Design of Phosphorus Centered Janus Head Ligands

Abstract

The scope of this thesis was the preparation of a Janus Head ligand based on the N,P,N ligand di-2-picolylphenylphosphane and the synthesis of different metal complexes containing this Janus Head ligand. The resulting metal complexes were to be investigated by single crystal X-ray diffraction experiments. Janus Head ligands are a special form of hemilabile ligands. They contain at least two different Lewis bases as donors but the characteristic of theses compounds is the spatial orientation of these donors. By application of the organolithium compound nbutyllithium and the group 14 silylamide [Sn{N(SiMe3)2}2] the dianionic Janus Head ligand [PhP(CHPy)2]2- could be generated in which one coordination site is allocated by the N,P,N or N,P claw, respectively, while in the opposite direction the metal ion is chelated by the two negative charged carbon atoms. Besides the dianionic ligand also metal complexes with the monoanionic ligand [PhP{C(H)Py}(CH2Py)]- could be prepared and characterized. Within this work it was also possible to synthesize phosphoranes containing oxygen, sulfur or selenium as heteroatom. The investigations based on experimental electron density studies could elucidate the hindered reactivity of [PhP(CH2Py)2LiCl]2 compared to the reactivity behaviour of the lithium chloride-free phosphane ligand.