Search results for "ether"
showing 10 items of 986 documents
Versatility and dynamics of the copper(I) coordination sphere in sterically hindering tris(pyrazolyl)methane-incorporating macrobicycles
2009
Two arene-capped macrobicycles (1 and 2) incorporating the tris(pyrazolyl)methane (Tpm) chelate have been prepared from a benzylthiol-functionalized Tpm precursor (3). Reaction of either macrobicycle with Cu(CH3CN)4+ leads to tetrahedral or trigonal-planar, fluxional complexes incorporating the Cu(CH3CN)+ subunit ([Cu(1)(CH3CN)]+ and [Cu(2)(CH3CN)]+). The acetonitrile ancillary ligand does not fit inside the macrobicycle cavity and can be removed by heating under vacuum, which produces the [Cu(1)]+ and [Cu(2)]+ species probably involving intramolecular thioether coordination. The [Cu(1)(CH3CN)]+ complex was shown to convert slowly in wet acetone into a helical coordination polymer, which is…
Oxidovanadium(V) Complexes with Aminoethanol Bis(phenolate) [O,N,O,O] Ligands: Preparations, Structures, N-Dealkylation and Condensation Reactions
2011
The reactions between [VO(acac)2] (acac– = acetylacetonate ion) or [VO(OPr)3] and trianionic tetradentate N,N-bis(2-methylene-4,6-alkylphenolate)aminoethanolate ligands, [L13– (4,6-dimethyl), L23– (4-methyl, 6-tert-butyl), L33– (4-tert-butyl, 6-methyl), L43– (4,6-di-tert-butyl)], afford mononuclear complexes [VO(L1)] (1) and [VO(L2)] (2) with a trigonal bipyramidal coordination sphere around the VV ion, or dinuclear octahedral complexes [V2O2(L3)2] (3) and [V2O2(L4)2] (4). In methanol an adduct with the formula [VO(L1)(MeOH)]·1/2MeOH (5) is obtained. According to multinuclear NMR spectroscopy all those complexes have a mononuclear structure in CDCl3 solutions. In wet polar solvents complex …
The first silver(I) nitrate π-complexes with unsaturated organosilicons: Synthesis and structural characterization of [Ag(DADPS)xNO3] (DADPS=diallyld…
2011
Abstract Tetraethylene glycol dimethyl ether (tetraglyme) was used for the first time to induce the activation of silver nitrate resulting in the step-by-step formation of complexes with diallyldiphenylsilane (DADPS). Two crystal compounds of this series were examined by FTIR spectroscopy and X-ray diffraction. The analysis of the obtained data showed that the Ag (C C) η 2 -interaction is involved in the synergistic effect of intra and intermolecular forces. In particular the interlayer π–π stacking interactions promoted by asymmetric weak Ag C(phenyl) bond have a significant influence on the thermal behavior and stability of the synthesized products. It was also found that a decrease of si…
17O NMR and molecular mechanical studies of arylmethylenemalonaldehydes
1990
The 17O NMR spectra of six different arylmethylenemalonaldehydes were measured for various solvents and temperatures. The 17O NMR chemical shifts and line widths of the carbonyl oxygens of the malonaldehyde fragment show a clear variation in the series of monoaryl compounds studied. The differences between the 17O NMR chemical shifts of the formyl oxygens correlate well with two conformationally dependent 1H–1H and 1H–13C coupling constants for the same compounds. Molecular mechanical calculations were also performed in order to relate the present data with the conformational preferences of the malonaldehyde fragment of the arylmethylenemalonaldehydes.
The generalizability of Older Adult Self-Report (OASR) syndromes of psychopathology across 20 societies
2020
Contains fulltext : 217516.pdf (Publisher’s version ) (Closed access) Objectives: As the world population ages, psychiatrists will increasingly need instruments for measuring constructs of psychopathology that are generalizable to diverse elders. The study tested whether syndromes of co-occurring problems derived from self-ratings of psychopathology by US elders would fit self-ratings by elders in 19 other societies. Methods/design: The Older Adult Self-Report (OASR) was completed by 12 826 adults who were 60 to 102 years old in 19 societies from North and South America, Asia, and Eastern, Northern, Southern, and Western Europe, plus the United States. Individual and multigroup confirmatory…
Structural effects of macrocyclic compounds and their partition in sodium dodecylsulphate aqueous solutions
2003
The partition of 1,4,7,10,13,16-esaoxacyclooctadecane (18C6), 4,7,13,16-tetraoxa-1,10-diazacyclooctadecane (2.2), 2,5,8,11,14,17-esaoxabicyclo[16.4.0]dicosane (B18C6) and 2,5,8,15,18,21-esoxatricyclo[20.4.0.09.14]esacosane (Cy218C6) in sodium dodecyl sulfate (SDS) aqueous solutions and their effect on the structure of surfactant aggregates has been investigated by small-angle neutron scattering. Results from data analysis have shown that by increasing macrocycle concentration the SDS micelles dimensions reduce for all systems investigated. At the same time information on macrocycles partition between the micellar and the continuous phase have been obtained. It was found that an appreciable …
Phenyl 2,4,6-tribromophenyl ether
2001
The title compound, C12H7Br3O, is the third well characterized of a total of 209 different brominated diphenyl ethers. The bromine-substituted rings pack in the crystal in a common plane with the same ring from symmetry-related neighbouring molecules. The short Br⋯Br contact distance [3.519 (2) A], together with a pair of considerably longer Br⋯Br contact distances [3.966 (2) A], may be part of a model describing this packing.
Complexation behaviour of hexadentate ligands possessing N2O4and N2O2S2cores: differential reactivity towards Co(ii), Ni(ii) and Zn(ii) salts and str…
2004
Reactions of divalent metal salts of Co, Ni and Zn with 1,2-di(salicylaldimino-o-phenylthio) ethane (H2L1) and 1,2-di(naphthaldimino-o-phenylthio) ethane (H2L2), having N2O2S2 cores, and 1,2-di(O-salicylaldimino-o-hydroxyphenyl) ethane (H2L3), having a N2O4 core, have been explored. Out of the three ligands and the nine products obtained from the corresponding reactions, two ligands and seven products were crystallographically characterized. However, all the ligands and the products were characterized by analytical and spectral methods. Reaction of H2L1 and H2L2 with Co(II) salts results in oxidative cleavage of the C-S bond to produce a Co(III) product bound to two dissimilar tridentate li…
Head-to-tail connected double calix[4]arenes
1997
New macrotricyclic compounds consisting of two calix[4]arene substructures connected by aliphatic chains of various length (three to five carbon atoms) between two oppositep-positions and two distal phenolic oxygens have been synthesized. Starting withp-tert-butyl-calix[4]arene, two O-protected phenolic units are attachedvia ether links in 1,3-position by reaction with the corresponding tosylates. After deprotection, the new calix[4]arene is formed by fragment condensation with 2,6-bisbromomethylated 4-alkylphenols. The structure of one example (8c) has been confirmed by single crystal X-ray analysis. Both calixarene parts assume the cone conformation, a molecule of acetonitrile being inclu…
4-Bromophenyl 2,6-dibromophenyl ether
2002
The title compound, C12H7Br3O, is an example of a compound related to some important flame retardants, e.g. decabromodiphenyl ether. Salient intermolecular interactions are the short contacts between the bromine substituents and the C atoms of the aromatic ring system. The molecules make up chains through these short Br⋯C contacts; these chains pack into sheets parallel to the ab plane, and copies of these sheets pack on to each other along the c axis in a tweed-like pattern.