Synthesis, Crystal Structure and Intermolecular Magnetic Interactions of a New N-TEMPO Radical

Abstract

A new N-TEMPO-3,5-di-tert-butylsalicylaldimine radical (1) has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV-vis, and EPR spectroscopy and temperature dependent magnetic susceptibility. X-ray diffraction revealed that H-atoms of γ-CH in TEMPO and CH<inf>3</inf> in salicylaldimine moieties, are located in close contact with the neighboring NeO radical group in crystal 1. The temperature dependence of the magnetic susceptibility (x<inf>m</inf>) of 1 has been fitted by the CurieeWeiss law with θ = -0.3 K within 10-300 K, suggesting the presence of a weak intermolecular antiferromagnetic interaction between radical centers at T < 10 K. It has been demonstrated that radical 1 possesses crystal structure involving co-existence of antiferromagnetic and ferromagnetic interactions through C-H/O-N• contacts of γ-CH and tBu groups hydrogen atoms, in which the former path dominates over the latter. © 2011 Elsevier Masson SAS. All rights reserved.