Chalcogenolates bonding

Substitution reactions involving silylated chalcogen reagents represent a powerful approach in metal-group-XVI cluster synthesis.Compounds such as E(TMS)2 and RE-TMS react readily with metal salts to form metal chalcogenide or chalcogenolate bonds (Equations (13)-(15)). The driving force for the reaction is the thermodynamically favorable formation of an X—Si bond and elimination of X-TMS (where X = halide, OAc, etc.). 

The starting material is always the chalcogenol and, consequently, is more used for thiols than selenols and tellurols. There are several types of reactions depending if the starting materials are metal hydrides (hydrogen elimination), complexes with M C (alkane elimination), M-N (transamination), or M-O (hydrolysis) bonds. 

The most common method for the formation of M-E (M = Si, Ge, Sn E = S, Se, Te) bonds is the reaction of group 14 metal halides with chalcogenolate salts or chalcogenols/bases. Some recent examples are as follows. 

The aminoboranes, R2IUNR2, and phosphinoboranes, R2B PR2, can also exist in monomeric molecnlar form or as dimeric, trimeric or polymeric snpermolecnles (depending npon the nature of R and R ). Dative bond self-assembly is not limited to amino derivatives. Halogen bridging can induce similar effects and numerous organometallic fluorides and chalcogenolates also form cyclic supermolecules. 

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