Paper: CSIR-NET December 2014 · Subject: Physical Chemistry · Chapter: Group Theory · Topic: Symmetry Elements Point Groups · Marks: 2 · Difficulty: Medium
Under review — part of this question (a structure or an option) is not clear in the source scan. 4AB is checking it against the original book; the answer shown may change.
The point group symmetries for trans- $\left[\mathrm{Cr}(\mathrm{en})_{2} \mathrm{F}_{2}\right]^{+}$and $\left[\mathrm{TiCl}_{6}\right]^{3-}$, respectively, are
(a)$D_{4d}$ and $D_{3d}$
(b)$D_{3d}$ and $D_{4d}$
(c)$D_{4h}$ and $D_{3h}$
(d)$D_{3h}$ and $D_{4h}$
Answer
Under review — not yet confirmed.
Answer: C
The source book printed no answer; this one was worked out and checked — see the explanation.
[TiCl6]3- is Oh; no option is fully correct.
Explanation
With the en chelate rings idealised as point ligands, trans-[Cr(en)₂F₂]⁺ is D₄h. [TiCl₆]³⁻ is a regular octahedron (O_h), which no option gives; (c) is the only option with the correct D₄h assignment. The printed question is defective.