DIAZOSULFONATE SUBSTITUENTS - A ROUTE TO TRANSITION-METAL COMPLEXES WITH SWITCHABLE WATER SOLUBILITY

The single-crystal X-ray structure analysis of the diazosulfonate p-H2 N-C6H4N=N-SO3Na 3 features a Z configuration of the diazo moiety and a nitrogen-sulfur bond. Each sodium atom is coordinated by one diazosul fonate substituent in a chelating manner. Upon reaction of 3 with exce ss salicylaldehyde, the highly water-soluble Schiff base ligand 6 is o btained in good yield. Treatment of ZnCl2 with 2 equiv. of 6 gives the zinc complex 7. In all cases, the solubilizing diazosulfonate groups can be cleaved off photolytically, which offers an opportunity to prec ipitate the molecules from their aqueous solutions.