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In the first part of the thesis the synthesis, the coordination chemistry and the reactivity of a ligand containing a triphenylphosphine and a phosphaalkene group are reported. Condensation of ortho-diphenylphosphinobenzaldehyd (9) with 2,4,6-tri-tert.-butyl-phenylphosphine yielded the σ2, σ3-diphosphorus chelating species 11 with an E-configurated phosphaalkene unit as indicated by analysis of the NMR-spectra. It was shown that E-11 forms stable Mo(0), Pd(II) and Pt(II) chelate complexes (13 - 15). Beside the addition of alcohols and the UV light induced E-/Z-isomerisation, 11 was reacted with various dialkylacetylenedicarboxylates yielding the unusual phosphirane/ phosphinine systems 19 - 21, bearing an ylidic phosphorus atom within the six-membered ring. Temperature dependent 1H-, 31P{1H}- and 13C{¹H}-NMR-spectra indicate a restricted rotation in 19 and 20. The ylidic character as well as the delocalisation within these molecules were also established via X-ray structural analysis of 20.

The second part of the work concerns the synthesis of new chiral, hydrophilic mono and bidentate phosphorus containing ligands. The sulfonated dibenzophosphole 24 was obtained by nucleophilic phosphination with NaPH₂. Alkylation of 24 with different chiral electrophiles yielded the novel bidentate water-soluble ligands 25 - 28 as pure enantiomers. The catalytic activity of these ligands was tested in the Rh(I)-catalyzed hydrogenation of acetamidocinnamicacidmethylester under biphase (H₂O/CH₂Cl₂) conditions. Furthermore, the homochiral phospholane (2R,5R)-31 was obtained by reaction of NaPH₂ with the cyclic sulfate (2S,5S)-29 in liquid ammonia followed by treatment of intermediate (2R,5S)-30 with n-BuLi in ether. Making use of the PH-functionality, it was possible to show the capability of 31 as a precursor for chiral ligands by reacting it with fluorobenzene derivatives bearing group activated C-F bonds (e.g. CN, COOLi, SO₃K) in ortho- or para-position. Multidentate ligands are accessible by addition of 31 to unsaturated compounds like 2-vinylpyridine and 1-vinylimidazole, yielding ligands with different hard-soft N, P donor sets. N-quarternization affords the corre-sponding phosphine substituted cations 42 and 43.

Using the cyclic sulfate (2S,5S)-29, it was also possible to synthesize the new hydrophilic chiral alkyl sulfates 44 - 46 by nucleophilic ring opening with various P-nucleophiles. Beside the solubility in water, chiral alkyl sulfates may act as precursers for new C₁- and C₂-symmetric chelating ligands.

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