Novel Routes to Branchd-chain and Amino-sugars from Levoglucosenone, a Chiral Synthon Available from Cellulose. Structural Determination at Quaternary Carbon Atom by X-Ray Diffraction

Alkali metal coadsorption systems represent a step along the pathway from simple model adsorbate overlayers to more technologically relevant real systems. However, such is their complexity that very few systems have been structurally determined. Here we present a surface X-ray diffraction investigation of one of these systems, Ni (100)-(3×3)- (Cs+O) . Here a structural determination is particularly challenging due to the presence of three species in the surface layers and by the size of the unit cell. As a first step, anomalous scattering has been used to determine whether there is a contribution of the nickel substrate to the fractional order diffraction intensity. Measurements of the fractional order rods at 10 eV and 200 V below the nickel K edge (8333 eV) were used to probe the nickel contribution to the fractional order rods. It was found that the intensity of the scattering was unchanged, indicating that the fractional order peaks are caused by scattering from the coadsorbates only. This shows that the nickel surface layers are not changed by the adsorption and thus sets a useful constraint on the number of possible structures.

Download Full-text

Silver and Gold Complexes with Benzimidazolin-2-ylidene Ligands

Zeitschrift für Naturforschung B ◽

10.1515/znb-2009-11-1228 ◽

2009 ◽

Vol 64 (11-12) ◽

pp. 1458-1462 ◽

Cited By ~ 18

Author(s):

Mareike C. Jahnke ◽

Jennifer Paley ◽

Florian Hupka ◽

Jan J. Weigand ◽

F. Ekkehardt Hahn

Keyword(s):

Carbon Atom ◽

Silver Oxide ◽

Silver Complexes ◽

X Ray Diffraction ◽

Gold Complexes ◽

X Ray ◽

Linear Fashion ◽

Diffraction Structure ◽

Benzimidazolium Salts

The dicarbene silver complexes 1a, b of the type [Ag(NHC)2][AgBr2] (NHC = N,N'-dialkylbenzimidazolin- 2-ylidene) have been prepared from the parent benzimidazolium salts by reaction with silver oxide. The silver complexes have been used for the transfer of the carbene ligand to gold(I) giving the gold complexes [AuCl(NHC)] 2a, b in good yields. Crystals of 2a, b have been obtained from chloroform/pentane solutions, and X-ray diffraction structure analyses revealed gold(I) atoms coordinated in a linear fashion by an NHC carbon atom and a chloro ligand

Download Full-text

Addition of boranes to (E)-(η5-C5H5)2Zr(CH=CHPh)Cl

Open Chemistry ◽

10.2478/s11532-013-0216-5 ◽

2013 ◽

Vol 11 (5) ◽

pp. 811-816

Author(s):

Patrick Ferland ◽

Kathleen Prosser ◽

Jeremy Bourque ◽

Ian Edwards ◽

Nathan Hamilton ◽

...

Keyword(s):

Carbon Atom ◽

Diffraction Study ◽

Zirconium Oxide ◽

Organic Molecule ◽

X Ray Diffraction ◽

Space Group ◽

X Ray

AbstractIn this study, the addition of boranes to (E)-(η5-C5H5)2Zr(CH=CHPh)Cl (3) has been examined in order to investigate the regioselectivity of these ‘hydroboration’ reactions. We have found that these additions proceed with remarkable selectivity to give exclusive formation of a saturated organic molecule where one carbon atom has both the boron and the zirconium fragments. These reactions do not proceed via a conventional hydroboration reaction, but instead go through an initial transmetalation step to generate (E)-(η5-C5H5)2Zr(H)Cl (1) and the corresponding alkenyl boron intermediate, whereupon subsequent hydrozirconation of this latter species gives the geminal products. An x-ray diffraction study has been conducted on gem-(η5-C5H5)2Zr(CH(Bpin)CH2Ph)Cl (pin = 1, 2-O2C2Me4) (2). Crystals of 2 were orthorhombic with a = 18.545(3) Å, b = 15.713(3) Å, c = 16.157(3) Å in the space group Pccn. An x-ray diffraction study has also been conducted on the trinuclear zirconium oxide species (η5-C5H5)2ZrO2[ZrCl(η5-C5H5)2]2(4). Crystals of 4 were orthorhombic with a = 13.6000(8) Å, b = 14.2252(8) Å, c = 17.6500(10) Å in the space group P2(1)2(1)2(1).

Download Full-text

Oxygen chemisorption on Cu(110): A structural determination by x-ray diffraction

Physical Review B ◽

10.1103/physrevb.41.5420 ◽

1990 ◽

Vol 41 (8) ◽

pp. 5420-5423 ◽

Cited By ~ 90

Author(s):

R. Feidenhans’l ◽

F. Grey ◽

R. L. Johnson ◽

S. G. J. Mochrie ◽

J. Bohr ◽

...

Keyword(s):

Structural Determination ◽

X Ray Diffraction ◽

X Ray ◽

Oxygen Chemisorption

Download Full-text

X-Ray diffraction structure determination of a novel peptide oxazol-5(4H)-one with a chiral carbon atom in the heterocyclic moiety

Journal of the Chemical Society Perkin Transactions 1 ◽

10.1039/p19910003386 ◽

1991 ◽

pp. 3386 ◽

Cited By ~ 9

Author(s):

Claudio Toniolo ◽

Giovanni Valle ◽

Fernando Formaggio ◽

Marco Crisma ◽

Wilhelmus H. J. Boesten ◽

...

Keyword(s):

Carbon Atom ◽

Structure Determination ◽

X Ray Diffraction ◽

X Ray ◽

Chiral Carbon ◽

Diffraction Structure ◽

Heterocyclic Moiety

Download Full-text

1,1-Carboboration Reactions of Strongly Electrophilic 2-Borylethyl Thioethers

Zeitschrift für Naturforschung B ◽

10.5560/znb.2014-4190 ◽

2014 ◽

Vol 69 (11-12) ◽

pp. 1357-1364 ◽

Cited By ~ 2

Author(s):

Christina Eller ◽

Bastian Billmann ◽

Constantin G. Daniliuc ◽

Gerald Kehr ◽

Gerhard Erker

Keyword(s):

Carbon Atom ◽

Addition Product ◽

The Other ◽

X Ray Diffraction ◽

X Ray ◽

Hb C

Abstract The RSCH2CH2B(C6F5)2 boranes 3a (R=Ph) and 3b (R=Et) were in situ generated by HB(C6F5)2 hydroboration of the respective vinylthioethers. Their treatment with R1-C≡C- SiMe3 acetylenes resulted in clean 1,1-carboboration to give the respective RSCH2CH2-substituted alkenylboranes 4 (3 examples). Likewise, the reagents 3 underwent 1,1-carboboration with the acetylenes Ar2P-C≡C-SiMe3 to give the tetrasubstituted alkenylboranes 6, featuring a geminal pair of RSCH2CH2=B(C6F5)2 substituents at one carbon atom and the Me3Si=PAr2 pair at the other (3 examples). The compounds 6 feature an internal B···P interaction. The conceptually related Mes2PCH2CH2B(C6F5)2 borane (2) does not undergo 1,1-carboboration with ArS-C≡C-SiMe3 but forms the 1,2-P=B-FLP addition product 7 to the acetylene instead. Compounds 4a, 4c, 6a, and 7 were characterized by X-ray diffraction.

Download Full-text