reacts with HCl or other chloride sources to form complex ions: the red  (found in potassium trichloridocuprate(II) ) (it is a dimer in reality, , a couple of tetrahedrons that share an edge), and the green or yellow  (found in potassium tetrachloridocuprate(II) ).
Some of these complexes can be crystallized from aqueous solution, and they adopt a wide variety of structures.
Copper(II) chloride also forms a variety of coordination complexes with ligands such as ammonia, pyridine and triphenylphosphine oxide:
: (tetragonal)
: (tetrahedral)
However "soft" ligands such as phosphines (e.g., triphenylphosphine), iodide, and cyanide as well as some tertiary amines induce reduction to give copper(I) complexes.