Field supported slow magnetic relaxation in a quasi-one-dimensional copper(II) complex with a pentaheterocyclic triphenodioxazine

Abstract

A new copper(II) complex (I) was obtained by the reaction of a sterically crowded 2,4-di-(tert-butyl)-9-chloro-benzo[5,6][1,4]oxazine[2,3-b]phenoxazine bridging ligand with Cu(II) hexafluoroacetylacetonate. Compound I is a quasi-one-dimensional complex in which the Cu(hfac)(2) moieties are co-crystallized with the triphenodioxazine molecules through only weak Cu center dot center dot center dot N short intermolecular interactions (the Cu center dot center dot center dot N distances are 2.732 and 2.752 angstrom). The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(u) ion with S = 1/2, the compound demonstrates a slow magnetic relaxation behaviour at a weak applied magnetic field (H-DC = 500 Oe). The EPR spectra and DC magnetic measurements show the strong axial anisotropy of the g-tensor. The temperature dependence of the relaxation time is well described by the combination of one-phonon direct and two-phonon Raman processes.