What is the best Lewis Structure of ICl4- when using a formal charge argument?

Question

What is the best Lewis structure for ICl4- when considering formal charge arguments? 
Many resources, including a Yahoo! Answers discussion (http://answers.yahoo.com/question/index?qid=200712...), classify ICl4- as a species with six electron domains. It is beneficial to be familiar with this question and answer before proceeding. According to formal charge guidelines, the negative formal charge should be placed on the more electronegative atom. However, as mentioned in the answer above, a Lewis structure depicting ICl4- as having six electron domains places this negative formal charge on iodine. 
Why not consider creating a double bond between iodine and chlorine using one of the lone pairs on iodine? This adjustment would assign the negative formal charge to chlorine, consistent with formal charge principles, and would yield a five electron domain arrangement with a seesaw geometry. 
My assumption is that empirical data suggests ICl4- is square planar in structure. How can this observation be reconciled with formal charge considerations?

Anonymous · Accepted Answer

I can’t answer all of this, but I can answer this part:
“… Why not create a double bond (using one of the lone pairs on the iodine) between I and Cl, …”
Very simple:  the (most likely) p orbitals that would be involved in double bond formation, 5p on iodine and 3p on chlroine, would have very poor overlap and thus would not be able to form a stable double bond. (By the time you get to 5p orbitals, the space they occupy is pretty large, so their electron cloud is fairly diffuse.)

Anonymous · Answer

This Site Might Help You.RE:What is the best Lewis Structure of ICl4- when using a formal charge argument?Most resources (such as this Yahoo! Answer: http://answers.yahoo.com/question/index?qid=200712&hellip; list IC4- as a 6 electron domain species.  It&rsquo;s worth being familiar with this question / answer before continuing.Formal charge guidelines tell us to put the negative formal&hellip;

Anonymous · Answer

You can’t put a double bond on Cl because of the octet rule, which would be broken if you had a double bond. With the structure suggested in the answer, all Cl’s follow the octet rule. I does break the octet rule, however, it is very large and polarizable and it has access to d orbitals. Cl is less polarizable and does not have access to d orbitals.
With those two considerations in mind… basically. the molecule is just more stable with the negative on the I than with it on the Cl.
Plus, with the square planar shape, the molecules are the maximum distance apart. If you put the negative on the Cl (a double bond, at that), that would shove the other Cls VERY close to eachother, and all of that electron density so close is not a stable conformation.

Anonymous · Answer

It would be set up like this “:” means lone pair of electrons, ignore the “~” ~~~:~~:~~~~: H—O—Br===O: ~~~:~~: the formal charge would be as follows: H: 1-1/2(2)-0=0 O: 6-1/2(4)-4=0 Br: 7-1/2(6)-4=0 O: 6-1/2(4)-4=0 Br can hold extra electrons because it can leak those electrons over to the D orbital

Zion White

What is the best Lewis Structure of ICl4- when using a formal charge argument?

4 Answers

AI-Powered Insights

Want to answer this question?

Categories

Tags

Related Questions