Which one of the following pairs is isostructural (i.e., having the same shape and hybridization) ?
- [BCl3 and BrCl3]
- [NH3 and NO3-]
- [NF3 and BF3]
- [BF4- and NH4+]
Answer
(4) [BF4- and NH4+]
Solution
(1) BCl3: sp2, trigonal planar; BrCl3: sp3d (3 bp + 2 lp), T-shaped.
(2) NH3: sp3, pyramidal; NO3-: sp2, trigonal planar.
(3) NF3: sp3, pyramidal; BF3: sp2, trigonal planar.
(4) BF4-: 4 bp + 0 lp ⇒ sp3, tetrahedral; NH4+: 4 bp + 0 lp ⇒ sp3, tetrahedral.
∴ BF4- and NH4+ are isostructural.
Answer: (4)