Crystal structures of the gold NHC complex bis-(4-bromo-1,3-di-ethyl-imidazol-2-yl-idene)gold(I) iodide and its 1:1 adduct with trans-bis-(4-bromo-1,3-diethyl-imidazol-2-yl-idene)di-iodido-gold(III) iodide.

The first title compound, [Au(C7H11BrN2)2]I, crystallizes in the space group P without imposed symmetry. The cations and anions are linked to form chains by Br⋯I⋯Br halogen-bond linkages. The second title compound, [Au(C7H11BrN2)2][AuI2(C7H11BrN2)2]I2, is an adduct of the first and its formally I2-oxidized AuIII analogue. It also crystallizes in space group P , whereby both gold atoms occupy inversion centres. The extended structure is a reticular layer involving Br⋯I⋯Br and I⋯I⋯Au linkages. © Büssing et al. 2021.