Abstract
Published information on the chemistry of these complexes stabilised by cyclopentadienyl and other ligands is systematised, and modes of formation of a metal–hydrogen bond in their synthesis are discussed. Consideration is given to the influence on this bond of the structure of various types of transition-metal hydrides containing one, two, or three cyclopentadienyl groups in the coordination sphere. The possibility of stabilising the bond with σ-donor ligands is discussed. The chemical properties of these compounds and the possibility of their use as catalysts are examined. A list of 160 references is included.