The correct order of metal-carbon distance is (1) Fe(η⁵-Cp)₂ > Co(η⁵-Cp)₂ > Ni(η⁵-Cp)₂ (2) Fe(η⁵-Cp)₂ >… · ABC26IN0282
Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Metal Carbonyls · Exam: CSIR NET 2019 · Marks: 2 · Difficulty: Hard
The correct order of metal-carbon distance is (1) $\mathrm{Fe}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Co}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Ni}(\eta^5\text{-}\mathrm{Cp})_2$ (2) $\mathrm{Fe}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Ni}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Co}(\eta^5\text{-}\mathrm{Cp})_2$ (3) $\mathrm{Ni}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Fe}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Co}(\eta^5\text{-}\mathrm{Cp})_2$ (4) $\mathrm{Ni}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Co}(\eta^5\text{-}\mathrm{Cp})_2 > \mathrm{Fe}(\eta^5\text{-}\mathrm{Cp})_2$
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
Cp2Fe 10e- +8e- = 18 e- Number of electron in anti-bonding orbital = 0 Cp2Co 10e- +9e- = 19e- Number of electron in anti-bonding orbital = 1 Cp2Ni 10e- +10e- = 20e- Number of electron in anti-bonding orbital = 2 As the number of electron present in the anti-bonding orbital increases , M-ligand bond becomes weak and hence, bond length increases. Therefore, the correct order of M-C distance is Cp2Ni > Cp2Co > Cp2Fe
Explanation as extracted from the printed page; notation may be imperfect.