Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Metal Carbonyls · Exam: NET JUNE 2014 · Marks: 2 · Difficulty: Medium
${}^{1}\mathrm{H}$ NMR spectrum of $[\eta^{5}\text{-}\mathrm{C}_{5}\mathrm{H}_{5}\mathrm{Rh})(\mathrm{C}_{2}\mathrm{H}_{4})_{2}]$ at $-20^{\circ}\mathrm{C}$ shows a typical AA' XX' pattern in the olefinic region. On increasing the temperature to $-70^{\circ}\mathrm{C}$, the separate lines collapse into a single line which is due to
(a)free rotation of the ethylene ligand about the metal-olefin bond
(b)interamolecular exchange between the ethylene ligands
(c)intermolecular exchange between the ethylene ligands
(d)change in hapticity of the cyclopentadienyl ligand