Q51 · CSIR NET Chemistry, December 2016
Paper: CSIR NET December 2016 · Subject: Inorganic Chemistry · Chapter: Coordination Chemistry · Topic: Reaction Mechanisms Substitution · Marks: 2 · Difficulty: Hard
For $\mathrm{OH}^{-}$ catalysed $S_{N}1$ conjugate base mechanism of $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}\right]^{2+}$, the species obtained in the first step of the reaction is/are
(a)$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{OH})\right]^{2+}+\mathrm{Cl}^{-}$
(b)$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{NH}_{2}\right) \mathrm{Cl}\right]^{+}+\mathrm{H}_{2}\mathrm{O}$
(c)$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{NH}_{2}\right)\right]^{2+}+\mathrm{CI}$
(d)$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}(\mathrm{OH})\right]^{+}$ Only
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
S_N1CB starts with deprotonation of an ammine by OH⁻: [Co(NH₃)₄(NH₂)Cl]⁺ + H₂O.
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