Modern aspects of pseudohalogen chemistry: News from CN- and PN-chemistry

The pseudohalogen concept still provides a powerful tool to understand the correlation between chemical properties, structure and bonding of pseudohalogen species. Starting from a modern version of the pseudohalogen concept, this research report gives an overview on different subjects of CN- and PN-chemistry dealt with in our group. One of our fundamental interests lies in the synthesis and study of structure and bonding of resonance stabilized pseudohalides such as methanides, amides or binary PN-pseudohalides. The first chapter describes new syntheses of alkaline dinitroso- and nitro(nitroso)cyanomethanides, methanide-based ionic liquids and their chemical properties. The second chapter de- als with azaphospholes which can be considered (i) as resonance stabilized dimers of P-analogues of covalent azides in case of the triazadiphospholes or (ii) as [3+2] cycloaddition product of a hidden PNN 1,3 dipole (P-analogue of a covalent azide) with dipolarophiles possessing NN or PN moieties. Starting from a [3+2] synthetic tool kit, new PN-heterocycles (triazadiphospholes and tetrazaphospholes) and a new synthetic approach called GaCl3- assisted [3+2] cycloaddition are discussed.