A number of tert-butyl-substituted, cyclic, saturated and unsaturated diaminocarbene, diaminosilylene, and diaminogermylene compounds were investigated using inner shell electron energy loss spectroscopy (ISEELS) and ab initio calculations. These compounds, each of which contains a divalent group 14 element (C, Si, Ge), are of particular interest since they are stable indefinitely, and thus, they are readily accessible for detailed spectroscopic analysis. The C 1s and N 1s spectra of the hydrogenated tetravalent analogues of the saturated carbene, of di-tert-butyldiazabutadiene, and of di-tert-butyldiazabutane were also obtained to assist with spectral interpretation. Our analysis shows that there is significant π-allyl delocalization over the N−EII−N fragment in all three species. Further, in the unsaturated species there is additional aromatic delocalization. Both theory and experiment indicate that the divalent center of the carbene is qualitatively different from that in the germylenes or silylenes.

ZUSCHRIFTEN und jedes Napfchen wurde mit 100 pL 3,3',5,5'-TetramethyIbenzidin-Substrat (KPL, Gathersburg, MD, USA) versetzt. Nach drei Minuten wurde die colorimetrische Reaktion durch Zugabe von 100 pL l~ H,PO, pro Napfchen becndet, und die optische Dichte wurde bei 450 nm bestimmt. Alle NMR-Experimente wurden bei 25 "C mit einem Varian-UnityPlus-600-MHz-Spektrometer ausgefuhrt; es wurden suszeptibilitatsangepaflte NMR-Rohrchen (Shigemi) mit einem Probenvolumen von 220 pL vcrwendet. Die Probe enthielt 35 PM E-Selectin-Konstrukt und 1 7 5 0~~ des Sialyl-LewisX-Mimetikums 2 in lOOmM deuteriertem Imidazol (pH 7.4) und 1 mM CaCI, in D,O. Da jedes E-SelectinlhIgG-Molekul zwei Bindungsstellen fur Sialyl-LewisX enthalt, betrug das tatsachliche Verhaltnis Protein:Ligand 1:25. NOESY-Spektren wurden mit einem Spinlock-Filter [6] vor I, von 20 ms Dauer und 9 kHz Feldstarke aufgenommen. Die Repetitionszeit betrug 1.85 s. Die Spektren wurden mit 384 komplexen Punkten in f , und 32 Scans pro l,-lnkrement aufgenommen. Die Strukturrechnungen wurden mit dem Distanzgeometrie-Programm DGII (INSIGHTII, MSI) auf einer SGI-Workstation durchgefuhrt. 22 nichttriviale, von NOE-Daten abgeleitete Abstandsgrenzen wurden verwendet. Die Konformation der vier Kohlenhydratringe wurde fur das ungebundene Mimetikum 2 aus homonuclearen und heteronuclearen Kopplungskonstanten abgeleitet und durch Analyse von Transfer-NOE-Intensitaten fur gebundenes 2 plausibilisiert. Die Zuckerkonformationen wurden durch 36 Abstandsgrenzen zwischen Kohlenstoffatomen, die wcniger als 3 A im selben Ring auseinander liegen, fixiert. 50 Strukturen wurden rnit der Dreiecksbedingung geglattet und im vierdimensionalen Raum eingebettet. Die Strukturen wurden mit 10000 Simulated-Annealing-Schritten verfeinert. Dabei wurde die Molekulmasse mit dem Faktor 1000 multipliziert. Die Strukturen wurden dann in 250 Schritten energieminimiert (conjugate gradient). Die Summe der van-der-Waals-Radien wurde zur Einschrankung verwendet. Alle anderen nichtbindenden Wechselwirkungen wurden van den Rechnungen ausgeschlossen, um mogliche van Kraftfeldparametern hervorgerufene Artefakte zu eliminieren. Dadurch spiegelt die Strukturvielfalt im Ensemble der Strukturen tatsachlich die gemessenen Daten wider und ist nicht bloB eine Folge der Energieminirnierung. 19 berechnete Strukturen konvergierten zu Konformationen, die alle Abstandseinschrankungen innerhalb van 0.05 A erfullten. Der rmsd-Wert der Strukturen betrug 0.25 A fur dieSchweratome van Fucose, Galactose, (lR,2R)-1,2-Cyclohexandiol (cyc-2) und die Ca-C( 0)-Atome der (S)-Cyclohexylmilchsaure (cyc-1). Der rmsd-Wert fur alle Schweratome des Molekuls betrug 1.16 A.

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This paper presents the first use of close range terrestrial hyperspectral imaging to explore by-products from the iron and steel industry at a dump site cross section, using established mapping approaches in geological remote sensing. Laboratory reflectance measurements, X-Ray diffraction and chemical analysis provided a benchmark for the imaging results. In addition, terrestrial laser scanning was applied to create a high resolution 3D model of the studied section, for hyperspectral image and classification integration. Results demonstrate the applicability of spectral methods for remote discrimination and mapping of materials from iron and steel production which are of potential economic interest. This will aid the appraisal of resource distribution for urban mining and material recycling.

The aromatic stabilization of cyclic phosphenium cations (general type C2N2P+) was studied by experimental methods (synthesis, multinuclear NMR, single crystal X‐ray crystallography) and quantum chemical calculations (ab initio methods). The structures of the 1,3,2‐diazaphosphole derivatives [(tBuN–CH=CH–NtBu)P+]Cl− (1), (tBuN–CH2–CH2–NtBu)P–Cl (2), [(tBuN–CH=CH–NtBu)P]+PF6− (3) and [(tBuN–CH2–CH2‐NtBu)]P+PF6− (4) were examined by single crystal X‐ray diffraction. The chloro phosphane [(tBuN–CH=CH–NtBu)P]+Cl− (1) has an ionic P–Cl bond and contains an aromatically stabilized phosphenium cation [shortest distance P···Cl = 275.9(2) pm], while the CC‐saturated compound (tBuN–CH2–CH2–NtBu)P–Cl (2) is covalent. The two chloro‐phosphanes 1 and 2 differ sharply in their volatility and solubility in organic solvents. Compound 2 is soluble in hydrocarbons and sublimes readily at 90 °C/0.1 Torr but 1 is insoluble in hexanes and not volatile below 180 °C/0.1 Torr. The degree of aromatic stabilization in the phosphenium cation 1 was investigated by ab initio methods. For the model cations [RN–CH2–CH2–NR]P+ and [(RN–CH=CH–NR)P]+, thermochemical stabilization energies of 25.8 kcal · mol−1 (R = H) and 28.1 kcal · mol−1 (R = Me) were obtained from isodesmic hydrogenation reactions at the RHF/MP2/6–31G*//RHF/6–31G* level.

No abstract

The S-alkylation of imidazolidine-2-thione with alcohols offers a low cost alternative to the use of alkyl iodides. Concentrated hydroiodic acid give consistently high yields whereas the yields with HBr and HCl are lower and vary with the type of alcohol. Pharmaceutically interesting products (III) are isolated after treatment of the reaction mixture with aq. NaOH. -(DENK*, M. K.; YE, X.; Tetrahedron Lett. 46 (2005) 44, 7597-7599; Guelph-Waterloo Cent. Grad. Stud. Chem., Guelph, Ont. N1G 2W1, Can.; Eng.) -Mais 06-128

We evaluated the opportunities and performance of a new type of systematic pixel sharp calibration site for airborne hyperspectral mineral mapping in the environment of an operational copper deposit in Mongolia. The calibration site was designed to be used for estimation of sensitivity and quantification of key minerals in individual pixels in specific geological scenarios. The layout of the calibration site was done with two different copper-containing rock samples, a low copper-containing rock material from the mine, tailing material from the mine, and calibration materials with well-defined known spectral features. The scaled coverage of the sample materials was designed to develop statistical approaches to quantify target minerals in airborne surveys on a pixel-based approach. The data collection included the description of the calibration materials with geochemical, x-ray diffraction, and microscopic and electron raster microscopic methods. Using visible and near-infrared airborne sensors and shortwave infrared airborne sensors, data of the calibration site were collected with multiple repeats from six altitudes. After rectification and atmospheric correction of pixels, sharp measurements of absorption features of clay minerals at 1400, 1900, and 2200 nm were performed and statistically analyzed. Correlations between coverage and absorption features especially around 2200 nm are shown, and influences of flight altitude on sensitivity of the detection and the stability of the measurements are investigated. The results of the calibration field are used for the quantitative estimations of clay minerals in an exploration area near the mine site. The results are also shining new light on methodologies for ground truthing in hyperspectral surveys. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.