Six-coordinated nickel(II) complexes with benzothiadiazole Schiff-base ligands: synthesis, crystal structure, magnetic and HFEPR study.

Two new nickel(II) complexes, namely Ni(L1)2 (1) and Ni(L2)2·CH2Cl2(2) were obtained by reacting nickel(II) acetate tetrahydrate with the benzothiadiazole Schiff base ligands HL1 = 2-[4-(2,1,3-benzothiadiazole)imino]methyl-phenol or HL2 = 2-[(2,1,3-benzothiadiazol-4-ylimino)methyl]-6-methoxyphenol in the presence of Et3N. The tridentate NNO chelate ligands induce a distorted octahedral environment around the nickel(II) ions. Single crystal X-ray diffraction analysis reveals elongated Ni-N bonds with the nitrogen atom of the benzothiadiazole ring in both complexes. Intermolecular hydrogen bonds and π-π stacking interactions create two-dimensional and three-dimensional supramolecular arrays, respectively, for complexes 1 and 2. Magnetic susceptibility and high-field electron paramagnetic resonance measurements show the presence of significant magnetic anisotropy, with an axial distortion parameter D of -8--10 cm-1.

Field-induced mononuclear cobalt(II) single-molecule magnet (SMM) based on a benzothiadiazole-ortho-vanillin ligand.

A unique π-conjugated benzothiadiazole-ortho-vanillin ligand (HL), characterized by single crystal X-ray diffraction and DFT calculations, has been prepared by condensation between 4-amino-benzothiadiazole (BTD) and ortho-vanillin. Its reaction with cobalt(II) acetate afforded the complex of formula [CoL2]·CH2Cl2 (1), for which the coordination environment of the cobalt centre is a distorted octahedron and the ligand acts as a monoanionic tridentate NNO chelate in its phenolate form. Intermolecular π-π stacking interactions between the π-conjugated BTD units provide an antiferromagnetic coupling pathway, as indicated by the analysis of the dc magnetic measurements of a crystalline sample of the complex and supported by DFT type calculations. The static magnetic behaviour of 1 is analysed according to spin-orbit coupling and zero-field splitting models. Remarkably, the complex exhibits slow relaxation of the magnetization under dc applied magnetic fields being thus a new example of field-induced mononuclear single-molecule magnet (SMM).

A bis-chelate o-vanillin-2-ethano-lamine copper(II) complex bearing both imine and amine forms of the ligand.

The mol-ecular bis-chelate complex (2-{[(2-hy-droxy-ethyl-κO)amino-κN]meth-yl}-6-meth-oxy-phenolato-κO)(2-{[(2-hy-droxy-eth-yl)imino-κN]meth-yl}-6-meth-oxy-phenolato-κO)copper(II), [Cu(C10H14NO3)(C10H12NO3)] or [Cu(HL im)(HL am); HL im = C10H14NO3; HL am = C10H12NO3, represents the first compound containing a salicyl-idene-2-ethano-lamine type ligand in both imino HL im (Schiff base) and amino HL am (reduced Schiff base) forms that has been structurally characterized on the basis of X-ray data. Two mol-ecules of the monodeprotonated ligands coordinate the CuII ion in an (N,O phen)-bidentate and an (N,O phen,O alc)-tridentate fashion in the case of the imino and amino forms, respectively. The shape of the CuN2O3 coordination polyhedron is a distorted square-pyramid (geometry index τ5 = 0.26). Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds, involving H atoms of the amino and hy-droxy-ethyl groups, create a two-dimensional supra-molecular array extending parallel to (010).

Synthesis and crystal structure of a solvated CoIII complex with 2-hy-droxy-3-meth-oxy-benzaldehyde thio-semicarbazone ligands.

The title CoIII complex, bis-[bis-(2-hy-droxy-3-meth-oxy-benzaldehyde thio-semi-carbazonato)cobalt(III)] di-thio-nate-dimethylformamide-methanol (1/4/3), [Co(C9H10N3O2S)2]2(S2O6)·4C3H7NO·3CH3OH, with monodeprotonated 2-hy-droxy-3-meth-oxy-benzaldehyde thio-semicarbazone as ligands crystallizes in the space group P . The asymmetric unit consists of two mononuclear [CoL 2]+ cations, one di-thio-nate anion (S2O6)2- as counter-anion and seven solvate mol-ecules (four di-methyl-methanamide and three methanol). Each CoIII ion has a moderately distorted octa-hedral S2N2O2 geometry. In the crystal, the components are linked by numerous N-H⋯O and O-H⋯O contacts.

A binuclear CuII/CaII thio-cyanate complex with a Schiff base ligand derived from o-vanillin and ammonia.

The new heterometallic complex, aqua-1κO-bis-(µ2-2-imino-methyl-6-meth-oxy-phenolato-1κ2 O 1,O 6:2κ2 O 1,N)bis-(thio-cyanato-1κN)calcium(II)copper(II), [CaCu(C8H8NO2)2(NCS)2(H2O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thio-cyanate in methanol under ambient conditions. The Schiff base ligand (C8H9NO2) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH4SCN. The title compound consists of a discrete binuclear mol-ecule with a {Cu(µ-O)2Ca} core, in which the Cu⋯Ca distance is 3.4275 (6) Å. The coordination geometries of the four-coordinate copper atom in the [CuN2O2] chromophore and the seven-coordinate calcium atom in the [CaO5N2] chromophore can be described as distorted square planar and penta-gonal bipyramidal, respectively. In the crystal, O-H⋯S hydrogen bonds between the coordinating water mol-ecules and thio-cyanate groups form a supra-molecular chain with a zigzag-shaped calcium skeleton.

Crystal structure of {2-[({2-[(2-amino-eth-yl)amino]-eth-yl}imino)-meth-yl]pheno-lato}aqua-copper(II) bromide.

In the mononuclear copper(II) title complex, [Cu(C11H16N3O)(H2O)]Br, the Cu(II) atom is coordinated by one O and three N atoms of the Schiff base ligand that forms together with one water mol-ecule a slightly distorted [CuN3O2] square-pyramidal polyhedron. The deviation of the Cu(II) atom from the mean equatorial plane is 0.182 (2) Å. The equatorial plane is nearly coplanar to the aromatic ring of the ligand [angle between planes = 10.4 (1)°], and the water molecule is situated in the apical site. All coordinating atoms (except the imine nitro-gen) and the bromide ion contribute to the formation of the N-H⋯Br, O-H⋯Br and O-H⋯O hydrogen bonds, which link mol-ecules into chains along [01-1].