Insertion vs. addition of oligomeric difluorosilylenes. Evidence for the attack of oligomeric difluorosilylenes on the carbon-carbon double bond as an initial step in the insertion reactions with trans- and cis-difluoroethylene

1,1-Difluoro-2,2,3,3-tetramethyl-1-silirane: synthesis and novel chemistry. Reinterpretation of difluorosilylene reaction mechanisms

“…The exceptional reactivity of silirane lb must result in formation of diradical 5 on collision with a molecule of in terms of silirane intermediates. [13][14] We suggest that most of the products of the reactions of SiF2 with olefins and acetylenes are readily explicable in terms of initial formation of difluorosiliranes and difluorosilirenes (see Schemes I and II).…”

“…Equation 3 can be used to calculate kq as a function of AG23 by using either Marcus (eq 5) or RW (eq 6) functions for both AG*23 and AG*3q. This is facilitated by the assumption of equal intrinsic barriers for both-electron-transfer processes, 13 and by consideration of the energetics of the system given by AGso + AG23 = -£0-o (7) where £0.0 is the spectroscopic energy of the excited state. 14 The results of such a calculation10 are shown in Figure 2.…”

“…Soc., 99, 241 (1977). (13) The assumption of equal Intrinsic barriers for excited-state and ground-state processes Is justified as long as the differences in shape, size, and solvation between the states (i.e., the Stokes shift) are small. (14) Equation 7 holds if the entropy changes associated with the excitation are small,2•5 a condition met by most of the systems studied so far.…”

A systematic investigation of the reaction of SiF2 with ethylene and six methyl-substituted ethylenes. II. Characterization of polymeric products, open chain organosilicon derivatives, and 1,2-disilacyclobutanes

“…Rather, speculation concerning the me&-three types of products: 1,2-disilacyclobutanes, anism of the reaction of SiF, with unsaturated oropen chain compounds, and polymers. These ganic compounds has been based upon the strucproducts were characterized by a of tures of the volatile products (6)(7)(8) which are in fact "F, l3C, and 29Si nmr spectroscopy.…”