Reversible hydrogen storage under ambient conditions has been identified as a major bottleneck in enabling a future hydrogen economy. Herein, we report an amorphous vanadium(III) alkyl hydride gel that binds hydrogen through the Kubas interaction. The material possesses a gravimetric adsorption capacity of 5.42 wt % H2 at 120 bar and 298 K reversibly at saturation with no loss of capacity after ten cycles. This corresponds to a volumetric capacity of 75.4 kgH2 m(-3) . Raman experiments at 100 bar confirm that Kubas binding is involved in the adsorption mechanism. The material possesses an enthalpy of H2 adsorption of +0.52 kJ mol(-1) H2 , as measured directly by calorimetry, and this is practical for use in a vehicles without a complex heat management system.
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http://dx.doi.org/10.1002/cphc.201501093 | DOI Listing |
Dalton Trans
July 2022
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
[VCl(THF)] offers a convenient entrance point into the chemistry of carbene stabilized V(III) complexes. Herein we report the paramagnetic mono- and biscarbene complexes [VCl(cAAC)] 1, [VCl(cAAC)(THF)] 1(thf), [VCl(IMes)] 2, [{VCl(IiPr)(μ-Cl)}] 3, [VCl(IDipp)] 4, [VCl(SIDipp)] 5, [VCl(SIDipp)(THF)] 5(thf), [VCl(IBu)] 6, [VCl(cAAC)] 7 and [VCl(IiPr)] 8. Reaction of 1 with MesMgCl, MesLi and LiNPh afforded the complexes [VCl(Mes)(cAAC)] 9, [cAACH][VClMes]10 and [VCl(NPh)(cAAC)] 11.
View Article and Find Full Text PDFInorg Chem
October 2021
Institute of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria.
We report the synthesis of vanadium(V) oxo complex with a pincer-type dianionic mesoionic carbene (MIC) ligand and the general formula [VOCl(L)]. A comparison of the structural (SC-XRD), electronic (UV-vis), and electrochemical (cyclic voltammetry) properties of with the benzimidazolinylidene congener (general formula [VOCl(L)]) shows that the MIC is a stronger donor also for early transition metals with low d-electron population. Since electrochemical studies revealed both complexes to be reversibly reduced, the stronger donor character of MICs was not only demonstrated for the vanadium(V) but also for the vanadium(IV) oxidation state by isolating the reduced vanadium(IV) complexes and ([Co(Cp*)] = decamethylcobaltocenium).
View Article and Find Full Text PDFACS Omega
November 2019
Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami Osawa, Hachioji, Tokyo 192-0397, Japan.
(Arylimido)vanadium(V) dichloride complexes containing anionic -heterocyclic carbene (NHC) ligands that contain weakly coordinating B(CF) moieties (WCA-NHC) of the type [V(NAr)Cl(WCA-NHC-Ar')] (, Ar = 2,6-MeCH, Ar' = 2,6- PrCH) showed significant catalytic activity for ethylene polymerization in the presence of Al cocatalysts (MAO and Al Bu); the activity by the -MAO catalyst (19 500 kg-PE/mol-V·h; TOF 11 600 min) is the highest among those reported using the other (imido)vanadium(V) complexes in the presence of MAO, and the -Al Bu catalyst showed higher activity (66 000 kg-PE/mol-V·h; TOF 39 200 min). The V K-edge X-ray absorption near-edge structure (XANES) analyses (in toluene) strongly suggest the formation of certain vanadium(III) species by reduction with Al Bu accompanying structural changes; the EXAFS analysis suggests the presence of the arylimido ligand and one V-Cl bond (2.34 ± 0.
View Article and Find Full Text PDFPolymers (Basel)
July 2019
Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266000, China.
A series of vanadium complexes bearing iminopyridine bidentate ligands with various electronic and steric properties: [CHPh], [CMeCHCMe], [Ph] and [2,6-PrPh] were prepared and characterized by IR spectroscopy and microanalytical analysis. The catalytic capacity of all the complexes has been investigated for isoprene polymerization and was controlled by tuning the ligand structure with different -alkyl and -aryl groups. Activated by methylaluminoxane (MAO), the aryl-substituted complex [Ph] exhibited high -1,4 selectivity (75%), and the resultant polymers had high molecular weights ( = 6.
View Article and Find Full Text PDFMolecules
May 2019
CNR-Istituto per lo Studio delle Macromolecole (ISMAC), via A. Corti 12, I-20133 Milano, Italy.
Herein, we report the homo- and co-polymerization of ethylene (E) with norbornene (NB) catalyzed by vanadium(III) phosphine complexes of the type VCl(PMePh) [n = 2 (), 1 ()] and VCl(PR) [R = phenyl (Ph, ), cyclohexyl (Cy, ), -butyl (Bu, )]. In the presence of EtAlCl and ClCCOOEt (ETA), - exhibit good activities for the polymerization of ethylene, affording linear, semicrystalline PEs with a melting temperature of approximately 130 °C. Mainly alternating copolymers with high comonomer incorporation were obtained in the E/NB copolymerization.
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