This volume is the fourth in the series and offers both quality and breadth. As a whole it reflects two increasingly discernible trends in modern structural chemistry. One trend is that parallel to the ever increasing specialization of techniques, there is a strong interaction between the techniques. This interaction crosses the boundaries between various experiments, between the experiments and computations, experiments and theory, and organic and inorganic chemistry. The other trend is the ever increasing penetration of the most modern aspects of structural chemistry the rest of chemistry, making the demarkation of structural chemistry increasingly fuzzy which is the most welcome development from a structural chemist's point of view.