Density functional studies of catalytic alkane dehydrogenation by an iridium pincer complex with and without a hydrogen acceptor

Fan, Hua‐Jun; Hall, Michael B.

doi:10.1016/s1381-1169(02)00198-x

Cited by 15 publications

(2 citation statements)

References 76 publications

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“…This endothermic reaction is highly desirable since it requires no harsh oxidants and only produces hydrogen as a byproduct . Pioneering work in this area revealed that the heat required to drive this reaction can deactivate the catalyst, leading to poor performance Since the mechanistic features of metal-catalyzed acceptorless dehydrogenation of ethane (eq ) are poorly understood, here we use a combination of mass spectrometry based experiments and DFT calculations to examine the details of each of the elementary steps of the simple two step catalytic cycle shown in Scheme .…”

Section: Introductionmentioning

confidence: 99%

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

et al. 2020

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Acceptorless dehydrogenation of ethane was achieved in the gas phase via a two-step catalytic cycle involving ternary cationic metal hydrides, [(phen)M(H)]+, 1, and metal ethides, [(phen)M(CH2CH3)]+, 2, (where M = Ni, Pd, or Pt, and phen = 1,10-phenanthroline). Species 1 and 2 were generated and their reactivity studied in a quadrupole ion trap mass spectrometer. It was found that 1 readily reacted with ethane releasing H2 and forming 2, with the relative reactivity being Pt > Ni ≫ Pd. Density functional theory (DFT) calculations for this metathesis reaction agree with the experimental reactivity order. Species 2 can in turn be converted into 1 and release ethylene when sufficient energy is supplied via collision-induced dissociation. DFT calculations also provided insight into competing side reactions (e.g., dehydrogenation of 2 and formation of protonated phen ligand) that become competitive during this endothermic step. The catalytic cycle can be repeated in the mass spectrometer several times. Multiple entry points into the cycle have been identified and discussed.

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Section: Introductionmentioning

confidence: 99%

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

et al. 2020

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“…In recent years, there has been considerable growth in the coordination chemistry and applications of monoanionic terdentate PCP “pincer” (PCP = 2,6-C 6 H 3 (EPR 2 ) 2 ) and related ligands . Of particular interest has been their use in the alkane dehydrogenation chemistry of iridium, where PCP ligand stabilization of intermediates appears to be a key factor; some of these systems exhibit surprisingly long-term catalytic activity at temperatures up to 250 °C …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Platinum Coordination Chemistry of the Perfluoroalkyl Acceptor Pincer Ligand, 1,3-(CH₂P(CF₃)₂)₂C₆H₄

et al. 2007

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The synthesis of perfluoroalkyl-substituted "pincer"-type PCP ligands, 1,3-C6H4(CH2P(Rf)2)2 (Rf = CF3, C2F5), and platinum coordination studies (Rf = CF3) are reported. 1,3-C6H4(CH2P(CF3)2)2 (CF3PCPH) reacts at ambient temperatures with (cod)Pt(Me)Cl (cod = 1,5-cyclooctadiene) and (cod)PtMe2 to afford unmetalated PCPH-bridged products [(CF3PCPH)Pt(Me)Cl]x and cis-[(CF3PCPH)PtMe2]2, respectively. cis-[(CF3PCPH)PtMe2]2 is soluble and has been spectroscopically and crystallographically characterized. Thermolysis of these compounds results in the loss of methane and the formation of metalated complexes (CF3PCP)PtCl and (CF3PCP)PtMe. Treatment of (CF3PCP)PtCl with MeMgBr provides an alternative route to (CF3PCP)PtMe. The carbonyl cation (CF3PCP)Pt(CO)+SbF6- (nu(CO) = 2143 cm(-1)) was readily prepared by chloride abstraction with AgSbF6 under 1 atm CO. nu(CO) data indicates that RfPCP ligands are electronically analogous to trans acceptor phosphine complexes such as trans-((C2F5)2PMe)2Pt(Me)(CO)+ (nu(CO) = 2149 cm-1).

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Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes

Slagt

Rodríguez

Grutters

et al. 2004

Chemistry A European J

109

112

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A variety of para-substituted NCN-pincer palladium(II) and platinum(II) complexes [MX(NCN-Z)] (M=Pd(II), Pt(II); X=Cl, Br, I; NCN-Z=[2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z](-); Z=NO(2), COOH, SO(3)H, PO(OEt)(2), PO(OH)(OEt), PO(OH)(2), CH(2)OH, SMe, NH(2)) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water-soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by (195)Pt NMR spectroscopy and DFT calculations. Both the (195)Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the sigma(p) Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The sigma(p) value for the para-PtI group itself was determined to be -1.18 in methanol and -0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH(2)OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen-bonding interactions.

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Density functional studies of catalytic alkane dehydrogenation by an iridium pincer complex with and without a hydrogen acceptor

Cited by 15 publications

References 76 publications

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

Synthesis and Platinum Coordination Chemistry of the Perfluoroalkyl Acceptor Pincer Ligand, 1,3-(CH₂P(CF₃)₂)₂C₆H₄

Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes

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Density functional studies of catalytic alkane dehydrogenation by an iridium pincer complex with and without a hydrogen acceptor

Cited by 15 publications

References 76 publications

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

A Two-Step Catalytic Cycle for the Acceptorless Dehydrogenation of Ethane by Group 10 Metal Complexes: Role of the Metal in Reactivity and Selectivity

Synthesis and Platinum Coordination Chemistry of the Perfluoroalkyl Acceptor Pincer Ligand, 1,3-(CH2P(CF3)2)2C6H4

Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes

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Synthesis and Platinum Coordination Chemistry of the Perfluoroalkyl Acceptor Pincer Ligand, 1,3-(CH₂P(CF₃)₂)₂C₆H₄