Synthesis and Structure of a Dinuclear Gold(II) Complex with Terminal Fluoride Ligands

The potential for reductive elimination of fluorine from dinuclear gold(II) for catalysis has prompted our efforts to synthesize a dinuclear gold(II) fluoride complex. This has been achieved with bis(2,6-dimethylphenyl)formamidinate bridging ligands. In order to obtain this product, it was necessary first to synthesize the corresponding dinuclear gold(II) nitrate, which reacts readily with KF in a metathesis reaction. The nitrate complex and fluoride complexes have been structurally characterized. The Au−Au distance in the dinuclear fluoride, 2.595 Å, is longer than the distance found in the analogous chloride complex, 2.567 Å. This result is consistent with the presence of a fluoride “π electron effect” on the filled Au 5d orbitals. The Raman spectrum shows an Au−Au stretch at 206 cm−1, which agrees with Woodruff’s rules and the density functional theory computational model used for modeling the complex.