Influence of the substituent on the phosphine ligand in novel rhenium(i) aldehydes. Synthesis, computational studies and first insights into the antiproliferative activity

Abstract

Cyrhetrenyl aldehyde derivatives [(η⁵-C₅H₄CHO)Re(CO)₂PR₃] with R = methyl (Me, 2a), phenyl (Ph, 2b), and cyclohexyl (Cy, 2c) were synthesized by a photochemical reaction from the starting material [(η⁵-C₅H₄CHO)Re(CO)₃] (1) and the corresponding phosphines. The complexes were fully characterized by FT-IR, ¹H, ¹³C and ³¹P NMR spectroscopy, elemental analysis and mass spectrometry. The molecular structures of 2a–c have also been determined. Electronic structure calculations by TD-DFT and electrochemical studies are in sound agreement with the effect of the substitution of one carbonyl group by a phosphine ligand. Additionally, the antiproliferative activity of complexes 1 and 2a–c was studied on the human cancer cell lines HT-29 and PT-45 using an MTT assay. Out of all new compounds, only the triphenylphosphine derivative 2b exhibited pronounced cytotoxic effects on both cell lines, being ca. 1.5 times more potent than cisplatin.