114 research outputs found
Le dĂ©cret dâĂ©mancipation imaginaire : monarchisme et esclavage en AmĂ©rique du Nord et dans la CaraĂŻbe au temps des rĂ©volutions
Dans les AmĂ©riques de lâĂ©poque coloniale, et notamment dans la CaraĂŻbe, les esclaves sont souvent influencĂ©s par la rumeur annonçant quâun roi a dĂ©crĂ©tĂ© leur Ă©mancipation, mais que les propriĂ©taires dâesclaves ou les autoritĂ©s coloniales refusent de le publier. Au nom de ces lois imaginaires, de nombreuses rĂ©voltes dâesclaves se dĂ©clenchent du milieu du xviie siĂšcle jusquâau cĆur du xixe, avec un apogĂ©e dans les annĂ©es qui suivent la RĂ©volution française.In the colonial Americas and especially in the Caribbean, black slaves were often influenced by the rumor that a king had decreed their emancipation. The refusal of slaveowners and colonial authorities to honor this imaginary decree set off revolts from the mid-seventeenth to the mid-nineteenth century, their number peaking after the outbreak of the French Revolution
Interrupted Continuities: Transatlantic Relations during and after the Age of Revolutions (1775â1824)
This essay reviews the following works: Connections after Colonialism: Europe and Latin America in the 1820s. Edited by Matthew Brown and Gabriel Paquette. Tuscaloosa: University of Alabama Press, 2013. Pp. vii + 328. 35.00 cloth. ISBN: 9780674735385. Imperial Portugal in the Age of Atlantic Revolutions: The Luso-Brazilian World, c. 1770â1850. By Gabriel Paquette. New York: Cambridge University Press, 2013. Pp. vi + 445. 25.00 paper. ISBN: 9780300219845. Crisis in an Atlantic Empire: Spain and New Spain, 1808â1810. By Barbara H. Stein and Stanley J. Stein. Baltimore: John Hopkins University Press, 2014. Pp. ix + 773. 34.95 cloth. ISBN: 9780826520777
La RepĂșblica Holandesa y su posiciĂłn en el contexto colonial americano despuĂ©s de 1713
During the War of Spanish Succession, the Dutch Republic fought alongside the Austrians and their allies against the Bourbon party. Still, and in spite of its alliance with England, the treaties of Utrecht did not leave the Dutch Republic in a good position. In this article, these treatiesâ consequences for the commercial and colonial Dutch expansion in the Atlantic world are analyzed.Durante la guerra de SucesiĂłn española, la RepĂșblica Holandesa luchĂł junto al bloque aliado austracista contra la opciĂłn borbĂłnica. Sin embargo, y a pesar de su alianza con Inglaterra, la RepĂșblica Holandesa no saliĂł bien restablecida de los tratados de Utrecht. En este artĂculo se analizarĂĄn las consecuencias que estos tratados tuvieron para la expansiĂłn comercial y colonial de Holanda en el AtlĂĄntico
Synthesis, Structure, and Properties of Compounds in the NaHSO_4âCsHSO_4 System. 1. Crystal Structures of Cs_2Na(HSO_4)_3 and CsNa_2(HSO_4_)3
Exploratory synthesis in the NaHSOâ-CsHSOâ system, aimed at discovering novel proton conducting solids, resulted in the new compounds CsNaâ(HSOâ)â and CsâNa(HSOâ)â. Single-crystal X-ray diffraction (performed at room temperature) revealed CsNaâ(HSOâ)â to crystallize in the cubic space group P2â3 with lattice parameters a=10.568(2)Ă
and Z=4, whereas CS2Na(HSOâ)â, studied by both single-crystal neutron and X-ray methods, crystallizes in the hexagonal space group P6â/m. The latter compound has lattice parameters a=8.5712(17) and c=9.980(2)Ă
, and Z=2. The unit cell volumes are 1180.4(4) and 634.9(2)Ă
Âł, respectively, giving calculated densities of 2.645 and 3.304 mg mâ»Âł. Refinement using all observed reflections yielded a weighted residual, R-w(FÂČ), of 0.0515 based on FÂČ X-ray values for CsNaâ(HSOâ)â. For CsâNa(HSOâ)â the analogous X-ray and neutron values were 0.0483 and 0.1715, respectively. Both structures contain a single, crystallographically distinct, asymmetric hydrogen bond (as confirmed by NMR investigations) and unique, three-membered (HSOâ)â rings. The geometric match between the NaOâ octahedra and the rings suggests the sodium polyhedra may serve to template the (HSOâ)â unit. In CsNaâ(HSOâ)â the rings form a distorted cubic close-packed array. The Cs atoms are located within the "octahedral" sites of this array, and the Na atoms, within the "tetrahedral" sites. The rings in CSâNa(HSOâ)â are linked together by NaO6 octahedra to form infinite Na(HSOâ)â chains that extend along 001. The hexagonal compound exhibits disorder about the sulfate tetrahedron that suggests a P6â/m â P6 phase transition may occur upon cooling
Cerium(III) and cerium(IV) nitrate complexes of trialkylphosphine oxides
Abstract
The reactions of ammonium cerium(IV) nitrate, (NH4)2Ce(NO3)6 (CAN) with trialkylphosphine oxides, R3PO (R= Et, iPropyl, nBu3, iBu3PO, tBu3PO, Cy3PO (Cy = cyclohexyl) and Oct3PO (Oct = n-octyl)) have been investigated by 31-P NMR spectroscopy in a variety of conditions. Reactions with acetone solutions of excess of CAN and R3PO and of solid CAN with chloroform solutions of R3PO and aqueous solutions of CAN with chloroform solutions of R3PO led to the observation of Ce(NO3)4(R3PO)2. 31-P NMR spectroscopy and conductimetric titration of acetone solutions of CAN with R3PO confirm the initial reactions is the formation of Ce(NO3)4(R3PO)2 (R = Et, Bu, Cy, Oct) followed by a slower reaction to form the ionic [Ce(NO3)3(R3PO)3][NO3]. The isolation of pure cop-lexes has not proved possible in most cases but crystals suitable for x-ray analysis were extracted in some instances. The structures of the Ce(IV) complexes [Ce(NO3)4(Cy3PO)2] and [Ce(NO3)3(Et3PO)3][NO3] and the related Ce(III) complexes [Ce(NO3)3(Cy3PO)3] and [Ce(NO3)3(H2O)3(Et3PO)] are reported
Intermolecular Interactions in Molecular Crystals and Their Effect on Thermally Activated Delayed Fluorescence of Helicene-Based Emitters
Here, we discuss the influence of the crystal structure on the photophysical properties of two new TADF emitters containing a non-planar helical moiety. The presence of solvent in the crystal lattice of a diaza[5]helicene-based compound alters molecular packing significantly and suppresses aggregation. This results in more intense TADF emission and an increase in PLQY. Solution-processed OLED devices gave a maximum external quantum efficiency of 7.1%
Lanthanide tri- and tetrathionates and their complexes with triphenylphosphine oxide
Lanthanide tri- and tetrathionate containing species have been prepared in solution by the reaction of potassium tri- and tetrathionate with lanthanide perchlorates. Unstable solid materials from these reactions have been examined by infrared spectroscopy and electrospray mass spectrometry (ESI MS). There was evidence of the formation of S3O62- and S4O62- coordination to lanthanide ions, but it was not possible to produce material suitable for single crystal x-ray studies. The reaction of ethanol solutions from Ln(ClO4)3 / K2SnO6 (n = 3,4) with triphenylphosphine oxide yielded crystalline materials which have been characterised by infrared spectroscopy, electrospray mass spectrometry, elemental analysis and single crystal X-ray diffraction. The trithionate complexes [Ln(S3O6)(Ph3PO)4]ClO4.3H2O (Ln = Nd, Tb) have been isolated. The tetrathionate / Ph3PO reaction gave rise to significant disproportionation giving a small quantity of [Nd(S4O6)(Ph3PO)4(H2O)]ClO4, a different isomer of [Nd(S3O6)(Ph3PO)4H2O]ClO4, neodymium sulfate and elemental sulfur. The crystal structures of the two isomers of [Nd(S3O6)(Ph3PO)4H2O]ClO4 and that of [Nd(S4O6)(Ph3PO)4H2O]ClO4 are reported. The structure of [Er(H2O)5(Ph3PO)2].5Ph3PO.3[ClO-4], formed during the attempted preparation of erbium trithionate complexes, is also described
The asymmetric aza-silyl-prins reaction: Synthesis of enantiopure piperidines
The design and development of the first asymmetric aza-silyl-Prins reaction is reported, giving rise to valuable and diverse piperidines and pipecolic acid derivatives in both high yields and as single enantiomers. The creation of a novel chiral auxiliary-homoallylic amine for the aza-silyl-Prins reaction is essential to its success
Hydride Transfer to Gold: Yes or No? Exploring the Unexpected Versatility of Au···HâM Bonding in Heterobimetallic Dihydrides
The potential for coordination and H-transfer from Cp2MH2 (M = Zr, W) to gold(I) and gold(III) complexes was explored in a combined experimental and computational study. [(L)Au]+ cations react with Cp2WH2 giving [(L)Au(Îș2-H2WCp2)]+ (L = IPr ( 1 ), cyclic (alkyl)(amino)carbene ( 2) , or phosphines PPh3 (3) and Dalphos-Me (4) [IPr = 1,3-bis(diisopropylphenyl)imidazolylidene; Dalphos-Me = di(1-adamantyl)-2-(dimethylamino)phenyl-phosphine], while [Au(DMAP)2]+ (DMAP = p-dimethylaminopyridine) affords the C2-symmetric [Au(Îș-H2WCp2)2]+ (5) . The Dalphos complex 4 can be protonated to give the bicationic adduct 4H , showing Au(I)âŠH+-N hydrogen bonding. The gold(III) Lewis acid [(C^N-CH)Au(C6F5)(OEt2)]+ binds Cp2WH2 to give an Au-H-W Ï-complex. By contrast, the pincer species [(C^N^C)Au]+ adds Cp2WH2 by a purely dative WâAu bond, without Au···H interaction. The biphenyl-based chelate [(C^C)Au]+ forms [(C^C)Au(”H)2WCp2]+, with two 2-electron-3-centre W-HâŠAu interactions and practically no Au-W donor acceptor contribution. In all these complexes strong but polarised W-H bonds are maintained, without H-transfer to gold. On the other hand, the reactions of Cp2ZrH2 with gold complexes led in all cases to rapid H-transfer and formation of gold hydrides. Relativistic DFT calculations were used to rationalize the striking reactivity and bonding differences in these heterobimetallic hydride complexes along with an analysis of their characteristic NMR parameters and UV-Vis absorption properties
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