| Abstract
| - New, five-coordinate, iridium(I) bis-ethene complexes [fac-(bpa-R)IrI(ethene)2]+ (1+: R =H, 2+: R = Me, 3+: R = Bz; bpa-H = N,N-di(2-pyridylmethyl)amine, bpa-Me = N-methyl-N,N-di(2-pyridylmethyl)amine, bpa-Bz = N-benzyl-N,N-di(2-pyridylmethyl)amine) wereprepared. In contrast to their previously reported rhodium analogues, these iridium speciesdo not readily lose one of their two ethene fragments to form square planar mono-ethenecomplexes [mer-(bpa-R)IrI(ethene)]+. Heating complex 1+ results in N−H activation at thebpa-H ligand and formation of the dinuclear iridium(III) species [{(mer-μ2-bpa#)IrIII(ethyl)(MeCN)}2]2+ (42+) with bridging amides (bpa# = bpa-H deprotonated at NHamine). Heatingbpa-Bz complex 3+ results in aromatic C−H activation of the ligand benzyl group to formdinuclear iridium(III) species [{(bpa-Bz#)IrIII(μ2-H)}2]2+ (52+) with unsupported hydride bridges(bpa-Bz# = bpa-Bz cyclometalated at the benzylic C2-position). The dimeric structure of 52+easily breaks up in MeCN, giving the mononuclear species [(bpa-Bz#)IrIII(H)(MeCN)]+ (6+).Complex 52+ is also light-sensitive: glass-filtered daylight converts it to a geometrical isomer,72+, in which the cyclometalated benzyl functionality of one of the two ligands has switchedits position with a pyridyl donor.
- Bis-ethene species [mer-(bpa-R)IrI(ethene)2]+ do not easily lose one of their ethene ligands, and attempts to remove one of the ethene ligands lead to oxidative ligand activations: N−H activation in the case of the bpa-H ligand (R = H) and C−H activation of the benzyl group in the case of the bpa-Bz ligand (R = Bz).
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