6533b7d6fe1ef96bd1266f85

RESEARCH PRODUCT

A nucleophilic gold complex.

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Solid-state auride salts featuring the negatively charged Au– ion are known to be stable in the presence of alkali metal counterions. While such electron-rich species might be expected to be nucleophilic (in the same manner as I–, for example), their instability in solution means that this has not been verified experimentally. Here we report a two-coordinate gold complex (NON)AlAuPtBu3 (where NON is the chelating tridentate ligand 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) that features a strongly polarized bond, Auδ––Alδ+. This is synthesized by reaction of the potassium aluminyl compound [K{Al(NON)}]2 with tBu3PAuI. Computational studies of the complex, including quantum theory of atoms in molecules charge analysis, imply a charge at gold (−0.82) that is in line with the relative electronegativities of the two metals (Au: 2.54; Al: 1.61 on the Pauling scale). Consistently, the complex is found to act as a nucleophilic source of gold, reacting with diisopropylcarbodiimide and CO2 to give the Au–C bonded insertion products (NON)Al(X2C)AuPtBu3 (X = NiPr, 4; X = O, 5). A two-coordinate monovalent gold complex that features a highly polarized aluminium–gold covalent bond, Alδ+–Auδ−, has been synthesized using a very strongly electron-donating aluminyl ligand. In solution, the complex reacts as a nucleophilic source of gold towards heteroallenes such as carbodiimides and CO2.