H.J. Bowley

Spectral, magnetic and electrical studies on complexes of some first row transition elements with pyrazinecarboxylic acid

Abstract The preparation and some properties of complexes of pyrazinecarboxylic acid with manganese, iron, cobalt, nickel and copper are described. Magnetic measurements, electronic and infrared spectra indicate that coordination takes place through the carboxyl group and a nitrogen atom of the aromatic ring. Electrical conductivity measurements made at room temperature yield conductivity values ranging from 1.7 × 10 −13 Ω −1 m −1 to 1.9 × 10 −8 Ω −1 m −1 . Iron and nickel complexes show transitions from ohmic to space charge limited conduction. The temperature dependences of conductivity are measured and discussed.

Thermal and electrical studies on quinoxaline compounds of some first row transition metal ions

Abstract The chloro and bromo compounds of quinoxaline with manganese(II), cobalt(II), nickel(II) and copper(II) have been prepared in ethanolic solution. The thermal behaviour of these compounds was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The thermal decomposition studies show that the compounds dichlorobis(quinoxaline) cobalt(II), dibromobis(quinoxaline) cobalt(II) and dibromobis(quinoxaline) manganese(II) form intermediate compounds before the metal halide is produced. The other compounds undergo decomposition with loss of organic ligand and the formation of the metal halide. Electrical conductivities at room temperature range from 1.4 × 10 −6 Ω −1 m −1 for MnCl 2 Q to 2.3 × 10 −3 Ω −1 m −1 for both CoCl 2 Q 2 and CoBr 2 Q 2 . There appears to be a correlation between electrical conductivity and coordination number of the metal atom. From the temperature dependence of conductivity, information has been obtained for donor or acceptor ionization energies. Decomposition temperature, as electrically determined, is in good agreement with the TG method.

Thermal and electrical studies on pyrazine-2,3-dicarboxylic acid compounds of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II)

Abstract Some new compounds of pyrazine-2,3-dicarboxylic acid with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) have been prepared in aqueous solution. The thermal behaviour of these compounds has been studied by thermogravimetry (TG), and differential scanning calorimetry (DSC) techniques. The compounds are all hydrated. Thermal decomposition studies show that these compounds lose water followed by organic ligand to give the metal oxide. Electrical conductivity measurements were made at room temperature. Ohmic and space charge limited conduction is observed. A current component opposing the applied voltage is observed in the compounds, with the exception of the copper compound.

Thermal studies on fumaric acid and crotonic acid compounds of cobalt(II) and nickel(II)

Abstract Some new compounds of fumaric acid and crotonic acid with cobalt and nickel have been prepared in aqueous solution. These compounds, which have been characterized by analyses, magnetic moments, vibrational and electronic spectra, have polymeric octahedral structures. They are all hydrated, with the exception of the cobalt compound of crotonic acid, which is anhydrous. The thermal behaviour of the compounds has been studied by thermogravimetry and differential thermal analysis. Thermal decomposition studies show that the hydrated compounds lose water followed by organic ligand to give the metal oxide. The anhydrous compound loses organic ligand to give the metal oxide.

The spectral and magnetic properties of some chloro and thiocyanato transition metal complexes of the aminopyridines and a study of their performance as colouring materials for poly(vinyl chloride)

Abstract Complexes of 2-,3- and 4-aminopyridine with the chlorides and thiocyanates of cobalt(II), nickel(II) and copper(II) have been prepared. Spectral and magnetic studies show that the cobalt complexes of 2- and 3-aminopyridine have tetrahedral structures while all the other complexes have octahedral structures. The decomposition temperatures for the complexes have been reported. The performance of the complexes as colouring materials for poly(vinyl chloride) (PVC) has been investigated. Amines cause degradation of PVC. The present investigation has shown that, when the amine is incorporated in a metal complex, no degradation can be detected.

Thermal, spectral, magnetic and electrical studies of cobalt(II) and nickel(II) with 3-(3-pyridyl)acrylic acid

Abstract The preparation and some properties of the complexes of 3-(3-pyridyl)acrylic acid with cobalt and nickel are described. Spectral, magnetic and solubility studies show that the complexes, which are hydrated, have polymeric octahedral structures. The thermal behaviour of these compounds has been studied by thermogravimetry (TG) and differential thermal analysis (DTA). Thermal decomposition studies show that the compounds lose water of crystallization followed by organic ligand to give the metal oxide. Electrical conductivity measurements at room temperature give results of 1.00×10 −6 Ω −1 m −1 and (1.6 ± 0.4)×10 −4 Ω −1 m −1 for the cobalt and nickel complexes respectively. The current-voltage characteristics exhibit hysteresis, which is very marked for the nickel compound, and is attributed to current arising from dipolar orientation superimposed on a conduction current.

STRUCTURAL AND ELECTRICAL STUDIES OF SOME FIRST ROW COMPLEXES OF PYRAZINAMIDE

Abstract Complexes of pyrazinamide with the cobalt(II) chloride and bromide, nickel(II) thiocyanate and bromide and copper(II) chloride and bromide are described. Magnetic measurements and electronic and infrared spectroscopy have been used to intestigate the stereochemistry of the complexes. Electrical measurements have shown the existence of two types of conduction in the compounds-ohmic and space charge effects with carrier trapping.

Electrical and structural properties of chloro complexes of cobalt, nickel, copper and zinc with 3-(3-pyridyl)acrylic acid

Abstract The preparation and some properties of the chloro complexes of 3-(3-pyridyl)acrylic acid with cobalt, nickel, copper and zinc are described. Magnetic measurements, electronic and infrared spectra indicate that the compounds have octahedral structures with the 3-(3-pyridyl)acrylic acid bonded to the metal ions through the nitrogen atom in the aromatic ring system. Electrical conductivities for the compounds at room temperature lie in the narrow range from 1.8 × 10−6 Ω−1 m−1 (for the cobalt compound) to 3.7 × 10−5 Ω−1 m−1 (for the nickel compound). The current-voltage characteristics for all of the compounds are anomalous in exhibiting hysteresis which appears to be due to the presence of the olefinic bond. The activation energy for conduction in the cobalt compound has been obtained from the temperature dependence of the conductivity.

Thermal studies on itaconic acid compounds of some transition metal ions

Abstract Some new compounds of itaconic acid with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) have been prepared in aqueous solution. The thermal behaviour of these compounds has been studied by thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) techniques. The compounds are all hydrated except the copper compound which is anhydrous. Thermal decomposition studies show that the hydrated compounds lose water followed by organic ligand to give the metal oxide. The copper compound loses organic ligand to form copper oxide.

Spectral and magnetic properties of some chloro and bromo transition metal complexes of isonicotinamide and a study of their performance as colouring materials for poly(vinyl chloride)

Abstract Complexes of isonicotinamide with the chlorides and bromides of iron(II), cobalt(II), nickel(II) and copper(II) have been prepared. Spectral and magnetic studies have shown that the complexes have polymeric octahedral structures. The decompositions of the complexes were studied by thermogravimetry. The performances of the complexes as colouring materials for poly(vinyl chloride) have also been investigated.