Synthesis, characterization and X-ray crystal structures of [Ni(Me-sal)2dpt] and [Ni(Me-sal)dpt]Cl

Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes

Pentacoordinate Ni(ii) complexes with pentadentate Schiff base ligands possess large and negative values of axial magnetic anisotropy. The relationship between the shape of the coordination polyhedron and uniaxial anisotropy is outlined.

A Ni(ii) dinuclear complex bridged by end-on azide-N and phenolate-O atoms: spectral interpretation, magnetism and biological study

A new dinuclear complex, [Ni(L)(μ_1,1-N₃)Ni(L)(OH₂)₂]·ClO₄(1), has been synthesized. It shows the presence of ferromagnetic interactions and is endowed with both anti-mycobacterial and anticancer properties.

Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s(-1) scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, (1)H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction.

{2,2'-[3-Aza-pentane-1,5-diylbis(nitrilo-methyl-idyne)]dipyrrol-1-yl}(4-methyl-pyridine)cobalt(III) tetra-phenyl-borate

The title compound, [Co(C₁₄H₁₇N₅)(C₆H₇N)](C₂₄H₂₀B) or [Co{(pyrrole)₂dien}(4-Mepy)]BPh₄ where (pyrrole)₂dien is 2,2′-[(3-aza­pentane-1,5-diylbis(nitrilo­methyl­idyne)]dipyrrole and 4-Mepy is 4-methyl­pyridine, contains a penta­dentate (pyrrole)₂dien ligand furnishing an N₅ set, such that two of the pyrrole N atoms and two of the dien N atoms occupy the equatorial positions while one of the imine N atoms of the (pyrrole)₂dien ligand occupies the axial position. The 4-methyl­pyridine ligand occupies an axial position trans to one of the imine N atoms of the penta­dentate ligand. In the observed conformation of the penta­dentate ligand, the pyrrole rings attain asymmetrical positions owing to the structural demands. The geometry of the resulting CoN₆ coordination can be described as distorted octa­hedral.

[5,5'-Dihydr-oxy-2,2'-[o-phenyl-enebis(nitrilo-methyl-idyne)]diphenolato}copper(II) methanol disolvate

In the title compound, [Cu(C(20)H(14)N(2)O(4))]·2CH(3)OH, the Cu(II) ion is coordinated by two N [Cu-N = 1.933 (2) and 1.941 (2) Å] and two O [Cu-O = 1.890 (2) and 1.9038 (19) Å] atoms from the tetra-dentate Schiff base ligand 5,5'-dihydr-oxy-2,2'-[o-phenyl-enebis(nitrilo-methyl-idyne)]diphen-olate (L) in a distorted square-planar geometry. In the crystal, inter-molecular O-H⋯O hydrogen bonds link two CuL mol-ecules and four solvent mol-ecules into a centrosymmetric cluster. The crystal packing exhibits short inter-molecular C⋯C contacts of 3.185 (4) and 3.232 (4) Å.

A fast response hafnium selective polymeric membrane electrode based on N,N'-bis(alpha-methyl-salicylidene)-dipropylenetriamine as a neutral carrier

In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis(alpha-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf(4+) (Hafnium(IV)) over a wide concentration range (2.0 x 10(-7) to 1.0 x 10(-1)M) with the determination coefficient of 0.9966 and slope of 15.1+/-0.1 mVdecades(-1). The limit of detection is 1.9 x 10(-7)M. The electrode has a fast response time of 18s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf(4+) ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf(4+) in solutions by standard addition method for real sample analysis.

{2,2'-[1,1'-(3-Aza-pentane-1,5-diyl-dinitrilo)diethyl-idyne]diphenolato}(piperidine)cobalt(III) tetra-phenyl-borate

The title compound, [Co(C₂₀H₂₃N₃O₂)(C₅H₁₁N)](C₂₄H₂₀B) or [Co{(Me-sal)₂dien}(pprdn)]BPh₄, where (Me-sal)₂dien is 2,2′-[1,1′-(3-aza­pentane-1,5-diyldinitrilo)diethyl­idyne]diphenolate and pprdn is piperidine, contains a penta­dentate (Me-sal)₂dien ligand furnishing an N₃O₂ set, such that two of the N and one of the O atoms of the salicyl­idene rings define three positions of an equatorial plane, whereas the secondary amine N atom and the other O atom of the salicyl­idene lie in axial positions. The piperidine ligand occupies an equatorial position trans to one of the imine N atoms of the salicyl­idene. In the observed conformation of the penta­dentate ligand, the salicyl­idene rings attain asymmetrical positions owing to the structural demands. The geometry of the resulting CoN₄O₂ coordination can be described as distorted octa­hedral. The asymetric unit contains two formula units.