Synthesis, structure, and properties of a 1-D copper(II) complex with nitronyl nitroxide radicals

摘要

A 1-D chain complex [Cu(NIT4Py)(IDA)]_(infinity) (NIT4Py = 2-(4'-pyridyl)-4,4,5,5-tetramethylimi-dazoline-l-oxyl-3-oxide and IDA = iminodiacetate) has been prepared and characterized by single-crystal X-ray diffraction, IR, TGA, and magnetic analysis. Each Cu(II) is five-coordinate with distorted square pyramidal geometry. Each IDA bridges two Cu(II) ions via one carboxylate which occupies the axial site of Cu(II), leading to a chain structure composed of Cu(II)-radical cations and IDA anions. In the complex, there exist three magnetic exchange pathways, (i) interaction between units of (Cu(II)-NIT4Py) through IDA, (ii) Cu(II)-NIT4Py interaction, and (iii) NIT4Py-NIT4Py interaction through space. Compared with the first two magnetic interactions, the last magnetic exchange interaction should be too weak to be counted because of the large distance of the neighboring NIT4Py molecules (4.993 A). Analysis of the magnetic properties was performed using the Bleany-Bowers (dimer) model, showing that the complex exhibited both weak antiferromagnetic interaction between the Cu(II) and NIT4Py, and between the units of (Cu(II)-NIT4Py) through IDA with exchange coupling parameters J= -7.28 cm~(-1) and zJ' = -0.40cm~(-1).