Synthesis, characterisation and cytotoxicity studies of ruthenium arene complexes bearing trichlorogermyl ligands

The synthesis of five half sandwich ruthenium(II) trichlorogermyl complexes of the type [(η6-Arene)Ru(PR3)Cl(GeCl3)] (PR3 = Phosphane and phosphite ligands; Arene = p-cymene or C6H5-OC2H4OH) is reported: [(η6-p-cymene)Ru(P(OMe)3)Cl(GeCl3)] (1), [(η6-p-cymene)Ru(P(OPh)3)Cl(GeCl3)] (2), [(η6-p-cymene)Ru(PPh3)Cl(GeCl3)] (3), [(η6-p-cymene)Ru(pta)Cl(GeCl3)] (pta = 1,3,5-triaza-7-phosphaadamantane) (4) and [(η6-C6H5-OC2H4OH)Ru(pta)Cl(GeCl3)] (5). The nature of the η6-arene and phosphane ligand was varied and the complexes have been prepared by facile insertion of GeCl2 (from GeCl2.(dioxane)) into the Ru-Cl bonds of the respective easily accessible precursor complexes [(η6-Arene)Ru(PR3)Cl2]. The complexes were fully spectroscopically characterized by 1H, 13C{1H} and 31P{1H} NMR spectroscopy, UV-Vis, ATR-IR, HRMS (ESI) and their thermal behavior elucidated by TGA. Their cytotoxicity to human ovarian carcinoma (A2780) and non-tumorigenic human embryonic kidney HEK293 cell lines is also reported, and represents the first cytotoxic investigations of Ru(II) germyl complexes to date. The first DFT studies (B3LYP; basis set 6-31+G(d,p) for H, C, O, P, Cl, N, and Ge atoms and DGDZVP for Ru atom) on trichlorogermyl ruthenium complexes were carried out on complex 2 and 5 in order to gain insights into the bonding situation between Ru and Ge and are reported.