A General Route to Strictly Dinuclear Cu(II)/Ln(III) Complexes. Structural Determination and Magnetic Behavior of Two Cu(II)/Gd(III) Complexes

Abstract

Starting from a single precursor, bis(3-methoxysalicylaldehydato)copper (II), which contains an O(4)Cu chromophore, three routes to discrete dinuclear Cu(II)/Ln(III) complexes (Ln = Pr, Eu, Gd, Yb) are described. The pairs of chromophores occurring in the resulting complexes are either O(4)Cu/O(4)Ln or O(2)N(2)Cu/O(4)Ln, the coordination sphere of the Ln ions being completed, in both cases, with six oxygen atoms afforded by three nitrato ions. Two Cu/Gd complexes involving either two tridentate ligands (2) or one hexadentate ligand (7) have been structurally characterized. They crystallize in the monoclinic space groups P2(1)/n (No. 14) (2) and P2(1)/c (No. 14) (7). The cell parameters are a = 9.7185(7) Å, b = 16.7839(12) Å, c = 14.8868(8) Å, beta = 97.445(5) degrees, and Z = 4 (2) and a = 9.7656(9) Å, b = 19.889(2) Å, c = 15.870(2) Å, beta = 95.512(9) degrees, and Z = 4 (7) respectively. The magnetic properties of six Cu/Ln complexes have been determined. A quantitative analysis of the magnetic properties of the Cu/Gd complexes shows that the interaction is of the ferromagnetic type with a J constant varying from 4.8 to 7.0 cm(-)(1). The decrease of the interaction parallels the variation of the dihedral angle between the two halves (OCuO and OGdO) of the bridging core.

CuLn complexes with a single μ-oximato bridge

“…The Cu(Sal) 2 , [9] Gd(hfa) 3 Á2H 2 O [10] complexes were obtained as previously described, as the ligand 1-(2,4,4-trimethyl-2-imidazolidinyl)-1-ethanone oxime resulting from the reaction of butanedione monoxime with 2-methyl-1,2-diaminopropane in a 1/1 ratio in diethyl ether [11]. As the different complexes are obtained with the Two original dinuclear (Ln Yb, 3 and Ln Er, 4) and one trinuclear Cu II -Ln III -Cu II (Ln Gd, 5) complexes derived from a polydentate non symmetrical Schiff base ligand H 2 L have been prepared.…”

Synthesis and Magnetism of Copper(II)-lanthanide(III)-copper(II) Heterotrinuclear Complexes with N,N′-bis [2-(dimethylamino)ethyl]oxamidocopper(II)

“…For the Cu II -Gd III -Cu II trinuclear system (S Cu1 = S Cu2 = 1/2, S Gd = 7/2), the theoretical expression for magnetic susceptibility is given by Equation (1) The results indicate that the positive sign of J corresponds to a ferromagnetic Gd III -Cu II interaction and the negative sign of J¢ to an antiferromagnetic Cu II -Cu II interaction. The small J value may account for the fact that 4f-electrons are shielded by the outer shell electrons [29]. However, the ferromagnetic interaction existing in the present complex between Gd III and Cu II , which was also observed in previous reports of polynuclear copper(II)-gadolinium(III) clusters with different bridges [12,13,21,[30][31][32], is interesting because gadolinium(III) has unpaired electrons in 7f orbitals and at least one of them, or one linear combination, can give a nonzero overlap with the magnetic orbitals on copper(II).…”

Some Mixed Ligand Complexes of Lanthanum(III) Using 1-Nitroso-2-napthol and Amino Acids

“…Further, chiral mixed ligand complexes also used as catalysts in various important chemical transformations like epoxidation [8], resolution of racemic compounds [9] and other asymmetric synthesis [10,11]. In addition to these, some mixed ligand complexes also have potential applications in advanced materials such as semiconductors [12], magnetic [13] and non-linear optical materials [14]. Amongst these, mixed ligand complexes with amino acids as a ligand are of great importance for enzymemetal ion substrate complexes [15].…”