$\left[\mathrm{Co}(\mathrm{CO})_{4}\right]$ is isolobal with
(a)$\mathrm{CH}_{4}$
(b)$\mathrm{CH}_{3}$
(c)$\mathrm{CH}_{2}$
(d)CH
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
[Co(CO)₄]• is a 17-electron d⁹ ML₄ fragment with one frontier orbital holding one electron, isolobal with the methyl radical CH₃• (e.g. Co₂(CO)₈ ↔ ethane, HCo(CO)₄ ↔ methane).