New mixed valence defect dicubane cobalt(II)/cobalt(III) complex : synthesis, crystal structure, photoluminescence and magnetic properties

Abstract

A new defect dicubane cobalt(II)/cobalt(III), [(CoII2CoIII2L42(H2O)(CH3COO)(CH3COOH]. 4H2O complex (1) where H2L = [1–(3–hydroxypropyliminomethyl)naphthalene–2–ol], has been synthesized and characterized by element analysis, FT–IR, solid UV–Vis spectroscopy and single crystal X–ray diffraction. The crystal structure determination shows a cationic tetrameric arrangement consisting of a defect dicubane core with two missing vertexes. Each cobalt ion has a distorted octahedral geometry with six coordinate ordered CoII and CoIII ions. The solid state photoluminescence properties of complex (1) and its ligand H2L have been investigated under UV light at 349 nm in the visible region. H2L exhibits blue emission while complex (1) shows red emission at room temperature. Variable–temperature magnetic susceptibility measurements on the complex (1) in the range 2–300 K indicate an antiferromagnetic interaction.