Vladimír Jorík

The spectroscopic and structural properties of copper(II) complexes of the novel tridentate (ONO) pyridine N-oxide ligand Hpoxap

Abstract A tridentate ligand (Hpoxap=2-(o-hydroxyphenyliminomethyl)pyridine N-oxide) has been synthesised by the Schiff condensation of 2-pyridinecarboxaldehyde N-oxide with 2-aminophenol. A series of copper(II) complexes with this ONO-donor ligand has been prepared and their spectroscopic properties (electron, vibration, ESR) were studied. The structures for two complexes have been determined by X-ray analysis. The structure of [Cu(poxap)(OAc)] consists of isolated neutral molecules in which the copper(II) atom is situated in a slightly distorted square-planar surrounding. The structure of [Cu(poxap)(H2O)(NO3)] consists of neutral molecules which are interconnected by hydrogen bonds giving rise to a ladder structure of copper(II) ions with two different Cu⋯Cu distances of 5.27 and 7.41 A. The copper atoms are in a slightly distorted square-pyramidal environment with the tridentate ligand poxap− and the water molecule in the basal plane; the apical position being occupied by an oxygen atom of the nitrate anion. Magnetic susceptibility studies were undertaken and these confirm predominantly a dimeric character of the complex.

Ni-W alloy coatings deposited from a citrate electrolyte

Ni-W alloy coatings were deposited by applying current pulses with different pulse parameters at 60°C onto mild steel substrates from aqueous electrolytes with different tungstate concentration. Morphology and composition of the alloys were analyzed by SEM and EDX, respectively. XRD was used to determine metallic phases. Scanning electron micrographs revealed that deposition parameters had a strong effect on the morphology of the coatings. Increasing the duty cycle or decreasing the off time led to a compact morphology. Corrosion properties of the coatings were investigated by potentiodynamic polarization in a chloride medium. It was found that compact morphology of the deposits and high content of tungsten in the coating contribute to satisfactory corrosion results of Ni-W alloy coatings under the conditions studied.

Combined powder diffraction and solid-state DFT study of [Cu (2,6-dimethoxynicotinate)2(μ-ronicol)2]n complex

Abstract Crystal structure of the title compound was solved from the laboratory powder diffraction data in the P21/c space group. Because Rietveld refinement yielded inaccurate geometry of the structural moieties the structure was finally refined by means of geometry optimization using DFT/plane waves approach in the solid state. The asymmetric unit of [Cu{2,6-(MeO)2nic}2(μ-ron)2]n consists of the copper(II) atom located on an inversion centre, one 2,6-dimethoxynicotinate anion and one ronicol molecule which acts as a bridging ligand coordinated via oxygen atom of the hydroxymethyl group as well as the nitrogen atom of the pyridine ring – μ-ron = bridging 3-pyridylmethanol. Each copper (II) complex unit is connected to the other four units through the ronicol ligands forming 2D sheets running parallel to the bc plane. The structure is stabilized by a strong intramolecular hydrogen bond O—H…O and supported by weak C—H…O hydrogen bonds.

Self-assembly hydrogen-bonded supramolecular arrays from copper(II) halogenobenzoates with nicotinamide: Structure and EPR spectra

Nicotinamide was employed as a supramolecular reagent in the synthesis of six new copper(II) bromo-, iodo-, fluoro- and dibromobenzoate complexes. Structures of [Cu(2-Brbz)2(nia)2(H2O)2] (I), [Cu(2-Ibz)2(nia)2(H2O)2] (II), [Cu(2-Fbz)2(nia)2(H2O)2] (III), [Cu(4-Brbz)2(nia)2(H2O)2] (IV), [Cu(3,5-Br2bz)2(nia)2(H2O)2] (V), [Cu(F-Fbz)2(nia)2(H2O)] · H2O (VI) (nia = nicotinamide, 2-Brbz = 2-bromobenzoate, 4-Brbz = 4-bromobenzoate, 3,5-Br2bz = 3,5-dibromobenzoate, 2-Ibz = 2-iodobenzoate, 2-Fbz = 2-fluorobenzoate, 4-Fbz = 4-fluorobenzoate) were determined using X-ray analysis. Compound [Cu(2-Brbz)2(nia)2] · 2H2O (VII) was prepared by a new method and also characterized by X-ray powder diffraction and EPR spectroscopy. Compounds I–V are monomeric complexes with a square-bipyramidal coordination sphere around the Cu2+ ion. Complex VI is monomeric with coordination environment around the Cu2+ ion of a tetragonal-pyramid. Complexes I and VII present examples of coordination isomerism. Molecules of all compounds are connected by N—H⋯O and O—H⋯O hydrogen bonds from the NH2 groups of nicotinamide and water molecules which create supramolecular hydrogen-bonding-coordination chains and networks.

CCDC 910181: Experimental Crystal Structure Determination

Related Article: Jozef Halaska, Danica Cechova, Michael K. Lawson, Zdeňka Růžickova, Vladimir Jorik, Marian Koman, Marian Valko, Bojan Kozlevcar, Jan Moncol|2016|Chem.Papers|70|101|doi:10.1515/chempap-2015-0203

Copper oxalate complexes: synthesis and structural characterisation

Six copper(II) oxalate complexes, namely {K2[Cu(ox)2]}n (1), {(Hiz)2[Cu(ox)2]}n (2), {[Cu(ox) (N-Bzliz)2]}n (3), (HMeiz)2[Cu(ox)2] (4), {[Cu(ox)(Meiz)2]}n (5), and [Cu(Hox)2(H2O)2](N-Bzliz) (6) where ox = oxalate ion, iz = imidazole, N-Bzliz = N-benzylimidazole, Meiz = 2-methylimidazole, were synthesised and characterised by single crystal X-ray diffraction (complexes 1–5) or powder X-ray diffraction (compound 6). The three-dimensional crystal packing structures of 2, 4, and 5 are consolidated by intermolecular hydrogen bonds linking the oxygen atom of the oxalate group and the amine or imine group of the imidazole-based part into chains. The molecules of complex 6 are held together by intermolecular hydrogen bonds between the oxygen atoms of the oxalate group and coordinated water molecules.

Powder diffraction and solid state DFT study of the trans-bis(5-methylsalicylato)-bis(N,N-diethylnicotinamide)-diaquacopper(II) complex structure

Abstract The title compound, [Cu(5-Mesal)2(denia)2 (H2O)2] (5-Mesal = 5-methylsalicylato, denia = N,N-diethylnicotinamide) crystallizes in the triclinic unit cell. Crystal structure was solved from the laboratory powder diffraction data. Each copper(II) atom is situated on an inversion centre and is coordinated by two O atoms from two 5-Mesal ligands [Cu—O 2.00(3) Å], two N atoms from two denia ligands [Cu—N 2.05(2) Å], and two water molecules [Cu—Ow 2.80(3) Å] in a highly distorted octahedral geometry. In the crystal structure, intermolecular O—H … O hydrogen bonds link the molecules into chains extended in direction [1 –1 0]. The optimization in solid state with DFT/plane-waves approach revealed the large value of Cu—Ow bond length [2.793 Å].