MAGNETIC-PROPERTIES OF NEW FE-6(TRIETHANOLAMINATE(3-))(6) SPIN-CLUSTERS

We report the magnetic properties of three cyclic hexanuclear iron(III ) spin-clusters ([Fe-6(tea)(6)].6MeOH (1), [NaFe6(tea)(6)]ClO4.2MeOH ( 2) and [LiFe6(tea)(6)]ClO4.2MeOH (3), (tea: triethanolaminate(3-)). Th e intra-molecular exchange coupling between the Fe-III-spins is determ ined by measurements of the magnetic susceptibility in the range 2-300 K. The zero-field splitting of the lowest cluster spin states (E/k(B) < 200 K) is studied by ESR (electron-spin resonance) at frequencies b etween 9.5 and 350 GHz, The level splitting is analyzed by the irreduc ible-tenser operator technique. (C) 1998 Elsevier Science B.V. All rig hts reserved.