Syntheses, crystal structures and magnetic properties of a new thienyl-substituted nitronyl nitroxide and its copper(II) complex

Abstract

A new building block for molecule-based magnetic materials − thiophene-substituted nitronyl nitroxide, NIT2-thp, [1, NIT2-thp = 4,4,5,5-tetramethyl-2-(thiophenal-2-yl)imidazoline-1-oxyl-3-oxide] and its copper(II) complex [Cu(hfac)2]3(NIT2-thp)2 (2) (hfac = hexafluoroacetylacetonate) have been synthesized and characterized structurally and magnetically. For 1, dimers were formed and arranged through intermolecular interactions, the shortest contact between nitroxide groups is 4.115 Å among adjacent dimers. In 2 two types of copper interaction with 1 give three colinear Cu(II) ions linked by two μ − 1,4 bridging nitroxide ligands. The central metal ion is in a distorted octahedron, axially coordinated by two nitroxide oxygen atoms, while the two external metal ions are in distorted square-pyramidal environments with the nitroxide oxygen atom coordinated in the basal plane. Magnetic susceptibility data for 1 and 2 have been measured in the range 3–300 K. There are antiferromagnetic interactions (J = −3.89 cm−1) between the dimers of 1 and also ferromagnetic interactions in 2. The magnetic properties of 1 and 2 are discussed in connection with their crystal structures.