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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: txprof on July 20, 2018, 10:31:11 AM

Title: reaction of SiCl4 with Si-H
Post by: txprof on July 20, 2018, 10:31:11 AM

I am trying to figure out whether SiCl4 will react with an Si-H bond spontaneously. Anyone have any advice of resources/literature that can help me?

Title: Re: reaction of SiCl4 with Si-H
Post by: Phalcone42 on July 20, 2018, 11:01:09 AM

Perhaps a simple start would be to look at the bond energies of the Si-H, Si-Cl, Si-Si, and H-Cl bonds and do simple summations. (Hint: sum of products - sum of reactants)
http://www.wiredchemist.com/chemistry/data/bond_energies_lengths.html

This should at least give the theoretical spontaneity, but there are often many effects which can impeded the theoretical.

Title: Re: reaction of SiCl4 with Si-H
Post by: Enthalpy on July 23, 2018, 05:02:08 AM

One aspect is that the reaction releases good heat. Good first check.

This doesn't suffice for a reaction to start spontaneously (if this is what you mean, because "spontaneous" has a special meaning in chemistry). For instance a forest burning in the atmosphere releases heat, but it needs a cause to catch fire.

SiH₄ starts many reactions spontaneously, for instance it catches fire in the atmosphere at or just above room temperature.

Telling why is more tricky. It needs to find a reaction path where all the energy hurdles are low, and for that, many species must be considered and combined, including free radicals. The weak Si-H bond eases such reaction paths.

Title: Re: reaction of SiCl4 with Si-H
Post by: yuehuizhou on August 21, 2018, 04:59:13 PM

It will form a mixed structure from SiCl4 and SiH4 --> 2 SiH2Cl2.