Syntheses and Electron Density Determination of Novel Polyimido Sulfur Ylides

Three major aims have been pursued in the course of this thesis: I) Classification of the S-C, S-N and Li-C interactions in a polyimido sulfur ylide by use of an experimental electron density study. II) Syntheses of various metal complexes of a polyimido sulfur ylide. III) Design of a tridentate Janus-head ligand containing hard nitrogen and soft phosphorus donor sites.The compound [(thf)Li2{H2CS(NtBu)2}]2 was chosen for the investigation involved in I. It was possible to determine the bond situations of sulfur ylides and within the Li3C motif of lithiumorganic compounds for the first time by an experimental approach. The polymorphism of the target compound was analyzed to find a disorder-free modification. One modification was suitable for an electron density determination involving a multipole refinement on the basis of high-order X-ray data. The subsequent analysis along Bader"s QTAIM made it possible to a) preclude hypervalency at the sulfur atom, b) classify all bonds involving the sulfur atom as electrostatically reinforced single-bonds and by these means to confirm the ylidic character of the S-C bond, and c) proof that the Li-C bonds are predominantly ionic, without any attractive Li-Li interactions.The second aim was accomplished by the synthesis fo a tin and a magnesium specis. Nevertheless, no general synthetic access could be established.A Janus-head ligand of the N2SCP type (aim III) could be prepared by reacting lithiated alkyl phosphanes with S(NtBu)2. The formation of a dimer by homobimetallic complexation shows that the synthesis of catalytically active heterobimetallic complexes should be possible in the future.