Complexes of trimethylsilyl trifluoromethanesulfonate with nitrogen, oxygen, and phosphorus donors

2016 ◽  
Vol 94 (4) ◽  
pp. 424-429 ◽  
Author(s):  
Alasdair P.M. Robertson ◽  
Saurabh S. Chitnis ◽  
Seth Chhina ◽  
Hector J. Cortes S. ◽  
Brian O. Patrick ◽  
...  
Keyword(s):  
Solid Phase ◽  
Donor Ligands ◽  
Solution Stability ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lewis Bases ◽  
Trimethylsilyl Trifluoromethanesulfonate ◽  
Solid State Structures ◽  
Lower Basicity

The Lewis acceptor chemistry of Me3SiOTf with p-block Lewis bases has been explored and a library of complexes has been characterized by spectroscopic and, where possible, crystallographic methods. Compounds with the generic formula [Me3Si(L)][OTf] (L = 4-dmap, pyr, imz, OPMe3, OPCy3, OPPh3, OpyrMe, dmso, PMe3) were isolated from 1:1 mixtures of Me3SiOTf and the respective ligand in CH2Cl2. Characterization by NMR spectroscopy confirmed the solution stability of all but [Me3Si(PMe3)][OTf], with indications that the latter dissociates into PMe3 and Me3SiOTf. Solid-state structures of [Me3Si(4-dmap)][OTf], [Me3Si(pyr)][OTf], [Me3Si(OPCy3)][OTf], [Me3Si(OPPh3)][OTf], [Me3Si(OpyrMe)][OTf], and [Me3Si(PMe3)][OTf] were elucidated by single crystal X-ray diffraction, confirming the envisaged ionic formulations resulting from the displacement of the OTf anion from the silicon center of Me3SiOTf by the incoming ligand. Mixtures of Me3SiOTf with other related donors, including ChPPh3 (Ch = S or Se), NEt3, SMe2, PPh3, 2,2′-bipy, or Me2CO, show no evidence of reaction under ambient conditions, reflecting the lower basicity and (or) greater steric encumbrance of these ligands. Reactions of Me3SiOTf with bis-donor ligands yielded complexes of the generic formulae [Me3Si(L–L)SiMe3][OTf]2 (L–L = 4,4′-bipy, tmeda, dmpe) and [Me3Si(L–L)][OTf] (L–L = 4,4′-bipy, tmeda, dmpe). The tmeda and dmpe complexes, however, were found to dissociate in solution, with complexes only prevailing in the solid phase. X-ray diffraction studies of [Me3Si(4,4′-bipy)SiMe3][OTf]2 and [Me3Si(dmpe)SiMe3][OTf]2 confirmed the expected connectivities and ionic formulations, with Si–ligand bond lengths comparable to those observed in [Me3Si(pyr)][OTf] and [Me3Si(PMe3)][OTf], respectively.

Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3

2018 ◽  
Author(s):  
Katherine Marczenko ◽  
James Goettel ◽  
Gary Schrobilgen
Keyword(s):  
Room Temperature ◽  
Triphenylphosphine Oxide ◽  
Donor Ligands ◽  
Mechanical Shock ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Coordination ◽  
Xenon Trioxide ◽  
Distorted Octahedra ◽  
Coordination Spheres

Oxygen coordination to the Xe(VI) atom of XeO<sub>3</sub> was observed in its adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO<sub>3</sub>, which detonates when mechanically or thermally shocked, the solid [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3</sub>, [(CH<sub>3</sub>)<sub>2</sub>SO]<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub>,<sub> </sub>and (C<sub>5</sub>H<sub>5</sub>NO)<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> adducts are insensitive to mechanical shock, but undergo rapid deflagration when ignited by a flame. Both [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3 </sub>and (C<sub>5</sub>H<sub>5</sub>NO)<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> are air-stable whereas [(CH<sub>3</sub>)<sub>2</sub>SO]<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> slowly decomposes over several days and [(CH<sub>3</sub>)<sub>2</sub>CO]<sub>3</sub>XeO<sub>3</sub> undergoes adduct dissociation at room temperature. The xenon coordination sphere of [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3</sub> is a distorted square pyramid which provides the first example of a five-coordinate XeO<sub>3</sub> adduct. The xenon coordination spheres of the remaining adducts are distorted octahedra comprised of three Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO<sub>3</sub>. Quantum-chemical calculations were used to assess the Xe---O adduct bonds, which are predominantly electrostatic σ-hole bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the xenon atoms.

Water soluble biguanide salts and their 1,3,5-triazine derivatives as inhibitors of acetylcholinesterase and α-glucosidase

2020 ◽  
Vol 235 (10) ◽  
pp. 465-475
Author(s):  
Ozge Gungor ◽  
Seda Nur Kertmen Kurtar ◽  
Muhammet Kose
Keyword(s):  
Spectroscopic Method ◽  
Substitute Aniline ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
Nucleophilic Reaction ◽  
X Ray ◽  
Triazine Derivatives ◽  
Acidic Conditions ◽  
Approved Drugs ◽  
Solid State Structures

AbstractSeven biguanide derivatives were prepared by the nucleophilic reaction between dicyandiamide and p-substitute aniline derivatives or memantine or adamantine under acidic conditions. The cyclization of the biguanide compounds were also conducted via acetone to give 1,3,5-triazine derivatives. The structures of the synthesized compounds were characterized by analytical methods. The solid state structures of [HL5]Cl, [H2L7]Cl2, [HL1a]Cl and [HL5a]Cl were investigated by X-ray diffraction study. The acetylcholinesterase and α-glucosidase inhibitor properties of the compounds were then evaluated by the spectroscopic method. The compounds were found to show considerable acetylcholinesterase and α-glucosidase inhibitory activities compared to the approved drugs. The cyclization of biguanide derivatives with acetone did not affect inhibition of acetylcholinesterase, yet increased the α-glucosidase inhibition.

Wide angle X-ray diffraction study of the solid-phase chlorinated poly(ethylene)

Polymer ◽  
2004 ◽  
Vol 45 (18) ◽  
pp. 6341-6348 ◽  
Author(s):  
S. Stoeva ◽  
A. Popov ◽  
R. Rodriguez
Keyword(s):  
Diffraction Study ◽  
Solid Phase ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Poly Ethylene

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Synthesis and structure of large 24-mer and 36-mer oxamate-based macrocycles

2017 ◽  
Vol 72 (7) ◽  
pp. 461-474 ◽  
Author(s):  
Saddam Weheabby ◽  
Mohammad A. Abdulmalic ◽  
Evgeny A. Kataev ◽  
Tatiana A. Shumilova ◽  
Tobias Rüffer
Keyword(s):  
Oxalyl Chloride ◽  
Spectroscopic Studies ◽  
Equimolar Amount ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Accessible Volume ◽  
Hydrogen Bond Interactions ◽  
Work Up ◽  
Solid State Structures

AbstractPoly(cyclic) oxamates represent novel and potentially multidentate ligands for coordination chemistry. To obtain them, the treatment of 2-nitroaniline with two equivalents of oxalyl chloride afforded N,N′-bis(2-nitrophenyl)oxalamide (1), and by reduction of 1 with [NH4][CO2H] and Pd/C, N,N′-bis(2-aminophenyl)oxalamide (2, bapoxH6) was synthesized. After the addition of an equimolar amount of oxalyl chloride to a THF solution of 2 and aqueous work-up the 24-membered macrocycle H8L2 was obtained. In analogues experiments, the addition of ethoxalyl and oxalyl chloride to 2 afforded the 36-membered macrocycle H12L3. The addition of Cu(OAc)2·H2O and NaOH to 2 gave rise to the formation of [Cu2(bapoxH4)(OAc)2] (4). The identities of 1, 2 and H8L2 were determined by elemental analysis, IR, NMR spectroscopic studies and by mass spectrometry. The solid state structures of H8L2, H12L3 and 4 have been determined by single-crystal X-ray diffraction studies. Macrocycle H12L3 forms chains through intermolecular hydrogen bonds, while packing of 4 consists of layers held by intermolecular dispersion and hydrogen bond interactions. 24-mer H8L2 forms a cavity with a diameter of about 7.5 Å corresponding to an accessible volume of about 120 Å3 according to the well-established 55% solution and was found to bind bromide and iodide anions selectively.

PREPARATION OF ANTIMONY-PLATINUM SURFACE ALLOY ELECTRODE BY ATOM DIFFUSION IN THE SOLID PHASE

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3999-4004
Author(s):  
HIROSHI MATSUI ◽  
KAZUFUMI WATANABE
Keyword(s):  
Diffraction Pattern ◽  
Low Temperatures ◽  
Solid Phase ◽  
Electrochemical Measurement ◽  
X Ray Diffraction ◽  
Platinum Surface ◽  
X Ray ◽  
Atom Diffusion ◽  
Heat Treated ◽  
Titanium Substrates

Antimony-platinum bilayers were prepared on titanium substrates by the two-step electrodeposition in the usual baths, and then surface alloys were formed by the atom diffusion in the solid phase. The simple antimony layer was little influenced by the substrate in both the measurements of X-ray diffraction and the i - E characteristic in a sulfuric acid solution. Regarding the bilayers, the catalytic activity in hydrogen evolution reaction was very sensitive to the presence of platinum, while the hydrogen adsorbability was quite insensitive. An interaction between antimony and platinum was confirmed by the appearance of a new dissolution wave in the electrochemical measurement and the occurrence of a new diffraction in the X-ray diffraction pattern after the heat-treatment of about 400°C. Although the new diffraction disagreed with any of the reported alloys, clear diffraction pattern of PtSb 2 alloy was observed, when the bilayers were heat-treated at about 600°C for one hour. Considering the penetration depth of X-ray, the alloying of antimony and platinum seems to occur also at low temperatures at least at the top surface.

Effect of NABr on the Pore Size and Surface Morphology of Cu Foam Prepared by Hydrogen Bubble Templating

2021 ◽  
Vol 880 ◽  
pp. 83-88
Author(s):  
Mary Donnabelle L. Balela ◽  
Reginald E. Masirag ◽  
Francis O. Pacariem Jr. ◽  
Juicel Marie D. Taguinod
Keyword(s):  
Polyethylene Glycol ◽  
Cuprous Oxide ◽  
Active Material ◽  
Current Collector ◽  
Hydrogen Bubble ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Foam ◽  
Interconnected Pores

Binderless supercapacitor electrodes are currently being employed to increase the surface contact between the active material and current collector, leading to enhanced capacitance. In binderless electrodes, the active material is directly grown on the surface of the current collector, omitting the use of insulative polymer-based binders. In this work, Cu foam was successfully electrodeposited on Cu sheet by dynamic hydrogen bubble templating (DHBT) using polyethylene glycol (PEG) and sodium bromide (NaBr) as additives. The current density was set at 3 A·cm-2 and electrodeposition was performed for 20 s. At 200 mg/L PEG, increasing the NaBr concentration from 0 to 80 mM produced Cu foam with decreasing pores sizes of about 75.15 to 34.10 μm. However, the walls of the interconnected pores became thicker as the pore diameters were reduced. This indicates that NaBr promotes Cu deposition rather than hydrogen evolution reaction (HER), leading to smaller pore sizes. X-ray diffraction confirms the oxidation of the Cu foam under ambient conditions forming cuprous oxide (Cu2O). The Cu2O/Cu foam was then utilized as binderless electrode for supercapacitor, resulting to a specific capacitance of 0.815 F·cm-2 at 5 mV·s-1. Results show the potential of the fabricated Cu2O/Cu foam as binderless electrode for pseudo-type supercapacitors.

X-Ray and Magnetic Measurements of TmFeTi2O7

2014 ◽  
Vol 215 ◽  
pp. 470-473 ◽  
Author(s):  
Tamara V. Drokina ◽  
German A. Petrakovskii ◽  
Dmitrii A. Velikanov ◽  
Maksim S. Molokeev
Keyword(s):  
Spin Glass ◽  
Solid Phase ◽  
Magnetic Measurements ◽  
Diffraction Method ◽  
Freezing Temperature ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
History Of

In this paper we are reported about a peculiarity of the crystal structure and the magnetic state of TmFeTi2O7. The compound TmFeTi2O7 has been synthesizedusing the solid-phase reaction method. Using X-ray diffraction method the disorder in the distribution of the iron ions over five nonequivalent crystal sites was observed, also the populations of the iron atoms positions were determined. We show that below Tf = 6 K the magnetization of TmFeTi2O7 depends on the magnetic history of the sample. There are indications for spin glass state. This results allow us to assume the state of spin glass is realized below freezing temperature Tf = 6 K in TmFeTi2O7.

scholarly journals Syntheses, Solid-state Structures and Catalytic Activity of Zinc Carboxylate Complexes in Lactide Polymerization

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1365-1374 ◽  
Author(s):  
Christoph Scheiper ◽  
Christoph Wölper ◽  
Dieter Bläser ◽  
Joachim Roll ◽  
Stephan Schulz
Keyword(s):  
Ring Opening ◽  
Zinc Complex ◽  
X Ray Diffraction ◽  
Polymerization Catalysts ◽  
Co Catalyst ◽  
Carboxylate Complexes ◽  
X Ray ◽  
Carboxylate Groups ◽  
Solid State Structures ◽  
Lactide Polymerization

Abstract Three dinuclear zinc carboxylate complexes [L1-3Zn(μ,η2-O2CPh)]2 (1, 2, 4) containing either the bidentate N,N′-chelating β-diketiminate ligand RNC(Me)C(H)C(Me)NR (R = 2,6-iPr2-C6H3, L1, complex 1), the tridentate O,N,N-chelating ligand OC(Me)C(H)C(Me)NCH2CH2NMe2 (L2, complex 2) or the bis-N,N′-chelating bis-β-diketiminate ligand RNC(Me)C(H)C(Me)NNC(Me)- C(H)C(Me)NR (R = 2,6-iPr2-C6H3, L3, complex 4) were synthesized and characterized including single-crystal X-ray diffraction. Reaction of the neutral bis-β-diketimine (L3(H)2) with two equivalents of ZnMe2 leads to the expected heteroleptic dinuclear zinc complex L3(ZnMe)2 3 in 93% yield. Further reaction with benzoic acid PhCO2H leads to complex 4. Complex 2 forms a rather strong carboxylate-bridged dimer, whereas the carboxylate groups in complexes 1 and 4 act as asymmetrical bridges between both Zn atoms, pointing to the formation of a weakly bonded dimer. The zinc atoms in 1 and 4 are tetrahedrally coordinated, whereas in 2 the coordination number is increased to five due to the coordination of the pendant donor arm. The ring opening polymerization (ROP) of rac-lactide was investigated with the zinc complexes 1-4 and diazabicycloundec-7-ene (DBU) as a co-catalyst. Complexes 2 and 3 are active polymerization catalysts, which in the presence of DBU converted 200 equiv. of rac-lactide into polylactide within 10 min at ambient temperature. The analysis of the crude polymer showed that the lactide polymerization with catalyst 2 occurs via a slightly modified activated-monomer mechanism.

Sign in / Sign up

Export Citation Format

Share Document