Paper: CSIR-NET June 2014 · Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Organometallic Compounds – General · Marks: 2 · Difficulty: Medium
The ligand(s) that is (are) fluxional in $\left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right)\left(\eta-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Fe}(\mathrm{CO})_{2}\right]$ in the temperature range $221-298\,\mathrm{K}$, is (are)
(a)$\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}$
(b)$\eta^{1}-\mathrm{C}_{5} \mathrm{H}_{5}$
(c)$\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}$ and CO
(d)$\eta^{1} \mathrm{C}_{5} \mathrm{H}_{5}$ and CO
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
In (η⁵-Cp)(η¹-Cp)Fe(CO)₂ the σ-bound η¹-cyclopentadienyl undergoes fast 1,2-metal shifts (ring whizzing), averaging its protons; the η⁵ ring and the CO are static.