GOC and Organic Chemistry BasicshardMCQ SINGLE

While heavily halogenated carbanions are stabilized by inductive effects, why is the trichloromethylGOC and Organic Chemistry Basics Chemistry Question

Question

While heavily halogenated carbanions are stabilized by inductive effects, why is the trichloromethyl carbanion ($CCl_3^-$) significantly more stable than the trifluoromethyl carbanion ($CF_3^-$), despite fluorine being more electronegative?

Answer: C

💡 Solution & Explanation

Although F has a stronger $-I$ effect, Cl possesses vacant 3d orbitals. The negative charge on the carbon atom can delocalize into these vacant d-orbitals of adjacent chlorine atoms via $p\pi-d\pi$ back-bonding (resonance), providing substantial stabilization unavailable to $CF_3^-$.

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