Abstract:
The study of coordination complexes begun with the discovery of the cobalt ammines in the last years of the eighteenth century. Many theories were advanced to explain the formation of these compounds. It was not until 1893, however, when Werner and Miolati: Z. Physikal. Chem., 12, 35 (1893). put forward his ideas, that the basis for modern developments in coordination chemistry was laid. The ideas of Werner were transfered to an electronic basis by Sidgwick: J. Chem. Soc., 123, 725 (1923). and Lowry: J. Soc. Chem, Ind., 42, 316 (1923). The idea of a coordinate bond, in which the ligand donates an electron pair to the central metal atom was due to these two workers. The two theories which are used nowadays to explain the behaviour of these compounds are Pauling's valancy bond theory and the ligand field theory, which consists of the electrostatic theory together with the molecular orbital theory.
