The total valence electron count and the structure type adopted by the complex $\left[\mathrm{Fe}_{3}(\mathrm{CO})_{15}\mathrm{C}\right]$ respectively, are
(a)74 and nido
(b)60 and closo
(c)84 and arachno
(d)62 and nido
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
Fe₅C(CO)₁₅: 5×8 + 4 (C) + 30 = 74 = 14n + 4 for n = 5 → nido (square pyramid with the carbide in the open face).