Update for Reactions of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes: A Never-Ending Story?

Recently reported reactions of group 4 metallocene bis(trimethylsilyl)acetylene complexes from the last two years are summarized. This could be considered as a never-ending story. A recently reported alternative and very straightforward method for the preparation of the well-known alkyne complex Cp 2 Ti(η 2 -Me 3 SiC 2 SiMe 3 ) reported by Beckhaus et al. could in the future have a great effect on the application of this complex. Similar improvements made earlier by Tilley and co-workers for the Zr analogue Cp 2 Zr(py)(Me 3 SiC 2 SiMe 3 ) have enabled preparative organometallic and organic chemists to establish this reagent for a wide range of coupling reactions. Examples of this are summarized in this review. These and similar reagents represent excellent sources to yield the very reactive coordinatively and electronically unsaturated complex fragments [Cp′ 2 M]. They will have a great potential for a large number of interesting applications in the future.