The bonding in molecules is most often described using the classical chemical ideas of covalency (bond multiplicity) and ionicity (atomic charges). The Mayer bond order is a natural extension of the Wiberg bond order, which has proved extremely useful in bonding analysis using semi-empirical computational methods, and the Mulliken population analysis to ab initio theories. The usefulness of the Mayer bond order has been tested in a number of inorganic molecules including sulfur–nitrogen rings, halogen–oxide molecules and transition metal dichloride molecules. The basis set dependence of the Mayer bond order is tested through the case studies presented. It is shown that the bond order can be fully or partially decomposed into the contributions from symmetry types for many interactions of interest to the inorganic chemist. The power of this approach is shown by examining the bonding in a variety of systems and is illustrated by detailed studies of the role of the ring size and electron count on the bonding in S–N rings, the role of hypervalency in the relative stabilities of mixed hydrogen and halogen peroxide isomers and the importance of s–d hybridization in the 3d transition metal dichloride molecules.

The Mayer bond order as a tool in inorganic chemistry

Resonance Raman spectra are obtained when the wave number of the exciting radiation is close to, or coincident with, that of an electronic transition of the scattering species. Such spectra are usually characterized by a very large enhancement of the intensities of particular Raman bands, sometimes with the appearance of intense overtone and combination tone progressions. The technique provides detailed information about excited electronic states because it is only the vibrational modes associated with the chromophore that are resonance-Raman active. Additionally, the high sensitivity is such that compounds at concentrations as low as 10−6 mol/L may be detected, enabling resonance Raman spectroscopy to be used as an analytical tool and for the study of chromophores in molecules of biological interest.

Resonance Raman Spectroscopy, and Its Application to Inorganic Chemistry. New Analytical Methods (27)

Phosphorane iminato complexes of main group elements

The trisulfur radical anion [S3]˙− is well-known from inorganic chemistry textbooks as the blue chromophore in ultramarine blues in which this highly reactive species is trapped in a zeolitic framework. Recent findings have revealed that [S3]˙− has a multi-faceted role in a variety of media, including alkali metal–sulfur batteries, aqueous solutions at high temperatures and pressures, and ionic liquids; it has also been used to detect trace amounts of water in organic solvents. This tutorial review illustrates how various physical techniques are used to identify a reactive species in solution and shows how elucidation of electronic structures can be used to explain spectroscopic and structural properties. Examples of the function of [S3]˙− in materials science, electrochemistry, analytical chemistry and geochemistry are used to illustrate the widespread influence of this fundamentally important triatomic sulfur species.

Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry.

Stability and abundance of the trisulfur radical ion S 3 - in hydrothermal fluids

Crystal and molecular structure of [n-Bu4N+][S3N3-] and the vibrational assignments and electronic structure of the planar six-membered ring of the trisulfur trinitride anion

Reaction of triphenylphosphine with tetrasulfur tetranitride: synthesis and structure of 1,5-bis(triphenylphosphinimino)cyclotetrathiazene, (Ph3P:N)2S4N4

The thio analog of peroxynitrite, [SSNS]-: preparation, electronic structure, resonance Raman spectrum, and formation of complexes with nickel and cobalt

Central role of the trisulfur trinitride(1-) and tetrasulfur pentanitride(1-) ions in the deprotonation of tetrasulfur tetraimide and in the reductive or nucleophilic degradation of tetrasulfur tetranitride

J. Bojes

Papers

Crystal and molecular structure of [n-Bu4N+][S3N3-] and the vibrational assignments and electronic structure of the planar six-membered ring of the trisulfur trinitride anion

Reaction of triphenylphosphine with tetrasulfur tetranitride: synthesis and structure of 1,5-bis(triphenylphosphinimino)cyclotetrathiazene, (Ph3P:N)2S4N4

The thio analog of peroxynitrite, [SSNS]-: preparation, electronic structure, resonance Raman spectrum, and formation of complexes with nickel and cobalt

Central role of the trisulfur trinitride(1-) and tetrasulfur pentanitride(1-) ions in the deprotonation of tetrasulfur tetraimide and in the reductive or nucleophilic degradation of tetrasulfur tetranitride

Direct synthesis of the S4N5− ion from tetrasulphur tetranitride