[Mn-18](2 ) and [Mn-21](4 ) single-molecule magnets

Abstract

The synthesis and structural characterization of the two new Mn complexes [Mn18O14(O2CMe)18 (hep)4(hepH)2(H2O)2] (ClO4)2 (1) and [Mn21O16(O2CMe)16 (hmp)6(hmpH)2(pic)2(py)(H2O)] (ClO4)4 (3) are presented, together with a detailed study of their magnetic properties. Complex 1 possesses a ground-state spin of S = 13, and the ground-state spin for 3 is estimated to be S = 17/2 or 19/2. Both complexes 1 and 3 are new examples of single-molecule magnets (SMMs), displaying frequency-dependent out-of-phase AC signals, as well as magnetization vs. DC field hysteresis at temperatures below 1 K. Complex 1 straddles the classical/quantum interface by also displaying quantum tunneling of the magnetizatio..