Chloride-bridged, defect-dicubane {Ln4} core clusters: syntheses, crystal structures and magnetic properties

Three chloride-bridged lanthanide compounds, [Ln4Cl6(CH3OH)12(OH)2]·4Cl·2CH3OH [Ln = Gd (1), Dy (2) and Er (3)], have been unexpectedly isolated by the reactions of LnCl3·6H2O and N,N′-bis(salicylidene)-1,2-(phenylene-diamine) (H2L). X-ray crystallographic analysis reveals a triclinic cell with a unique defect-dicubane {Ln4} core and the structure across this series is nominally isomorphic. Measurements of direct current magnetic susceptibility and isothermal magnetization give insight into the relevant cluster Hamiltonians for 1, 2, and 3, and alternating current susceptibility shows slow relaxation in 2, but not in 1 or 3 down to 2 K and up to 1 kHz.