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

• Published in: Thermochimica acta 1987-12, Vol.122 (2), p.403-412
• Main Authors: Allan, J.R., Paton, A.D., Turvey, K., Bowley, H.J., Gerrard, D.L.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Inorganic chemistry and origins of life; Kinetics and mechanism of reactions
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/0040-6031(87)87058-2

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 2Q to 2.3 × 10 −3 Ω −1 m −1 for both CoCl 2Q 2 and CoBr 2Q 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.