Rod-shaped [Mn 6] complexes as single-molecule magnets

Abstract

The preparation, X-ray crystal structures, and magnetic properties of four new rod-shaped hexanuclear Mn clusters [Mn 6(O 2CCH 3) 6(EdeaH) 2(tmp) 2] ( 1), [Mn 6(O 2CCH 3) 6(mdeaH) 2(tmp) 2] ( 2), [Mn 6(O 2CCF 3) 6(teaH 2) 2(tmp) 2]·2MeCN ( 3) and [Mn 6(O 2CPh) 6(EdeaH) 2(tmp) 2]·2Et 2O ( 4), where teaH 3 is triethanolamine and tmpH 3 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.