Ernst J.B.,University of Munster |
Tada M.,Research Center for Materials Science |
Tada M.,Nagoya University |
Glorius F.,University of Munster
Journal of the American Chemical Society | Year: 2016
Here we report, for the first time, an extensive characterization of an N-heterocyclic carbene (NHC)-modified supported heterogeneous catalyst. The existence of the metal-carbene bond could be proven by 13C-SS-NMR experiments. Furthermore, it could be shown that the modification with NHCs does not structurally change the catalyst itself. The effect of the nature and the loading of the NHC on the activity and selectivity of the heterogeneous catalyst is presented by a hydrogenation study, finally leading to an NHC-enabled tunable heterogeneous catalyst for chemoselective hydrogenation. © 2016 American Chemical Society.
Hassan R.M.,Assiut University |
Alaraifi A.,King Saud University |
Fawzy A.,University of Umm Al - Qura |
Zaafarany I.A.,University of Umm Al - Qura |
And 3 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2010
The kinetics of oxidation of kappa-carrageenan (KCAR) as a sulfated polysaccharide by cerium(IV) in aqueous perchlorate solutions at a constant ionic strength of 2.0 mol dm-3 have been investigated, spectrophotometically. The results showed a first-order dependence in [Ce IV] and fractional-first-order kinetics in carrageenan concentration. A kinetic evidence for the formation of 1:1 complex has been revealed. The hydrogen ion dependence of the reaction rate indicated that the oxidation process is acid catalyzed. The oxidation product was identified by the spectral data and elemental analysis. The activation and thermodynamic parameters have been evaluated and a relevant reaction mechanism is suggested and discussed. © 2010 Elsevier B.V. All rights reserved.
Shin J.-Y.,Nagoya University |
Yamada T.,Research Center for Materials Science |
Yamada T.,Japan Science and Technology Agency |
Yoshikawa H.,Research Center for Materials Science |
And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014
Although aromatic compounds occupy a central position in organic chemistry, antiaromatic compounds have demonstrated little practical utility. Herein we report the application of an antiaromatic compound as an electrode-active material in rechargeable batteries. The performance of dimesityl-substituted norcorrole nickel(II) complex (NiNC) as a cathode-active material was examined with a Li metal anode. A maximum discharge capacity of about 207 mAhg -1 was maintained after 100 charge/discharge cycles. Moreover, the bipolar redox property of NiNC enables the construction of a Li metal free rechargeable battery. The high performance of NiNC batteries demonstrates a prospective feature of stable antiaromatic compounds as electrode-active materials. The balance of power: A discharge capacity of greater than 200 mA h g-1 over 100 charge/discharge cycles was found for a rechargeable battery with an antiaromatic norcorrole NiII complex (NiNC) as a cathode-active material and a Li metal anode. The bipolar redox property of NiNC also enabled the construction of a Li metal free rechargeable battery with high discharge capacity (see scheme) and good cycle performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Hatanaka T.,Research Center for Materials Science |
Ohki Y.,Research Center for Materials Science |
Tatsumi K.,Research Center for Materials Science
Chemistry - An Asian Journal | Year: 2010
A coordinatively unsaturated iron-methyl complex having an N-heterocyclic carbene ligand, [Cp*Fe-(LMe)Me] (1; Cp *=η5-C5Me5, L Me=1,3,4,5-tetramethyl-imidazol-2-ylidene), is synthesized from the reaction of [Cp*Fe(TMEDA)Cl] (TMEDA=N,N,N',N'- tetramethylethylenediamine) with methyllithium and LMe. Complex 1 is found to activate the C-H bonds of furan, thiophene, and benzene, giving rise to aryl complexes, [Cp*Fe(LMe)-(aryl)] (aryl=2-furyl (2), 2-thienyl (3), phenyl (4)). The C-H bond cleavage reactions are applied to the dehydrogenative coupling of furans or thiophenes with pinacolborane (HBpin) in the presence of tert-butylethylene and a catalytic amount of 1 (10 mol% to HBpin). The borylation of the furan/thiophene or 2-substituted furans/thiophenes occurs exclusively at the 2-or 5-positions, respectively, whereas that of 3-substituted furans/thiophenes takes place mainly at the 5-position and gives a mixture of regioisomers. Treatment of 2 with 2 equiv of HBpin results in the quantitative formation of 2-boryl-furan and the borohydride complex [Cp *Fe(LMe)(H2Bpin)] (5). Heating a solution of 5 in the presence of tert-butylethylene led to the formation of an alkyl complex [Cp*Fe-(LMe)CH2CH2tBu] (6), which was found to cleave the C-H bond of furan to produce 2. On the basis of these results, a possible catalytic cycle is proposed. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.