This book presents several helpful synthetic methods for diverse multinuclear complexes. The results described can be used to selectively connect mononuclear as well as multinuclear complexes with other metal complexes to construct valuable photofunctional compounds. Using the new synthetic methods, it was possible to selectively connect several types of metal complexes in a single step under relatively mild reaction conditions. This so-called building block approach utilizes various C–C coupling reactions between metal complexes with functional groups as active moieties. Owing to the large pi-conjugation systems, the multinuclear complexes synthesized using coupling reactions showed a strong absorption ability over a wide range of visible light and long emission lifetimes, which are ideal properties for photosensitizers and light absorbers. By combining these coupling methods with the newly developed hydrogenation reactions, the binding mode of the linkers in multinuclear complexes can be modified in order to tune the photophysical properties and photocatalytic ability. As such, the synthesized multinuclear complexes can be used for various purposes, e.g., as photocatalysts and photosensitizers, and in light-harvesting systems. The synthetic methods and strategies presented in this book diversify not only the structures but also functions of multinuclear complexes.