The intermediate $\left[\mathrm{Fe}(\mathrm{SCN})\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}\right]^{2+}$ is detected in the reaction of $\left[\mathrm{Co}(\mathrm{NCS})\left(\mathrm{NH}_{3}\right)_{5}\right]^{2+}$ with $\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ in aqueous medium to produce $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ and $\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$. The mechanism of the reaction is
(a)Interchange dissociative
(b)Interchange associative
(c)Inner sphere electron transfer
(d)Outer sphere electron transfer
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Detecting [Fe(SCN)(H₂O)₅]²⁺ shows the thiocyanate bridged the two metals and was transferred from Co to Fe during electron transfer — the signature of an inner-sphere mechanism.