Electrochemical and Structural Characterization ofcis- andtrans-[Cp(CO)Ru(μ-As(C6H5)2)]2, Isomers That Undergo Two-Electron-Transfer Oxidations

Dimaio, A.-J.; Rheingold, Arnold L.; Chin, Teen T.; Pierce, David T.; Geiger, William E.

doi:10.1021/om9709998

Cited by 9 publications

(12 citation statements)

References 26 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies of 4 2+/0 in ref were conducted by oxidizing 4 °. However, the couple is represented here as a reduction to correlate its electron-transfer-induced metal−metal bond cleavage with that of 1 0/2- and 2 0/2- .…”

Section: Referencesmentioning

confidence: 99%

“…Concerted multielectron transfer reactions occur widely in chemistry and biology. − Although seemingly paradoxical, the electrostatic restrictions on such processes are lifted when an accompanying structural or compositional change (proton transfer, ligand binding, or ion-pair formation) makes transfer of a second unit of charge more favorable than the first. Some years ago, we encountered a family of ligand-bridged binuclear complexes that undergo one-step, two-electron transfer by a mechanism wherein the stoichiometry of the redox center does not change. − Experimental − and computational − studies have been conducted on many such systems, from which it is evident that metal−metal bond cleavage accompanied by structural reorganization provides the necessary driving force for a multielectron event.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Energetics of Concerted Two-Electron Transfer and Metal−Metal Bond Cleavage in Phosphido-Bridged Molybdenum and Tungsten Carbonyl Complexes

Uhrhammer

Schultz

2002

J. Phys. Chem. A

View full text Add to dashboard Cite

The kinetics and thermodynamics of concerted two-electron transfer and metal-metal bond cleavage in the binuclear phosphido-bridged complexes [M 2 (µ-PPh 2 ) 2 (CO) 8 ] 0/2-[M ) Mo (1 0/2-), W(2 0/2-)] have been determined by variable scan-rate cyclic voltammetry in 0.3 M TBAPF 6 /acetone. The reductions of 1°and 2°a re accompanied by an increase of 1.08 Å in M-M distance and expansion and contraction by 29°of the M-P-M and P-M-P angles, respectively, within an intact M 2 (µ-PPh 2 ) 2 unit. The one-electron electrode potentials of these systems are highly inverted: ∆E°′ ) E 2 °′ -E 1 °′ ) +0.17 V for 1 0/2and +0.18 V for 2 0/2-, and the rate constant of the second heterogeneous electron-transfer reaction is smaller than the first: k sh,2 /k sh,1 ) 0.1 for Mo and 0.018 for W. Results are consistent with progressive cleavage of the metal-metal bond in two one-electron steps, of which the second is rate-limiting, because it is accompanied by a larger part of the structural change. EHMO calculations reveal that the redox-active orbital is a metal-metal antibonding (σ*) orbital with substantial bridging-ligand character that decreases markedly in energy on passing from the metal-metal bonded M(I) 2 state to nonbonded M(0) 2 . Despite this feature, electron-transfer thermodynamics and kinetics are not significantly metal-dependent. Rather, comparisons with structurally similar sulfido-bridged complexes reveal that electron-transfer energetics are influenced more extensively by the bridging ligand, with more positive potentials and larger electron-transfer rates observed for RSversus R 2 Pbridged species.

show abstract

Section: Referencesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energetics of Concerted Two-Electron Transfer and Metal−Metal Bond Cleavage in Phosphido-Bridged Molybdenum and Tungsten Carbonyl Complexes

Uhrhammer

Schultz

2002

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…Electron-transfer reactions with first-row transition metals typically follow one-electron (1e – ) pathways. Therefore, many synthetic first-row metal complexes that have shown multielectron reactivity incorporate multiple metal centers, where each is oxidized/reduced by 1e – . − For complexes that achieve multielectron redox chemistry at monometallic centers, however, structural changes around the metal center and/or noninnocent ligands have been utilized to force a multielectron pathway over single electron transfer. − In these examples, the 1e – redox potentials associated with the metal center are shifted from their normal ordering to a condition known as potential inversion …”

Section: Introductionmentioning

confidence: 99%

Influence of Pyridine on the Multielectron Redox Cycle of Nickel Diethyldithiocarbamate

Richburg

Farnum

2019

Inorg. Chem.

View full text Add to dashboard Cite

Two-electron (2e − )-transfer reactions for monometallic complexes of first-row transition metals are uncommon because of the tendency of these metals to proceed through sequential one-electron (1e − )-transfer pathways. For this chemistry to be observed, structural changes upon electron transfer are often needed to shift the 1e − redox potentials to a condition of potential inversion where 2e − transfer becomes favorable. Nickel(II) dithiocarbamate complexes take advantage of these conditions to drive 2e − oxidation from Ni II to Ni IV . Here, we have studied the electrochemistry of Ni II (dtc) 2 , where dtc − is N,N-diethyldithiocarbamate in an acetonitrile solvent as a function of the scan rate and added pyridine to gain further insight into the mechanism for its 2e − oxidation to [Ni IV (dtc) 3 ] + . The scan rate dependence revealed evidence for an ECE mechanism in which the chemical step constituted ligand exchange between [Ni III (dtc) 2 ] + and Ni II (dtc) 2 . A pseudo-first-order rate constant for this reaction of 34 s −1 was obtained at 1 mM Ni II (dtc) 2 . The addition of pyridine to the electrolyte solution showed pronounced changes to the cyclic voltammetry (CV) that were consistent with the formation of a pyridine-bound Ni III complex, [Ni III (dtc) 2 (py) 2 ] + , which was stable at high scan rates but decomposed to [Ni IV (dtc) 3 ] + at low scan rates. The observed decomposition rate constant was well modeled with two parallel decay pathways, one through the dipyridine [Ni III (dtc) 2 (py) 2 ] + and another through a monopyridine [Ni III (dtc) 2 py] + . Overall, these data point to a mechanism for oxidation from Ni II (dtc) 2 to [Ni IV (dtc) 3 ] + that proceeds through an undercoordinated [Ni III (dtc) 2 ] + complex, which can be trapped on the time scale of CV experiments using pyridine ligands. These studies provide insight into how we may be able to control 1e − versus 2e − redox chemistry using the coordination environment and nickel oxidation state.

show abstract

“…Although, based on the reduction potentials, bpy appears to be the most electron-donating ligand for the Cu(II) complexes of the type Cu(NN 0 ) 2 (OTf) 2 , we cannot ignore the difference in stereoisomers, which may also inuence the observed redox potentials. 37 Interestingly, the complex 2 with a saturated and electrondonating hexyl substituted NN 0 hex ligand resulted in only slightly more cathodic shi by À20 mV compared to that of 1, containing an aromatic phenyl substituent. This small potential difference suggests that the type of substituents at the triazole N4 position have little effect on the electron density at the copper center.…”

Section: Electronic Spectra and Electrochemical Propertiesmentioning

confidence: 97%

Pyridine–triazole ligands for copper-catalyzed aerobic alcohol oxidation

et al. 2015

View full text Add to dashboard Cite

A series of [Cu(NN')]2(OTf)2 complexes containing pyridine-triazole ligands [OTf = OSO2CF3; NN' = NN'Ph (1), NN'hex (2), NN'py (3)] with different substituents at the triazole N4 position or 2,2'-bipyridine (bpy; 4) have been synthesized. Crystal structures of 1 and 3 reveal a trans-isomer with strong preference for regular-type triazole coordination (for 3) whereas the Cu-bipyridine complex 4 is more stable in a cis-form. Cyclic voltammetry of 1-4 suggest that the electron-donating strength follows the trend: bpy > NN'py > NN'hex ~ NN'Ph. The catalyst systems consisting of 5 mol% CuOTf2/NN'/TEMPO (TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxy) in the presence of 2x2.0 cm 2 Cu 0 sheets as a reducing agent and 10 mol% N-methylimidazole (NMI) exhibit good activities for aerobic oxidation of benzyl alcohol to benzaldehyde. Catalytic studies have shown that the activities were higher with more electron-rich N-based ligands. Furthermore, oxidation of aliphatic alcohols such as 1-hexanol and 2-methyl-1-pentanol using the Cu catalyst system with the NN'py ligand at room temperature afforded the corresponding aldehydes in >99% and 46% yields, respectively after 24 h.

show abstract

Electrochemical and Structural Characterization ofcis- andtrans-[Cp(CO)Ru(μ-As(C₆H₅)₂)]₂, Isomers That Undergo Two-Electron-Transfer Oxidations

Cited by 9 publications

References 26 publications

Energetics of Concerted Two-Electron Transfer and Metal−Metal Bond Cleavage in Phosphido-Bridged Molybdenum and Tungsten Carbonyl Complexes

Energetics of Concerted Two-Electron Transfer and Metal−Metal Bond Cleavage in Phosphido-Bridged Molybdenum and Tungsten Carbonyl Complexes

Influence of Pyridine on the Multielectron Redox Cycle of Nickel Diethyldithiocarbamate

Pyridine–triazole ligands for copper-catalyzed aerobic alcohol oxidation

Contact Info

Product

Resources

About