What are some examples of transition metal ions that wont be colored and why?

Sc3+ and Ti4+ ions have no electrons in the 3d subshell so they are colorless = they can't absorb energy to promote a 3d electron Cu+ and Zn2+ have 10 3d electrons = no space in the upper set of d orbitals so it isn't possible to promote an electron = no light in the visible region is absorbed = colourless