61663-66-9Relevant academic research and scientific papers
Silyl reagents (Me3Si-X) efficiently transfer X to Ir(H)2F(PtBu2Ph)2
Cooper, Alan C.,Huffman, John C.,Caulton, Kenneth G.
, p. 261 - 272 (2008/10/08)
Me3Si-X reagents react to completion at 25°C in a short time to convert Ir(H)2FL2 (L = PtBu2Ph) to Ir(H)2XL2. This involves formation of Ir-O, Ir-N, Ir-I, Ir-S and Ir-C(sp) bonds. Products include some η2-X ligands such as carboxylate and acetamide, NHC(O)CH3. The acetamide is shown to be η2 in the solid state and in solution, but readily rearranges, by a transition state with Ir-O bond cleavage, to effect site exchange of the two inequivalent hydrides. The same synthetic approach succeeds for the more crowded metallated species and these reactions are shown to fail when F is replaced by Cl in the iridium reagent. Unsaturation at Ir is suggested to be central to the mechanism of these F/X transposition reactions.
Identification of an elusive catalyst: IrH(η2-C6H4PtBu2) (Cl) (PtBu2Ph) as a precursor for C=C bond migration
Cooper, Alan C.,Caulton, Kenneth G.
, p. 41 - 51 (2008/10/08)
The catalytic isomerization of allylbenzene to cis/trans-β-Me styrene in solutions containing Ir(III) hydride halide, hydrido hydroxide and hydrido alkoxide Ir(H)2X(PtBu2Ph)2 (X=F, Cl, Br, I, OH, OCH2CF3) is described. Large variations in isomerization rate (kobs) are found to correlate with the electron donating ability (π+σ) of the X ligand: the rate is enhanced by more effective donation by the X ligands. A number of kinetic studies and phosphine exchange experiments utilizing a deuterium labeled phosphine, PtBu2(d5)Ph, indicate that the active isomerization catalyst is a 14-valence-electron Ir(III) species derived from the ortho-metallated complex, IrH(η2-C6H4PtBu 2)-(X)(PtBu2Ph), by phosphine dissociation. Using IrH(η2-C6H4PtBu 2)(Cl)(PtBu2Ph) as a catalyst precursor, the catalytic isomerization of α,α-d2-allylbenzene in the presence of an excess of 4-allyl anisole has yielded primarily d1cis/trans-β-Me styrene, which confirms that the isomerization proceeds via an insertion-elimination mechanism of a metal hydride bond.
Ligand redistribution reactions of five-coordinate d6 species: RuHX(CO)P2, IrH2XP2, and Cp*RuXP
Poulton, Jason T.,Hauger, Bryan E.,Kuhlman, Roger L.,Caulton, Kenneth G.
, p. 3325 - 3330 (2008/10/08)
For the species RuHXP2(CO), IrH2XP2, and Cp*RuXP (P = bulky phosphine, X = halide or pseudohalide), both homometallic halide exchange ([M]XP + [M]YP′ ? [M]YP + [M]XP′) and heterometallic halide exchange ([M]X + [M]′Y ? [M]Y + [M]′X) are found to be quite rapid. In addition, hydride exchange occurs for RuHCl(CO)P2 and RuDCl(CO)P′2, as well as for IrH2Cl(PtBu2Ph)2 and IrD2Cl(PtBu2Me)2. Exchange is generally faster for halides than for hydrides yet is much slower for the groups phenoxide, OSiPh3, and C2Ph. These equilibria favor the better donating halide being bonded to the less electron-rich metal center. A variable-temperature 1H NMR study of the degenerate exchange Cp*Ru(PtBu2Me)Cl + Cp*Ru′(PtBu2Me)Br ? Cp*Ru(PtBu2Me)Br + Cp*Ru′(PtBu2Me)Cl establishes a second-order rate law with ΔH≠ = 8.6 ± 0.8 kcal/mol and ΔS≠ = -20 ± 3 cal/(mol K). These results clearly indicate the transient existence in solution of halide- and/or hydride-bridged dimers of monomeric metal complexes.
