Predictable self-assembled [2 x 2] Ln(III)4 square grids (Ln = Dy,Tb)-SMM behaviour in a new lanthanide cluster motif

The ditopic carbohydrazone ligand (L1) produces the square, self-assembled [2 x 2] grids [Dy-4(L1)(4)(OH)(4)]Cl-2 (1) and [Ln(4)(L1)(4)(mu(4)-O)(mu(2)-1,1-N-3)(4)] (Ln = Dy (2), Tb (3)), with 2 exhibiting SMM behaviour. Two relaxation processes occur with U-eff = 51 K, 91 K in the absence of an external field, and one with U-eff = 270 K in the presence of a 1600 Oe optimum field.