Showing papers by "M. Salah El Fallah published in 2004"

Crystal structure and magnetic interactions in nickel(II) dibridged complexes formed by two azide groups or by both phenolate oxygen-azide, -thiocyanate, -carboxylate, or -cyanate groups.

Abstract: Tridentate/tetradentate Schiff base ligands L1 and L2, derived from the condensation of o-vanillin or pyridine-2-aldehyde with N,N-dimethylethylenediammine, react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of dinuclear complexes of formulas [Ni(L1)(μ1,1-N3)Ni(L1)(N3)(OH2)]·H2O (1), {[Ni(L1)(μ1,1-NCS)Ni(L1)(NCS)(OH2)][Ni(L1)(μ-CH3COO)Ni(L1)( NCS) (OH2)]} (2) {[2A][2B]}, [Ni(L1)(μ1,1-NCO)Ni(L1)(NCO)(OH2)]·H2O (3), and [Ni(L2-OMe)(μ1,1-N3)(N3)]2 (4), where L1 = Me2N(CH2)2NCHC6H3(O-)(OCH3) and L2 = Me2N(CH2)2NCHC6H3N. We have characterized these complexes by analytical, spectroscopic, and variable-temperature magnetic susceptibility measurements. The coordination geometry around all of the Ni(II) centers is a distorted octahedron with bridging azide, thiocyanate/acetate, or cyanate in a μ1,1 mode and μ2-phenolate oxygen ion for 1−3, respectively, or with a double-bridging azide for 4. The magnetic properties of the complexes were studied by magnetic sus...

End-to-end single cyanato and thiocyanato bridged Cu(II) polymers with a new tridentate Schiff base ligand: Crystal structure and magnetic properties

Abstract: A new tridentate Schiff base ligand HL (L = C14H19N2O), derived from the condensation of benzoylacetone and 2-dimethylaminoethylamine in a 1 ∶ 1 ratio, reacts with copper(II) acetate and cyanate, thiocyanate or azide, to give rise to several end-to-end polymeric complexes of formulae [CuL(µ1,3-NCO)]n1, [CuL(µ1,3-NCS)]n2 and the complex 3 has two crystallographically independent units of formula [CuL(N3)] in the asymmetric unit cell. Complex 3 exists in dimeric form rather than as a polymeric chain. Compound 1 is the first report of a singly end-to-end cyanate bridged polymeric chain of Cu(II) with a Schiff base as a co-ligand. There are many examples of double NCS bridged polymeric chains, but fewer singly bridged ones such as compound 2. We have characterized these complexes by analytical, spectroscopic, structural and variable temperature magnetic susceptibility measurements. The coordination geometry around the Cu(II) centers is distorted square pyramidal for 1 and 2 and square planar for complex 3. The magnetic susceptibility data show slight antiferromagnetic coupling for the polymers having J values −0.19 and −0.57 cm−1 for complexes 1 and 2 respectively. The low values of J are consistent with the equatorial–axial disposition of the bridges in the polymers.

Syntheses and magneto-structural study of several polynuclear copper(II) complexes derived from 1,3-Bis(dimethylamino)-2-propanolato.

Abstract: The syntheses, structural characterization, and magnetic behavior of the three new polynuclear copper(II) complexes with formulas [Cu(4)(eta(2):mu-CH(3)COO)(2)(mu-OH)(2)(mu-OH(2))(mu-bdmap)(2)](ClO(4))(2).H(2)O (1), [Cu(8)(NCO)(2)(eta(1):mu-NCO)(4)(mu-OH)(2)(mu(3)-OH)(2)(mu-OH(2))(3)(mu-bdmap)(4)](ClO(4))(2)x2H(2)O (2), and [Cu(9)(eta(1):mu-NCO)(8)(mu(3)-OH)(4)(OH(2))(2)(mu-bdmap)(4)](ClO(4))(2).4H(2)O (3), in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, are reported. Tetranuclear complex 1 crystallizes in the triclinic system, space group P, with unit cell parameters a = 12.160(1) A, b = 13.051(1) A, c = 13.235(1) A, alpha = 110.745(1) degrees , beta = 109.683(1) degrees , gamma = 97.014(1), and Z = 2. Octanuclear complex 2 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 26.609(1) A, b = 14.496(1) A, c = 16.652(1) A, beta = 97.814(1) degrees , and Z = 4, and nonanuclear complex 3 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 24.104(1) A, b = 13.542(1) A, c = 24.355(1) A, beta = 109.98(1) degrees , and Z = 4. The magnetic behavior of the three complexes has been checked showing strong antiferromagnetic coupling in all the cases.

Polynuclear and 1-D derivatives of 1,3-bis(dimethylamino)-2-propanolato ligand. Structure and magnetic characterization.

Abstract: Several new CuII derivatives of the 1,3-bis(dimethylamino)-2-propanolato (bdmap) ligand with formula [Cu2(bdmap)(acac)(NH3)3(MeOH)](ClO4)2 (1), [Cu2(bdmap)(NO2)3(H2O)]4 (2) and [Cu2(bdmap)(OH)(ox)0.5(H2O)2]n(ClO4)n·nH2O (3) were synthesized and characterized both structurally and magnetically. Dinuclear compound 1 crystallises in the monoclinic system, space group P21/c , octanuclear compound 2 crystallises in the triclinic space group P and the 1-D alternating system 3 crystallises in the monoclinic system, space group P2/n. Magnetic analysis indicates strong antiferromagnetic coupling for all derivatives, mainly due to the interaction through the alkoxo O-atom of the bdmap ligand. The effect on the magnetic behaviour of the additional bridging ligands is analysed.