Magnetic properties of a new N-TEMPO-tert-butyl substituted salicylaldimines and their biradical palladium(II) complexes

Abstract

A new TEMPO bearing tert-butylated salicylaldimines 1 and 2, as well as early reported 3, and their bis(N-TEMPO-tert-butylated salicylaldiminato)palladium(II) biradical complexes 4-6 have been synthesized and characterized by elemental analyses, IR, UV/vis, ESR and an SQUID magnetometer. The solid state g-factors (2.0116-2.0168) for 4-6 suggest the existence of the significant metal-orbital contribution to the SOMO of nitroxyl radicals. The chi T-m vs. T plots for I and 2 indicate that the chi T-m decreases as T is lowered from 300 to 20 K, suggesting the existence of weak antiferromagnetic interactions in these radicals. Variable-temperature dependence (10-300 K) magnetic susceptibility data for biradical complexes 4-6 revealed the existence of ferromagnetic and antiferromagnetic behavior around at 10-220 K range for 4. The 1/chi(m) data for 1-6 follow the Curie Weiss law with negative theta throughout the above temperature range. (C) 2012 Elsevier Masson SAS. All rights reserved.