- Monomeric or Dimeric Aluminum Complexes as Catalysts for Cycloaddition between CO2 and Epoxides
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A monomeric aluminum complex containing aliphatic tetradentate ligand L1 (HOCMe2CH2NMeCH2CH2NMeCH2CMe2OH) was synthesized and used as a catalyst for cycloaddition between CO2 and epoxides in the presence of PPNCl as a cocatalyst. To check the effect of ligand L1, coordinated to the aluminum center, on the activity of cycloaddition, the new ligand HOCMe2CH2NMe2, which corresponds to half of L1, was systematically designed to make monomeric or dimeric aluminum complexes. Comparison of the catalytic properties of the aluminum complex containing the tetradentate ligand with those of the two related aluminum complexes containing the bidentate ligand under the same conditions revealed that the first system showed higher activity than the other two for cycloaddition between CO2 and epoxides in the presence of PPNCl, which was the best cocatalyst out of the six compounds nBu4PBr, nBu4NCl, nBu4NBr, nBu4NI, DMAP, and PPNCl. The aluminum complexes 1-3 demonstrate catalytic activity for cycloaddition between CO2 and epoxides in the presence of cocatalysts.
- Kim, So Han,Han, Sang Yeop,Kim, Jeong Hee,Kang, Yi Young,Lee, Junseong,Kim, Youngjo
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- Heteroleptic Tin(IV) Aminoalkoxides and Aminofluoroalkoxides as MOCVD Precursors for Undoped and F-Doped SnO2 Thin Films
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A series of asymmetric and potentially bidentate amino alcohols and amino fluoro alcohols (RNOH) having a different number of methyl/trifluoromethyl substituents at the α-carbon atom, [HOC(R1)(R2)CH2NMe2] (R1 = R2 = H (dmaeH); R1 = H, R2 = CH3 (dmapH); R1 = R2 = CH3 (dmampH); R1 = H, R2 = CF3 (F-dmapH); R1 = R2 = CF3 (F-dmampH)) have been used to develop new monomeric and heteroleptic tin(IV) amino(fluoro)alkoxides [Sn(OR)2(ORN)2] (R = Et, Pri, But). These new complexes, which were thoroughly characterized by spectroscopy (IR and multinuclei NMR (1H, 13C, 19F, and 119Sn)) as well as single-crystal X-ray studies on representative samples, were investigated for their thermal behavior to determine their suitability as MOCVD precursors for the deposition of metal oxide thin films. The two most suitable compounds, [Sn(OBut)2(dmamp)2] and [Sn(OBut)2(F-dmamp)2], were used in a direct liquid injection chemical vapor deposition (DLI-CVD) process to deposit undoped SnO2 and F-doped SnO2 thin films, respectively, on silicon and quartz substrates. Film growth rates at different temperatures (from 400 to 700 °C), film thickness, crystalline quality, and surface morphology were investigated. The films deposited on quartz showed high transparency (above 80%) in the visible region and low carbon contamination on the surface (11-13% from XPS), which could easily be removed completely with 2 min of Ar+ sputtering.
- Daniele, Stéphane,Decams, Jean-Manuel,Guillon, Hervé,Jeanneau, Erwann,Mishra, Shashank,Verchère, Alexandre
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- Heteroleptic manganese compounds as potential precursors for manganese based thin films and nanomaterials
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Heteroleptic manganese compounds, [Mn(tmhd)(TMEDA)Cl]2 (1), [Mn(tmhd)(dmamp)]2 (2), Mn2(tmhd)2(edpa)2(μ-THF) (3), [Mn(dmampea)(NEt2)]2 (4), and Mn(dmampea)(iPr-MeAMD) (5), were synthesized and characterized. Compound 5 was a volatile liquid. Structural analysis revealed that 1-4 were dimers. Compounds 1 and 3, 2, and 4 had distorted octahedral, distorted trigonal-bipyramidal, and distorted tetrahedral geometries around the Mn centers, respectively. Based on thermogravimetric analysis, the residues of 2 and 3 were expected to be MnO and Mn3O4, respectively. According to thermogravimetric analysis, 4 showed a higher residual value, whereas 5 exhibited a lower value than those expected for manganese nitrides. This journal is
- Chung, Taek-Mo,Kim, Chang Gyoun,Lee, Ga Yeon,Lee, Sunju,Park, Bo Keun
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- Efficient Aluminum Catalysts for the Chemical Conversion of CO2 into Cyclic Carbonates at Room Temperature and Atmospheric CO2 Pressure
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A series of dimeric aluminum compounds [Al(OCMe2CH2N(R)CH2X)]2 [X=pyridin-2-yl, R=H (PyrH); X= pyridin-2-yl, R=Me (PyrMe); X=furan-2-yl, R=H (FurH); X= furan-2-yl, R=Me (FurMe); X=thiophen-2-yl, R=H (ThioH); X= thiophen-2-yl, R=Me (ThioMe)] containing heterocyclic pendant group attached to the nitrogen catalyze the coupling of CO2 with epoxides under ambient conditions. In a comparison of their catalytic activities with those of aluminum complexes without pendant groups at N [X=H, R=H (HH); X=H, R=Me (HMe)] or with non-heterocyclic pendant groups [X=CH2CH2OMe, R=H (OMeH); X=CH2CH2NMe2, R=H (NMe2H); X=CH2CH2NMe2, R=Me (NMe2Me)], complexes containing heterocycles, in conjunction with (nBu)4NBr as a cocatalyst, show higher catalytic activities for the synthesis of cyclic carbonates under the same ambient conditions. The best catalyst system for this reaction is PyrH/(nBu)4NBr system, which gives a turnover number of 99 and a turnover frequency of 4.1 h?1, making it 14- and 20-times more effective than HH/(nBu)4NBr and HMe/(nBu)4NBr, respectively. Although there are no direct interactions between the aluminum and the heteroatoms in the heterocyclic pendants, electronic effects combined with the increased local concentration of CO2 around the active centers influences the catalytic activity in the coupling of CO2 with epoxides. In addition, PyrH/(nBu)4NBr shows broad epoxide substrate scope and seven terminal epoxides and two internal epoxides undergo the designed reaction.
- Kim, Yoseph,Hyun, Kyunglim,Ahn, Duseong,Kim, Ran,Park, Myung Hwan,Kim, Youngjo
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p. 4211 - 4220
(2019/08/12)
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- Synthesis and characterization of Nickel(II) aminoalkoxides: Application to molecular precursors for MOCVD of Ni thin films
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Novel single precursors for Ni, Ni(dmamp)2 (1), Ni(deamp) 2 (2), and Ni(emamp)2 (3), were synthesized by the metathesis reaction between [Ni(NH3)6]Cl2 and two equiv. of Na(dmamp), Na(deamp), and Na(emamp), respectively. Complexes 1-3 have been characterized by IR, 1H NMR, and 13C NMR spectroscopies, and microanalytical data, as well as single-crystal X-ray diffraction studies. Through GC/MS analysis of the gaseous species generated by the decomposition of 1, a self-reduction pathway to form metallic Ni was studied. By the metalorganic chemical vapor deposition of 1, metallic Ni hexagonal-phase thin films were obtained at 250 °C and cubic-phase thin films were obtained at 400 °C.
- Yoo, Seung Ho,Choi, Hana,Kim, Hyo-Suk,Park, Bo Keun,Lee, Sun Sook,An, Ki-Seok,Lee, Young Kuk,Chung, Taek-Mo,Kim, Chang Gyoun
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scheme or table
p. 1833 - 1839
(2011/06/25)
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