal of the rhomb (J₃ = 鈭?.9 cm^鈭?) and a weak ferromagnetic coupling (J₂ = +5.8 cm^鈭?) along the side of the rhomb connected by a double O-bridge. In 2 the three exchange interactions are negative (J₁ = J₂ = 鈭?.3 cm^鈭? and J₃ = 鈭?.7 cm^鈭?). A magneto-structural correlation with the ratio between the Ni-O-Mn bond angle and the Mn-O bond length is also discussed for double O-bridged Mn-Ni pairs.