Novel mixed-valent Co(2)(II)Co(4)(III)Ln(4)(III) aggregates with ligands derived from tris-(hydroxymethyl)aminomethane (Tris)

Isostructural Co(2)(II)Co(4)(III)Ln(4)(III) (Ln = Y (1), Gd (2) and Dy (3)) coordination clusters formed using the ligand Tris are the first examples of 3d-4f complexes involving this ligand and show weak ferromagnetic coupling between the Co-II ions and slow relaxation (SMM) behaviour for 3.