New frontiers in coordination chemistry

Gutmann, Viktor and Resch, Gerhard (1988) New frontiers in coordination chemistry. Accademia Peloritana dei Pericolanti, Classe di Scienze FF. MM. NN., LXVI. pp. 41-63.

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atti_3_1988_41.pdf - Submitted Version

For tris (phenantroline) iron complexes effects due to changes in temperature, substitution, nature of solvent and redox state are found to have little influence on the charge density pattern around the coordination centre. Similar behaviour is found for Lewis acid-base indicator molecules, namely bis (phenantroline) iron (II) cyanide and the mixed complexes of $Cu^2^+ and Ni^2^+$ with tetramethylethylenediamine and acetylacetonate as ligands. It is proposed to extend the molecular concept in order to provide an understanding for the changes in qualitites as related to the changes in the charge density pattern. According to the proposed concept of molecular system organization, each complex species is considered as hierarchically organized, in order to retain its integral configuration under different conditions. The charge density area around the coordination centre is considered as the highest hierarchic level, to which the areas of the molecular boundaries are subordinated. To them the mobile $\pi \$-electron system is subordinated, whereas the areas of the structural framework are considered as the lowest hierarchic level. Various observations including the isokinetic and isoequilibrium relationships led us to consider the whole solution as organized and the complex species as superordinated te the bulk solvent molecules, but subordinated to the molecules near the surface and the inner voids.