Metal complexes, with thioaldehydes

Thioaldehydes have been used as ligands in metal complexes with osmium (76CC1044 77CC901 83JA5939) and rhenium (83JA1056). The first metal complexes with thio- (and seleno)-acetaldehyde as ligands were... 

Treatment of the dithiolato complexes 111 with MeLi or AlMe3 afforded the unusual thioaldehyde(thiolato) complexes 113, which in solution and in the crystal form dimers (112). The dimers could reversibly be cleaved by addition of PMe3 to the metal center (Scheme 26).68,69... 

The thioketene dimetallic complex 493 reacts with H to give an anionic thioacyl complex (494). Protonation of494, by cleavage of a metal - carbon bond, gives a thioaldehyde complex (495) which is stabilized by PPhj... 

A valuable route to metallocene complexes is through a cyclometalla-tion reaction with removal of a p-proton from the substrate and elimination of an alkane or arene. Typical of this approach is the formation of zirconocene 1-butene 4 (Scheme 5.3). The C-H activation method avoids the problem of dimerisation of the ir-component since there is none of this initially free of the metal. The method also facilitates the formation of complexes of components which are unstable in the free state, such as ben-zyne, cycloalkynes, and thioaldehydes. It is normally successful for crosscouplings when the component generated on the metal is strongly bound. If this is not the case, exchange with the second ir-component may take place, as described for zirconocene 1-butene (Scheme 5.3), giving the unwanted dimer or mixtures (see Section 5). 

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