First dinuclear rhodium(II) complexes with triazolopyrimidines and the prospect of their potential biological use.

Five novel rhodium(II) complexes of general formula [Rh2(μ-OOCCH3)4L2], where L is a triazolopyrimidine derivative, in particular dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) for (1), 5,7-diethyl-1,2,4-triazolo[1,5-a]pyrimidine (detp) for (2), 7-isobutyl-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) for (3), 7-hydroxy-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (HmtpO) for (4) and 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) for (5) are reported. These first representatives of paddle-wheel dirhodium complexes with triazolopyrimidines have been characterized by IR and NMR spectroscopy as well as by single-crystal X-ray diffraction studies. Three of the new complexes (1), (2) and (5) were thoroughly screened in vitro for their cytotoxicity against human breast cancer cell line MCF-7 and L929 murine fibroblast cells. Favorably, they show significantly less effective inhibition on the cell growth of L929 than cisplatin under identical conditions. Complexes (1) and (5) display moderate cytotoxic activity (IC50 = 16.3-21.5 μM) against MCF-7 cells which is induced via reactive oxygen species-independent pathways. Extensive studies of rhodium complexes (1), (2) and (5) against microorganisms have shown that the tested compounds exhibit antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) while (5) significantly inhibited the growth of Malassezia furfur. The highest antibacterial, and antifungal activity, was observed for (5).