A novel heterobimetallic complex composed of the imide-bridged [3]ferrocenophane and the tridentate palladium(II) complex

The imide-bridged [3]ferrocenophane, 2-pyridyl-1,1′-ferrocenedicarboximide, served as a monodentate ligand to form the corresponding heterobimetallic complex 4 with the palladium(II) complex bearing the tridentate podand ligand, through displacement of the ancillary acetonitrile. The X-ray crystal-structure determination revealed that the pyridyl nitrogen of the ferrocenophane coordinates to the palladium center with distortion of the ferrocenophane moiety, which lies below the coordination plane of palladium. Such a structure is considered to be present even in solution, resulting in four nonequivalent broad signals of Cp protons in the 1H-NMR spectrum, due to the electronic environment effect of the coordination plane of palladium. A π–π stacking interaction was observed between the benzene ring of the podand moieties and the pyridine ring of the neighboring molecule in the crystal packing of 4.