The copper atom is in the +1 oxidation state in which it has a full (totally occupied) set of 'd' orbitals. There can be no transitions between the non-degenerate orbitals and so there can be no frequencies of light absorbed due to d-d transitions.
CuCl2 does not have a full set of 'd' orbitals is has a d9 configuration becuase the copper atom is in the (II) oxidation state and transitions can happen to absorb light.