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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Ipodlover on February 06, 2008, 06:40:47 PM

Title: Structure of SnI2 and SnI4, account for difference in melting points.
Post by: Ipodlover on February 06, 2008, 06:40:47 PM

SnI2= 320C
SnI4= 145C

SnI4 is pretty straight forward, i think it should be tetrahedral

http://en.wikipedia.org/wiki/Sncl2

But SnI2 is much heavier, and its solid at room temperature, i was thinking more like I-Sn=I. I don't know what the right structure would be, either I-Sn-I or I=Sn-I, or something different.

I think the difference i melting point is due to dipole moment, but im not sure how to word it nicely. Any suggestions, ideas... ?

Thanks.

Title: Re: Structure of SnI2 and SnI4, account for difference in melting points.
Post by: 0000000 on February 14, 2008, 09:46:48 AM

At the beginning, you can not write solid structures like this

 

Quote from: Ipodlover on February 06, 2008, 06:40:47 PM

thinking more like I-Sn=I. I don't know what the right structure would be, either I-Sn-I or I=Sn-I, or something different.

because there is a connected structure within the solid piece of SnI2, that so it is solid ;)

notice that in one form there is lonely electrons pair (SnI2) and in the second there is not (SnI4) and because of that the attraction is bigger therefore the crystal energy is huge, this is why the MP, BP... are different.