Silylenes arenes

The low-temperature solution reactions of silylenes with arenes, which involve silyl cation intermediates, have been reviewed,80 and another pertinent review is available.81... 

A bizarre silylene insertion into the I—I bond has been suggested as the initial step in the mechanism for the low-temperature (—90 °C) reaction of dihalosilylenes (SiF2, SiCl2, SiBr2) with solutions of iodine in toluene, as shown in equation 58125. These reactions can be considered to involve electrophilic attack on an arene by SiX2l+126. 

Silylene-based pincer ligands offer exciting reactivities in terms of transition metal complex formation and their applications in catalytic systems. The pincer complex [SiCSi)Ni(II) can be synthesized by oxidative addition of C—H bond of the corresponding [SiC(H)Si] ligand. [SiCSi]Ni(II) complex has been employed as catalyst for Ni-catalyzed Sonogashira reactions (8). Moreover bis(silylene) pincer complexes of iridium and rhodium reveal strong 5-donating ability of divalent silicon and have demonstrated selectivity in catalytic C—H borylation reactions with arenes (9). 

Stabilized silylium ions can be also used to transfer silyl groups to singlet carbene analogues. As outlined previously, silylation of N-heterocyclic silylenes gives access to aromatic silaimidazolium ions [27]. Likewise, the reaction of stannylene 104 with arene-stabilized silylium borates results in the formation of stable... 

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