Three new dinuclear bis-μ-azido-bridged Cu(II) compounds with di-2-pyridylamine as a ligand: Syntheses, X-ray structure and magnetic measurements

Abstract

Three new dinuclear copper(II) compounds: [Cu 2(dpyam) 2(μ 1,1-N 3) 2(O 2CH) 2] ( 1), [Cu 2(dpyam) 2(μ 1,1-N 3) 2(O 2CCH 3) 2] ( 2) and [Cu 2(dpyam) 2(μ 1,1-N 3) 2(O 2CCH 2CH 3) 2] ( 3) have been synthesized and characterized crystallographically and spectroscopically. Compounds 1, 2 and 3 consist of a dinuclear unit in which both Cu(II) ions are connected through two end-on azido bridges providing a distorted square pyramidal geometry with a CuN 4O chromophore. The Cu⋯Cu separations are 3.195, 3.200 and 3.247 Å for compounds 1, 2 and 3, respectively. The magnetic properties have been measured in the range from 5 to 300 K and correlated with the molecular structures. All three compounds show a medium to weak ferromagnetic exchange interactions between the Cu(II) ions dominated by the bridging azido ligands, with a singlet-triplet splitting ( J) of 63.3, 63.8 and 5.1 cm −1, for compounds 1, 2 and 3, respectively. A large zero-field splitting of about 0.4 cm −1 is observed in the EPR for compounds 1 and 2.