The last decade has seen the emergence and explosive growth of a new field of condensed matter science: materials chemistry. Transcending the traditional boundaries of organic, inorganic and physical chemistry, this new approach aims to create new molecular and lattice ensembles with unusual physical properties. One of its pioneers, the author has worked on structure-property relations in the inorganic and metal-organic solid state for over 40 years. His seminal work on mixed-valency compounds and inorganic charge transfer spectra in the 1960s set the scene for this new type of chemistry, and his discovery of transparent metal-organic ferromagnets in the 1970s laid the ground rules for much current work on molecular magnets. He has also published extensively on molecular metals and superconductors, especially on charge transfer salts combining conductivity with magnetism. This indispensable volume brings together for the first time a selection of his articles on all these topics, grouped according to theme. Each group is prefaced by a brief introduction for the general reader, putting the articles into their context in the evolution of the subject and describing the intellectual circumstances in which each project was conceived and executed.