Search results for "Cobalt"

Novel Three-Dimensional Cage Assembly of amgr;(4)-Carbonato-Bridged Cobalt(II) Compound [Co(2)(bpm)(H(2)O)(2)(CO(3))(OH)]NO(3).4H(2)O.

2001

The new three-dimensional cobalt(II) complex of formula [Co2(bpm)(H2O)2(CO3)(OH)]NO3·4H2O (1) is obtained from aqueous solutions containing cobalt(II) nitrate hexahydrate, 2,2‘-bipyrimidine (bpm), ...

Trinuclear Nickel(II) and Cobalt(II) Complexes Constructed from Mannich–Schiff‐Base Ligands: Synthesis, Crystal Structures, and Magnetic Properties

2019

Synthesis and Electrochemical Reactivity of sigma-Bonded and N-Substituted Cobalt Porphycenes.

1998

The first synthesis and characterization of sigma-bonded and N-substituted cobalt porphycenes is reported. The investigated compounds are represented as (Pc)Co(R) and (N-CH(3)OEPc)CoCl, where R is CH(3) or C(6)H(5), Pc is the dianion of 2,3,6,7,12,13,16,17-octaethylporphycene (OEPc), 2,7,12,17-tetrapropylporphycene (TPrPc), or 2,7,12,17-tetraethyl-3,6,13,16-tetramethylporphycene (EtioPc), N-CH(3)OEPc is the monoanion of N-methyl-2,3,6,7,12,13,16,17-octaethylporphycene. Each sigma-bonded (Pc)Co(R) derivative can be reversibly reduced or oxidized by two electrons, but a slow migration of the sigma-bonded R group occurs following electrogeneration of [(Pc)Co(R)](+)()(*)() leading, as a final p…

Density functional theory based screening of ternary alkali-transition metal borohydrides: a computational material design project.

2009

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K M1; and 1 alkali, alkaline earth or 3d / 4d transition metal atom M2 plus two to five BH4  groups, i.e., M1M2BH42‐5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1Al/ Mn/ FeBH44, Li/ NaZnBH43, and Na/ KNi/ CoBH43 alloys are …

Coordinating behaviour of a new pyridylhydrazone; tris-complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with 2-pyridylcarb…

1991

The preparation and characterization oftris-complexes of MnII, CoII, NiII, CuII and ZnII with a new pyridylhydrazone, 2-pyridylcarbaldehyde-N,N-dimethylhydrazone (pch), are described. In all the complexes pch behaves as a bidentate ligand binding through the pyridine and azomethyne nitrogen atoms. The complexes appear to be monomeric, high spin six-coordinate, and a distorted octahedral stereochemistry around the metal is suggested. The e.p.r. results for both CuII compounds indicate a mainly dx2−y2 ground state with a static Jahn-Teller distortion, whilst for the MnII complex the e.p.r. data indicates a very low symmetry for the MnN6 polyhedron.

Cimetidine complexes derived from cobalt(II), nickel(II) and copper(II) salts of polyatomic anions

1986

Cobalt(II), nickel(II) and copper(II) complexes [M(CM)2]X2 (X = BF4 or NO3) have been prepared with cimetidine (CM). Powder data, molar conductivities, magnetic moments, i.r. and electronic spectra support apseudo-octahedral stereochemistry with MN2N 2 ⋆ S2 chromophore and tentative structures are proposed for the complexes. Their properties are compared with these of previously prepared complexes.

Interfacial Self-Assembly of Water-Soluble Cationic Porphyrins for the Reduction of Oxygen to Water

2012

Meet at the border: Assembly of the water-soluble cobalt tetrakis(N-methylpyridinium-4-yl)porphyrin [CoTMPyP]4+ at soft interfaces is enhanced and stabilized by its interfacial interaction with the lipophilic anion (C6F5)4B−. The supramolecular structure thus formed (see picture) provides excellent catalytic activity in the four-electron reduction of oxygen.

Synthesis and Spectroscopic Characterisation ofbis-Complexes of Cobalt(II), Nickel(II) and Copper(II) with N,N,N′N′-Tetraethylpyridinecarboxamide

1994

Abstract Bis-complexes of Co(II), Ni(II) and Cu(II) with tedpa (N,N,N′N′-tetraethyl-pyridinedicarboxamide) having the general formula [M(tedpa)2]X2 (X = ClO4, PF6) have been synthesized and characterised by i.r., electronic and e.p.r. spectra. The spectroscopic results suggest that the tedpa acts in these compounds as tridentate ligand through two oxygen atoms and a nitrogen (from the pyridine ring) atom. A distorted octahedral environment (MN2O4 chromophores) for the metal atoms is inferred from the spectroscopic data.

Synthesis, crystal structure and magnetic properties of two-dimensional malonato-bridged cobalt(ii) and nickel(ii) compounds

2004

Two isostructural malonato-bridged complexes of formula {[M(H2O)2][M(mal)2(H2O)2]}n [M = Co(II) (1), Ni(II) (2); H2mal = malonic acid] have been synthesised and characterized by X-ray diffraction. Their structure consists of corrugated layers of trans-diaquabismalonatemetalate(II) and trans-diaquametal(II) units bridged by carboxylate–malonate groups in the anti–syn conformation. Two crystallographycally independent metal atoms occur in 1 and 2. The malonate anion acts simultaneously as a bidentate and bis-monodentate ligand. Variable-temperature (1.9–295 K) magnetic susceptibility measurements indicate the occurrence of weak antiferro- (1) and ferromagnetic (2) interactions between the cob…

A New Co-Ni-Heterometallic Butterfly Complex Obtained via a Novel Synthesis Approach

2011

Abstract. The heterometallic complex [Co2Ni2(OH)2(O2CtBu)6(HOEt)6]·2EtOH (1) with a so called butterfly structural motif was prepared by reaction of the homometallic precursor complexes [Co2(H2O)(O2CtBu)4(HO2CtBu)4] and [Ni2(H2O)(O2CtBu)4(HO2CtBu)4] in an one to one ratio under elevate temperature. Complex 1 was characterized by single-crystal X-ray diffraction, atomic absorption spectroscopy, elemental analyses, IR spectroscopy, and mass spectrometry. The magnetic data show an overall antiferromagnetic behavior, which can be explained with three different coupling constants, resulting in a paramagnetic ground state.