Reactivity of the [Au(C^N^C)Cl] complex in the presence of H 2 O and N-, S- and Se-containing nucleophiles: a DFT study.

Gold complexes are promising compounds used in cancer chemotherapy. Besides their steric features, which enable biomolecule interactions, the redox instability and the high affinity of gold with cellular nucleophiles influence the biological action in these complexes. Both features were herein theoretically investigated for the [Au(C^N^C)Cl] probe complex (C^N^C = 2,6-diphenylpyridine) using H2 O, CH3 SH/CH3 S- , CH3 Se- and meim-4-H (4-methylimidazole) as biomimetic nucleophiles. Based on the results, the lowest energy reaction path followed two consecutive steps: (1) chloride-exchange ([Formula: see text] = 4.14 × 107 M-1 s-1 ) and (2) reduction of the resulting Au(III) metabolite to the corresponding Au(I) analog with chelate ring-opening ([Formula: see text] =+0.15 V-data based on the reaction with CH3 Se- ). These findings bring new insights about the mechanism of the Au(III) complex/biomolecule interaction in the cell, which is responsible for triggering biological responses.