Q9 · CSIR-NET Chemistry, June 2018
Paper: CSIR-NET June 2018 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Hard
The reaction of $[(\eta^{5}\text{-}\mathrm{C_5H_5})\mathrm{Fe}(\mathrm{CO})_2]$ with $\mathrm{CH_3I}$ gives compound A. The $^{1}\mathrm{H}$ NMR spectrum of A shows two singlets in an integrated intensity ratio of 3:5. Compound A upon interaction with $\mathrm{PPh_3}$ gives compound B. The $^{1}\mathrm{H}$ 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)
(c)
(d)
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
[CpFe(CO)₂]⁻ + CH₃I → CpFe(CO)₂CH₃ (CH₃ : Cp = 3 : 5). PPh₃ induces CO insertion to CpFe(CO)(PPh₃)(COCH₃), giving 3 : 5 : 15 (b).
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