Redox Reactions Of Polyhydride Complexes of Rhenium: electrochemistry and Reactions With Alkyl Isocyanides

Allison, Joe D.; Cameron, Charles J.; Wild, Robert E.; Walton, Richard A.

doi:10.1016/s0022-328x(00)81019-0

Cited by 20 publications

(16 citation statements)

References 12 publications

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“…CpMo(OH)(PMe3)3 is unstable relative to PMe3 dissociation and formation of the 16-electron CpMo(OH)(PMe3)2 complex, a spin triplet complex. 49 The deprotonation process [equation (7)] is predicted as too unfavorable when using PMe3 or H2O as a base. Thus, this pathway is possible only in the presence of unoxidized 1.…”

Section: Methodsmentioning

confidence: 99%

Formation of organometallic hydroxo and oxo complexes by oxidation of transition metal hydrides in the presence of water. X-Ray structures of [CpMo(OH)(PMe3)3][BF4] and [CpMo(O)(PMe3)2][BF4]

Fettinger¹,

Kraatz²,

Poli³

et al. 1999

J. Chem. Soc., Dalton Trans.

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de Formation of organometallic hydroxo and oxo complexes by oxidation of transition metal hydrides in the presence of water. X-Ray structures of [CpMo(OH)(PMe3)3][BF4] and [CpMo(O)(PMe3)2][BF4]

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Section: Methodsmentioning

confidence: 99%

Formation of organometallic hydroxo and oxo complexes by oxidation of transition metal hydrides in the presence of water. X-Ray structures of [CpMo(OH)(PMe3)3][BF4] and [CpMo(O)(PMe3)2][BF4]

Fettinger¹,

Kraatz²,

Poli³

et al. 1999

J. Chem. Soc., Dalton Trans.

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“…Low temperatures can increase the lifetime of unstable TMHRCs. A good example is [Re 2 (μ-H) 4 H 4 (PPh 3 ) 4 ] •+ , which is only stable in solution for several minutes at room temperature but persists for several hours at 0 °C . In cyclic voltammetry experiments, the irreversible oxidations of [Mo(CO) 2 (dppe) 2 H] + , [W(CO) 2 (dppe) 2 H] + , and [W(CO) 2 (dppm) 2 H] + became reversible when the solution temperature was decreased to −60 °C .…”

Section: Synthesis and Stabilitymentioning

confidence: 99%

“…While the diamagnetic rhenium octahydride Re 2 (μ-H) 4 H 4 (PPh 3 ) 4 reacts very slowly with nucleophiles such as t -BuNC, the oxidized TMHRC analogue [Re 2 (μ-H) 4 H 4 (PPh 3 ) 4 ][PF 6 ] does so rapidly, giving diamagnetic [Re 2 (μ-H) 3 H 2 (PPh 3 ) 4 ( t -BuNC) 2 ][PF 6 ] and liberating H 2 in the process . Other examples include ReH 5 (PPh 3 ) 2 L (L = PPh 3 , PEt 2 Ph, pyridine, piperidine, or cyclohexylamine), which are activated to attack by isonitriles upon electrochemical oxidation; the end products are Re(I) species …”

Section: Introductionmentioning

confidence: 99%

Transition-Metal Hydride Radical Cations

Shaw

Estes

et al. 2016

Chem. Rev.

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Transition-metal hydride radical cations (TMHRCs) are involved in a variety of chemical and biochemical reactions, making a more thorough understanding of their properties essential for explaining observed reactivity and for the eventual development of new applications. Generally, these species may be treated as the ones formed by one-electron oxidation of diamagnetic analogues that are neutral or cationic. Despite the importance of TMHRCs, the generally sensitive nature of these complexes has hindered their development. However, over the last four decades, many more TMHRCs have been synthesized, characterized, isolated, or hypothesized as reaction intermediates. This comprehensive review focuses on experimental studies of TMHRCs reported through the year 2014, with an emphasis on isolated and observed species. The methods used for the generation or synthesis of TMHRCs are surveyed, followed by a discussion about the stability of these complexes. The fundamental properties of TMHRCs, especially those pertaining to the M-H bond, are described, followed by a detailed treatment of decomposition pathways. Finally, reactions involving TMHRCs as intermediates are described.

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“…There is still much to learn about the mechanisms of reactions of odd-electron transition metal hydride complexes. Such species are often generated by the oxidation or reduction of stable even-electron complexes. − Hu, Norton, and co-workers and Poli have reviewed cases where the oxidation of a diamagnetic hydride MHL n to a paramagnetic hydride cation [MHL n ] + decreases the p K a for proton loss from the metal significantly, often by greater than 20 p K a units (Scheme ). This was first discovered by Ryan, Tilset, and Parker when they measured the electrochemical potentials E 1 and E 2 and then used known p K a 1 values in a thermochemical cycle to obtain p K a 2 .…”

Section: Introductionmentioning

confidence: 99%

Systematic Trends in the Electrochemical Properties of Transition Metal Hydride Complexes Discovered by Using the Ligand Acidity Constant Equation

2020

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Understanding the thermodynamics of paramagnetic transition metal hydride complexes, especially of the abundant 3d metals, is important in the design of electrocatalysts and organometallic catalysts. The pK a MeCN([MHLn]+/[MLn) of paramagnetic hydrides in MeCN are estimated for the first time using the ligand acidity constant (LAC) equation where contributions to the pK a MeCN from each ligand are simply added together, with the sum corrected for effects of charge and 5d metals. The pK a LAC–MeCN([MHLn]+/MLn) of over 200 hydride complexes MHLn are used, along with their electrochemical potentials from the literature, in an uncommonly applied thermochemical cycle in order to reveal systematic trends in the redox couples MIII/II and MV/IV (M = Cr, Mo, W), MnII/I, ReVI/V and ReIV/III, MIII/II and MIV/III (M = Fe, Ru, Os), and MIII/II and MII/I (M = Co, Rh, and Ir) and allow the estimation of the bond dissociation free energies BDFE(MH) of the unoxidized hydrides MHLn and the prediction of the electrochemical potential for their oxidation. Density functional theory (DFT) calculations are used to validate the pK a LAC–MeCN values of hydrides of WIII, MnII, FeIII, RuIII, CoII, and NiIII. When a pK a LAC–MeCN is less than zero for a given complex [MHLn]+, the oxidation of MHLn is irreversible due to proton loss from the oxidized complex to the solvent. When pK a LAC–MeCN ≫ 0, the oxidation is reversible when there is no gross change in the coordination geometry upon a change in the redox state. Twenty paramagnetic hydrides prepared in bulk all have pK a LAC–MeCN > 8.

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Redox Reactions Of Polyhydride Complexes of Rhenium: electrochemistry and Reactions With Alkyl Isocyanides

Cited by 20 publications

References 12 publications

Formation of organometallic hydroxo and oxo complexes by oxidation of transition metal hydrides in the presence of water. X-Ray structures of [CpMo(OH)(PMe3)3][BF4] and [CpMo(O)(PMe3)2][BF4]

Formation of organometallic hydroxo and oxo complexes by oxidation of transition metal hydrides in the presence of water. X-Ray structures of [CpMo(OH)(PMe3)3][BF4] and [CpMo(O)(PMe3)2][BF4]

Transition-Metal Hydride Radical Cations

Systematic Trends in the Electrochemical Properties of Transition Metal Hydride Complexes Discovered by Using the Ligand Acidity Constant Equation

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