Structural consequences of electron-transfer reactions. 25. Electron-transfer-induced isomerizations of cobalt-, nickel-, and palladium-cyclooctatetraene complexes: the role played by the ligand vs. metal composition of the redox orbital

Geiger, William E.; Rieger, Phillip H.; Corbato, Carolyn; Edwin, Joseph; Fonseca, Esteban; Lane, Gregg A.; Mevs, Judith M.

doi:10.1021/ja00059a028

Cited by 24 publications

(16 citation statements)

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“…Although the reversible isomerization between the alkylidene-bridged structure and ylide structure seems to be without precedent, we noted two other relevant studies which focused on the reversible structural changes caused by the reduction. In 1979, Moraczewski and Geiger reported reversible electrochemical isomerization of [(Cp)Co(COT)] ( 6 , 7 ) (Scheme ). This complex shows CV behavior very similar to that of complex 2 ; the existence of isomers is proved by 1 H NMR spectra.…”

Section: Resultsmentioning

confidence: 99%

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

et al. 1997

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Electrochemical investigations concerning the reduction of an alkylidene adduct of a cobaltadithiolene complex are described. [(Cp)Co{S2C2(COOMe)2}{C(COOMe)2}] (Cp = η5-C5H5) exists as an equilibrium mixture of alkylidene-bridged (2) and ylide forms (3) in solution. Both isomers are reducible by one electron, but the radical anion of the bridged form (2 - ) undergoes rapid and irreversible isomerization to the ylide form anion (3 - ). Conventional cyclic voltammetry (CV), thin-layer CV, optically transparent thin-layer electrode (OTTLE), and differential pulse polarography (DPP) have been used to establish these mechanisms. In the reaction with trimethyl phosphite, an X-ray structure analysis and CV have also been used to prove the existence of the ylide structure.

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Section: Resultsmentioning

confidence: 99%

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

et al. 1997

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“…The fact that various types of organometallic reactions are accelerated in odd-electron complexes suggests the possibility that metal−olefin isomerization processes may be profitably enhanced by oxidation or reduction of 18-electron complexes. Electron-transfer-induced isomerizations have been studied in depth for cyclooctatetraene (COT) complexes of Co , and, to a lesser extent, Ni and Pd . Cyclooctadiene (COD) complexes of the later transition metals have also received some attention, , but the metal−1,5-COD bond has generally been found to be unisomerized in the electron-transfer products.…”

Section: Introductionmentioning

confidence: 99%

16-Electron through 19-Electron Complexes of the 1,5-COD and 1,3-COD Isomers of (η⁵-C₅Ph₅)Rh(η⁴-C₈H₁₂): Electrochemical Evidence for an Oxidatively Induced Agostic Interaction

et al. 1998

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The redox properties of Cp‡Rh (1,5-COD) (1) and Cp‡Rh (1,3-COD) (2) (Cp‡ = η5-C5Ph5, COD = η4-cyclooctadiene) have been investigated by cyclic voltammetry and bulk coulometry. Both compounds display a four-membered electron-transfer series involving complexes of overall 2+, 1+, 0, and 1− charges. The 19-electron complexes [Cp‡Rh(COD)]- are short-lived, rapidly releasing [C5Ph5]-. The persistent 17-electron complexes [Cp‡Rh(COD)]+ have been characterized by ESR and optical spectroscopies. Complex 1 + displays an axially symmetric g-tensor, demonstrating that the 17-electon system retains the approximate C 2 v symmetry of its 18-electron precursor. The oxidized forms of 2 n + (n = 1 or 2) undergo slow isomerization to those of 1 n +; that is, isomerization of the diolefin ligand from the 1,3- to the 1,5-isomer occurs in the higher oxidation states of [Cp‡Rh(COD)] n +. The 1,3-COD ligand imparts an unexpected thermodynamic stabilization of the higher Rh oxidation states. Formation of the 17-electron and 16-electron complexes occurs at potentials ca 0.25 and 0.62 V, respectively, lower than expected. The increasing stabilization of the Rh(II) and Rh(III) complexes is ascribed to progressive formation of an agostic interaction between the metal atom and the hydrogen on carbon 5 of the 1,3-cyclooctadiene ring.

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“…Furthermore, various valence isomerizations of cationic and anionic states leading to a range of electronically and structurally unusual species were described in the literature. 14–17 However, most of these interesting processes were irreversible, which disqualifies them from potential application in stimuli-responsive materials. The appealing exception is the electron-rich π-expanded COT derivative, octamethoxytetraphenylene (OMT), capable of undergoing a reversible structural rearrangement upon two-electron chemical and electrochemical oxidation.…”

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Reversible structural rearrangement of π-expanded cyclooctatetraene upon two-fold reduction with alkali metals

et al. 2022

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Structural consequences of electron-transfer reactions. 25. Electron-transfer-induced isomerizations of cobalt-, nickel-, and palladium-cyclooctatetraene complexes: the role played by the ligand vs. metal composition of the redox orbital

Cited by 24 publications

References 2 publications

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

16-Electron through 19-Electron Complexes of the 1,5-COD and 1,3-COD Isomers of (η⁵-C₅Ph₅)Rh(η⁴-C₈H₁₂): Electrochemical Evidence for an Oxidatively Induced Agostic Interaction

Reversible structural rearrangement of π-expanded cyclooctatetraene upon two-fold reduction with alkali metals

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Structural consequences of electron-transfer reactions. 25. Electron-transfer-induced isomerizations of cobalt-, nickel-, and palladium-cyclooctatetraene complexes: the role played by the ligand vs. metal composition of the redox orbital

Cited by 24 publications

References 2 publications

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

Structural Changes Induced by Electron-Transfer Reactions. Isomerization of an Alkylidene Moiety by Reversible Metal−Carbon Bond Cleavage in an Alkylidene-Bridged Cobaltadithiolene Complex

16-Electron through 19-Electron Complexes of the 1,5-COD and 1,3-COD Isomers of (η5-C5Ph5)Rh(η4-C8H12): Electrochemical Evidence for an Oxidatively Induced Agostic Interaction

Reversible structural rearrangement of π-expanded cyclooctatetraene upon two-fold reduction with alkali metals

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16-Electron through 19-Electron Complexes of the 1,5-COD and 1,3-COD Isomers of (η⁵-C₅Ph₅)Rh(η⁴-C₈H₁₂): Electrochemical Evidence for an Oxidatively Induced Agostic Interaction