Synthesis of (N,N'-Bis(2-Hydroxyethyl)Ethane-1,2-Diamine)Malonatoplatinum(II) and X-Ray Crystal Structure of the Cis-R,S-Isomer

Abstract

Hydroxyethyl substituted amineplatinum(II) and (IV) complexes are an interesting class of platinum based antitumour compounds due to their uncoordinated hydroxy groups. These hydroxy groups could play an important role in the mode of action of such complexes with respect to their ability to act as donor or acceptor for hydrogen bonds. Moreover, their chemistry in solution is of interest because it was found that there is the possibility of an intramolecular attack to form ethanolatoamine chelated species which are responsible for very stable monoadducts with 5'-GMP. Furthermore, there is the possibility of derivatisation at the OH site to form a new series of platinum compounds which may be used for a carrier mediated transport to tumour tissues. In this context a series of (N,N'-bis(2-hydroxyethyl)ethane-l,2-diamine)-platinum(II) complexes has been synthesised. During purification of one of the platinum based compounds, it was possible to isolate (SP-4-3)-R,S-(N,N'-bis(2-hydroxyethyl)ethane-l,2-diamine)malonatoplatinum(ll) and to resolve the structure by single crystal structure analysis. Intra- and intermolecular hydrogen bonds have been found which may explain the spontaneous crystallisation of the cis-R,S isomer and the stabilisation of the boat conformation of the malonatoplatinum(II) six-membered ring.