What is the structure of #I_3^(-)#?

1 Answer
Aug 7, 2017

Do you want #I_2^(-)# or #I_3^-#?

Explanation:

#I_3^-# is a 22 valence electron system which gives 3 lone pairs around the central iodine atom...according to #"VSEPR"# the formal hybridization is #dsp^3#, which gives a trigonal bipyramidal structure with respect to the electron pairs.

However because we describe structure on the basis of bonding pairs of electrons, not non-bonding pairs, the structure is linear to a first approx., because the non-bonding pairs of electrons occupy the equatorial plane.......

And if we write Lewis structures of the ion we get.....

#I-stackrel(-)I-I# in which the CENTRAL iodine has 8 VALENCE electrons, and thus it is assigned the formal negative charge.

With #I_2^(-)# I don't know what you want..........