- REACTIVITY OF ALLYLIC AND VINYLIC SILANES, GERMANES, STANNANES AND PLUMBANES TOWARD SH2' OR SH2 SUBSTITUTION BY CARBON- OR HETEROATOM-CENTERED FREE RADICALS
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Compounds of the type CH2=CHCH2MR3 and (E)-PhCH=CHMR3 (M = Si, Ge, Sn, Pb) were allowed to react with a series of heteroatom-centered radicals (PhY*, Y = S, Se, Te, derived from PhYYPh) and carbon-centered radicals ((CH3)2CH* derived from (CH3)2CHHgCl).We report that alkenylplumbanes and, under forcing conditions, alkenylgermanes undergo SH2 or SH2' substitution of the metal by chain mechanism analogous to those previously reported for alkenylstannanes.Alkenylsilanes are unreactive.Based solely upon product yields, the following trends were observed: The reactivity of the alkenylmetals follow the order metal = Pb > Sn > Ge (> Si).The allylmetals were more reactive then the β-metallostyrenes toward the reactants employed in this study.The chalcogen series PhYYPh exhibits the reactivity order Y = S > Se > Te.
- Light, James P.,Ridenour, Michael,Beard, Lois,Hershberger, James W.
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- METAL-HALOGEN BONDING STUDIES WITH GROUP IV A TRIALKYLMETAL HALIDES
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Halogen redistribution reactions have been found to take place between benzyl bromide or benzyl iodide and the Group IV A silicon, germanium, tin, and lead containing trialkylmetal chlorides.However, for the reactions of the Si, Ge and Sn compounds, a quaternary ammonium halide catalyst was necessary to enable the equilibria to be established at reasonably rapid rates.The equilibrium constants at 50 deg C have been measured for each of these halogen redistributions.They have been found to increase gradually on going down in Group IV A from silicon to lead, being conside rably less than unity in the case of silicon and somewhat greater than unity in the case of lead for both the R3MCl + BzBr and R3MCl + BzI reactions.The ΔG0 values for these equilibria have been calculated, and it is suggested that their differences may be explained in terms of the relative importance of p?-d? contributions to the halogen-metal bonding in the various Group IV A trialkylmetal halide systems.
- Friedrich, Edwin C.,Abma, Charles B.,Vartanian, Paul F.
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p. 203 - 212
(2007/10/02)
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