N-Heterocyclic Carbene Platinum(IV) as Metallodrug Candidates: Synthesis and (195)Pt NMR Chemical Shift Trend

A series of octahedral platinum(IV) complexes functionalized with both N-heterocyclic carbene (NHC) ligands were synthesized according to a straightforward procedure and characterized. The coordination sphere around the metal was varied, investigating the influence of the substituted NHC and the amine ligand in trans position to the NHC. The influence of those structural variations on the chemical shift of the platinum center were evaluated by (195)Pt NMR. This spectroscopy provided more insights on the impact of the structural changes on the electronic density at the platinum center. Investigation of the in vitro cytotoxicities of representative complexes were carried on three cancer cell lines and showed IC(50) values down to the low micromolar range that compare favorably with the benchmark cisplatin or their platinum(II) counterparts bearing NHC ligands.