PUB - Publikationen an der Universität Bielefeld

A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L4- (H4L = N, N'-bis(2-(1,8-naphthalenediol) methylidene) propylenediamine). Reaction of H4L with copper acetate results in the formation of the unsymmetrical dinuclear Cu-II complex [LCu2] (3), which has been structurally characterized by single-crystal X-ray diffraction. One Cu-II ion is coordinated by a N2O2 compartment of L4- and the other Cu-II ion is coordinated by an O-4 compartment of L4- while they are bridged by two aryloxide functions of L4-. A dimerization of two molecules of 3 to a tetranuclear entity 32 occurs through formation of weak apical Cu-O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2-290 K) established a strong intradimer exchange coupling J(12) = -371 cm(-1). This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged Cu-II complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol.