Coordination Chemistry-21 covers the proceedings of the 21st International Conference on Coordination Chemistry. The book discusses several studies that tackle topics that concern the field of chemistry. The text is organized into two parts: plenary lectures and section lectures. The first four chapters are parts of the plenary lectures and include the following topics: valence electron distributions in transition metal complexes; coordination compounds with metal to metal bonds; solar energy storage reactions involving metal complexes; and electron transfer in blue copper proteins. The remaining 11 chapters are organized into five sections according to the theme of the study. The first section deals with electronic structure of coordination compounds, while the second section covers unusual properties of coordination compounds in the solid state. Section 3 devotes itself to the coordination chemistry in solution; Section 4 tackles ligand activity in transition metal complexes. The last section discusses the application of coordination chemistry to biology. The book will be of great interest to researchers in the field of chemistry, since it presents several studies relevant to the advancement of the field.