Sense of sequential 1,5-sigmatropic rearrangements of dimethyl-3,3-dialkyl-3H-pyrazole-4,5-dicarboxylates. Crystal and molecular structures of two dimethyl-4,5-dialkyl-1H-pyrazole-1,3-dicarboxylates

1991 ◽  
Vol 69 (3) ◽  
pp. 373-378 ◽  
Author(s):  
Christopher S. Frampton ◽  
Michael W. Majchrzak ◽  
John Warkentin
Keyword(s):  
Dicarboxylic Acid ◽  
Key Words ◽  
Dimethyl Ester ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Methyl Group ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Sigmatropic Rearrangements ◽  
Methoxycarbonyl Group

3,3-Dialkyl-3H-pyrazole-4,5-dicarboxylic acid dimethyl esters (4), obtained by cycloaddition of R1R2C=N+=N− (R1 = R2 = CH3; R1 = CH3, R2 = CH2CH3) to CH3O2CC≡CCO2CH3, rearrange thermally by 1,5-sigmatropic alkyl shifts to both N and C. The latter rearrangement is followed by two successive 1,5-sigmatropic shifts of a methoxycarbonyl group. Final products of the threefold rearrangement were shown to be 4,5-dialkyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl esters (6), rather than the isomeric 3,4-dialkyl-1H-pyrazole-1,5-dicarboxylic acid dimethyl esters (7), by means of single crystal X-ray diffraction. Those products therefore result from alkyl migration to C-4 of 4, followed by sequential migration of the methoxycarbonyl group, initially at C-4, to C-3 and then to N-2 of 4. In the initial alkyl migration step, ethyl migrates in preference to methyl, and in subsequent migration steps the methoxycarbonyl group migrates faster than the ethyl or methyl group. Crystals of 4-ethyl-5-methyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl ester (6b) are monoclinic, of space group P21/n, with a = 7.907(1) Å, b = 11.087(2) Å, c = 13.199(3) Å, V = 1124.9(4) Å 3, Dc = 1.34 g cm−3, Dm = 1.33 g cm−3 for Z = 4, and R1 = 0.0772 (R2 = 0.0626) for 1474 reflections (R1 = 0.0428, R2 = 0.0422 for 903 reflections with I > 3σ(I)). The structure of 6a is similar. Key words: 3,3-dialkyl-3H-pyrazoles, 1,5-sigmatropic rearrangements of; 4,5-dialkyl-1H-pyrazoles, crystal and molecular structures; 1,5-sigmatropic rearrangements of pyrazoles, sense of.

Lewis-Base Adducts of Group 1B Metal(I) Compounds. XXI The Crystal and Molecular Structures of the Unsolvated Forms of Dibromotris(triphenylphosphine)dicopper(I) and 'step' Tetrabromotetrakis(triphenyl-phosphine)tetracopper(I)

1985 ◽  
Vol 38 (8) ◽  
pp. 1243 ◽  
Author(s):  
JC Dyason ◽  
LM Engelhardt ◽  
C Pakawatchai ◽  
PC Healy ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Molecular Structures ◽  
Lewis Base ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Triphenyl Phosphine ◽  
X Ray ◽  
Crystal And Molecular Structures

The crystal structures of the title compounds have been determined by single-crystal X-ray diffraction methods at 295 K. Crystal data for (PPh3)2CuBr2Cu(PPh3) (1) show that the crystals are iso-morphous with the previously studied chloro analogue, being monoclinic, P21/c, a 19.390(8), b 9.912(5), c 26.979(9) Ǻ, β 112,33(3)°; R 0.043 for No 3444. Cu( trigonal )- P;Br respectively are 2.191(3); 2.409(2), 2.364(2) Ǻ. Cu(tetrahedral)- P;Br respectively are 2.241(3), 2.249(3); 2.550(2), 2.571(2) Ǻ. Crystals of 'step' [PPh3CuBr]4 (2) are isomorphous with the solvated bromo and unsolvated iodo analogues, being monoclinic, C2/c, a 25.687(10), b 16.084(7), c 17.815(9) Ǻ, β 110.92(3)°; R 0.072 for No 3055. Cu( trigonal )- P;Br respectively are 2.206(5); 2.371(3), 2.427(2) Ǻ. Cu(tetrahedral)- P;Br are 2.207(4); 2.446(2), 2.676(3), 2.515(3) Ǻ.

Kupfer(I)-Komplexe mit ungesättigten Stickstoffliganden, V / Kupfer(I)-Komplexe mit Diazadienen als Chelate und Brücken: Röntgenstrukturenuntersuchungen an (DAD)Cu(μ-Cl)2Cu(DAD), [(DAD)2Cu]⁺ (CuCl2)-, (DAD)CuCl, [μ-(DAD)2Cu5Cl5]n und [μ-(DAD)Cu(OTf)]n (DAD = Diazadien) / Copper(I) Complexes with Unsaturated Nitrogen Ligands, V Copper(I) Complexes with Chelating and Bridging Diazadienes: X-Ray Diffraction Studies of (DAD)Cu(μ-Cl)2Cu(DAD), [(DAD)2Cu]+ (CuCl2)-, (DAD)CuCl, [μ-(DAD)2Cu5Cl5]n and [μ-(DAD)Cu(OTf)]n (DAD = Diazadiene)

1990 ◽  
Vol 45 (10) ◽  
pp. 1369-1382 ◽  
Author(s):  
Heindirk tom Dieck ◽  
Lutz Stamp
Keyword(s):  
Coordination Polymer ◽  
Molecular Complexes ◽  
Molecular Structures ◽  
Coordination Geometry ◽  
Halide Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nitrogen Ligands ◽  
Crystal And Molecular Structures ◽  
Irregular Geometries

Diazadienes RN = CR′-CR′ = NR (DAD) form molecular complexes with copper(I) halides of composition (DAD)CuX, the structures of which vary from [(DAD)2Cu]+(CuCl2)⁻ with a non-tetrahedral bis(chelated) cation, over [(DAD)CuCl]2 with asymmetrically bridging chloro ligands to planar three-coordinate (DAD)CuCl. The composition of the isolated complexes depends on the relative concentrations or on the solvent. The “soft” coordination geometry of copper is underlined by the structure of the coordination polymer of composition (DAD)2Cu5Cl5, in which Cu atoms of coordination number 2, 3 and 4 and very irregular geometries are encountered and where the DAD ligands are exclusively bridging. Halide ions and sp2-nitrogen donors are very competitive. Bridging DAD ligands are also encountered in (DAD)Cu-Y with the less nucleophilic anions trifluoromethane-sulphonate or perchlorate. Crystal and molecular structures are established for all these coordination geometries and the causes are discussed for the coordination flexibility of copper(I)

S4N4 und seine Derivate: Isolierung und Struktur von S4N4H+[SnCl5(H2O)]– und (S3N2NH2+)2[SnCl6]2– / S4N4 and its Derivatives: Isolation and Structure of S4N4H+[SnCl5(H2O)]- and (S3N2NH2+)2[SnCl6]2-

1986 ◽  
Vol 41 (5) ◽  
pp. 581-586 ◽  
Author(s):  
Konrad Holl ◽  
Ulf Thewalt
Keyword(s):  
Acetic Acid ◽  
Molecular Structures ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal And Molecular Structures

Among the reaction products of S4N4 with SnCl4 in chloroform, that contains acetic acid and small amounts of water, there are two salts S4N4H+[SnCl5(H2O)]- (A) and (S3N2NH2+)2[SnCl6]2- (B), both containing protonated SnNm units. The crystal and molecular structures of A and B have been determined by X-ray diffraction. A: monoclinic, P21/c, a = 9.084(2), b - 23.758(4), c = 6.587(1) Å , β = 101.86(3)°, Dc = 2.383 g·cm-3 and Z = 4. B: monoclinic, P21/n, a = 9.882(3), b = 12.873(4), c = 6.807(2) Å , β = 93.77(5)°, Dc = 2.352 g·cm-3 and Z = 2. The structures of the cations in both compounds agree well with those found of other salts containing these cations.

The Crystal and Molecular Structure of Pentane-2,4-dionato-(2,3,5,6-tetrahepto-2,3-dicarbomethoxo[2.2.1]bicycloheptadiene)rhodium(I), Rh(C5H7O2) (C7H6(CO2CH3)2)

1975 ◽  
Vol 53 (18) ◽  
pp. 2707-2713 ◽  
Author(s):  
Debbie Allen ◽  
Colin James Lyne Lock ◽  
Graham Turner ◽  
John Powell
Keyword(s):  
Crystal And Molecular Structure ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Intensity Data ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Square Planar ◽  
Rhodium Atom

The crystal and molecular structures of pentane-2,4-dionato-(2,3,5,6-tetrahapto-2,3-dicarbomethoxo[2.2.1]bicycloheptadienerhodium(I), Rh(C5H7O2)(C7H6(CO2CH3)2), have been measured by single crystal X-ray diffraction. The orange crystals are monoclinic, space group P21/c, Z = 4, a = 9.245(4), b = 9.003(4), c = 21.680(15) Å, β = 113.41(5)°. The calculated and observed densities are 1.645 and 1.642(5) respectively. Intensity data were collected on a Syntex [Formula: see text] diffractometer and a full matrix least squares refinement on 3010 observed reflections leads to a conventional R = 0.0660. The structure can be considered as a roughly square planar arrangement of ligands around the rhodium atom composed of two β-ketoenolate oxygen atoms (Rh—O, 2.037(5) and 2.025(5) Å ) and the centers of the two ethylenic groups. The Rh—C distances for the olefin group attached to the two carbomethoxo groups, 2.117(8), 2.108(8) Å, appear to be slightly larger than those for the other olefinic group, 2.087(7), 2.082(6), and the corresponding C=C distances of 1.375(10) and 1.410(9) Å are different at the 95% confidence level.

The effects of protonated heterocyclic cations on the structural and magnetic properties of tetrachlorocuprate(ii) anions; X-ray, magnetochemical and EPR studies

2018 ◽  
Vol 42 (19) ◽  
pp. 15705-15713 ◽  
Author(s):  
Ülo Kersen ◽  
Andrzej Wojtczak ◽  
Alina Bienko ◽  
Julia Jezierska
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Diffraction Data ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Spectral Parameters ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Structural And Magnetic Properties ◽  
Heterocyclic Cations

The crystal and molecular structures and magnetic properties of two new complexes (HMepy)2[CuCl4]·2H2O, 2, and (H2Me2ppz)[CuCl4], 3, formed by tetrachlorocuprate(ii) anions and organic heterocyclic cations, have been determined by the analysis of their X-ray diffraction data, magnetic susceptibility behaviour and EPR spectral parameters.

Complexes of (CF3)3B with Sterically Crowded Amines. Unexpected Side Products from the Trifluoromethylation of Cl2BN(t-Bu)(Bz). Crystal and Molecular Structures of (CF3)3BNH(CH2)6, HO(CF3)2BCH(Ph)NH(t-Bu)(Bz) and Ph(CF3)2BCHN(t-Bu)(Bz)

1992 ◽  
Vol 47 (6) ◽  
pp. 772-782 ◽  
Author(s):  
Andreas Ansorge ◽  
David J. Brauer ◽  
Hans Bürger ◽  
Frank Dörrenbach ◽  
Burkhard Krumm ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amine Complexes ◽  
Crystal And Molecular Structures ◽  
Rearrangement Reaction

Trifluoromethylation of C12BN(CH2)6, Cl2B(tmp), tmp = 2,2,6,6-tetramethylpiperidino, and Cl2BN(t-Bu)(Bz) with three equivalents of CF3Br/P(NEt2)3 yields the amine complexes (CF3)3B · NH(CH2)6 (1), (CF3)3B ·NH2CMe2(CH2)2CHCMe2 (2) and (CF3)3B · NH2(Bz) (3). The preparation of 3 was accompanied by formation of three unexpected trifluoromethylboron derivatives X(CF3)2BCH(Ph)NH(t-Bu)(Bz) (D), X = Br (4), Cl (5), and (Ph)(CF3)2BCHN(t-Bu)(Bz) (6), the latter being formed from 4 by HBr elimination and rearrangement. Reaction of 4 with H2O, EtOH, HCONMe2 and Me3SnH yielded D, X = OH (7), EtO (8), HCOO (9), and (Ph)(CF3)2BCH2NH(t-Bu)(Bz) (10), respectively. The structures of 1, 6 and 7 have been determined by X-ray diffraction analysis.

Crystal structures of 1-(m-nitrophenyl)-2,2-dicarboethoxy-3-phenyl-pyrrolidin-5-one (C22H22N2O7) (I) and 1-(p-chlorophenyl)-2,2-dicarboethoxy-3-phenyl-pyrrolidin-5-one (C22H22NO5Cl) (II)

1989 ◽  
Vol 189 (3-4) ◽  
Author(s):  
G. D. Nigam ◽  
G. Mattern ◽  
R. Fröhlich
Keyword(s):  
Crystal Structures ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Crystal And Molecular Structures

AbstractThe crystal and molecular structures of 1-(m-nitrophenyl)-2,2-dicarboethoxy-3-phenyl-pyrrolidin-5-one (I) and 1-(p-chlorophenyl)-2,2-dicarboethoxy-3-phenyl-pyrrolidin-5-one (II) have been determined by X-ray diffraction methods. (I) crystallizes in the monoclinic space group

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