The π‐conjugated molecule N,N′‐bis(4′‐dimethylaminophenyl)‐1,4‐benzoquinone diimine (L2) was incorporated into the palladium(II) complex 1 bearing the N,N′‐bis(2‐phenylethyl)‐2,6‐pyridinedicarboxamide ligand, to afford the redox‐active conjugated palladium(II) homobimetallic complex 2. An X‐ray crystal structure determination of 2 reveals that two palladium complex units are bridged by the quinone diimine moiety to form the C2‐symmetrical 2:1 complex with an anti configuration, and that the bridging π‐conjugated spacer moieties are aligned along a straight line almost parallel to the a axis, to form the columns of the π‐conjugated molecules in the molecular packing. Variable temperature 1H NMR studies of the conjugated complex 2 indicate that the syn configuration is enthalpically more favorable than the anti configuration in CD2Cl2 by 1.0 kcal/mol, but entropically less favorable by 4.5 cal/mol from the van’t Hoff plot. The redox function of the quinone diimine moiety is modulated by complexation with the palladium complex 1. The conjugated complex 2 shows three separate redox waves assignable to the successive one‐electron reduction of the quinone diimine moiety and one‐electron oxidation process of the two terminal dimethylamino groups. Chemical reduction of 2 in THF with CoCp2 resulted in the appearance of ESR signals with weak 105Pd coupling centered around g = 2.0041. The added electrons are considered to be delocalized over the PdII‐quinone diimine d‐π* system in the complex.

A triangle with a calixarene‐like cone configuration: the trimetallamacrocycle [{Pd(en)(L)}3]6+ (1; L=N,N′‐bis(4‐dimethylaminophenyl)‐1,4‐benzoquinonediimine, en=ethylenediamine; see picture for a space‐filling view). The coordination array of the redox‐active π‐conjugated bridging quinonediimine spacer of L and the palladium unit determines whether conjugated 1 or a conjugated polymeric complex is formed.

Ein Dreieck mit einer Calixaren‐artigen Kegelkonfiguration: der Trimetallamakrocyclus [{Pd(en)(L)}3]6+ 1 (L=N,N′‐Bis(4‐dimethylaminophenyl)‐1,4‐benzochinondiimin, en=Ethylendiamin; das Bild zeigt eine Kalottendarstellung). Je nach der koordinativen Anordung des redoxaktiven π‐konjugierten Chinondiimin‐Spacers von L und der Palladiumeinheit entsteht entweder das konjugierte 1 oder ein konjugiertes Koordinationspolymer.