Synthesis, X-ray structures, and cytotoxicity of rhenium(I) carbonyl 2-(dimethylamino)ethoxide complexes

Abstract

The complexes [Re(η 2-Me 2NCH 2CH 2O)(CO) 3(μ-OH)Re(η 2-Me 2NCH 2CH 2OH)(CO) 3] ( 1) and [Re 3(μ 3-OH)(μ-OH) 2(μ-OCH 2CH 2NMe 2H)(CO) 9] ( 2) have been synthesised and characterised by single-crystal X-ray diffraction analysis. Complex 1 exists as hydrogen-bonded dimers in the solid state and in solution. Proton NMR, 1H– 1H COSY and NOESY spectroscopic studies showed that the structure of 1 is static in solution, and that only one of the many possible geometric isomers of 1 exists. The hydrogen atom on the ammonio nitrogen of 2 is involved in intramolecular NH⋯O hydrogen-bonding with a bridging OH group. Complexes 1 and 2 were shown to be potent in suspended tumour cell lines in suppressing growth but were more selective in inhibiting the growth of cultures from solid tumours. The compounds [NBu n 4][ReO 4] and [NEt 4] 2[ReBr 3(CO) 3] were also very active against the suspended cell lines and selective against solid tumours. All the compounds tested are inactive against normal cells.