Magnetic behavior of a manganese(II) complex of nitroxide-substituted 1,3-di(4-pyridyl)benzene

Magnetic interaction between two magnetic metals separated by a sizable dia magnetic ligand is generally very weak. A new spin-introduced bidentate, N- t-butyl-N-oxy-3,5-dipyridylaniline (1) was designed and synthesized to expl ore the spin-introducing effect on sizable ligands. A Mn(hfac), complex of 1 was prepared and its structure was elucidated by X-ray structure analysis . The complex 1 . Mn(hfac)(2) has a one-dimensional helical alternate-chain structure; a double-helix structure is constructed by the two chains. The ferromagnetic interaction between Mn(II) and the nitroxide spins was observ ed. The analysis using Seiden's model allows the estimation of J = + 0.33 K for Mn(II)-nitroxide interaction. In accordance with this result, the N-t- butyl-N-oxy-3-pyridylaniline (2)-derived Mn(hfac), complex, 2(2). Mn(hfac)( 2), revealed a comparable magnetic interaction between the Mn(II) spin and the nitroside spins, showing J = + 0.19 K by a trimer model analysis. Thus, the magnetic interaction between the Mn(II) ions can be improved by introd uction of the nitroxide group into the diamagnetic bidentate through the sp in communication between the nitroxide and Mn(II) spins. (C) 2001 Elsevier Science Ltd. All rights reserved.