Rod-shaped [Mn6] complexes as single-molecule magnets

The preparation, X-ray crystal structures, and magnetic properties of four new rod-shaped hexanuclear Mn clusters [Mn6(O2CCH3)6(EdeaH)2(tmp)2] (1), [Mn6(O2CCH3)6(mdeaH)2(tmp)2] (2), [Mn6(O2CCF3)6(teaH2)2(tmp)2]·2MeCN (3) and [Mn6(O2CPh)6(EdeaH)2(tmp)2]·2Et2O (4), where teaH3 is triethanolamine and tmpH3 is the tris-hydroxymethyl propane ligand, are reported. DC magnetization data along with AC magnetic susceptibility studies show that these complexes have weak antiferromagnetic coupling, appreciable magnetoanisotropy, and ground states of up to S = 4. Though all four complexes show a frequency-dependent out-of-phase signal in the AC susceptibility, a characteristic of single-molecule magnets (SMMs), only complexes 1, 2, and 4 are likely to be SMMs with ground states ranging from S = 2 to S = 4. Complex 3 shows the weakest AC signal and the lowest spin ground state of S ≈ 1, likely due to small structural differences and intermolecular interactions.