title: The influence of ligand field effects on the magnetic exchange of high-spin Co(II)-semiquinonate complexes.
abstract: [Co(Me(4)cyclam)(tropolonate)](PF(6)) was synthesised and structurally characterised. Its electronic and W-band EPR spectra have been analysed by means of the angular overlap calculation of the Spin Hamiltonian parameters that provided also a satisfactory reproduction of the temperature dependence of the magnetic susceptibility. The present results can be interpreted assuming a pseudo-octahedral character for the Co(II) center. This prompted us to reconsider the model formerly used for the analysis of the magnetic coupling between hs-Co(II) and the paramagnetic o-semiquinonate ligand in the corresponding derivatives [Co(Me(4)cyclam)(PhenSQ)](PF(6)) and [Co(Me(4)cyclam)(DTBSQ)](PF(6)). These results indicate that the effect of the magnetic coupling is active only below 50 K and that a more refined model of exchange coupling between Co(II) and semiquinonato ligands is needed to quantitatively analyze the magnetic behaviour of this class of systems.
authors.affiliation: UdR INSTM and Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy. alessandro.bencini@unifi.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bencini
authors.forename: Alessandra
authors.initials: A
authors.lastname: Beni
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Costantino
authors.forename: Andrea
authors.initials: A
authors.lastname: Dei
authors.forename: Dante
authors.initials: D
authors.lastname: Gatteschi
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Sorace