The resonance Raman stretching frequency ( $\nu$ o-o. in $\mathrm{cm^{-1}}$ ) of $\mathrm{O_2}$, is 1580. The $\nu$ o-o for $\mathrm{O_2}$ in bound oxy-hemoglobin is close to
(a)1600
(b)1900
(c)800
(d)1100
Answer
Answer (as printed): D
Explanation
$\mathrm{O_2}$ in free state, $\nu_{\text{o-o}} = 1580\,\mathrm{cm^{-1}}$ when $\mathrm{O_2}$ bound to hemoglobin, it makes strong coordinate bond with Fe of hemoglobin and O-O bond strength decreases slightly, so in oxy-hemoglobin, $\nu_{\text{o-o}} = 1100\,\mathrm{cm^{-1}}$.