Formation of Dinuclear Iridium Complexes by NHC-Supported C–H Bond Activation

The formation of
dinuclear iridium complexes by NHC-supported aryl-CH
bond activation reactions is reported. Complex IrH5(PiPr3)2 (1) reacts with 1,3-bis­(3-methylimidazolium)­benzene
bis­(tetrafluoroborate) ([C6H4(HImMe)2]­[BF4]2) to give the dinuclear species {[IrH2(PiPr3)2]2[μ-C6H2(ImMe)2]} (2), with a
core formed by five fused rings. Complex 1 also reacts
with 1,1′-diphenyl-3,3′-alkylenedi­imidazolium
dihalides ([(CH2)n(HImC6H5)2]­X2; n = 2, 3, 4). The reactions lead to the dinuclear complexes {[IrH2(PiPr3)2]2[μ-(CH2)n(ImC6H4)2]} (n = 2 (3), 3 (4), 4 (5). These compounds can be described as
two six-coordinate d6-iridium dihydride metal fragments
containing an orthometalated phenylimidazolylidene, which are connected
through an alkylene linker. In contrast to the di­imidazolium
salts, 1,1′-diphenyl-3,3′-methylenedi­benzimidazolium
dibromide ([CH2(HBzImC6H5)2]­Br2) reacts with 1 to give a 1:1 mixture
of the mononuclear complexes IrH2Br­{κ-N-(HBzImC6H5)}­(PiPr3)2 (6) and IrH2{κ2-C,C-(MeBzImC6H4)}­(PiPr3)2 (7). The latter and
its analogous IrH2{κ2-C,C-(PhBzImC6H4)}­(PiPr3)2 (8) can be also obtained,
as pure solids, by means of the reactions of 1 with 1-methyl-3-phenylbenz­imidazolium
tetrafluoroborate and 1,3-diphenylbenz­imidazolium chloride,
respectively.