(1,3‐Dimethylimidazolidine‐2‐selone‐κ Se )bis(1,10‐phenanthroline‐κ 2 N , N ′)copper(II) bis(perchlorate) and bis(2,2′‐bipyridyl‐κ 2 N , N ′)(imidazolidine‐2‐thione‐κ S )copper(II) bis(perchlorate)

In the first title salt, [Cu(C 12 H 8 N 2 ) 2 (C 5 H 10 N 2 Se)](ClO 4 ) 2 , the Cu II centre occupies a distorted trigonal–bipyramidal environment defined by four N donors from two 1,10‐phenanthroline (phen) ligands and by the Se donor of a 1,3‐dimethylimidazolidine‐2‐selone ligand, with the equatorial plane defined by the Se and by two N donors from different phen ligands and the axial sites occupied by the two remaining N donors, one from each phen ligand. The Cu—N distances span the range 1.980 (10)–2.114 (11) Å and the Cu—Se distance is 2.491 (3) Å. Intermolecular π–π contacts between imidazolidine rings and the central rings of phen ligands generate chains of cations. In the second salt, [Cu(C 10 H 8 N 2 ) 2 (C 3 H 6 N 2 S)](ClO 4 ) 2 , the Cu II centre occupies a similar distorted trigonal–bipyramidal environment comprising four N donors from two 2,2′‐bipyridyl (bipy) ligands and an S donor from an imidazolidine‐2‐thione ligand. The equatorial plane is defined by the S donor and two N donors from different bipy ligands. The Cu—N distances span the range 1.984 (6)–2.069 (7) Å and the Cu—S distance is 2.366 (3) Å. Intermolecular π–π contacts between imidazolidine and pyridyl rings form chains of cations. A major difference between the two structures is due to the presence in the second complex of two N—H...O hydrogen bonds linking the imidazolidine N—H hydrogen‐bond donors to perchlorate O‐atom acceptors.