Dinuclear Rh(II) complexes with one polypyridyl ligand, structure, properties and antitumor activity

Rhodium(II) complexes [Rh2(μ-OAc)2(OAc)(bpy)(H2O)2]PF6 (1), [Rh2(μ-OAc)2(OAc)(phen)(H2O)2](PF6)·H2O (2), [Rh2(μ-OOCCH3)3(OOCCH3)(phen)] (3) and [Rh2(μ-O2CCH3)3(O2CCH3)(Ph2phen)] (4) (Ph2phen = 4,7-diphenyl-1,10-phenanthroline) have been synthesized and characterized by means of NMR, IR and UV–Vis spectroscopic methods. X-ray structure of complex 4·1.5(CH3COCH3) has been determined and its geometry and electronic structure has been elucidated using OPBE and B3LYP DFT methods. The compounds are active cytostatic agents against tumor cells.

Graphical abstractRhodium(II) complexes [Rh2(μ-OAc)3(N–N)(H2O)3]PF6 and [Rh2(μ-OAc)3(OAc)(N–N)] (N–N = polypyridyl) have been characterized using NMR, IR and UV–Vis spectroscopic methods. X-ray structure of complex [Rh2(μ-OAc)3(OAc)(Ph2phen)]has been determined and its electronic structure has been elucidated using DFT methods. Optimized geometry of complex agrees well with crystallographic data. The HOMO is δ∗dyz and LUMO π∗phen orbital. Calculated UV–Vis spectra of compound 4 indicate that absorption in 15 000–20 000 cm−1 results from CT transition, mainly from δ∗(Rh2), π∗(Rh2) and σ(Rh2) orbitals to the π∗phen and σ∗(Rh2) orbitals. The compounds are promising cytostatic agents against Caco-2 tumor cells.Figure optionsDownload full-size imageDownload as PowerPoint slide