Metal-chalcogen double bonds

Although the high reactivity of metal-chalcogen double bonds of isolated heavy ketones is somewhat suppressed by the steric protecting groups, Tbt-substituted heavy ketones allow the examination of their intermolecular reactions with relatively small substrates. The most important feature in the reactivity of a carbonyl functionality is reversibility in reactions across its carbon-oxygen double bond (addition-elimination mechanism via a tetracoordinate intermediate) as is observed, for example, in reactions with water and alcohols. The energetic basis... 

In the case of alkynes obtaining the data on the stereoselectivity of the insertion process is straightforward since Z/ -geometry of the double C=C can be easily determined in intermediate complexes and in the products (cf. Schemes 3 and 4). For example, the intermediate complexes dealing with metal-chalcogen bonds transformations were isolated and structurally characterized [48, 49], as well as the insertion pathway was characterized by theoretical calculations for homogeneous catalysis with molecular complexes [50] and for heterogeneous catalysis with nanoparticles [51]. The topic is discussed in detail for various heteroatoms and metal complexes in the other chapters of this book [20-28]. 

---