Q20 · CSIR NET Chemistry, June 2021
Paper: CSIR NET June 2021 · Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: 18 Electron Rule · Marks: 2 · Difficulty: Medium
Consider the following statement (s) in the context of organometallic complex (x) 
X A. The carbene ligand donates two electrons to the metal and accepts d electrons to make a $\pi$ bond B. The C (carbene) is nucelophilic C. Rotation around the $\mathrm{Cr}=\mathrm{C}(\mathrm{OMe})\mathrm{Me}$ double bond has low barrier ($<10\,\mathrm{kcal/mol}$) Correct statement(s) is/are:
X A. The carbene ligand donates two electrons to the metal and accepts d electrons to make a $\pi$ bond B. The C (carbene) is nucelophilic C. Rotation around the $\mathrm{Cr}=\mathrm{C}(\mathrm{OMe})\mathrm{Me}$ double bond has low barrier ($<10\,\mathrm{kcal/mol}$) Correct statement(s) is/are:(a)A and B
(b)A only
(c)A and C
(d)B and C
Answer
Answer: C ✓ checked by 4AB · confidence medium
Explanation
In a Fischer carbene the carbon σ-donates and π-accepts (A true), is electrophilic (B false), and the Cr=C rotation barrier is low (C true) — A and C (c).
Study loop for Organometallic Compounds