Bis(2-amino alcohol-κN)dicarboxylatoplatinum(II) complexes -: Elegant synthesis via ring-opening of bis(2-amino alcoholato-κ2N,O)platinum(II) species with dicarboxylic acids

Synthesis and purification of bis(2-amino alcohol-kappa N)dicarboxylatoplatinum(ii) complexes is problematic because of the use of light-sensitive silver(I) salts and the competing ring-closing side-reactions, especially after release of the chloro-or iodo ligands of the dihalogeno starting platinum(ii) species. A novel synthetic procedure, namely selective synthesis of doubly ring-closed bis(2-amino alcoholato-kappa N-2, O)platinum(II) compounds as the purification step and subsequent coordination of dicarboxylates in the absence of silver(I) via a ring-opening reaction, yielded a series of new complexes, which were characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography. Exemplarily, the ring-opening of bis(2-aminoethanolato-kappa N-2,O)platinum(ii) was performed in the NMR tube by means of oxalic acid and investigated by H-1 and Pt-195 NMR spectroscopy. The reaction was found to be highly efficient: within 3 h complete transformation to the dicarboxylatoplatinum(ii) complex was observed. Contrary, when sodium oxalate was used, no reaction could be detected at all during a period of one day.