Synthesis and redox properties of a phosphine-subsituted para-dioxolene and its bimetallic palladium complex

2008 ◽  
Vol 86 (10) ◽  
pp. 976-981 ◽  
Author(s):  
Sharon L Caldwell ◽  
Joe B Gilroy ◽  
Rajsapan Jain ◽  
Evan Crawford ◽  
Brian O Patrick ◽  
...  
Keyword(s):  
Palladium Complex ◽  
Electronic Spectroscopy ◽  
Chemical Oxidation ◽  
Redox Properties ◽  
Redox Activity ◽  
Redox Potentials ◽  
Cationic Complex ◽  
Bridging Ligands ◽  
Reduction Potentials ◽  
Bimetallic Palladium

Oxidation of 2,5-bis(diphenylphosphino)-1,4-hydroquinone (8) with iodobenzene diacetate produces the corresponding bis(phosphine) substituted benzoquinone (9), the first phosphine-substitued quinone. Cyclic voltammetry studies reveal that the redox functionality of the quinone unit in 9 is retained, and the reduction potentials render this compound slightly more easily reduced than the parent p-benzoquinone. Reaction of the precursor hydroquinone 8 with Pd(hfac)2 affords a binuclear complex 10 with the hydroquinonate ligand bridging two Pd(hfac) substrates. The redox activity of the bridging dioxolene ligand is retained in complex 10, although there are significant changes in the redox potentials relative to those of the free quinone 9. Chemical oxidation of 10 with AgPF6 yields a persistent cationic complex 11, which, based on EPR and electronic spectroscopy, can be formulated as containing a bridging semiquinone ligand.Key words: p-quinones, phosphines, bridging ligands, redox properties.

Effect of protonation, composition and isomerism on the redox properties and electron (de)localization of classical polyoxometalates

2017 ◽  
Vol 2 (11) ◽  
Author(s):  
Xavier López
Keyword(s):  
Inorganic Compounds ◽  
Redox Properties ◽  
Theoretical Research ◽  
Redox Activity ◽  
Redox Potentials ◽  
Transition Metal Atoms ◽  
Computational Data ◽  
Keggin Anions ◽  
Dawson Structure

Abstract This publication reviews some relevant features related with the redox activity of two inorganic compounds: [XM12O40]q- (Keggin structure) and [X2M18O62]q- (Wells-Dawson structure). These are two well-known specimens of the vast Polyoxometalate (POM) family, which has been the subject of extensive experimental and theoretical research owing to their unmatched properties. In particular, their redox activity focus a great deal of attention from scientists due to their prospective related applications. POMs are habitually seen as ‘electron sponges’ since many of them accept several electrons without losing their chemical identity. This makes them excellent models to study mechanisms of electrochemical nature. Their redox properties depend on: (i) the type and number of transition metal atoms in the structure, (ii) the basicity of the first reduced species and, occasionally, of the fully oxidized species; (iii) the size of the molecule, (iv) the overall negative charge of the POM, and (v) the size of the central heteroatom. In the last years, important collaboration between the experimental and theoretical areas has been usual on the development of POM science. In the present chapter three of these synergies are highlighted: the influence of the internal heteroatom upon the redox potentials of Keggin anions; the dependence of the redox waves of Fe-substituted Wells-Dawson compounds with pH; and the role of electron delocalization and pairing in mixed-metal Mo/W Wells-Dawson compounds in their ability to accept electrons. In these three cases, a complete understanding of the problem would not have been possible without the mutual benefit of experimental and computational data.

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding

2019 ◽  
Author(s):  
Andrew Rosen ◽  
M. Rasel Mian ◽  
Timur Islamoglu ◽  
Haoyuan Chen ◽  
Omar Farha ◽  
...  
Keyword(s):  
Density Functional ◽  
Metal Organic Frameworks ◽  
Redox Activity ◽  
Screening Methods ◽  
Bridging Ligands ◽  
Metal Centers ◽  
Computational Screening ◽  
Open Metal Sites ◽  
Metal Organic ◽  
Unsaturated Metal Sites

<p>Metal−organic frameworks (MOFs) with coordinatively unsaturated metal sites are appealing as adsorbent materials due to their tunable functionality and ability to selectively bind small molecules. Through the use of computational screening methods based on periodic density functional theory, we investigate O<sub>2</sub> and N<sub>2</sub> adsorption at the coordinatively unsaturated metal sites of several MOF families. A variety of design handles are identified that can be used to modify the redox activity of the metal centers, including changing the functionalization of the linkers (replacing oxido donors with sulfido donors), anion exchange of bridging ligands (considering μ-Br<sup>-</sup>, μ-Cl<sup>-</sup>, μ-F<sup>-</sup>, μ-SH<sup>-</sup>, or μ-OH<sup>-</sup> groups), and altering the formal oxidation state of the metal. As a result, we show that it is possible to tune the O<sub>2</sub> affinity at the open metal sites of MOFs for applications involving the strong and/or selective binding of O<sub>2</sub>. In contrast with O<sub>2</sub> adsorption, N<sub>2</sub> adsorption at open metal sites is predicted to be relatively weak across the MOF dataset, with the exception of MOFs containing synthetically elusive V<sup>2+</sup> open metal sites. As one example from the screening study, we predict that exchanging the μ-Cl<sup>-</sup> ligands of M<sub>2</sub>Cl<sub>2</sub>(BBTA) (H<sub>2</sub>BBTA = 1<i>H</i>,5<i>H</i>-benzo(1,2-d:4,5-d′)bistriazole) with μ-OH<sup>-</sup> groups would significantly enhance the strength of O<sub>2</sub> adsorption at the open metal sites without a corresponding increase in the N<sub>2</sub> affinity. Experimental investigation of Co<sub>2</sub>Cl<sub>2</sub>(BBTA) and Co<sub>2</sub>(OH)<sub>2</sub>(BBTA) confirms that the former exhibits only weak physisorption, whereas the latter is capable of chemisorbing O<sub>2</sub> at room temperature. The chemisorption behavior is attributed to the greater electron-donating character of the μ-OH<sup>-</sup><sub> </sub>ligands and the presence of H-bonding interactions between the μ-OH<sup>-</sup> bridging ligands and the O<sub>2</sub> adsorbate.</p>

Photochromic and Redox Properties of Bisterpyridine Ruthenium Complexes Based on Dimethyldihydropyrene Units as Bridging Ligands

2011 ◽  
Vol 50 (21) ◽  
pp. 10581-10591 ◽  
Author(s):  
Neus Vilà ◽  
Guy Royal ◽  
Frédérique Loiseau ◽  
Alain Deronzier
Keyword(s):  
Ruthenium Complexes ◽  
Redox Properties ◽  
Bridging Ligands

β-Tetrabromo-meso-tetrakis(4′-substituted phenyl)porphyrins: synthesis and electrochemical redox properties

2011 ◽  
Vol 15 (09n10) ◽  
pp. 883-889 ◽  
Author(s):  
P. Bhyrappa ◽  
V. Velkannan
Keyword(s):  
Linear Relationship ◽  
Redox Properties ◽  
Redox Potentials ◽  
Electrochemical Redox ◽  
Hammett Parameter

A series of 2,3,12,13-tetrabromo-5,10,15,20-tetrakis(4′-substituted phenyl)porphyrins, H2 T(4′-R Ph) PBr4 ( R = OCH3 , t-butyl, H and CO2CH3 ) and their metal ( Co(II) , Cu(II) , and Zn(II) ) complexes were synthesized and their electrochemical redox properties were explored. The plot of E1/2vs. the Hammett parameter (σp) of the substituents (R) follow a fairly linear relationship for the ring centered redox potentials.

scholarly journals Unveiling Extreme Photoreduction Potentials of Donor-Acceptor Cyanoarenes to Access Aryl Radicals from Aryl Chlorides

2021 ◽  
Author(s):  
Jinhui Xu ◽  
Jilei Cao ◽  
Xiangyang Wu ◽  
Han Wang ◽  
Xiaona Yang ◽  
...  
Keyword(s):  
Limited Range ◽  
Redox Potentials ◽  
Aryl Chlorides ◽  
Aryl Radicals ◽  
Reduction Potentials ◽  
Anion Form ◽  
Donor Acceptor ◽  
High Reduction ◽  
Very High ◽  
Excited Radical

Since the seminal work of Zhang in 2016, donor-acceptor cyanoarene-based fluorophores, such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), have been widely applied in photoredox catalysis, and used as excellent metal-free alternatives to noble metal Ir- and Ru-based photocatalysts. However, all the reported photoredox reactions involving this chromophore family are based on harnessing the energy from a single visible light photon, with a limited range of redox potentials from -1.92 V to +1.79 V. Here, we document the unprecedented discovery that this family of fluorophores can undergo consecutive photoinduced electron transfer (ConPET) to achieve very high reduction potentials. One of the newly synthesized catalysts, 2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile (3CzEPAIPN), possesses a long-lived (12.95 ns) excited radical anion form, 3CzEPAIPN<sup>•</sup><sup>−</sup>*, which can be used to activate reductively recalcitrant aryl chlorides (E<sub>red </sub>≈ -1.9 to -2.9 V) under mild conditions. The resultant aryl radicals can be engaged in synthetically valuable aromatic C-B, C-P, and C-C bond formation to furnish arylboronates, arylphosphonium salts, arylphosphonates, and spirocyclic cyclohexadienes, respectively.

Substituent effects of cis-dioxobis(dithiocarbamato) molybdenum(VI) on redox properties: redox potentials for one-electron reduction and second-order rate constants for oxygen atom transfer

1998 ◽  
Vol 269 (2) ◽  
pp. 260-268 ◽  
Author(s):  
Kei Unoura ◽  
Akira Yamazaki ◽  
Akira Nagasawa ◽  
Yoshikiyo Kato ◽  
Hiroki Itoh ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Rate Constants ◽  
Substituent Effects ◽  
Second Order ◽  
Redox Properties ◽  
Atom Transfer ◽  
Redox Potentials ◽  
Oxygen Atom Transfer ◽  
Order Rate ◽  
Electron Reduction

Product-Derived Bimetallic Palladium Complex Catalyzes Direct Carbonylation of Sulfonylazides

2016 ◽  
Vol 128 (18) ◽  
pp. 5635-5639 ◽  
Author(s):  
Jin Zhao ◽  
Zongyang Li ◽  
Shaole Song ◽  
Ming-An Wang ◽  
Bin Fu ◽  
...  
Keyword(s):  
Palladium Complex ◽  
Bimetallic Palladium

A TTFV–pyrene-based copolymer: synthesis, redox properties, and aggregation behaviour

RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23952-23956 ◽  
Author(s):  
Eyad A. Younes ◽  
Kerry-Lynn M. Williams ◽  
Joshua C. Walsh ◽  
Celine M. Schneider ◽  
Graham J. Bodwell ◽  
...  
Keyword(s):  
Ph Value ◽  
Redox Properties ◽  
The Self ◽  
Redox Activity ◽  
Repeat Units ◽  
Aggregation Behaviour ◽  
Reversible Redox ◽  
Conjugated Copolymer ◽  
External Stimuli ◽  
Self Aggregation

A new π-conjugated copolymer containing tetrathiafulvalene vinylogue and pyrene repeat units was synthesized and exhibited reversible redox activity, while the self-aggregation behaviour in the solution phase was responsive to external stimuli such as solvent and pH value.

Elektrochemisches Verhalten der Nitrophenole und ihrer Reduktionsprodukte an Graphitelektroden/ Electrochemical Behavior of the Nitrophenols and Their Reduction Products at Graphite Electrodes

1981 ◽  
Vol 36 (7) ◽  
pp. 840-845 ◽  
Author(s):  
Elli Theodoridou ◽  
Dimitrios Jannakoudakis
Keyword(s):  
Aqueous Solutions ◽  
Electrochemical Behavior ◽  
Ph Dependence ◽  
Chemical Oxidation ◽  
Potential Range ◽  
Cyclic Voltammograms ◽  
Hanging Mercury Drop Electrode ◽  
Oxidation Peak ◽  
Graphite Electrodes ◽  
Reduction Potentials

Abstract The electrochemical reduction of the isomeric nitrophenols at graphite electrodes is investigated in aqueous solutions with pH = 1-13 and is compared with the electro-chemical oxidation of their reduction products. o-Nitrophenol and p-nitrophenol are reduced to the corresponding amines, as the observed oxidation peaks in their cyclic voltammograms can be simulated by those of o-and p-aminophenol. m-Nitrophenol is reduced to m-hydroxylaminophenol, as its oxidation peak appears at much more negative » potential than that of m-aminophenol, within the potential range of the oxidation of phenylhydroxylamine. The pH-dependence of the reduction potentials of the nitrophenols at the graphite electrodes is discussed in comparison with that at a hanging mercury drop electrode.

Synthesis and hydrolysis of gas-phase lanthanide and actinide oxide nitrate complexes: a correspondence to trivalent metal ion redox potentials and ionization energies

2015 ◽  
Vol 17 (15) ◽  
pp. 9942-9950 ◽  
Author(s):  
Ana F. Lucena ◽  
Célia Lourenço ◽  
Maria C. Michelini ◽  
Philip X. Rutkowski ◽  
José M. Carretas ◽  
...  
Keyword(s):  
Gas Phase ◽  
Metal Ion ◽  
Oxidation States ◽  
Redox Potentials ◽  
Trivalent Metal ◽  
Ionization Energies ◽  
Reduction Potentials ◽  
Hydrolysis Of ◽  
Nitrate Complexes

Gas-phase hydrolysis of lanthanide/actinide MO3(NO3)3−ions relates to the stabilities of the MIVoxidation states, which correlate with IV/III solution reduction potentials and 4th ionization energies.

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