For the complexes(A) $\left[\mathrm{Ni}(\mathrm{H}_{2}\mathrm{O})_{6}\right]^{2+}$ (B) $\left[\mathrm{Mn}(\mathrm{H}_{2}\mathrm{O})_{6}\right]^{2+}$ (C) $\left[\mathrm{Cr}(\mathrm{H}_{2}\mathrm{O})_{6}\right]^{3+}$ (D) $\left[\mathrm{Ti}(\mathrm{H}_{2}\mathrm{O})_{6}\right]^{3+}$the ideal octahedral geometry will not be observed in
(a)(A) and (D)
(b)(C) and (D)
(c)(B) only
(d)(D) only
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
Only Ti³⁺ (t₂g¹) has an orbitally degenerate ground state, so it shows a (weak) Jahn–Teller distortion. Ni²⁺ d⁸, high-spin Mn²⁺ d⁵ and Cr³⁺ d³ are non-degenerate (d).