American Chemical Society, Organometallics, 24(24), p. 5964-5972, 2005
DOI: 10.1021/om050594k
Full text: Unavailable
New, five-coordinate, iridium(I) bis-ethene complexes [fac-(bpa-R)Ir-I(ethene)(2)](+) (1(+): R = H, 2(+): R = Me, 3(+): R = Bz; bpa-H = NN-di(2-pyridylmethyl)amine, bpa-Me = N-methyl-N,N-di(2-pyridylmethyl)amine, bpa-Bz = N-benzyl-N Y-di(2-pyridylmethyl)amine) were prepared. In contrast to their previously reported rhodium analogues, these iridium species do not readily lose one of their two ethene fragments to form square planar mono-ethene complexes [mer-(bpa-R)Ir-I(ethene)1(+). Heating complex 1(+) results in N-H activation at the bpa-H ligand and formation of the dinuclear iridium(III) species [{(mer-mu(2)-bpa(#))Ir-III(ethyl)(MeCN)}(2)](2+) (4(2+)) with bridging amides (bpa(#) = bpa-H deprotonated at NHamine). Heating bpa-Bz complex 3(+) results in aromatic C-H activation of the ligand benzyl group to form dinuclear iridium(III) species [{(bpa-Bz(#))Ir-III(mu(2)-H)}(2)](2+) (5(2+)) with unsupported hydride bridges (bpa-Bz(#) = bpa-Bz cyclometalated at the benzylic C2-position). The dimeric structure of 5(2+) easily breaks up in MeCN, giving the mononuclear species [(bpa-Bz(#))Ir-III(H)(MeCN)](+) (6(+)). Complex 5(2+) is also light-sensitive: glass-filtered daylight converts it to a geometrical isomer, 7(2+), in which the cyclometalated benzyl functionality of one of the two ligands has switched its position with a pyridyl donor.