Palladacycles of the type [Pd(PhPCHPPh-P,P)(C,N:C,N)] (C,N:C,N = bis(N-2,3,4-trimethoxybenzylidene)-4,4'-sulfonyldianiline or -4,4'-oxydianiline) can undergo a spontaneous slow chelate-to-bridging diphosphane coordination shift in solution. Following this strategy a tailor-made synthetic procedure was devised that culminates in isolation of double A-frame tetranuclear palladium complexes.

Thiosemicarbazones are used as ligands forming many examples of compounds. Chemistry of these molecules with palladium often includes cyclopalladated but in some cases coordination compounds were reported. Structure of these complexes has not been widely described; different studies show wide structures variety. The treatment of these ligands with palladium salts lead the formation of these kind of complexes which structure and reactivity is more similar to organometallic cyclopalladated compounds than expected.

This paper presents 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.