inorganic

in d⁵ complexes the elctronic configuration is t_2g³ and e_g² so all the orbitals are half filled...and according to Hund's rule the electron in all the orbitals will have the same spin..so for an electron to make transition from t_2g to e_g..it wud need energy to change it's spin ..so it absorbs high energy light and emits less energy light..that's why it appears pale..whereas in case of d¹ or d² no such thing happens...

@govind

Does not ur explaination justify weak field ligand complexes ONLY????

wat abt strong field ligand complexes where electrons are paired???

@Tapas..U're right my explanation is only justified for weak field ligands only..coz in case of strong field ligands pairing occurs ..so there will be no such problem in that case and the compounds with strong field ligands will have intense colour..