Synthesis, structure and magnetic properties of hexanuclear CoIII-LnIII clusters

Reaction in CH3CN of cobalt pivalate and lanthanide nitrates in the presence of 2-(hydroxymethyl)pyridine (hmpH), sodium azide and KOH affords heterometallic hexanuclear [CoIII2DyIII4(OH)2(hmp)4(piv)8(N3)2(NO3)2] (Ln = PrIII (1), NdIII (2), EuIII (3), GdIII (4), TbIII (5), DyIII (6), HoIII (7), ErIII (8)) clusters. Variable-temperature solid-state magnetic susceptibility measurements for 2-8 in the temperature range 1.8-300 K were carried out. It was found that only compound 6 (Dy) displays an out-of-phase signal in the ac susceptibility and thus slow relaxation of the magnetization.