59637-65-9Relevant academic research and scientific papers
Electron-transfer studies of a peroxide dianion
Ullman, Andrew M.,Sun, Xianru,Graham, Daniel J.,Lopez, Nazario,Nava, Matthew,De Las Cuevas, Rebecca,Mueller, Peter,Rybak-Akimova, Elena V.,Cummins, Christopher C.,Nocera, Daniel G.
supporting information, p. 5384 - 5391 (2014/06/09)
A peroxide dianion (O22-) can be isolated within the cavity of hexacarboxamide cryptand, [(O2)∪mBDCA-5t-H 6]2-, stabilized by hydrogen bonding but otherwise free of proton or metal-ion association. This feature has allowed the electron-transfer (ET) kinetics of isolated peroxide to be examined chemically and electrochemically. The ET of [(O2)∪mBDCA-5t-H6] 2- with a series of seven quinones, with reduction potentials spanning 1 V, has been examined by stopped-flow spectroscopy. The kinetics of the homogeneous ET reaction has been correlated to heterogeneous ET kinetics as measured electrochemically to provide a unified description of ET between the Butler-Volmer and Marcus models. The chemical and electrochemical oxidation kinetics together indicate that the oxidative ET of O22- occurs by an outer-sphere mechanism that exhibits significant nonadiabatic character, suggesting that the highest occupied molecular orbital of O 22- within the cryptand is sterically shielded from the oxidizing species. An understanding of the ET chemistry of a free peroxide dianion will be useful in studies of metal-air batteries and the use of [(O 2)∪mBDCA-5t-H6]2- as a chemical reagent.
Synthesis and study of olefin metathesis catalysts supported by redox-switchable diaminocarbene[3]ferrocenophanes
Varnado Jr., C. Daniel,Rosen, Evelyn L.,Collins, Mary S.,Lynch, Vincent M.,Bielawski, Christopher W.
, p. 13251 - 13264 (2013/09/12)
A redox-switchable ligand, N,N′-dimethyldiaminocarbene[3] ferrocenophane (5), was synthesized and incorporated into a series of Ir- and Ru-based complexes. Electrochemical and spectroscopic analyses of (5)Ir(CO) 2Cl (15) revealed that 5 displayed a Tolman electronic parameter value of 2050 cm-1 in the neutral state and 2061 cm-1 upon oxidation. Moreover, inspection of X-ray crystallography data recorded for (5)Ir(cis,cis-1,5-cyclooctadiene)Cl (13) revealed that 5 was sterically less bulky (%VBur = 28.4) than other known diaminocarbene[3] ferrocenophanes, which facilitated the synthesis of (5)(PPh3)Cl 2Ru(3-phenylindenylid-1-ene) (18). Complex 18 exhibited quasi-reversible electrochemical processes at 0.79 and 0.98 V relative to SCE, which were assigned to the Fe and Ru centers in the complex, respectively, based on UV-vis and electron pair resonance spectroscopic measurements. Adding 2,3-dichloro-5,6-dicyanoquinone over the course of a ring-opening metathesis polymerization of cis,cis-1,5-cyclooctadiene catalyzed by 18 ([monomer] 0/[18]0 = 2500) reduced the corresponding rate constant of the reaction by over an order of magnitude (pre-oxidation: kobs = 0.045 s-1; post-oxidation: kobs = 0.0012 s-1). Subsequent reduction of the oxidized species using decamethylferrocene restored catalytic activity (post-reduction: kobs = up to 0.016 s -1, depending on when the reductant was added). The difference in the polymerization rates was attributed to the relative donating ability of the redox-active ligand (i.e., strongly donating 5versus weakly donating 5 +) which ultimately governed the activity displayed by the corresponding catalyst.
DDQ-promoted dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones by a radical ion mechanism
Ding, Ye,Huang, Zhangjian,Yin, Jian,Lai, Yisheng,Zhang, Shibo,Zhang, Zhiguo,Fang, Lei,Peng, Sixun,Zhang, Yihua
supporting information; experimental part, p. 9495 - 9497 (2011/10/31)
A novel and facile DDQ-mediated dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones is described. The formation of lactones proceeds by a radical ion mechanism, which has been established by DPPH?-mediated chemical identification, ESR spectroscopy and an enol intermediate trapping.
Na+-Catalyzed Reduction of Semiquinone Radical Anions by NADH Analogues
Fukuzumi, Shunichi,Tokuda, Yoshihiro
, p. 1497 - 1500 (2007/10/02)
Stable radical anions such as p-chloranil radical anion (Cl4Q-.) are reduced by NADH analogues, 1-benzyl-1,4-dihydronicotinamide (BNAH) and 10-methyl-9,10-dihydroacridine (AcrH2), to yield the corresponding hydroquinone anions.The addition of NaClO4 to the BNAH-Cl4Q-. system results in a significant increase in the rate of the one-electron reduction of Cl4Q-., while no acceleration effect has been observed by the addition of Bu4NClO4.
On the Reaction of Chloranil with Cyanide Ions - an ESR Study
Rehorek, Detlef,Janzen, Edward G.
, p. 705 - 717 (2007/10/02)
The reaction of chloranil 1 with cyanide ions in acetonitrile and methanol solutions has been studied.The ESR spectra revealed the formation of semiquinone anion radicals 7, 8, and 9.The latter has been found as its protonated form in methanol only.In addition, both 1 and 2,3-dicyano-5,6-dichloro-1,4-benzoquinone 4 gave tetracyanoethylene anion radicals 6 upon reaction with cyanide ions in acetonitrile.Using 13C-labelled cyanide 6 was shown to originate from the fragmentation of the cyanide addition product to 4.Using the spin trapping technique it was found that no cyanyl free radicals are formed during the thermal reaction of either 1 or 4 with cyanide ions.
