[Borek]

This is tough, I am not convinced "undissociated" an "complexed" means exactly the same in this context. Yes, in both cases we speak about an entity with a formula CuSO₄ (give or take some water molecules), but whether they are identical - I don't know.

NaOH is considered a strong base, which is commonly assumed to mean "fully dissociated". Yet the stability constant Na⁺/OH^- is around 0.63, which means in 0.9 M NaOH almost exactly half is in the form of NaOH complex.