Acetylene complexes of metallocenes of titanium, zirconium and hafnium. I. Synthesis, structure, and spectral characteristics

Acetylene complexes of metallocenes of group IV metals are of great importance for coordination and organic chemistry since they show high reactivity to various substrates and are used as catalysts for many chemical processes. However, in spite of many attempts before, the first acetylene complex of one of these metals was obtained by Fachinetti and Floriani in 1974 only. The present review gives the detailed information about the development of the methods for the synthesis of various acetylene complexes of titanocenes, zirconocenes, and hafnocenes including those for the synthesis of the complexes with dehydrobenzoic or trans-acetylenic ligands, anionic, cationic complexes and other ones. A great attention is paid to their structures and spectral characteristics.