Tuning the Lewis acidity of difluorido gold(III) complexes: the synthesis of [AuClF2(SIMes)] and [AuF2(OTeF5)(SIMes)]

The synthesis and structural characterisation of the difluorido organo gold(III) complexes [AuClF2(SIMes)] and [AuF2(OTeF5)(SIMes)] are presented. The substitution of a fluorido ligand in [AuF3(SIMes)] by an OTeF5 group increases the Lewis acidity of the Au moiety. A scale for carbene affinities is presented, which correlates calculated and experimental values for the Lewis acidity of the metal centre in akin compounds.