Naphthalenediol-based bis(Salamo)-type homo- and heterotrinuclear cobalt(II) complexes: Syntheses, structures and magnetic properties

Abstract

Homo- and heterotrinuclear Co(II) complexes with a new acyclic bis(Salamo)-type ligand H4L, which bears a C-shaped O6 site by the metallation of the N2O2 Salamo moieties, were synthesized. The homotrinuclear complex [Co3(L)(OAc)2(CH3OH)2]·2CHCl3 (1) was obtained by the reaction of H4L with 3 equivalents of Co(OAc)2·4H2O. The heterotrinuclear complexes [Co2(L)Ca(OAc)2] (2), [Co2(L)Sr(OAc)2] (3) and [Co2(L)Ba(OAc)2(H2O)]·2CH3CH2OH (4) were acquired by the reaction of H4L with 2 equivalents of Co(OAc)2·4H2O and 1 equivalent of M(OAc)2 (M=Ca(II), Sr(II) and Ba(II)). In the crystal structures, the three metal(II) atoms occupy both the N2O2 and O6 sites of the ligand (L)4− moiety. Owing to the different nature of the N2O2 and O6 sites of the ligand H4L, the introduction of two different metal(II) atoms to the site-selective moiety, when compared with complex 1, leads to the replacement of the central Co(II) atom by different alkaline earth metal(II) atoms, namely the Ca(II), Sr(II) and Ba(II) atoms for complexes 2, 3 and 4, respectively. Magnetic measurements were performed on complexes 1–4, where an intramolecular ferromagnetic interaction was found in complex 3 and intramolecular antiferromagnetic interactions were found in complexes 1, 2 and 4. The magnetic susceptibilities above 50K obey the Curie–Weiss law and their constant values were determined for all the complexes.