Search results for "Hydride"

ChemInform Abstract: Photoelectrochemical Study of Electrochemically Formed Semiconducting Yttrium Hydride (YH3-x).

2010

Abstract The first photoelectrochemical study of semiconducting YH 3− x films formed by etching bulk Y metal in 0.5 M H 2 SO 4 solution is reported. The formation of semiconducting hydride having an indirect optical band gap, E g opt , of about 2.35 eV is confirmed by in situ photocurrent spectroscopy. The photoelectrochemical behaviour of such a phase was investigated both in alkaline and in acidic solutions. The flat band potential was estimated to be U fb =−1.25 V/NHE, independent of pH.

New sensing devices part 1: indole-containing polyamines supported in nanosized boehmite particles

2005

The synthesis, characterisation and optical properties of new sensing systems made by attaching different polyamine chains functionalised with an indole fluorophore to a boehmite matrix is reported for the first time. Firstly, a family of tri(alkoxy)alkylpolyaminosilanes have been reacted with indole-3-carboxaldehyde to form the corresponding Schiff bases which were reduced with sodium borohydride. The anchoring to the surface of the boehmite nanoparticles was carried out by reacting the precursors with the hydroxyl groups available in the surface of the support. The characterisation of the materials by elemental microanalysis, X-ray powder diffraction, CP-MAS 29Si NMR and electron microsco…

2003

Hydrogenolysis of the dialkyl complexes [Y(η5-C5Me4SiMe2R)(CH2SiMe3)2(THF)] (1a, R = Me; 1b, R = Ph) results in the formation of the tetranuclear dihydrido complexes [{(η5-C5Me4SiMe2R)Y}4(μ-H)4(μ3-H)4(THF)2] (2a, R = Me; 2b, R = Ph), characterized by NMR spectroscopy. 2a was studied by single crystal X-ray diffraction. In the solid state, an unsymmetrical tetrahedral configuration of four [Y(η5-C5Me4SiMe3)] units is observed, two of which contain each one molecule of THF. Each yttrium atom is bonded to two μ2- as well as three μ3-bridging hydrido ligands. Synthese und Charakterisierung eines vierkernigen Hydrid-Clusters von Yttrium [{η5-(C5Me4SiMe3)Y}4(μ-H)4(μ3-H)4(THF)2] Die Hydrogenolyse …

Organometallic early lanthanide clusters: syntheses and X-ray structures of new monocyclopentadienyl complexes.

2004

The reaction of Ln(BH(4))(3)(THF)(3) or LnCl(3)(THF)(3) with 1 equiv of KCp*' ligand (Cp' = C(5)Me(4)n-Pr) afforded the new monocyclopentadienyl complexes Cp*'LnX(2)(THF)(n) (X = BH(4), Ln = Sm, n = 1, 1a, Ln = Nd, n = 2, 1b; X = Cl, Ln = Sm, n = 1, 3a) and [Cp*'LnX(2)](n') (X = BH(4), n' = 6, Ln = Sm, 2a, Ln = Nd, 2b; X = Cl, Ln = Nd, 4b). All these compounds were characterized by elemental analysis and (1)H NMR. Crystals of mixed borohydrido/chloro-bridged [Cp*'(6)Ln(6)(BH(4))(12-x))Cl(x)(THF)(n')] (x = 10, n' = 4, Ln = Sm, 2a', Ln = Nd, 2b'; x = 5, n = 2, Ln = Sm, 2a' ') were also isolated. Compounds 2a, 2b, 2a', 2b', and 2a'' were structurally characterized; they all exhibit a hexameric…

Lactones. Part 15: Synthesis of chiral spirolactones with a carane system—insect feeding deterrents

2002

Abstract Starting from (+)-3-carene 1 several spirolactones with carane backbone were synthesized. δ-Hydroxy-γ-lactone 5 was obtained by acidic lactonization of a γ,δ-epoxy ester. Iodolactone 8 and bromolactone 9 were products of iodolactonization of γ,δ-unsaturated acid 7 and bromolactonization of γ,δ-unsaturated ester 3 respectively. The halo lactones were subjected to reductive dehalogenation with tributyltin hydride and dehydrohalogenation with DBU. The structures of the lactones obtained were confirmed by X-ray analysis and spectral data.

Influence of structural factors and enzyme type on the reactivity and enantioselectivity of the enzymatic esterification of bicyclic meso dialcohols

1992

The meso dialcohols 1–7, obtained from the Diels-Alder adducts furan/maleic anhydride, furan/dimethyl acetylenedi-carboxylate, and cyclopentadiene/maleic anhydride, were subjected to enzymatic esterification in organic solvents. A mixture of the corresponding chiral monoacetates and the meso diacetates was obtained. It has been found that reaction rate and enantioselectivity markedly depend on substrate structure, temperature, enzyme type, and nature of the solvent. The presence of an oxygen bridge and an exo configuration are the two structural features which lead to the highest enantioselectivity values.

Novel enantiomerically pure 2-amino-1,4-diols from chiral 4-hydroxymethyl-5-iodo-1,3-oxazin-2-ones

2004

Abstract Reduction of (4 S ,5 S ,6 S )-4-hydroxymethyl-5-iodo-6-methyl-1,3-oxazin-2-one 2a and (4 S ,5 S ,6 R )-4-hydroxymethyl-5-iodo-6-phenyl-1,3-oxazin-2-one 2b with tributyltin hydride in ethanol afforded 1,3-oxazin-2-one 3a and 1,3-oxazolidin-2-one 4b , respectively. Hydrolysis of 3a and 4b under basic conditions led to enantiomerically pure aminodiols 1a and 1b . Reduction of 2b in refluxing toluene led to the unexpected bicyclic tetrahydrofuro[3 a , d ]-1,3-oxazolidin-2-one 5 as the sole product.

Tuning the photophysical properties of anti-B18H22: efficient intersystem crossing between excited singlet and triplet states in new 4,4'-(HS)2-anti-…

2013

The tuning of the photophysical properties of the highly fluorescent boron hydride cluster anti-B18H22 (1), by straightforward chemical substitution to produce 4,4'-(HS)2-anti-B18H20 (2), facilitates intersystem crossing from excited singlet states to a triplet manifold. This subsequently enhances O2((1)Δg) singlet oxygen production from a quantum yield of ΦΔ ∼ 0.008 in 1 to 0.59 in 2. This paper describes the synthesis and full structural characterization of the new compound 4,4'-(HS)2-anti-B18H20 (2) and uses UV-vis spectroscopy coupled with density functional theory (DFT) and ab initio computational studies to delineate and explain its photophysical properties.

Formation and Reactivity of a Tantalocene Trihydride Containing an Aminoethyl‐Functionalised Ligand

2003

The complex [Cp*{C5H4(CH2CH2NMe2)}TaCl2] (1) was synthesised by reaction of the lithium salt LiC5H4(CH2CH2NMe2) with the tantalum compound [Cp*TaCl3(PMe3)]. Reduction of 1 with NaAl(H)2(OCH2CH2OMe)2 leads to the trihydride derivative [Cp*{C5H4(CH2CH2NMe2)}TaH3] (2). The oxidation of 2 in THF with ferrocenium ion leads to a cationic dihydride intermediate [Cp*{C5H4(CH2CH2NMe2)}TaH2]PF6 (3) with an intramolecular stabilization by the aminoethyl side-chain of the cyclopentadienyl ligand. The hemilabile character of the functionalised cyclopentadienyl ligand was checked by treating 3 with electron-donating ligands (e.g. phosphanes, sulfides, anions); in all cases, no displacement of the amino g…

Evidence of the Facile Hydride and Enolate Addition to the Imine Bond of an Aluminum−Salophen Complex

2007

The isolation of complexes 2 and 3, unambiguously characterized by single-crystal X-ray diffraction, demonstrates that nucleophilic additions to the aluminum-coordinated imino bond of salophen complex 1 can be achieved under very mild conditions.