Crystal and molecular structures of bis(4,4',6,6'-tetramethyl-2,2'-bipyridyl)copper(I) perchlorate, bis(4,4',6,6'-tetramethyl-2,2'-bipyridyl)copper(II) diperchlorate, and bis(4,4',6,6'-tetramethyl-2,2'-bipyridyl)copper(II) diperchlorate dihydrate. A search for copper(II) and copper(I) complexes with a common ligand environment