Question

The CORRECT statement(s) about the species is (are)

• A. CpMo(CO)$_3$ and CpW(CO)$_3$ are isoelectronic (where Cp is cyclopentadienyl)
• B. CH$_2^-$ and NH$_2$ are isolobal and isoelectronic
• C. BH and CH are isolobal and isoelectronic
• D. CH$_3$ and Mn(CO)$_5$ are isolobal

Hint:

The isolobal analogy helps relate organic radicals with organometallic fragments. Fragments with the same frontier orbital characteristics behave similarly in bonding.

Answer 1

The Correct Option is A, B, D

Step 1: Recall the isolobal principle.
Two fragments are isolobal if they have similar frontier orbitals (same number, symmetry, and approximate energy).
Step 2: Analyze CH$_3$.
CH$_3$ radical has one singly occupied orbital, similar to a d$^7$ metal complex fragment like Mn(CO)$_5$.
Thus, CH$_3$ and Mn(CO)$_5$ are isolobal.
Step 3: Analyze other options.
(A) CpMo(CO)$_3$ and CpW(CO)$_3$ are both 18e$^-$ complexes but differ in principal quantum number → not isolobal comparison.
(B) CH$_2^-$ and NH$_2$ differ in total electron count (10 vs 8 valence electrons).
(C) BH and CH differ in electron configuration and bonding.
Step 4: Conclusion.
Hence, the correct statement is (D).