A family of ferric catecholate complexes exhibiting unusual magnetic properties is described.

Complexes [(dpp-BIAN)0CoIII2]·MeCN (I) and [(Py)2CoI2] (II) were synthesized by the reaction between cobalt(II) iodide and 1,2-bis(2,6-diisopropylphenylimino)acenaphthene (dpp-BIAN) or pyridine (Py), respectively. The molecular structures of the complexes were determined by X-ray diffraction. The Co(II) ions in both compounds are in a distorted tetrahedral environment (CoN2I2). The electrochemical behavior of complex I was studied by cyclic voltammetry. Magnetochemical measurements revealed that when an external magnetic field is applied, both compounds exhibit the properties of field-induced single ion magnets.

A series of novel isomorphic mononuclear complexes [Ln(PyrCOO)(acac)(HO)] (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Y(9); acac - acetylacetonate (pentane-2,4-dionate) anion, PyrCOOH is pyrazine-2-carboxylic acid) were prepared. Slow magnetic relaxation indicating SMM behavior was found in complexes 3, 4, 6 and 8. For 4 (Dy), the anisotropy barrier is Δ/k = 77 K under a dc field of 1500 Oe. For 8 (Yb), the anisotropy barrier is Δ/k = 54 K under a dc field of 2000 Oe which is the highest presently known value for molecular Yb carboxylate complexes and for Yb molecular complexes in general.

Five new dysprosium complexes were synthesized and characterized: neutral Dy(NCS) 3 ·6(H 2 O) (1), [Dy(NCS) 3 (H 2 O)-(bpy) 2 ]·0.5(bpy)·H 2 O (2), and [Dy(NCS) 3 (H 2 O)(phen) 2 ]·phen· 0.5H 2 O (3), as well as ionic [Hbpy][Dy(NCS) 4 (bpy) 2 ]·H 2 O (4) and [Hphen][Dy(NCS) 4 (phen) 2 ] (5). In all complexes, the metal coordination number (CN) is 8. All complexes exhibit single-ion [a] N.