In past years extensive work has been published on double cyclometallated complexes containing two independent metallated phenyl rings.[1-4] In spite of such a wide range of publications, relatively few studies deal with double metallation of the same phenyl ring. In order to make this possible, it is necessary for the ligand to contain two substituents with potentially donor atoms, such as nitrogen or sulfur, which allow the formation of two five− or six− membered chelate rings.

This paper describes the preparation, characterization and structural study of novel tridentate [C,N,S] biscyclopalladated complexes with ligands derived from the condensation of a primary amine −2-(methylthio)aniline− with the corresponding aromatic dialdehyde −terephthalaldehyde−. The compounds are also interesting due to their close-to-planarity arrangement and to the presence of seven fused rings in their structure.