Single-molecule-magnet behavior and spin changes affected by crystal packing effects.

Five Mn 3Zn 2 heterometallic complexes have been synthesized and structurally and magnetically characterized. Spin ground states up to S = 6 have been observed for these complexes and are shown to depend on the cocrystallizing cation and on the terminal ligand. Large axial zero-field interactions ( D = -1.16 K) are the result of near-parallel alignment of the Mn (III) Jahn-Teller axes. High-frequency electron paramagnetic resonance, single-crystal magnetization hysteresis, and alternating current susceptibility measurements are presented to characterize [NEt 4] 3[Mn 3Zn 2(salox) 3O(N 3) 6X 2] [X (-) = Cl (-) ( 1), Br (-) ( 2)] and [AsPh 4] 3[Mn 3Zn 2(salox) 3O(N 3) 6Cl 2] ( 3) and reveal that 1 and 2 are single-molecule magnets ( U eff = 44 K), while 3 is not.