- Tris(2,6-diisopropylphenolato)titanium(IV) dihydridodiorganylborates: Synthesis and structures
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The reactions of tris(2,6-diisopropylphenolato)titanium(IV) chloride with alkali-metal dihydridodiorganylborates M(H2BR2) (M = Li, K; R = Me, C6H11, CMe3; BR2 = BC5H10, BC8H14) led to the corresponding titanium dihydridodiorganylborates. However, in almost all cases byproducts such as (2,6-diisopropylphenolato)diorganylboranes, triorganylboranes, diorganylboranes, diborane and tetrakis(2,6- diisopropylphenolato)titanium(IV) were also generated. (2,6-iPr 2C6H3O)3Ti(H2BR 2) compounds also resulted from the interaction of methyltris(2,6-diisopropylphenolato)titanium, for example, with catecholborane. In addition to the formation of tris(2,6-diisopropylphenolato) catecholboratotitanium(IV), B-methylcatecholborane was also formed The reaction of potassium dihydro-9-cyclooctylborate with 2,6-bis(2,2-di-tert-butyl-2- hydroxyethyl)pyridinetitanium dichloride (LTiCl2) led to the complex LTi(H2BC8H14)2. This compound showed no agostic C-H···Ti interaction in contrast to (2,6-iPr2C6H3O)3TiH 2BC8H14 and the corresponding titanium dihydridobis(cyclohexyl)borate.
- Knizek, Joerg,Noeth, Heinrich
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p. 1888 - 1900
(2011/06/26)
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- Formation and properties of hydrogenation catalysts based on palladium bisacetylacetonate and sodium tetrahydroborate
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Properties of the Pd(acac)2-nNaBH4 system in catalysis of the reactions of hydrogenation of alkenes, alkynes, and carbonyl and nitro groups were studied. A number of spectral methods (NMR, UV spectroscopy) and X-ray phase analysis were used to examine the main stages of formation of palladium hydrogenation catalysts produced in the interaction of Pd(acac)2 with sodium tetrahydroborate, and reasons for the bimodal nature of the dependence of the catalytic activity on the B/Pd ratio were considered.
- Titova,Belykh,Belonogova,Shmidt
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p. 1978 - 1985
(2010/06/17)
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- Thermal decomposition of B-N-H compounds investigated by using combined thermoanalytical methods
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The thermal decomposition of borazane BH3NH3 in the temperature range up to 500 K has been studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) combined with the FRIR spectroscopic and mass spectrometric analysis of the gas phase. Above 340 K borazane is decomposed in stages as the temperature is increased, The exothermic decomposition is accompanied by the release of approximately 2.2 mol H2/mol BH3NH3. This corresponds to a remarkable hydrogen storage density of 14.3 mass% related to the mass of borazane. In the gas phase above the solid decomposition residue monomeric aminoborane (BH2NH2), borazine (BHNH)3, which is the boron-nitrogen analog of benzene, and traces of diborane B2H6 were found beside hydrogen. The release of significant quantities of borazine was observed only at temperatures above 400 K.
- Baitalow,Baumann,Wolf,Jaenicke-R??ler,Leitner
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p. 159 - 168
(2008/10/08)
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- Preparation and properties of gallaborane, GaBH6: Structure of the gaseous molecule H2Ga(μ-H)2BH2 as determined by vibrational, electron diffraction, and ab initio studies, and structure of the crystalline solid at 110 K as determined by X-ray diffraction
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Gallaborane (GaBH6, 1), synthesized by the metathesis of LiBH4 with [H2GaCl]n at ca. 250 K, has been characterized by chemical analysis and by its IR and 1H and 11B NMR spectra. The IR spectrum of the vapor at low pressure implies the presence of only one species, viz. H2Ga(μ-H)2BH2, with a diborane-like structure conforming to C2ν symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements afforced by the results of ab initio molecular orbital calculations. Hence the principal distances (rα in A) and angles (∠α in deg) are as follows: r(Ga···B), 2.197(3); r(Ga-Ht), 1.555(6); r(Ga-Hb), 1.800(6); r(B-Ht), 1.189(7); r(B-Hb), 1.286(7); ∠Hb-Ga-Hb, 71.6(4); and ∠Hb-B-Hb, 110.0(5) (t = terminal, b = bridging). Aggregation of the molecules occurs in the condensed phases. X-ray crystallographic studies of a single crystal at 110 K reveal a polymeric network with helical chains made up of alternating pseudotetrahedral GaH4 and BH4 units linked through single hydrogen bridges; the average Ga···B distance is now 2.473(7) A. The compound decomposes in the condensed phases at temperatures exceeding ca. 240 K with the formation of elemental Ga and H2 and B2H6. The reactions with NH3, Me3N, and Me3P are also described.
- Downs,Greene,Johnsen,Brain,Morrison,Parsons,Pulham,Rankin,Aarset,Mills,Page,Rice
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p. 3484 - 3497
(2008/10/08)
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