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 KOtBu generated the bis-cyclometalated carbene carbonyl complexes [IrCl(CO){η2-1-(C6H4-4-F)-3-(C6H3-4-F)C3H2N2}2] (4), [Ru(CO)2{η2-1-(C6H4-4-F)-3-(C6H3-4-F)C3H2N2}2] (5), and [Ru(CO)2{η2-1-(C6H3-2,4-F2)-3-(C6H2-2,4-F2)C3H2N2}2] (6), which have been structurally characterized.

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