Crystal structure, magnetic and electrochemical properties of five-coordinate copper (II) complexes with 1,10-phenanthroline-5,6-dione

Three new five-coordinate CuII complexes, [Cu(tpy)(phen-dione)](PF6)2, [Cu(phen)(phen-dione)Cl]PF6 and [Cu(bpy)(phen-dione)Cl]PF6 (tpy = 2,2′;6′,2″-terpyridine, phen = 1,10-phenanthroline and phen-dione = 1,10-phenanthroline-5,6-dione) have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopies and cyclic voltammetry. The complex of [Cu(tpy)(phen-dione)](PF6)2 crystallized with one molecule of acetonitrile. The ortep drawing of [Cu(tpy)(phen-dione)](PF6)2 · CH3CN shows that the coordination geometry around CuII is a distorted trigonal- bipyramid. Due to the steric hindrance of View the MathML sourcePF6- in the unit cell, the tpy ligands in each complex cation cannot interact in a π–π fashion. The effective magnetic moment (μeff) of the complexes was measured by the Evans method. The cyclic voltammograms at Pt disk electrode for these complexes display only one reversible Cu(II)/Cu(I) redox couple.