Why can’t organozinc reagent react with alkylalkoxysilane？

we know that Grignard reagents can react with alylalkoxysilane ,such as： RMgCl + MeSi(OMe)3 → MeRSi(OMe)2 + MeOMgCl (R=phenyl & benzyl)。 But the organozinc reagent such as BnMgBr can’t react with alkylalkoxysilane under the same conditions，even if the additive TMEDA（N,N,N',N'-tetramethyl-ethane-1,2-diamine） or LiCl was used as catalyst 。

Compare electronegativities of magnesium and zinc and carbon. The difference for magnesium and carbon is $\pu{1.24}$, while for zinc it is $\pu{0.9}$ in Pauling scale. Also, the energy neccessary to oxidize $\ce{M^+}$ to $\ce{M^2+}$ (difference between second and first ionization energy) is about $\pu{715 kJ/mol}$ for magnesium compared to about $\pu{825 kJ/mol}$ for zinc. These informations both tell you that there is much larger negative charge (as in partial charge) on the carbon atom in organomagnesium compounds than in organozinc compounds. Magnesium is also more prone to leaving as a $\ce{MgX^+}$ moiety than zinc as $\ce{ZnX^+}$. In other words, the $\ce{C-Mg}$ bond breaks much more easily than $\ce{C-Zn}$ bond.