The CORRECT statement regarding the substitution of coordinated ligands in $\mathrm{Ni(CO)_4}$ and $\mathrm{Co(NO)(CO)_3}$ is: (Given: Co–N–O bond is nearly linear; atomic numbers of Co and Ni are 27 and 28, respectively)
(a)$\mathrm{Ni(CO)_4}$ and $\mathrm{Co(NO)(CO)_3}$ follow associative and dissociative pathways, respectively.
(b)Both $\mathrm{Ni(CO)_4}$ and $\mathrm{Co(NO)(CO)_3}$ follow associative pathway.
(c)Both $\mathrm{Ni(CO)_4}$ and $\mathrm{Co(NO)(CO)_3}$ follow dissociative pathway.
(d)$\mathrm{Ni(CO)_4}$ and $\mathrm{Co(NO)(CO)_3}$ follow dissociative and associative pathways, respectively.
Answer
Answer: D ✓ checked by 4AB · confidence high
The source book printed B; on checking, D is correct — see the explanation.
Printed B; Ni(CO)4 loses CO first, only the nitrosyl complex can accept a ligand.
Explanation
Ni(CO)₄ is 18-electron and substitutes dissociatively. Co(NO)(CO)₃ is also 18-electron, but its linear NO can bend (3-electron → 1-electron donor) to open a site, so it reacts associatively. The printed B is wrong.