Synthesis, structure and in vitro anticancer activity of pd(Ii) complex of pyrazolyl-s-triazine ligand; a new example of metal-mediated hydrolysis of s-triazine pincer ligand

Abstract

The square planar complex [Pd(PT)Cl(H2O)]*H2O (HPT: 6-(3,5-dimethyl-1H-pyrazol-1-yl)1,3,5-triazine-2,4(1H,3H)-dione) was obtained by the reaction of 2-methoxy-4,6-bis(3,5-dimethyl-1Hpyrazol-1-yl)-1,3,5-triazine (MBPT) pincer ligand with PdCl2 in a molar ratio (1:1) under thermal conditions and using acetone as a solvent. The reaction proceeded via C-N cleavage of one C-N moiety that connects the pyrazole and s-triazine combined with the hydrolysis of the O-CH3 group. The reaction of the chloride salt of its higher congener (PtCl2) gave [Pt(3,5-dimethyl-1H-pyrazole)2Cl2 ]. The crystal structure of [Pd(PT)Cl(H2O)]*H2O complex is stabilized by inter-and intra-molecular hydrogen bonding interactions. Hirshfeld analysis revealed that the H…H (34.6%), O…H (23.6%), and Cl…H (7.8%) interactions are the major contacts in the crystal. The charges at Pd, H2O, Cl and PT are changed to 0.4995, 0.2216, −0.4294 and −0.2917 instead of +2, 0, −1 and −1, respectively, using the MPW1PW91 method. [Pd(PT)Cl(H2O)]*H2O complex has almost equal activities against MDA-MB-231 and MCF-7 cell lines with IC50 of 38.3 µg/mL.