Abstract
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•Synthesis of the first substituted heterocyclic thiourea dianion platinum(II) complexes.•Spectroscopic data (such as FT-IR, 1H NMR, 31P-{1H} NMR) were used for characterization of the prepared complexes.•X-ray single crystal structures were determined for the [Pt(CPPT)(dppe)] and [Pt(CPPT)(dppb)] complexes.•The prepared complexes adopt a slightly distorted square planar geometry.
Treatment of one molar equivalent of [PtCl2(diphos)] (diphos = dppe, dppp, dppb or dppf) or [PtCl2(PPh3)2] with one molar equivalent of (H2CPPT) in the presence of Et3N afforded the new heterocyclic thiourea dianion complexes [Pt(κ2-CPPT)(diphos)] and [Pt(κ2-CPPT)(PPh3)2] (1–5). The synthesized complexes were characterized by FT-IR, 1H NMR and 31P-{1H} NMR spectroscopy. Moreover, X-ray single crystal structure determination for complexes [Pt(κ2-CPPT)(dppe)] (1) and [Pt(κ2-CPPT)(dppb)] (3) showed a four membered ring structure with the Pt(II) ion being central and adopting a slightly distorted square planar geometry. Furthermore, the X-ray structures showed that the sulfur atom is trans to the phosphine ligand with the shortest Pt-P bond, compared to the nitrogen atom that is trans to the other Pt-P bond. Interestingly, the obtained complexes, apart from previously synthesized ones, showed one isomer formation only. This behavior is probably due to the inductive effect for both of the heteroatoms and the chlorine atom on the pyridyl group. Generally, the prepared complexes showed similar behavior to their analogous non-substituted thiourea dianion complexes, with no observable effect of the heteroatom on the overall structure. Furthermore, antibacterial activities were tested against three pathogenic bacterial species; among the four tested complexes, complexes 4 and 2 showed high activity values.