Synthesis, Structural and Biological Studies of Some Half-Sandwich d6-Metal Complexes with Pyrimidine-Based Ligand

The reaction of metal precursors {[Cp*MCl2]2 (M=Rh, Ir)} with 2-
aminopyrimidine (L1) gave binuclear complexes as [(Cp*MCl2)2
(m-L1)], where L1 acted as a bridging ligand. While 2-
mercaptopyrimidine (L2) with [Cp*MCl2]2 {M=Rh(III), Ir(III)}
formed mononuclear di substituted complexes as [Cp*M(L2)2],
where L2 acted as a chelating as well as a monodentate ligand.
The reaction of [CpRu(PPh3)2Cl] with 2-mercaptopyrimidine (L2)
led to the formation of mononuclear complex as general
formula [CpRu(PPh3)(L2)] in presence of a base. 2-Mercaptopyrimidine
ligand resulted complexes with strained four-membered
metallacycle while 2-aminopyrimidine yielded bridged
complexes. HOMO-LUMO energy gaps and UV-Visible bands
were additionally rationalised by the DFT studies. The binding
ability of the complexes to the CT-DNA was confirmed using
UV-Visible and fluorescence spectroscopy. In vitro antibacterial
activity of the complexes was evaluated against human
pathogenic bacteria. Cytotoxicity of the complexes was examined
by the MTT assay over three cancerous and one noncancer
cell lines viz., BE, HT-29, MIA@Pa-Ca2 and ARPE-19.