Q52 · CSIR NET Chemistry, June 2018
Paper: CSIR NET June 2018 · Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Cluster Compounds Wade Rules · Marks: 2 · Difficulty: Hard
The reaction of $[(\eta^{5}-\mathrm{C_5H_5}\ (\mathrm{Fe(CO)_2})]^{-}$ with $\mathrm{CH_3I}$ gives compound A. The $^{1}\mathrm{H}$ NMR spectrum of A show two singlets in an integrated intensity ratio of 3 : 5. Compound A upon reaction with $\mathrm{PPh_3}$ give compound B. The 1H NMR spectrum of B shows 3 sets of signals in an integrated intensity ratio of 3 : 5 : 15. Compounds A and B respectively, are
(a)
(b)
and 
and (c)
(d)
and 
and Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
[CpFe(CO)₂]⁻ + CH₃I → CpFe(CO)₂CH₃ (Cp 5H : CH₃ 3H). PPh₃ induces migratory insertion to CpFe(CO)(PPh₃)(COCH₃), whose signals are 3 : 5 : 15 (b).
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