Search results for "Alkoxide"
showing 10 items of 39 documents
Novel route in the synthesis of MCM-41 containing framework aluminum and its characterization
1999
Abstract Mesoporous molecular sieve MCM-41 with incorporated structural aluminum (Al-MCM-41) was prepared by hydrolysis of a solution of tetraethoxysilane and aluminum isopropoxide in the presence of ammonia as a catalyst. This method provides Al-MCM-41 of different Si/Al ratios from 13 to 297 corresponding to 0.3–7 mol% Al within an hour. X-ray diffraction and nitrogen adsorption measurements showed that the Al-MCM-41 prepared by this method had a highly ordered structure of pore arrays. Most Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, which gave rise to cationic sites in the framework.
Di-n-butyltin(IV)-catalyzed dimethyl carbonate synthesis from carbon dioxide and methanol: An in situ high pressure 119Sn{1H} NMR spectroscopic study
2011
The reactivity of five di-n-butyltin(IV) complexes, n-Bu2Sn(OR)(2) (1), n-Bu2SnO (3), [n-Bu2Sn(OR)](2)O (4), (n-Bu2SnO)(2)(CO2) (6) and (n-Bu2SnO)(6)[(n-Bu2SnOR)(2)(CO3)](2) (7) (R = CH3), with CO2, suggested as possible catalyst precursors and key-intermediates for the direct synthesis of dimethyl carbonate from carbon dioxide and methanol, has been investigated using high-pressure Sn-119{H-1} NMR (HP-NMR) spectroscopy. Four of the five precursors studied, i.e. 3, 4, 6 and 7 give rise to an identical Sn-119{H-1} NMR pattern which can be explicitly attributed to the fingerprint of the dimeric form of the 1-methoxy-3-methylcarbonatotetrabutyldistannoxane {5}(2). However, with 1, a new pair o…
2-Tetrahydrofurfuroxo-vanadium-(III) and -(IV) complexes. Synthesis, structures and reactivities of [V2Mg2(μ3,δ2-thffo)2(μ,δ2-thffo)4Cl4]· 2CH2Cl2 an…
1997
Vanadium complexes of 2-tetrahydrofurfuroxide (2-tetrahydrofurylmethoxide) (thffo) with the metal in oxidation state III and IV have been prepared and characterized. The reaction of [VCl3(thf)3] with 1.5 equivalents of [Mg(thffo)2] in tetrahydrofuran (thf) or CH2Cl2 led to the formation of [V2Mg2(µ3,η2-thffo)2(µ,η2-thffo)4Cl4]· 2CH2Cl21. Its structure consists of centrosymmetric tetranuclear molecules and CH2Cl2 of crystallization. Two Mg and two V atoms have distorted octahedral geometry and form a nearly regular Mg2V2 rhombus. The V · · · V distance is 3.266(2) A. The reaction of [VOCl2(thf)2] with Na(thffo) in thf yielded [V2(µ,η2-thffo)2Cl2O2] 2. Two VOCl units are linked by alkoxide ox…
Selective Oxidation of n-Butane and Butenes over Vanadium-Containing Catalysts
2000
Abstract The oxidative dehydrogenation (OXDH) of n-butane, 1-butene, and trans-2-butene on different vanadia catalysts has been compared. MgO, alumina, and Mg–Al mixed oxides with Mg/(Al+Mg) ratios of 0.25 and 0.75 were used as supports. The catalytic data indicate that the higher the acid character of catalysts the lower is both the selectivity to C4-olefins from n-butane and the selectivity to butadiene from both 1-butene or trans-2-butene. Thus, OXDH reactions are mainly observed from n-butane and butenes on basic catalysts. The different catalytic performance of both types of catalysts is a consequence of the isomerization of olefins on acid sites, which appears to be a competitive reac…
Trapping Molecular SnBr 2 (OH) 2 by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH 2 CMe 2 O) 2 SnBr 2 ] 2 ·SnBr 2 (OH) 2 a…
2012
The synthesis of the intramolecularly coordinated stannylenes and their transition-metal complexes of the type RN(CH2CMe2O)2SnL [1: L = lone pair, R = Me; 2: L = lone pair, R = n-octyl; 5: L =W(CO)5, R = Me; 6: L = Cr(CO)5, R = Me; 7: L =W(CO)5, R = n-octyl; 8: L = Fe(CO)4, R = Me], and of the tin(IV) compounds RN(CH2CMe2O)2SnBr2 (9: R = Me), [MeN(CH2CMe2O)2SnBr2]2·SnBr2(OH)2 (10) and spiro-[RN(CH2CMe2O)2]2Sn (3: R = Me; 4: R = n-octyl) is reported. The compounds were characterized by elemental analyses, 1H, 13C, 119Sn, and 119Sn magic-angle spinning (5, 6) NMR spectroscopy, electrospray mass spectrometry, and single-crystal X-ray diffraction analysis.
Lanthanide molecular oxohydroxides: Synthesis and characterisation of [Y4(μ4-O)(μ-OEt)2(μ,η2-AAA)2(η2-AAA)3]2(μ3-OH)4(μ3-OEt)2 (HAAA = allylacetatoac…
2007
International audience; The reaction between Y5O(OPri)13 and allylacetatoacetate or 2-(methacryloyloxy)ethyl acetatoacetate in 1:5 stoichiometry afforded octanuclear oxohydroxo species. Structural characterization was achieved for the allylacetatoacetate derivative homo and copolymerisation reactions with styrene were evaluated for doping of polystyrene. Hydoxo species, Y4(OH)2(AAA)10, where also obtained by reacting Y[N(SiMe3)]3 and HAAA.
Atomic layer deposition of lithium containing thin films
2009
Five different lithium containing compounds, all representing different chemical systems, were studied in order to deposit lithium containing films by atomic layer deposition ALD. The studied compounds were a lithium β-diketonate Li(thd) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate), a lithium alkoxide LiOtBu (OtBu = tert-butoxide), a lithium cyclopentadienyl LiCp (Cp = cyclopentadienyl), a lithium alkyl n-butyllithium, and a lithium amide lithium dicyclohexylamide. Films containing lithium carbonate (Li2CO3) were obtained from alternate pulsing of Li(thd) and ozone in a temperature range of 185–300 °C. The film composition was analyzed by time-of-flight elastic recoil detection analysis (…
Solution structure of R2Sn(IV)-β-N-Acetyl-Neuraminate (R=Me, Bu) complexes in D2O and DMSO-d6: experimental NMR and DFT computational study.
2007
Two diorganotin(IV)-NANA complexes (NANA (1) = beta-N-acetyl-Neuraminic Acid = 5-amino-3,5-dideoxy-D-glycero-beta-D-galactononulosic acid) with formula Me(2)Sn(iv)NANA (2) and Bu(2)Sn(IV)NANA (3) were synthesized and characterized by (1)H, (13)C and (119)Sn NMR spectroscopy, both in D(2)O and DMSO-d(6) solutions. The experimental data in DMSO suggested the monosaccharide bidentate chelation via O1 carboxylate and vicinal O2 alkoxide atoms, which, in D(2)O, can be dynamically extended to a third binding site (O8 atom) of the pendant chain. Coordination at the tin atom is discussed on the basis of experimental NMR data and DFT calculation.
Synthesis, characterization and solid-state photoluminescence studies of six alkoxy phenylene ethynylene dinuclear palladium(II) rods
2015
A rare family of six discrete binuclear [PdCl(PEt3)2] phenylene ethynylene rods with alkoxy side chains (methoxy, ethoxy and heptoxy) have been developed, and their solid-state photoluminescence results have been presented and discussed. The shorter bridging ligands are of the general formula H–CuC– C6H2(R)2–CuC–H, where R = H, OCH3, OC 2H5, and OC7H15, whereas the longer ones are based on H– CuC–C6H4–CuC–C6H2(R)2–CuC–C6H4–CuC–H, where R = OCH3, OC 2H5. These ligands display increasing length in both the main dimension (backbone length) as well as the number of carbons in the side chains (R, alkoxide side chain) that stem from the central phenylene moiety. The X-ray crystal structures of tw…
Synthesis of block copolymers with poly(methyl methacrylate): P(B-b-MMA), P(EB-b-MMA), P(S-b-B-b-MMA) and P(S-b-EB-b-MMA)
1993
Well-defined diblock copolymers poly(butadiene-b-methyl methacrylate) (=P(B-b-MMA)) and triblock copolymers poly(styrene-b-butadiene-b-methyl methacrylate) (=P(S-b-B-b-MMA)) have been prepared by sequential anionic polymerization in THF. The synthesis of P(B-b-MMA) and P(S-b-B-b-MMA) was most efficient in the presence of lithium alkoxides. By this method side reactions are suppressed and the polymerization can be performed at higher temperatures. The resulting triblock copolymers have narrow molecular weight distribution. The 1,2-PB midblock was quantitatively hydrogenated with tosylhydrazide to enhance thermal stability. Alternatively the hydrogenation can be performed at elevated pressure…