J.R. Allan

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.

The thermal, spectral and magnetic studies of succinic acid compounds of some transition metal ions

Abstract Compounds of succinic acid with cobalt, nickel, copper and zinc have been prepared in aqueous solution. The compounds have been characterised by analyses, magnetic moments, and by vibrational and electronic spectra. The nickel, copper and zinc compounds have octahedral structures while the cobalt compound has a tetrahedral structure. The thermal behaviour of the compounds has been studied by thermogravimetry and differential thermal analysis. The compounds, which are hydrated, lose water of crystallisation followed by the organic ligand to give the metal oxide.

Thermal and electrical studies on porphyrin compounds of cobalt(II), copper(II) and zinc(II)

Abstract Thermogravimetric and differential thermal analysis data are reported for 5,10,15,20-tetraphenyl-21 H ,23 H -porphine metal(II) complexes where the metal is cobalt, copper and zinc. Similar data are also reported for 5,10,15,20-tetrakis(4-methoxyphenyl)-21 H ,23 H -porphine cobalt(II). For the above compounds the electrical conductivities have been measured. There is evidence for space-charge limited conduction, and conductivities at room temperature under an applied field of 1×10 4 V m −1 are all within a factor of two either side of 2×l0 −8 Ω −1 m −1 . Activation energies for forming free carriers have been measured from the temperature dependence of the electrical conductivities.

Thermal studies on maleic acid compounds of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II)

Abstract Compounds have been prepared from aqueous solutions using the carbonates of manganese, cobalt, nickel and zinc with maleic acid. The copper compound was prepared from aqueous solution using the sulphate and maleic acid. The compounds are all hydrated. The stereochemical configurations of the compounds have been deduced using spectral and magnetic properties. The metal atoms have been found to be in an octahedral environment. The thermal decomposition of the compounds has been studied using thermogravimetry and differential thermal analysis. The compounds have been found to undergo decomposition with loss of water molecules, followed by the organic ligand, to give the metal oxides.

Thermal, electrical and structural properties of chloro complexes of cobalt, nickel, copper and zinc with 6,7-dimethyl-2,3-di(2-pyridyl)quinoxaline

Abstract Some new compounds of 6,7-dimethyl-2,3-di(2-pyridyl)quinoxaline with cobalt(II), nickel(II), copper(II) and zinc(II) have been prepared in toluene. The cobalt and zinc compounds have tetrahedral structures while the nickel and copper complexes have octahedral structures. The thermal behaviour of these compounds has been studied by thermogravimetry and differential thermal analysis. Each compound is highly stable and decomposes, without formation of any intermediate compounds, to the metal oxide. The room temperature conductivities of the prepared compounds are all in the range 3.4 × 10−8 Ω−1 m−1 to 2.2 × 10−7 Ω−1 m−1. Evidence is advanced from current-voltage data and, more especially, from attenuated total reflectance spectra taken during application of an electric field, that the compounds undergo significant field-induced distortion that remains after removal of the field.

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.

Thermal studies on the chloro compounds of cobalt(II), nickel(II) and copper(II) with 4-aminoquinaldine

Abstract Some new chloro compounds of cobalt, nickel and copper with 4-aminoquinaldine were prepared. The compounds are all hydrated. Spectral and magnetic properties were used to deduce the stereochemistry. The complexes have polymeric octahedral structures. The thermal behaviour of the complexes was studied by TG and DTA. Thermal decomposition studies show that these compounds lose water followed by the organic ligand to give the metal oxide.

Structural characterisation and thermal analysis studies of the compounds of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with poly(crylic acid)

Abstract The compounds formed by the reaction of poly(acrylic acid) with the carbonates of manganese, cobalt, nickel, copper and zinc in aqueous solution have been prepared. The compounds are all hydrated. Spectral and magnetic properties have been used to deduce the stereochemistry of the compounds. The cobalt and zinc compounds have the metal ions in a tetrahedral environment while the manganese, nickel and copper compounds have the metal ions in an octahedral environment. The thermal behaviour of the compounds has been studied by thermogravimetry and differential thermal analysis. The decomposition studies show that these compounds lose water followed by the organic ligand, to give the metal oxide.

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.

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.