Two one-dimensional compounds based on pyramidal {TbCu4} units and formate ligand: chair-like [(H2O)2(ClO4)2]2- clusters and slow relaxation of magnetization.

With formate as ligand, two 1-D 3d-4f compounds (linear and zigzag) based on pyramidal {TbCu(4)} unit were obtained. Chair-like [(H(2)O)(2)(ClO(4))(2)](2-) clusters and μ(5)-η(1):η(4) bridging mode of formate were observed in the linear one which also displays slow relaxation of the magnetization.