LAUSR

Abstract N -[1-Alkylpyridin-4(1 H )-ylidene]amides (PYAs), also known as pyridinium amidates, are a class of recently introduced ligands for transition metal ions. Herein we report the synthesis of the Pt(PYA) complexes [PtCl(DMSO)(HL)]Cl 2 ( 1 ), [Pt(CH 3 )(DMSO)(L)]Cl ( 2 ) and [Pt(CH 3 )(PPh 3 )(L)]Cl ( 3 ) (L =  N -(1-benzylpyridin-4(1 H )-ylidene)picolinamide). L and [HL] + act as bidentate ligands coordinating through the pendant pyridine and either the amidate oxygen or nitrogen atoms to give the corresponding N , O or N , N linkage isomers. DFT calculations were carried out to determine the most energetically favorable isomeric forms of these compounds. For 1 the N , O coordination mode was lower in energy, while for 2 and 3 hardly any difference was found. In vitro cytotoxicity studies of [HL]Cl and 1 in human colorectal carcinoma HCT116, non-small cell lung carcinoma NCI-H460, and cervical carcinoma SiHa cells showed that both compounds are cytotoxic in the low μM range.