title: Ni5, Ni8, and Ni10 clusters with 2,6-diacetylpyridine-dioxime as a ligand.
abstract: In the present work, novel coordination possibilities for the system dapdoH(2)/Ni(II) (dapdoH(2) = 2,6-diacetylpyridine-dioxime) have been explored. Depending on the starting reagents and solution conditions, several clusters with nuclearities ranging from Ni(5) to Ni(10) were achieved and structurally characterized, namely, [Ni(5)(R-COO)(2)(dapdo)(2)(dapdoH)(2)(N(CN)(2))(2)(MeOH)(2)] in which R-COO(-) = benzoate (1) or 3-chlorobenzoate (2), [Ni(8)(dapdo)(4)(NO(3))(4)(OH)(4)(MeOH)(4)] (3), and [Ni(10)(dapdo)(8)(N(CN)(2))(2)(MeO)(MeOH)](NO(3)) (4). For the first time, pentadentate coordination for the dapdo(2-) ligand has been established. All compounds show a combination of square-planar and octahedrally coordinated nickel atoms. According to the Ni(2)(sp)Ni(3)(Oh) (1 and 2), Ni(4)(sp)Ni(4)(Oh) (3), and Ni(4)(sp)Ni(6)(Oh) (4) environments, these systems magnetically behave as trimer, tetramer, and hexanuclear clusters, respectively. dc magnetic measurements in the 2-300 K range of temperature reveal antiferromagnetic coupling for all compounds, and the correlation of the superexchange interaction with the torsion angles involving the oximato bridges is experimentally confirmed.
authors.affiliation: Departament de Química Inorgànica and Institut de Nanociència i Nanotecnologia de la Universitat de Barcelona (IN2UB), Martí i Franqués 1-11, 08028 Barcelona, Spain. albert.escuer@ub.edu
authors.forename: Albert
authors.initials: A
authors.lastname: Escuer
authors.forename: Jordi
authors.initials: J
authors.lastname: Esteban
authors.forename: Olivier
authors.initials: O
authors.lastname: Roubeau