title: Magnetic Properties of a Series of Trinuclear Complexes (CuL)(2)Mn.xB (L Representing the Deprotonated Form of N-(4-Methyl-6-oxo-3-azahept-4-enyl)oxamic Acid and B Representing Respectively H(2)O (x = 5, 4.5, 3, 1), (CH(3))(2)SO (x = 2), and C(5)H(5)N (x = 4)). Crystal and Molecular Structure of (CuL)(2)Mn.2(CH(3))(2)SO.
abstract: A series of (Cu, Mn, Cu) complexes have been prepared and characterized. They may be described by the overall formula (CuL)(2)Mn.xB where L stands for the deprotonated form of N-(4-methyl-6-oxo-3-azahept-4-enyl)oxamic acid and B for respectively H(2)O (with x = 5, 4.5, 3, 1), (CH(3))(2)SO (with x = 2), and C(5)H(5)N (with x = 4). The crystal and molecular structures of (CuL)(2)Mn.2(CH(3))(2)SO have been solved. The crystals are monoclinic, space group P2(1)/n with cell constants a = 8.362(2) Å, b = 14.426(3) Å, c = 24.442(6) Å, and Z = 4. In each (Cu, Mn, Cu) molecular unit the central Mn(II) ion is bridged to two copper(II) ions through two oxamato groups. Short intermolecular Cu.Cu distances lead to the formation of a chain-like packing pattern running parallel to the c-axis. Magnetic susceptibility measurements have been performed for the six complexes. Five complexes display the same behavior which corresponds to the occurrence of antiferromagnetic Cu-Mn interactions within isolated trinuclear units. The J values are between -29.4(2) and -33.8(5) cm(-)(1). Surprisingly the field and temperature dependence of the magnetization for (CuL)(2)Mn.4.5H(2)O confirms that a magnetic phase transition occurs at low temperature and that, below T(c) = 37 K, the complex displays weak ferromagnetism.
authors.affiliation: Laboratoire de Chimie de Coordination du CNRS, UPR 8241, liée par conventions à l'Université Paul Sabatier et à l'Institut National Polytechnique de Toulouse, 205 route de Narbonne, 31077 Toulouse Cedex, France, Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Granada, Spain, Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, POB 55, FIN-00014, Helsinki, Finland, and Department of Chemistry, University of Joensuu, POB 11, FIN-80101 Joensuu, Finland.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Costes
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Laurent
authors.forename: Jose Maria Moreno
authors.initials: JM
authors.lastname: Sanchez
authors.forename: Jose Suarez
authors.initials: JS
authors.lastname: Varela
authors.forename: Markku
authors.initials: M
authors.lastname: Ahlgren
authors.forename: Markku
authors.initials: M
authors.lastname: Sundberg