Search

In view of a renewed interest in the structural chemistry of organic derivatives of antimony(V) during the last decade, a brief account of the same is presented highlighting points of special importance and future growth. Attention is focussed on the structural and bonding aspects. Details about their synthesis are only included when they are applicable in general. [ABSTRACT FROM AUTHOR]

The available models and experimental results used in the description of magnetic order phenomena have been recently summarized in several papers. Among the materials showing low-dimensional magnetism, fluorides are of great interest as they provide examples for most of the different theoretical models. This article emphasizes the relationships between crystallographic features and dimensionality of the magnetic interactions in fluorides. The involved compounds are characterized by rings, chains, layers and three-dimensional arrangements of fluorinated MF6 octahedra. Spin-flop and zero-point spin-reduction phenomena are also considered, as many fluorides exhibit these behaviors. [ABSTRACT FROM AUTHOR]

The spectral and magnetic properties of simple high spin cobalt(II) complexes are reviewed with the aim of showing how it is possible to relate the experimental data to the electronic structure and the coordination geometry of the complexes. It is hoped that this may be of help to all researchers who need to characterize cobalt(II) complexes or use cobalt(II) as a spectroscopic probe. The data relative to electronic, EPR, MCD, NMR spectra as well as to magnetic susceptibility measurements are interpreted within an Angular Overlap approach. Energy level diagrams are employed to calculate the electronic spectra and then, applying the relevant perturbation μ, g, A values are calculated for different chromophores in different coordination environments. The underlying theory is sketched paying in every case much attention to show the possibility of calculating the electronic properties in low symmetry environments. An extensive compilation of available experimental data is presented. The chromophores are classified according to the coordination number and according to the donor atom set. [ABSTRACT FROM AUTHOR]

An account of the quantum theory of the molecular hypothesis for chemical substances is presented, and is used as a basis for a critical discussion of the theory of natural optical activity. Atoms and molecules are characterized as composite elementary excitations (or quasi-particles) of the macroscopic quantum-mechanical system we call matter, and the spontaneously broken space inversion symmetry revealed by the existence of optical isomerism is studied in this context. Special attention is paid to the representation of the space-inversion operator {ie1-1}. Finally a variety of microscopic quantum theories of natural optical activity are critically reviewed. [ABSTRACT FROM AUTHOR]