A Supramolecular Trinuclear Nickel(II) Complex with Asymmetric Salamo-type Ligand: Synthesis and Crystal Structure

Abstract

A supramolecular trinuclear Ni(II) complex, namely {[NiL(EtOH)(μ-OAc)]₂Ni}·EtOH, has been synthesized through the complexation of nickel(II) acetate tetrahydrate with 5-methoxy-4'-bromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H₂L). The Ni(II) complex comprises three Ni(II) atoms, two deprotonated L^2- units, two acetate aions, two coordinated and one non-coordinated ethanol molecules. In the crystal structure, the terminal Ni(II) (Ni2 or Ni2^#1) atom is located in the cis-N₂O₂ coordination cavity of the L^2- units and coordinated to an oxygen (O7) atom from the μ-acetato anion and an oxygen (O8) atom from the coordinated ethanol molecule in the axial positions. Meanwhile, the central Ni(II) (Ni1) atom is completed by quadruple μ-phenoxo oxygen (O3, O4, O3^#1 and O4^#1) atoms from two L^2- units and double μ-acetato oxygen (O6 and O6^#1) atoms. All the Ni(II) atoms are hexa-coordinated, showing slightly distorted octahedral coordination arrangements. The Ni(II) complex is linked to form an infinite 2D layer supramolecular structure through intermolecular O-H···O, C-H···O and C-H···p hydrogen bond interactions.