Disilenes Subject

The chapter table of contents contains subjects that were either unknown or merely distant hopes a decade ago, such as persistent silylenes, the dissociation of disilenes to silylenes and terminal silylene-transition metal complexes. The kinetics and spectroscopy of silylenes and theoretical treatments of silylene structure and reactivity have made such gigantic strides in the intervening years that they represent new vistas in our understanding. 

The reaction of 2,6-dimethylphenyl isocyanide 70 with the disilene 10 gives the disi-lacyclopropane imine 7188, the unusually bright red color of which was the subject of an intensive theoretical investigation (equation 13)89. 

The reaction types known to produce disilenes are summarized in Chart 1 and apply regardless of the ultimate stability of the product. Historically, thermal 4 + 2 cycloreversion of complex l,2-disilacyclohex-4-enes, i.e. a retro-Diels-Alder fragmentation came first8 -14, followed by silylene dimerization15 -17. This early work produced only indirect evidence for the formation of disilenes as reactive intermediates, but in retrospect it is clear that these species were indeed produced. The early history of the subject is discussed in Reference 1. The first directly observable and isolable disilene resulted from the dimerization of photochemically produced dimesitylsilylene18, ushering in a new era in disilene chemistry. These more recent developments are described in Reference 2. 

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