© 2022New 2,4-bis(2,4-dimethoxyphenyl)-1,3-dithia-2,4-diphosphetane 2,4-disulfide, (SAV-A2), was synthesized from the reaction P4S10 and 1,3-dimethoxybenzene. SAV-A2 was reacted with alcohols to form dithiophosphonic acid monoesters (HLn, HS2P((2,4-CH3O)2C6H3)(ORn); n=1–3, R1=2‑butyl‑; R2=n-pentyl-; R3=4‑tert‑but-benzyl-). The acids were converted to the ammonium salts ([NH4Ln]) to serve as the source of the ligands (Ln), to obtain Ni(II) complexes, ([Ni(Ln)2]). [Ni(L2)2] crystal structure was elucidated by single-crystal X-ray diffraction analysis. In addition, Density Functional Theory (DFT) calculations of [Ni(L2)2] was performed. The molecular docking studies of the complex with liver cancer protein, PDB ID: 3WZE and colon cancer antigen proteins, ID 2HQ6 were done compare with experimental and theoretical results. All compounds were tested on liver- and colon cancer cell lines. Among the complexes tested, [Ni(L3)2] showed an activity closer to that of cisplatin against the colon cancer cell line. The other compounds were found to be have less active.