<div><p>A new series of platinum(II) complexes based on thione ligands with general formula [Pt(thione)<sub>4</sub>]X<sub>2</sub> (X<sup>−</sup> = Cl<sup>−</sup>, NO<sub>3</sub><sup>−</sup>) has been synthesized and characterized using CHNS elemental analysis, infrared, <sup>1</sup>H and <sup>13</sup>C solution-state NMR as well as <sup>13</sup>C and <sup>15</sup>N solid-state NMR spectroscopy, and X-ray crystallography. The spectroscopic methods confirm the coordination of Pt(II) with thiocarbonyl groups via sulfur of the thione ligands. The X-ray structures showed a distorted square planar geometry for <b>1</b>, [Pt(MeImt)<sub>4</sub>]Cl<sub>2</sub> (MeImt = N-Methylimidazolidine-2-thione) while the hydrogen bonding interactions in <b>7</b>, [Pt(<i>i</i>PrImt)<sub>4</sub>](NO<sub>3</sub>)<sub>2</sub>·0.6(H<sub>2</sub>O) induce a bent see-saw distortion relative to the ideal square planar geometry. The <i>in vitro</i> cytotoxicity studies showed that <b>2</b>, [Pt(EtImt)<sub>4</sub>]Cl<sub>2</sub> is generally the most effective, a two-fold better cytotoxic agent than cisplatin and carboplatin against MCF7 (human breast cancer).</p></div