Innovative Syntheses of Ligands and Materials

Prof. Axel Schulz

 

This field of work includes the search for new synthesis strategies (see below) and the synthesis of new CN, PC and PN molecular compounds and their use as ligands in transition metal catalysis. An interesting example from recent research represents the GaCl₃-catalyzed [3+2] cycloaddition of "hidden" 1,3-PN dipole molecules and PN dipolarophiles developed by our research group, which led to the first-time synthesis (yields >95%) of triazadiphospholes and tetrazaphospholes. Azaphospholes formally represent resonance-stabilized 6π-electron Hückel aromatics. The experimental and theoretical studies on GaCl₃-catalyzed [3+2] cycloaddition led to a [3+2] synthesis kit, which is currently being further completed (see below). This project is supported by the DFG (SCHU 1170/4-1).

Binary azaphospholes represent elegant precursors for the in situ generation of PNP or NPN ligands. In addition, they can be used as starting substances for accessing binary PN or ternary PNGa oligo- or polymers, respectively.

Theoretical studies on the mechanism of GaCl₃-catalyzed [3+2] cycloaddition show that GaCl₃ dramatically lowers the energy barriers for the upstream elimination step.