Anti-leishmanial activity of Ni(ii), Pd(ii) and Pt(ii) β-oxodithioester complexesElectronic supplementary information (ESI) available: 1H NMR for ligand and weak interactions table. CCDC 925921 and 1055639-1055642. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5nj00765h

New functionalized planar β-oxodithioester cis -chelate complexes, [M(L) 2 ] (L = L1, methyl-3-hydroxy-3-( p -bromophenyl)-2-propenedithioate, M = Ni 1 , Pd 5 , Pt 9 ; L2, methyl-3-hydroxy-3-( p -fluorophenyl)-2-propenedithioate, Ni 2 , Pd 6 , Pt 10 ; L3, methyl-3-hydroxy-3-(naphthyl)-2-propenedithioate, Ni 3 , Pd 7 , Pt 11 ; methyl-3-hydroxy-3-( p -methoxyphenyl)-2-propenedithioate, Ni 4 , Pd 8 , Pt 12 ), have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1 H and 13 C NMR spectroscopy; the structures of 2-4 , 8 and 11 have been elucidated by X-ray crystallography. In all crystal structures, the metal has four-coordinate slightly distorted square planar geometry with a cis -configuration of the ligands. These complexes have been assessed for their use as anti-leishmanial agents; 7 and 9 showed impressive anti-promastigote and anti-amastigote efficacy with IC 50 values of 0.59 ± 0.10 μg mL −1 , 0.56 ± 0.10 μg mL −1 and IC 50 0.85 ± 0.27, 1.99 ± 0.08 μg mL −1 , respectively. Cytotoxicity assays on both compounds displayed toxicity on the promastigotes but less toxicity against RAW 264.7 cell lines at different concentrations. The Pd and Pt complexes exhibit luminescent characteristics in solution, originating from the intraligand charge transfer state. Twelve new β-oxodithioester complexes ( 1-12 ) of the type [M(L) 2 ] (M = Ni, Pd, Pt) have been synthesized and fully characterized. 7 and 9 showed impressive anti-leishmanial activity.