A tetradentate bisoxime and its supramolecular nickel(II) cluster: synthesis, crystal structure, and spectral properties

Abstract

Salen-type bisoxime 5,5′-dimethoxy-2,2′-[(ethylenedioxy)bis(nitrilomethylidyne)]diphenol (H₂L) and its trinuclear Ni(II) cluster {[(NiL)(n-BuOH)]₂(μ-OAc)₂Ni} · n-BuOH have been synthesized and structurally characterized. The structure of H₂L adopts an L-shape conformation where the two salicylaldoxime moieties are well separated. In the trinuclear Ni(II) cluster, two acetates coordinate to three Ni(II)'s through Ni–O–C–O–Ni bridges, four μ-phenoxos from two [NiL(n-BuOH)] units also coordinate to Ni(II), and two n-butanols coordinate to two terminal Ni(II)'s forming a distorted octahedral geometry. The Ni–O–C–O–Ni and μ-phenoxo bridges play important roles in assembling Ni(II) and the ligands. H₂L forms a rectangle-like large cave structure through O–H ··· N, C–H ··· O, and C–H ··· π hydrogen-bond interactions, whereas its trinuclear Ni(II) cluster exhibits a 3-D supramolecular network structure through intermolecular O–H ··· O, C–H ··· O, and C–H ··· π hydrogen-bond interactions.

Keywords:

• Bisoxime ligand; Trinuclear Ni(II) cluster; Synthesis; Crystal structure; Spectral property

Acknowledgments

This work was supported by the Foundation of the Education Department of Gansu Province (No. 0904-11) and the ‘Jing Lan’ Talent Engineering Funds of Lanzhou Jiaotong University, which are gratefully acknowledged.