Synthesis and cytotoxicity studies of novel NHC-Gold(I) pseudohalides and thiolates

The synthesis and biological evaluation of three gold pseudohalides and three gold thiolates, stabilised by the NHC ligand 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene (NHC*), in order to form stable gold(I) complexes is reported. Two separate procedures have been developed for the synthesis; the one for the pseudohalide complexes employs the use of a biphasic medium while the one for the thiolate complexes requires higher temperature for their formation. The gold complexes have been prepared in varying yields (44-81%) from the corresponding NHC*-Au-Cl precursor. One thiolate and two pseudohalide gold complexes were characterized by single crystal X-ray diffraction and showed the expected monomeric nature of all derivatives. All six complexes were submitted to the NCI 60 cancer cell panel for cytotoxicity tests; most of the complexes showed activity in the medium to low micromolar region, while the NHC*Au-SCN derivative was superior exhibiting nanomolar anticancer activity. (C) 2017 Elsevier B.V. All rights reserved.