Tri- and hexanuclear heterometallic Ni(ii)–M(ii) (M = Ca, Sr and Ba) bis(salamo)-type complexes: synthesis, structure and fluorescence properties

Abstract

Three heterometallic Ni(II)–M(II) (M = Ca, Sr and Ba) complexes, two discrete heterotrinuclear complexes [Ni₂(L)Ca(OAc)₂(CH₃OH)₂]·2C₂H₅OH·2CHCl₃ (1) and [Ni₂(L)Sr(OAc)₂(CH₃OH)₂]·2CH₃OH·2CH₂Cl₂ (2) and a discrete heterohexanuclear dimer [Ni₂(L)Ba(OAc)₂(CH₃OH)₂(H₂O)]₂·2CH₃OH (3), were synthesized with a naphthalenediol-based acyclic bis(salamo)-type ligand (H₄L), and characterized by elemental analyses, IR, UV-vis spectra, fluorescence spectra and X-ray crystallography. The heterometallic complexes were acquired by the reaction of H₄L with 2 equiv. of Ni(OAc)₂·4H₂O and 1 equiv. of M(OAc)₂ (M = Ca, Sr and Ba). The crystal structures of complexes 1–3 have been determined by single-crystal X-ray diffractions. 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, leads to the two Ni(II) atoms occupied both the N₂O₂ sites, an alkaline earth metal atom occupied the O₆ site of the ligand (L)⁴⁻ unit, respectively. Furthermore, the fluorescence properties have been discussed.