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Some new dichloro- and dibromotriphenylphosphino isonitrile and N-acyclic (NAC) carbene complexes of platinum(II) were synthesized, starting from suitable dinuclear precursors. The reaction of cyclohexylisonitrile with trans-[Pt(μ-X)X(PPh3)]2, followed by the addition of N,N-diethylamine afforded the corresponding N-acyclic carbene (NAC)derivatives cis-[PtX2(PPh3)(NAC)] in 61–64% isolated yield. The cis geometry was attributed based on the comparison with known structures. The stability of the complexes in pure DMSO, DMSO/H2O, and DMSO/NaClaq mixtures was evaluated. While pure DMSO, as well as DMSO/H2O, did not affect the nature of either dichloro- or dibromo-compounds, dibromo derivatives were not stable in the presence of chloride ions. Since a high concentration of chloride ions is essential to perform in vitro cell assays, only dichlorocomplexes were tested as cytotoxic agents against HepG2 and human tumor cells. Among the tested complexes, NAC derivatives showed a moderate effect on MSTO-211H.

A series of dibromo-N-acyclic (NAC) carbene complexes of platinum(II) were synthesized, starting from trans-[Pt(μ-Br)Br(PPh3)]2 and according to a protocol previously optimized for the preparation of analogous chlorinated compounds. In the first step of the synthesis, the ring opening of the dinuclear precursor was carried out using suitable isonitrile ligands, while the following step consisted of the addition of N,N-diethylamine to the products obtained in the first step. The two reactions were separately investigated, and attention was given to the differences between brominated and chlorinated systems.