Synthesis, Spectroscopic Characterization, and Cytotoxic Evaluation of Pentasubstituted Ruthenocenyl Esters

This article details the preparation and spectroscopic characterization of a focused library of new 18-electron ruthenocenyl complexes incorporating pentasubstituted Cp ester [C5(CO2R)5]− (for R = Me, Et, n-Pr, n-Bu, 2-Pr, 3-Pent, phenyl, and n-thiopropyl), carboxylic acid [C5(CO2H)5]−, and carboxylate ligands [C5(CO2H)4(CO2)]2−. Each complex has been characterized using Fourier transform IR and NMR spectroscopy and electrospray mass spectrometry, with single-crystal X-ray structural determinations reported for four complexes: [Ru(η5-C5H4(C5(CO2CH3)5)(η5-C5(CO2CH3)5)], K[Ru(η5-C5H5)(η5-C5(CO2H)4(CO2))].H2O, [Ru(η5-C5H5)(η5-C5(CO2H)5)]·2H2O, and [Ru(η5-C5H5)(η5-C5(CO2C6H5)5)]. Complexes were also evaluated for in vitro cytotoxic activity against a diverse panel of tumorigenic cell lines and a normal human cell line.