Synthesis Of Heavy N-Heterocyclic Tetrylenes: Influence Of Ligand Sterics On Structure

The synthesis and structural characterisation of [(NON(R))M] (NON=O(SiMe2NR)(2)](2-); R=tBu, Ph, 2,6-Me2C6H3 (Dmp), 2,6-iPr(2)C(6)H(3) (Dipp); M=Ge, Sn, Pb) is described. Germanium complexes [(NONPh)Ge], [(NONDmp)Ge] and [(NONDipp)Ge] are monomeric. Tin complexes [(NONPh)Sn](2), [(NONDmp)Sn](2) and [(NONtBu)Sn](2) are dimeric in the solid-state, with [(NONPh)Sn](2) forming a link through bridging N-atoms, [(NONDmp)Sn](2) linked through Sn...Ar contacts and [(NONtBu)Sn](2) forming the first distannene bearing two amido ligands. In contrast, [(NONDipp)Sn] is monomeric in the solid-state. The lead complexes [(NONPh)Pb](2) and [(NONDmp)Pb](2) are isostructual with their tin analogues while [(NONtBu)Pb] is monomeric in the solid-state. Solution phase NMR spectroscopic data suggest that all [(NON(R))M] compounds are monomeric in solution. Structural parameters, including buried volume (%V-bur) are discussed.