Effect of azide co-ligand on the crystal structures of rhodium and iridium metal complexes featuring pyridine-based thiourea derivatives: Characterization and in vitro biological studies

Half-sandwich rhodium and iridium metal complexes 1-4 were prepared by the reaction of the pyridine-based thiourea-derived ligands with rhodium and iridium metal dimers. Iridium complex 1 yielded a mono-dentate S bonded complex whereas others formed bidentate NS complexes 2-4. These complexes were further treated with NaN3 in methanol. Treatment of the monodentate complex 1 with NaN3 resulted in the formation of highly strained four-membered & kcy; 2 (N, S)- L azido complex 5 , whereas the reaction of the bidentate complexes 2-4 afforded stable six-membered & kcy; 2 (N, S)- L azido complexes 6-8. The general formula for these complexes can be formulated as [Cp*M(& kcy;2 (N, S)-L)N 3 ] where M = Rh/Ir, L = thiourea ligand. These metal complexes have been characterized by different spectroscopic techniques and their molecular structures have been confirmed by single-crystal X-ray study. All these azido complexes were isolated as air-stable bright red crystals and crystallized in a triclinic crystal system with space group P1 . Preliminary antibacterial and antioxidant screenings on the ligands and complexes show that they exhibit significant antibacterial activity and minimal antioxidant activity.