1838-13-7Relevant academic research and scientific papers
Polymer-graphene hybrid stabilized ruthenium nanocatalysts for the dimethylamine-borane dehydrogenation at ambient conditions
?en, Betül,Aygün, Ay?enur,?avk, Aysun,Duman, Sibel,Calimli, Mehmet Harbi,Bulut, Ela,?en, Fatih
, p. 578 - 583 (2019)
In this work, we reported a new catalyst consistent of graphene oxide (GO) – poly(N-vinyl-2-pyrrolidone) (PVP) hybrid supported ruthenium nanoparticles and called as Ru@GO-PVP. The GO-coupled PVP nanosheets were prepared with a new and straightforward pathway. The prepared Ru@GO-PVP nanocatalysts were characterized using some advanced analytic measurements such as XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction), TEM/HRTEM (Transmission electron microscopy/high resolution transmission electron microscopy), Raman and ICP (Inductively coupled plasma). The mean particle size of the catalyst was found to be 2.09 nm, and this catalyst having small particle size showed one of the highest catalytic activities with a very high TOF value of 896.54 h?1 in dehydrogenation of DMAB at room temperature. Therefore, the proposed hybrid and supported catalyst offer a new pathway to enhance the catalytic dehydrogenation of DMAB greatly, and this study presents a universal and powerful technique for such applications.
Dehydropolymerisation of Methylamine Borane and an N-Substituted Primary Amine Borane Using a PNP Fe Catalyst
Anke, Felix,Boye, Susanne,Spannenberg, Anke,Lederer, Albena,Heller, Detlef,Beweries, Torsten
, p. 7889 - 7899 (2020)
Dehydropolymerisation of methylamine borane (H3B?NMeH2) using the well-known iron amido complex [(PNP)Fe(H)(CO)] (PNP=N(CH2CH2PiPr2)2) (1) gives poly(aminoborane)s by a chain-growth mechanism. In toluene, rapid dehydrogenation of H3B?NMeH2 following first-order behaviour as a limiting case of a more general underlying Michaelis–Menten kinetics is observed, forming aminoborane H2B=NMeH, which selectively couples to give high-molecular-weight poly(aminoborane)s (H2BNMeH)n and only traces of borazine (HBNMe)3 by depolymerisation after full conversion. Based on a series of comparative experiments using structurally related Fe catalysts and dimethylamine borane (H3B?NMe2H) polymer formation is proposed to occur by nucleophilic chain growth as reported earlier computationally and experimentally. A silyl functionalised primary borane H3B?N(CH2SiMe3)H2 was studied in homo- and co-dehydropolymerisation reactions to give the first examples for Si containing poly(aminoborane)s.
Iron-catalyzed dehydrocoupling/dehydrogenation of amine-boranes
Vance, James R.,Schaefer, Andre,Robertson, Alasdair P.M.,Lee, Kajin,Turner, Joshua,Whittell, George R.,Manners, Ian
, p. 3048 - 3064 (2014)
The readily available iron carbonyl complexes, [CpFe(CO)2] 2 (1) and CpFe(CO)2I (2) (Cp = η-C5H 5), were found to be efficient precatalysts for the dehydrocoupling/dehydrogenation of the amine-borane Me2NH· BH3 (3) to afford the cyclodiborazane [Me2N-BH 2]2 (4), upon UV photoirradiation at ambient temperature. In situ analysis of the reaction mixtures by 11B NMR spectroscopy indicated that different two-step mechanisms operate in each case. Thus, precatalyst 1 dehydrocoupled 3 via the aminoborane Me2N=BH 2 (5) which then cyclodimerized to give 4 via an off-metal process. In contrast, the reaction with precatalyst 2 proceeded via Me 2NH-BH2-NMe2-BH3 (6) as the key intermediate, affording 4 as the final product after a second metal-mediated step. The related complex Cp2Fe2(CO)3(MeCN) (7), formed by photoirradiation of 1 in MeCN, was found to be a substantially more active dehydrocoupling catalyst and not to require photoactivation, but otherwise operated via a two-step mechanism analogous to that for 1. Significantly, detailed mechanistic studies indicated that the active catalyst generated from precatalyst 7 was heterogeneous in nature and consisted of small iron nanoparticles (≤10 nm). Although more difficult to study, a similar process is highly likely to operate for precatalyst 1 under photoirradiation conditions. In contrast to the cases of 7 and 1, analogous experimental studies for the case of photoactivated Fe precatalyst 2 suggested that the active catalyst formed in this case was homogeneous. Experimental and computational DFT studies were used to explore the catalytic cycle which appears to involve amine-borane ligated [CpFe(CO)]+ as a key intermediate.
P-C-Activated Bimetallic Rhodium Xantphos Complexes: Formation and Catalytic Dehydrocoupling of Amine-Boranes
Johnson, Heather C.,Weller, Andrew S.
, p. 10173 - 10177 (2015)
{Rh(xantphos)}-based phosphido dimers form by P-C activation of xantphos (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) in the presence of amine-boranes. These dimers are active dehydrocoupling catalysts, forming polymeric [H2BNMeH]n from H3B·NMeH2 and dimeric [H2BNMe2]2 from H3B·NMe2H at low catalyst loadings (0.1 mol %). Mechanistic investigations support a dimeric active species, suggesting that bimetallic catalysis may be possible in amine-borane dehydropolymerization.
Dehydrogenation of amine-boranes with a frustrated Lewis pair
Miller, Alexander J. M.,Bercaw, John E.
, p. 1709 - 1711 (2010)
Bulky tertiary phosphine/borane Lewis pairs PtBu 3/B(C6F5)3 react with amine-boranes to afford dehydrocoupling products and phosphonium borohydride salts.
Catalytic dehydrogenation of dimethylamine borane by group 4 metallocene alkyne complexes and homoleptic amido compounds
Beweries, Torsten,Hansen, Sven,Kessler, Monty,Klahn, Marcus,Rosenthal, Uwe
, p. 7689 - 7692 (2011)
Dehydrogenation of Me2NH·BH3 (1) by group 4 metallocene alkyne complexes of the type Cp2M(L)(η2- Me3SiC2SiMe3) [Cp = η5- cyclopentadienyl; M = Ti, no L (2Ti); M = Zr, L = pyridine (2Zr)] and group 4 metal amido complexes of the type M(NMe2)4 [M = Ti (8Ti), Zr (8Zr)] is presented.
RETRACTED ARTICLE: Monodispersed palladium-cobalt alloy nanoparticles assembled on poly(N-vinyl-pyrrolidone) (PVP) as a highly effective catalyst for dimethylamine borane (DMAB) dehydrocoupling
?elik, Betül,Yildiz, Yunus,Sert, Hakan,Erken, Esma,Ko?kun, Yagmur,?en, Fatih
, p. 24097 - 24102 (2016)
Herein we report the fabrication of monodispersed poly(N-vinyl-2-pyrrolidone) supported palladium-cobalt nanomaterials (3.45 ± 0.36 nm) and their outstanding efficiency as catalysts in dimethylamine-borane dehydrogenation. By the use of an ultrasonic double reduction method, palladium and cobalt cations were co-reduced in PVP solution and then the prepared nanocatalysts were characterized by UV-Vis, XRD, XPS and HR-TEM-EDX analyses. The nanocatalysts could be easily reused, and at extremely low concentrations and temperature they showed record catalytic activity, giving the best catalytic performance yet with a very high turnover frequency (330.94 h-1) and a low Ea value of 50.78 ± 2 kJ mol-1 for DMAB dehydrocoupling.
Ruthenium-catalyzed dimethylamineborane dehydrogenation: Stepwise metal-centered dehydrocyclization
Friedrich, Anja,Drees, Markus,Schneider, Sven
, p. 10339 - 10342 (2009)
Amine-borane dehydrogenation: Ruthenium PNP amido pincer complex I catalyzes the dehydrocoupling of dimethylamineborane to cyclic dimer (Me 2NBH2)2. The results are in agreement with a mechanism including initial alternati
Monodisperse Pt nanoparticles assembled on reduced graphene oxide: Highly efficient and reusable catalyst for methanol oxidation and dehydrocoupling of dimethylamine-borane (DMAB)
Yildiz, Yunus,Erken, Esma,Pamuk, Handan,Sert, Hakan,?en, Fatih
, p. 5951 - 5958 (2016)
Herein, monodisperse platinum (0) nanocatalyst assembled on reduced graphene oxide (Pt(0)@RGO) was easily and reproducibly prepared by the double solvent reduction method at room temperature. Pt(0)@RGO was characterized by X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS) and transmission electron microscopy (TEM) measurements that verify the formation of monodisperse Pt (0) nanoparticles on RGO. The catalytic and electrocatalytic performances of Pt(0)@RGO in terms of activity, isolability and reusability were investigated for both methanol oxidation and the dehydrocoupling of dimethylamine-borane (DMAB) in which Pt(0)@RGO was found to be highly active and reusable heterogeneous catalyst even at room temperature. The prepared nanoparticles can also electrocatalyze methanol oxidation with very high electrochemical activities (5.64 A/cm2 at 0.58 V for methanol,). The activation energy (Ea), activation enthalpy (ΔH#), and activation entropy (ΔS#) for DMAB dehydrogenation were calculated to be 59.33 kJ mol-1, 56.79 kJ mol-1 and -151.68 J mol-1K-1, respectively. The exceptional stability of new Pt(0)@RGO nanoparticles towards agglomeration, leaching and CO poisoning allow these particles to be recycled and reused in the catalysis of DMAB dehydrogenation and methanol oxidation. After four subsequent reaction and recovery cycles, Pt(0)@RGO retained ≥75% activity towards the complete dehydrogenation of DMAB.
A Highly Active Bidentate Magnesium Catalyst for Amine-Borane Dehydrocoupling: Kinetic and Mechanistic Studies
Ried, Alexander C. A.,Taylor, Laurence J.,Geer, Ana M.,Williams, Huw E. L.,Lewis, William,Blake, Alexander J.,Kays, Deborah L.
, p. 6840 - 6846 (2019)
A magnesium complex (1) featuring a bidentate aminopyridinato ligand is a remarkably selective catalyst for the dehydrocoupling of amine-boranes. This reaction proceeds to completion with low catalyst loadings (1 mol %) under mild conditions (60 °C), exceeding previously reported s-block systems in terms of selectivity, rate, and turnover number (TON). Mechanistic studies by in situ NMR analysis reveals the reaction to be first order in both catalyst and substrate. A reaction mechanism is proposed to account for these findings, with the high TON of the catalyst attributed to the bidentate nature of the ligand, which allows for reversible deprotonation of the substrate and regeneration of 1 as a stable resting state.
