IrH Cl Research Articles

N-Bridged Pincer Iridium Complexes for Highly Efficient Alkane Dehydrogenation and the Relevant Linker Effects

A series of iridium complexes (RPOCR′NP)–HCl (4–HCl) and (RPSCR′NP)Ir–HCl (5–HCl) (R = substituent on P; R′ = substituent on N) supported by N-linked pincer ligands, with the other linker being O- ...

Mechanism of Dimethylamine–Borane Dehydrogenation Catalyzed by an Iridium(III) PCP-Pincer Complex

The title complex (tBuPCP)IrH(Cl) (1; tBuPCP = κ3-2,6-(CH2PtBu2)2C6H3) appeared to be moderately active in NHMe2·BH3 (DMAB) dehydrogenation, allowing the systematic spectroscopic (variable-temperature NMR and IR) investigation of the reaction intermediates and products, under both stoichiometric and catalytic regimes, combined with DFT/M06 calculations. The formation of the hexacoordinate complex (tBuPCP)IrHCl(η1-BH3·NHMe2) (3) stabilized by a NH···Cl hydrogen bond is shown experimentally at the first reaction step. This activates both B–H and Ir–Cl bonds, initiating the precatalyst activation and very first DMAB dehydrogenation cycle. The same geometry is suggested by the DFT calculations for the key intermediate of the catalytic cycle, (tBuPCP)IrH2(η1-BH3·NHMe2) complex (6). In these complexes, DMAB is coordinated trans to the ipso carbon, allowing the steric repulsion between the amine–borane and tert-butyl groups at the phosphorus atoms to be overcome. Under catalytic conditions (2–5 mol % of 1) the h...

Hydrodesulfurization of Thiophene and Benzothiophene to Butane and Ethylbenzene by a Homogeneous Iridium Complex

Reaction of the dimer [Cp*IrHCl]2 (Cp* = η5-C5Me5) in benzene solution with either thiophene or benzothiophene at 90 °C in the presence of H2 gives the hydrogenolysis products [Cp*IrCl]2(μ-H)(μ-SC4H9) (1) and [Cp*IrCl]2(μ-H)[μ-S(C6H4)CH2CH3] (2), respectively, in high yields. Upon further thermolysis under H2, the completely desulfurized products, butane and ethylbenzene, can be made. Complexes 1 and 2 were characterized by single-crystal X-ray diffraction. In the absence of H2, reaction of [Cp*Ir HCl]2 with thiophene gives an additional trinuclear product [Cp*IrCl]3(H)(SC4H6) (3), which was also structurally characterized.