Dinuclear dihydride complexes of iridium: a study of structure and dynamics

Metal–Metal Synergy in Well-Defined Surface Tantalum–Iridium Heterobimetallic Catalysts for H/D Exchange Reactions

“…At the lowest temperature reached (228 K), the spin–lattice relaxation time ( T 1 ) measured for the hydride protons in 1 is 677 ms, and the minimum spin–lattice relaxation time T 1min is estimated to be 430 ms for a temperature of 203 K, which is in agreement with a classical iridium dihydride (versus a dihydrogen complex). , The IR spectrum of 1 exhibits a M-H stretching vibration signal at 2056 cm –1 which supports a terminal iridium hydride description. For comparison, the terminal Ir–H stretching frequency of Cp*IrH 4 is 2150 cm –1 , and those of Cp*Ir­(CO)­H 2 and Cp*Ir­(PMe 3 )­(CH 3 )H are 2131 and 2090 cm –1 , respectively, − while the absorption due to bridging hydride ligands typically occurs at lower wavenumbers, for instance at 936 cm –1 in {[Cp*Ir] 2 (μ-H) 3 }­{PF 6 } …”

“…46,47 The IR spectrum of 1 exhibits a M-H stretching vibration signal at 2056 cm -1 which supports a terminal iridium hydride description. For comparison, the terminal Ir-H stretching frequency of Cp*IrH4 is 2150 cm -1 45 and that of Cp*Ir(CO)H2 and Cp*Ir(PMe3)(CH3)H are 2131 and 2090 cm -1 respectively [48][49][50] while the absorption due to bridging hydride ligands typically occurs at lower wavenumbers, for instance at 936 cm -1 in {[Cp*Ir]2(μ-H)3}{PF6}. 51 Single crystals suitable for X-ray diffraction were grown upon sublimation of compound 1 (40°C under 10 -5 mBar).…”

Strongly Polarized Iridiumδ−–Aluminumδ+ Pairs: Unconventional Reactivity Patterns Including CO2 Cooperative Reductive Cleavage

“…Next, we probed the reactivity of these Al δ+ –Ir δ− derivatives toward electrophiles, and we first targeted carbon dioxide, given the importance of CO 2 activation by transition metals. , NMR monitoring of the reaction of 1 with CO 2 shows that a reaction occurs at room temperature, yet a complex mixture of species is formed. Among them, Cp*Ir­(CO)­H 2 and Cp*IrH 4 have been unambiguously identified. Unstable aluminum–oxo coproducts are most likely formed in the process and might explain why this reaction affords multiple products.…”

“…Gratifyingly, the coordination of the pyridine Lewis base to Al does not quench the reactivity of the Ir–Al motif and helps stabilize the resulting Al derivatives, leading to cleaner reactions that are easier to decipher. Indeed, treatment of 2 with CO 2 (0.8 atm, 10 equiv, rt) leads to the clean reductive cleavage of CO 2 , affording the iridium carbonyl species Cp*Ir­(CO)­H 2 , together with Cp*IrH 4 (see Figure S13) and the aluminum–oxo coproduct [( i Bu)­(OAr)­Al­(Py)] 2 (μ-O) ( 3 ), which is isolated in 86% yield (Scheme ).…”

Aminoethyl‐Functionalized Cyclopentadienyliridium Complexes: Photochemical C–H Activation and Carbonylation of Cycloalkanes

“…As the photolysis progressed, a new species showing a carbonyl stretch at 1996 cm –1 in the infrared spectrum and a hydride resonance at δ = –15.7 ppm ([D 8 ]toluene) in the 1 H NMR spectrum was formed (Scheme ). This was assigned to the dihydride complex 3 by comparison of its spectroscopic data with the analogue [Cp*Ir(CO)H 2 ] (ν CO = 1996 cm –1 in cyclohexane; δ = –15.8 ppm in C 6 D 6 );7,8 the latter was reported to form when 1b was irradiated under a hydrogen atmosphere 7…”