Zinc(II), ruthenium(II), rhodium(III), palladium(II), silver(I), platinum(II) and complexes of 2-(2′-hydroxy-5′-methylphenyl)-benzotriazole as simple or primary ligand and 2,2′-bipyridyl, 9,10-phenanthroline or triphenylphosphine as secondary ligands: Str

New complexes of 2-(2′-hydroxy-5′-methylphenyl)-benzotriazole (Hhmbt), [Zn(hmbt)2(H2O)2], [Zn(hmbt)(OAc)(H2O)2], [Pd(hmbt)(H2O)Cl], [Pd(hmbt)2], [M(PPh3)(hmbt)Cl], [M(L)(hmbt)]Cl (M(II) = Pd, Pt; L = bpy, phen), [Ag2(hmbt)2], [Ag(phen)(hmbt)], [Ag(PPh3)(hmbt)], [Rh(hmbt)2(H2O)2]Cl, [Ru(hmbt)2(H2O)2], [Ru(PPh3)(hmbt)2Cl] and cis-[MoO2(hmbt)2] have been synthesized. They have been structurally and spectroscopically characterized on the basis of elemental analysis, IR, NMR (1H, 13C, 31P), UV–vis. and ESI-mass spectroscopy, thermal and molar conductivity measurements. 2-(2′-Hydroxy-5′-methylphenyl)-benzotriazole behaves as a mononegative bidentate through the deprotonated phenolic oxygen and imine nitrogen atoms. The reported complexes have been tested against human breast cancer (MDA-MB231) and human ovarian cancer (OVCAR-8) cell lines. The complexes, [Ag(hmpbt)(PPh3)], [Rh(hmbt)2(H2O)2]Cl, [Pt(phen)(hmbt)]Cl and [Pd(phen)(hmbt)]Cl exhibit the highest growth inhibitory activity with mean IC50 values 1.37, 7.52, 5.24 and 4.85 μM (MDA-MB231) and 1.75, 8.50, 3.00 and 2.99 μM (OVACAR-8), respectively.