Interactions of trivalent lanthanide cations with tetradentate Schiff bases: New lanthanide(III) complexes from (1S,2S,N1E,N2E)–N,N′-bis(pyridin-2-ylmethylene)cyclohexane-1,2-diamine

The novel lanthanide(III) complexes [Ln(NO3)3(MeOH)L] (Ln = La 1, Pr 2), and [Ln(NO3)3L] · MeOH (Ln = Sm 3, Gd 4) where L = N,N′-bis(pyridin-2-ylmethylene)cyclohexane-1,2-diamine, have been obtained by direct reaction of the Schiff base ligand and the corresponding hydrated lanthanide(III) nitrates in methanol. All complexes were characterized spectroscopically and thermogravimetrically. Complexes 2 and 3 were also characterized with crystallographic studies. In the molecular structure of 2, Pr(III) is surrounded by all four nitrogen atoms of the Schiff base and seven oxygen atoms belonging to three bidentate chelating nitrato ligands and a coordinated methanol molecule, while in 3, Sm(III) is surrounded by all four nitrogen atoms of the Schiff base and six oxygen atoms belonging to three bidentate chelating nitrato ligands.