Bis-Cyclometalation of Fluorinated N-Aryl NHCs

The new imidazolium salts N,N'-bisfluoroarylimidazolium chloride (fluoroaryl = 4-fluorophenyl (1), 2,4-difluorophenyl (2), 2,4,6-trifluorophenyl (3)) have been prepared by the one-pot condensation of the appropriate aniline with glyoxal and formaldehyde. Reaction of the salts (1, 2) with [RuF2(CO)(3)](4) and [IrF3(CO)(3)] in the presence of KO'Bu generated the bis-cyclometalated carbene carbonyl complexes [IrCI(CO){eta(2)-1-(C6H4-4-F)-3-(C6H3-4-F)C3H2N2}(2)] (4), [Ru(CO)(2){eta(2)-1-(C6H4-4-F)-3-(C6H3-4-F)C3H2N2)(2)] (5), and [Ru(CO)(2){eta(2)-1-(C6H3-2,4-F-2)-3-(C6H2-2,4-F-2)-C3H2N2}(2)] (6), which have been structurally characterized.