169,820 research outputs found
Synthesis and characterisation of 3-and 4-(pentafluorosulfanyl) benzoic acid derivatives X-ray structure of 3-SF(5)-C(6)H(4)-COOH
No full textThe high yield synthesis of 3- and 4-(pentafluorosulfanyl)benzoic acid derivatives is described starting from the NO(2)-derivatives, which are reduced to the corresponding anilines. Then the NH(2)- group is converted to bromide and subsequently to the HC = O moiety. The benzaldeydes are then oxidised to the corresponding benzoic acids. The X-ray structure of 3-SF(5)-C(6)H(4)-COOH is also reported
Oxydiacetato Complexes of Thorium(IV), the Crystal Structures of Tetra-aquo Bis(oxydiacetato) thorium(IV) Hexahydrate and Di(sodium nitrate) Disodium Tris(oxydiacetato) thorium(IV).
No full textThe crystal and mol. structure of Th(oda)2(H2O)4.6H2O (I, H2oda = O(CH2CO2H)2) and Na2[Th(oda)3].2NaNO3 (II) were detd. from 3-dimensional x-ray diffraction data and refined by least squares to R = 0.049 and Rw = 0.049 for 2265 independent reflections for I and to R = 0.024 and Rw = 0.023 for 2196 independent reflections for II. Crystal parameters are as follows: I, tetragonal, space group P41212, a 10.335(2), c 20.709(5) Å, and Z = 4; II, monoclinic, space group C2/c, a 17.096(5), b 9.451(2), c 16.245(4) Å, β 107.8(1), and Z = 4. In both compds. the Th-atom lies on a crystallog. 2-fold axis. The coordination no. of Th in I is 10 (bicapped square antiprism geometry), the compd. is monomeric, the 2 oda ligands are tridentate to the metal, and 4 H2O complete the coordination sphere; in II the coordination no. of Th is 9 (tricapped trigonal prism geometry) with 3 oda ligands tridentate to the metal; the [Th(oda)3]2- and NO3- anions are held together through the Na ions which are coordinated both to the oda carboxylic O and to the nitrate O. I was prepd. from Th(NO3)4 and Hoda
Reactions of isocyanide complexes of Palladium(II) and Platinum(II) with azetidine: synthesis of acyclic diaminocarbene derivatives and X-Ray structure of [PdCl(PMe2Ph)(CH2CH2CH2NH){C(NCH2CH2CH2)NHC6H4OMe-p}]Cl*CH2Cl2
No full textAzetidine reacts in tetrahydrofuran (thf) at room temperature or below with the co-ordinated RNC ligand in each of the neutral cis-[MCl2(PPh3)(CNR)][M = Pd or Pt; R = C6H4OMe-p or But) and cationic trans-[MCl(PPh3)2(CNC6H4OMe-p)]BF4(M = Pd or Pt) complexes to form the corresponding derivatives containing the acyclic diaminocarbene moiety M–C([graphic omitted]H2)NHR. Azetidine reacts also with the bis(isocyanide) complexes cis-[PdCl2(CNR)2](R = But or C6H4OMe-p) converting one (R = But) or two (R = C6H4OMe-p) isocyanide ligands into acyclic carbenes
Crystal and molecular structure of 2,3,6,7-tetramethoxy-9-trichloromethyl-10-carboxymethyl-9,10-dihydroanthracene
No full textCl3O6C21H21, Mr=475.75, orthorhombic, P212121, a=21.895(3), b=12.101(2), and c=8.237(2) Å, V=2182.4(7) Å3, Dx=1.45 g cm-3 for Z=4, λ(Mo Kα)=0.71069 Åμ=3.99 cm-1, F(000) 984, room temperature, R=0.035 for 1877 observed reflections. The molecule exhibits a folded conformation: the dihedral angle between the benzene rings is 28.3(1)°. The central ring is characterized by a cis diaxal configuration of hydrogen atoms in the 9, 10 positions, confirming the 13-C NMR results
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Synthesis, characterization and crystal structure of [Pt(Me)(dppe){eta(1)-CH(PPh3)(COOEt)}]BF4. An example of overcrowded molecule and correlated properties
No full textThe complex [Pt(Me)(dppe){eta1-CH(PPh3)(COOEt)}]BF4 has been synthesized and characterized spectroscopically and structurally. It crystallizes in the space group P21/n, with lattice constants a=14.525(3) Å , b=14.931(3) Å , c=21.921(4) Å , beta=103.47(3)°. The X-ray analysis revealed a particularly overcrowded molecular structure containing high stereochemical constraints. The structural features account for specific chemical and physical properties of this compound, thus representing an interesting example of applied crystallography
Cyclization reaction of amines with dialkyl carbonates to yield 1,3-oxazinan-2-ones
No full textA number of six-membered cyclic carbamates (oxazinanones) were synthesized from the reaction of a primary amine or hydrazine with a dicarbonate derivative of 1,3-diols in a one-pot reaction, in good yield, short time span, and in the absence of a solvent. The reaction proceeds in two steps: an intermolecular reaction to give a linear intermediate and an intramolecular cyclization to yield the cyclic carbamate. This is the first example of a carbonate reacting selectively and sequentially, firstly at the carbonyl center to form a linear carbamate and then as a leaving group to yield a cyclic carbamate
Dimethyl(dimethylaminoethylene)amonium 2,6-dinitro-4-trifluoromethyl-benzenesulfonate
No full textthe paper report details of the preparation and the structural analysis of the title compound
Benzylamidine Complexes of Platinum(II) Derived by Nucleophilic Addition of Primary and Secondary Amines. X-Ray Crystal Structure of Trans-[PtCl2{Z-N(H)=C(NHMe)CH2Ph}2]
No full textThe reaction of cis- and trans-[PtCl(2)(NCCH(2)Ph)(2)] with a 5-fold excess of MeNH(2) and Me(2)NH in CH(2)Cl(2) at -10 degrees C affords in high yield the bis-amidine derivatives cis- and trans-[PtCl(2){Z-N(H)=C(NHMe)CH(2)Ph}(2)] (1a, 2a) and cis- and trans-[PtCl(2){EN(H)=C(NMe(2))CH(2)Ph}(2)] (3a, 4a), respectively. The complexes were characterized by means of elemental analysis, multinuclear NMR and FT-IR techniques. The X-ray diffraction analysis was carried out for trans-[PtCl(2){Z-N(H)=C(NHMe)CH(2)Ph}(2)] (2a)
Conversion of Nitriles Into Delta-2-1,3-oxazolines In Platinum(II) Complexes - Crystal-structure of trans-[PtCl2(N=C(Bu(t))OCh2Ch2)2]
No full textThe reactions of cis- and trans-[PtCl2(NCR)2] (R = p-MeC6H4, p-CF3C6H4, o-MeC6H4, Et, Pr(n), Pr(i) or Bu(t)) complexes with 2 equivalents of -OCH2CH2Cl, generated by deprotonation of HOCH2CH2Cl with LiBu(n), afford in high yield the bis(DELTA2-1,3-oxazoline) derivatives cis-and trans-[PtCl2{N=C(R)OCH2CH2}2]. The complexes have been characterized by their elemental analyses, IR, H-1 NMR, C-13-{H-1} NMR and FAB mass spectra. The structure of trans-[PtCl2{N=C(But)OCH2CH2}2] was established also by X-ray crystallography: monoclinic, space group P2(1)/n, a = 11.233(2), b = 8.741(2), c = 9.394(2) angstrom, beta = 101.61(3)degrees and Z = 2; R = 0.038 (R' = 0.042) for 2514 measured reflections with I greater-than-or-equal-to 3sigma(I). The N-C(R) and (R)C-O bond distances of 1.284(5) and 1.335(5) angstrom suggest that there is extensive electron delocalization within the N-C(R)-O system. The co-ordination geometry around Pt(II) is planar and the oxazoline rings are only slightly twisted. The formation of DELTA2-1,3-oxazolines from platinum(II)-co-ordinated nitriles has also been examined using HOCH2CH2Cl in the presence of the weak base NEt3. These reactions proceed through the initial formation of the bis(imido ester) complexes [PtCl2{NH= C(R)OCH2CH2Cl}2], present as their (Z,Z), (EE) and (E,Z) conformers, which slowly convert to the final cyclic DELTA2-1,3-oxazoline derivatives
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