Alkoxo-bridged dinuclear and tetranuclear copper(II) complexes with Schiff-bases derived from benzoylacetone and 1,n-diamino-n′-hydroxyalkanes (n, n′=3,2; 4,2; and 5,3)

Alkoxo-bridged copper(II) complexes with N,N'-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,3-diamino-2-propanol (H(3)bzacpro), N,N'-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,4-diamino-2-butanol (H(3)bzacbu), and N,N'-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,5-diamino-3-pentanol (H(3)bzacpen), [Cu-2(bzacpro)(CH3CO2)] (1), [Cu-4(bzacpro)(2)(C2H5O)(2)] (2), [Cu-2(bzacbu)(CH3CO2)] (3), [Cu-4(bzacbu)(2)(CH3O)(2)] (4), [Cu-4(bzacpen)(2)(CH3CO2)(2)] (5), and [Cu-4(bzacpen)(2)O].H2O (6) have been synthesized and characterized by measurements of the infrared and electronic spectra, and the magnetic susceptibilities. Single-crystal X-ray analyses revealed that 1 and 3 are dinuclear copper(H) complexes having a dinuclear core bridged by an alkoxo-oxygen atom of bzacpro or bzacbu and acetato-oxygen atoms, whereas 2, 4, 5, and 6 are tetranuclear copper(II) complexes composed of mu-alkoxo(bzacpro)-mu-ethoxo-, mu-alkoxo(bzacbu)-mu-methoxo-, mu-alkoxo(bzacpen)-mu-acetato-, and mu-alkoxo(bzacpen)-mu-oxo-bridged units, respectively. Magnetic-susceptibility data show that an antiferromagnetic interaction is operative within the dinuclear or tetranuclear core in 1-3, 5 and 6, whereas a ferromagnetic coupling is operative in 4. The crystal structures of the three Schiff-base ligands have also been elucidated.