D.L. Gerrard

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.

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 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.

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.

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.