Di(N-heterocyclic carbene) gold(III) imidate complexes obtained by oxidative addition of N-halosuccinimides

Abstract

The reaction between the gold(I) dicarbene complexes [Au2(μ2-MeIm(CH2)nImMe)2](PF6)2 (Im = imidazol-2-ylidene, n = 1, 2, 3) and N-bromosuccinimide affords the gold(III) complexes [{AuBr(N-suc)}2(μ2-MeIm(CH2)nImMe)2](PF6)2, in which both gold centres have a bromide and a N-succinimidate anion in the coordination sphere. In the case of the CH2CH2 bridge, two different conformers of the gold(III) complex are formed; the structure of the major species has been clarified by single crystal X-ray diffraction analysis, while the nature and the properties of the minor one have been investigated by means of DFT calculations. Compared to N-bromosuccinimide, oxidative additions are slower with the N-chloro- and faster with the N-iodosuccinimides. In both cases the reactions are scarcely selective and the products distribution markedly depends on halide size and reaction conditions.