Source of materialAmethanol solution( 5m l) of [Cu(MeCN) 4 ][ClO 4 ]( 1m mol, 0.240 g) was addeddropwise to amethanol solution of 4-methylpyridine (4 mmol, 0.381 g). The reaction mixture was refluxed for 4hand filtered, the filtrate was kept in aCaCl 2 desiccator. During the preparation, Cu(I)isoxidated to Cu(II)byair oxygen. After a few days, blue crystals suitable for X-ray analysis were obtained. Experimental detailsWhile the Hatoms bonded to aromatic Catoms were added geometrically and treated as riding, the methyl groups were rotated to fit the electron density. Att he same time, the oxygen atoms of perchlorate anions are disordered and split into two positions each. DiscussionDuring the past two decades, considerable attention has been paid to the chemistry of heterocyclic compounds and complexes with metal ions due to their chelating ability and their potentiallybeneficial chemical and biological activities [1,2].The formula unit of the title crystal structure consists of one Cu(II)c ation, four 4-methylpyridine molecules, and two perchlorate anions. The Cu(II)atom is tetra-coordinated by four nitrogen atoms of four 4-methylpyridine ligands in asquare-planar fashion, which is similar to the isotypic tetrakis(4-methylpyridine)nickel (