Self-assembly of N-heterocyclic derivatives of divalent germanium, tin, and lead

A new class of exceptionally stable asymmetric N-heterocyclic germylenes, stannylenes, and plumbylenes has been successfully isolated and characterized by single-crystal X-ray diffraction analysis and multinuclear NMR spectroscopy. Their stability results from tetrameric supramolecular aggregation through strong intermolecular Npy →E(II) (E=Ge, Sn, Pb) interactions involving the nitrogen atom of a neighboring pyridine moiety. The electronic structures and stabilities of the prepared divalent derivatives of Ge, Sn, and Pb in monomeric and aggregated forms are discussed based on theoretical investigations.