Three Novel Copper–Radical Complexes: Syntheses, Crystal Structures, and Magnetic Properties

Abstract

Abstract Three novel copper–radical complexes [Cu(PhCOO) 2 (NITpPy) 2 (H 2 O) 2 ] ( 1 ), [Cu 2 (Me 3 CCOO) 4 (NITpPy) 2 ] ( 2 ), and [{Cu 2 (Me 3 CCOO) 4 (NITpPy)} n ] ( 3 ) [NITpPy = 4,4,5,5‐tetramethyl‐2‐(4‐pyridyl)‐2‐imidazoline‐1‐oxyl 3‐oxide] were synthesized and characterized structurally as well as magnetically. It is noteworthy that the syntheses of complexes 2 and 3 are similar except for the temperature of the reaction between Cu(Me 3 CCOO) 2 · 2H 2 O and the NITpPy radical ligand. Our magnetic study of complexes 1 and 2 reveals that the antiferromagnetic interactions occur with a J value around –10 cm –1 between copper(II) and radicals when radicals use the pyridine nitrogen atom connected to the copper(II) ion. Yet the best‐fit parameters of complex 3 reveal that significant ferromagnetic interactions ( J 2 = 20.5 cm –1 ) take place in the copper radical when radicals coordinate the copper(II) ion with nitroxide directly.