In the last two decades we have developed a new type of transition-metal (TM)-catalyzed reaction of vinyl-substituted organosilicon compounds with olefins, known as a silylative coupling (SC, or trans-silylation; Scheme 1), that is complementary to metathesis. This reaction occurs by cleavage of the = C À H bond of an olefin and the = C À Si bond of a vinylsilane, in contrast to cross-metathesis, which uses the same substrates and also gives the same products (except the gem-isomer), by cleavage of the C=C bond. Various TM complexes (i.e. Ru, Rh, Ir, and Co) containing an MÀH and MÀSi bond initially, or one generated in situ, catalyze this process. [1,2] ) The mechanism for SC catalyzed by ruthenium complexes elucidated by Wakatsuki [3] and by us [4] involves insertion of a vinylsilane into the MÀH bond and b-Si transfer to the metal, with elimination of ethylene, to generate MÀSi species, then insertion of the alkene into the MÀSi bond and b-H transfer to the metal, with elimination of a substituted vinylsilane as product, and regeneration of the catalyst.The SC process under optimum conditions has become an excellent synthetic tool for the regio-and stereoselective synthesis of functionalized vinylsilicon compounds such as (E)-N-(silyl)vinylcarbazole, [5a] amides, [5b] 1-silyl-1-(boryl)-ethenes, [5c] functionalized cyclosiloxanes, cyclosilazanes, [5d] and silsesquioxanes [5e] as well as macromolecular organosilicon compounds containing (E)-1,2-bis(silyl)fragments. [6] These compounds can be used as synthetic reagents for organic synthesis and as materials precursors and are difficult to prepare by other TM-catalyzed reactions such as crossmetathesis. The trans-silylation reaction has recently been extended to other metalloids such as boron [7] and germanium.