An X-ray and neutron diffraction structure analysis of a triply-bridged binuclear iridium complex, [[(C5(CH3)5Ir)2(μ-H)3]+ [ClO4]−• 2C6H6]

Stevens, Raymond C.; McLean, Malcolm R.; Wen, T.; Carpenter, John D.; Bau, Robert; Koetzle, Thomas F.

doi:10.1016/s0020-1693(00)83097-2

Cited by 24 publications

(6 citation statements)

References 12 publications

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“…The approximately linear Hf–Ir–Cp* centroid angle (179.2(3)°) suggests the presence of three bridging hydrides across the two metals, arranged to favor a three-legged piano-stool coordination geometry around the {Cp*Ir} core. This value is in excellent agreement with values reported for systems featuring a Cp*Ir(μ-H) 3 bridging motif, such as [Cp*Ir(μ-H) 3 {Ta(CH 2 t Bu) 2 }{IrH 2 Cp*}] (178.9°), [Cp*Ir(μ-H) 3 Ru(η 5 -C 5 Me 4 Et)] (178.8°), [(Cp*Ir) 2 (μ-H) 3 ][ClO 4 ] (179.3°), and [Cp*Ir(μ-H) 3 Hf(CH 2 TMS) 2 Cp*] (176.0°), and in stark contrast with that found in [{Ta(CH 2 t Bu) 3 }{IrH 2 (Cp*)}] (151.3(4)°), which features two terminal Ir–H moieties or that found in [Cp*IrH 3 Al( i Bu)(OAr)] (143.8°), which features one terminal and two bridging hydrides. The Hf–C bond distances (on average 2.19 Å) are in the expected range for hafnium neopentyl groups. , The Hf–Ir separation of 2.6773(4) Å in 2 is 0.02 Å shorter than the sum of metallic radii of hafnium (1.442 Å) and iridium (1.260 Å), which translates in a formal shortness ratio very close to unity (FSR = 0.991) .…”

Section: Resultssupporting

confidence: 87%

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

et al. 2022

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Cp*IrH 4 reacts with Hf(Np) 4 (Np = CH 2 C(CH 3 ) 3 ) to yield the heterobimetallic complex [Hf(Np) 3 (μ-H) 3 IrCp*], 2. Treatment of 2 with neopentyl lithium (NpLi) results in the nucleophilic addition of a neopentyl moiety onto the Hf center, restoring Hf(Np) 4 and displacing the Cp*IrH 3 iridate fragment. By contrast, treatment of the tantalum/iridium analogue, [Ta(Np) 3 IrH 2 (Cp*)], 1, with NpLi triggers the α-hydrogen abstraction at a Ta-neopentyl moiety and leads to the formation of the alkylidene -ate complex [Li][{Ta(CH t Bu)(Np) 2 }{IrH 2 Cp*}], 4. The benzylidene analogue, [K][{Ta(CHPh)(Np) 2 }{IrH 2 Cp*}], 5, is obtained upon reacting 1 with benzyl potassium. An unusual vinyl oxo species, [{Li(THF) 3 }Ta(O)(Np) 2 {μ-C 2 H 3 }IrH(Cp*)], 6, is formed when the reaction of 1 with NpLi is carried out in THF, due to THF fragmentation.

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Section: Resultssupporting

confidence: 87%

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

et al. 2022

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“…The structure of 2 in the acidic media (pH 1−4) was determined by 1 H NMR (Figure ), X-ray analysis, and ESI-MS. Crystals of 2 ·NO 3 used in the X-ray analysis (Figure ) were obtained from a 0.1 M HNO 3 /H 2 O (pH 1) solution of 2 . The bonding parameters of 2 ·NO 3 are very close to those of 2 ·ClO 4 previously determined by X-ray and neutron diffraction structure analysis . The Ir···Ir distances of 2 ·NO 3 and 2 ·ClO 4 are 2.4677(4) and 2.465(3) Å, respectively.…”

Section: Resultssupporting

confidence: 78%

pH-Dependent H₂-Activation Cycle Coupled to Reduction of Nitrate Ion by Cp*Ir Complexes

2002

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This paper reports a pH-dependent H2-activation [H2 (pH 1-4) --> H+ + H- (pH -1) --> 2H+ + 2e-] promoted by CpIr complexes [Cp = eta5-C5(CH3)5]. In a pH range of about 1-4, an aqueous HNO3 solution of [CpIr(III)(H2O)3]2+ (1) reacts with 3 equiv of H2 to yield a solution of [(CpIr(III))2(mu-H)3]+ (2) as a result of heterolytic H2-activation [2[1] + 3H2 (pH 1-4) --> [2] + 3H+ + 6H2O]. The hydrido ligands of 2 display protonic behavior and undergo H/D exchange with D+: [M-(H)3-M]+ + 3D+ <==>[M-(D)3-M]+ + 3H+ (where M = CpIr). Complex 2 is insoluble in a pH range of about -0.2 (1.6 M HNO3/H2O) to -0.8 (6.3 M HNO3/H2O). At pH -1 (10 M HNO3/H2O), a powder of 2 drastically reacts with HNO3 to give a solution of [CpIr(III)(NO3)2] (3) with evolution of H2, NO, and NO2 gases. D-labeling experiments show that the evolved H2 is derived from the hydrido ligands of 2. These results suggest that oxidation of the hydrido ligands of 2 [[2] + 4NO3- (pH -1) --> 2[3] + H2 + H+ + 4e-] couples to reduction of NO3- (NO3- --> NO2- --> NO). To complete the reaction cycle, complex 3 is transformed into 1 by increasing the pH of the solution from -1 to 1. Therefore, we are able to repeat the reaction cycle using 1, H2, and a pH gradient between 1 and -1. A conceivable mechanism for the H2-activation cycle with reduction of NO3- is proposed.

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“…Very few diiridium complexes containing only hydrides as bridging ligands have been structurally characterized. The four such structures in the Cambridge Structural Database (CSD) have Ir−Ir distances ranging from 2.46 to 2.98 Å and include [(Cp*Ir) 2 (μ 2 -H) 3 ][ClO 4 ], {[Cp*(PMe 3 )(H)Ir] 2 (μ 2 -H)} 2 [PF 6 ], {[(Ph 2 PCH 2 CH 2 PPh 2 )Ir(H)] 2 (μ 2 -H) 3 }[BF 4 ], and [{(C 2 F 6 ) 2 PCH 2 CH 2 P(C 2 F 6 ) 2 }(H) 2 Ir(μ 2 -H)] 2 . In 8 , the Ir−Ir distance of 2.797(2) Å is somewhat longer than the average distance of the previously reported structures (2.62 Å).…”

Section: Resultsmentioning

confidence: 99%

Structural and Chemical Properties of Zwitterionic Iridium Complexes Featuring the Tripodal Phosphine Ligand [PhB(CH₂PPh₂)₃]^-

2002

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Several new iridium compounds bearing the PhB(CH2PPh2)3 - (herein abbreviated as [PhBP3]) ligand have been prepared and characterized, and a comparison of steric, electronic, and chemical properties is made with those of related pentamethylcyclopentadienyl (Cp*) and hydridotris(3,5-dimethylpyrazolyl)borate (TpMe 2 ) complexes. The complexes [PhBP3]Ir(H)(η3-C8H13) (2) and [PhBP3]Ir(H)(η3-C3H5) (3) were synthesized from the reaction of [Li(TMED)][PhBP3] (1) with the corresponding [(alkene)2IrCl]2 complex. These allyl complexes serve as precursors to the dihalides [PhBP3]IrX2 (10, X = I; 12, X = Cl). In addition to these dihalides, the five-coordinate species [PhBP3]IrMe2 (16) and [ClB(CH2PPh2)3]IrCl2 (13) have been isolated. Addition of CO to 2 or 3 gave [PhBP3]Ir(CO)2 (7), while reaction of H2 with 2 yielded {[PhBP3]IrH2}2 (8) in benzene and [PhBP3]Ir(COE)H2 (9) in THF (where COE = cyclooctene). Complex 2 reacted with PMePh2 to give [PhBP3]Ir(PMePh2)H2 (5) and 1,3-cyclooctadiene. The protonation of 5 with [H(OEt2)]{B[3,5-C6H3(CF3)2]4} gave the classical hydride complex {[PhBP3]Ir(PMePh2)H3}{B[3,5-C6H3(CF3)2]4} (6). In addition to the formation of allyl complexes 2 and 3, several C−H activation reactions have been observed; addition of PMe3 to 2 provided the cyclometalated product (4) and COE. Photolysis of 5 gave (A) and (B). Complex 9 catalyzes H/D exchange between COE and benzene-d 6. Metathesis reactions of diiodide 10 with LiBHEt3 gave [Li(THF) n ]{[PhBP3]Ir(H)2I} (14a) and [Li(THF) n ]{[PhBP3]Ir(H)3} (15). Comparison of the spectroscopic properties of related [PhBP3]Ir, Cp*Ir, and TpMe 2 Ir complexes suggests that relative donating abilities follow the trend [PhBP3] ≥ Cp* > TpMe 2 , and structural comparisons indicate that [PhBP3] is the most sterically demanding ligand.

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An X-ray and neutron diffraction structure analysis of a triply-bridged binuclear iridium complex, [[(C5(CH3)5Ir)2(μ-H)3]+ [ClO4]−• 2C6H6]

Cited by 24 publications

References 12 publications

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

pH-Dependent H₂-Activation Cycle Coupled to Reduction of Nitrate Ion by Cp*Ir Complexes

Structural and Chemical Properties of Zwitterionic Iridium Complexes Featuring the Tripodal Phosphine Ligand [PhB(CH₂PPh₂)₃]^-

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An X-ray and neutron diffraction structure analysis of a triply-bridged binuclear iridium complex, [[(C5(CH3)5Ir)2(μ-H)3]+ [ClO4]−• 2C6H6]

Cited by 24 publications

References 12 publications

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

pH-Dependent H2-Activation Cycle Coupled to Reduction of Nitrate Ion by Cp*Ir Complexes

Structural and Chemical Properties of Zwitterionic Iridium Complexes Featuring the Tripodal Phosphine Ligand [PhB(CH2PPh2)3]-

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pH-Dependent H₂-Activation Cycle Coupled to Reduction of Nitrate Ion by Cp*Ir Complexes

Structural and Chemical Properties of Zwitterionic Iridium Complexes Featuring the Tripodal Phosphine Ligand [PhB(CH₂PPh₂)₃]^-