Chemistry - Coordination Chemistry Question with Solution | TestHub

When oxygen is bound to$\mathrm{F}{\mathrm{e}}^{2+}$in heme, all the d-electrons of the Fe atom are forced into the three lower energy${\mathrm{t}}_{2\mathrm{g}}$orbitals and it produces low spin oxyhaemoglobin.

In oxyhaemoglobin,$\mathrm{F}{\mathrm{e}}^{2+}=\left[\mathrm{A}\mathrm{r}\right]3{\mathrm{d}}^6$



The sharp high energy transition between${\mathrm{t}}_{2\mathrm{g}}$and${\mathrm{e}}_{\mathrm{g}}$levels of the d-electrons is responsible for the bright red colour of oxyhaemoglobin.