The ligand mutual influence in coordination compounds

K. B. Yatsimirskii
1974 Pure and Applied Chemistry  
Three possible types of Iigand mutual influence (LMI)-trans-influence, cis~ influence and nondirecting influence-are discussed. Numerous thermodynamic, kinetic, structural and spectral quantitative characteristics of the LMI are presented. The model proposed based on the simple LCAO allows orbitals to be grouped according to their ability to transmit the different LMI and an assessment to be made of the factors which determine tbe magnitude of the LMI. A comparison of changing parameters of the
more » ... M-Hal (Cl-or I-) bonds in the nicket, palladium, platinum series has been made. The variations of the coordinated molecule under the action of other ligands are considered. These variations are revealed by changes in acid-base properties of ligands, in chemical shifts oftheir nuclei 1 H and 19 F, and also by changes in structuraJ and spectral data of coordinated polyatomic species. The Iigand mutual influence (LMI) in coordination compounds represents one of the . most important problems in modern coordination chem1stry. The LMI is generally utilized in the synthesis of new coordination com~ pounds of a desired geometric structure. The LMI affects the whole complex of physicochemical characteristics of coordination compounds (and, in the first place, thermodynamic and kinetic) and their physical parameters (bond length, angles, vibration frequencies, spectra, etc.). The introduction of a given ligand into the coordination sphere changes the electron density distribution both in bonds and in each coordinated species. Therefore, while considering changes caused by a given Iigand in the coordination sphere, it is expedient to distinguish, at least, between the two important aspects, namely, the Variation in metal-ligand bonds and the variation in the coordinated molecule itself. The second aspect of the LMI is of great significance in the treatment of many cardinal problems and, in particular, those of catalysis and biology. The LMI was formulated for Ptu complexes by Chernyaev in 1926 in terms of the directing influence known as the trans~influence 1 • Later on, this phenomenon was designated as the trans .. influence rule.
doi:10.1351/pac197438030341 fatcat:muqq532ij5frjmcd37zyhrxvfu