The number of peaks with relative intensities observed in the ¹ H NMR spectra of [(Cp)₂ Fe(CO)₂] at +30 °C… · ABC26IN1502
Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Organometallic Compounds – General · Exam: CSIR NET DEC 2019 · Marks: 2 · Difficulty: Medium
The number of peaks with relative intensities observed in the ${ }^{1} \mathrm{H} \mathrm{NMR}$ spectra of $\left[(\mathrm{Cp})_{2} \mathrm{Fe}(\mathrm{CO})_{2}\right]$ at +30 °C and - 80 °C in diethyl ether are, respectively
(a)two peaks $(1: 1)$ and four peaks $(5: 2: 2: 1)$
(b)one peak and two peaks $(1: 1)$
(c)two peaks (1 : 1) at both the temperatures
(d)one peak and four peaks $(5: 2: 2: 1)$
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
(η⁵-Cp)(η¹-Cp)Fe(CO)₂: at +30 °C the η¹ ring whizzes, so two singlets (1:1); at −80 °C the η¹ ring freezes into three environments, giving four peaks 5:2:2:1.