The ¹H NMR spectrum of [Ru (η⁴-C₈ H₈)(CO)₃] at 23°C consists of a sharp single line. The number of signals… · ABC26IN1439
Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Organometallic Compounds – General · Exam: CSIR NET DEC 2015 · Marks: 2 · Difficulty: Medium
The ${}^{1}\mathrm{H}$ NMR spectrum of $\left[\mathrm{Ru}\left(\eta^{4}-\mathrm{C}_{8} \mathrm{H}_{8}\right)(\mathrm{CO})_{3}\right]$ at $23^{\circ}\mathrm{C}$ consists of a sharp single line. The number of signals observed at low temperature ($-140\,{}^{\circ}\mathrm{C}$) in its spectrum is
(a)8
(b)6
(c)4
(d)2
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
When the 1,3-metal shifts freeze out, the η⁴-C₈H₈ ring has a mirror plane through the Ru(CO)₃ unit: the eight ring protons fall into four pairs — four signals.