Synthesis of N-Acylated 1,5-Benzodiazepines: Differentiation between Two Possible Acylation Sites via Hydrogen Bonding

2013 ◽  
Vol 68 (4) ◽  
pp. 397-402
Author(s):  
Carlos A. Escobar ◽  
Odette A. Alvarado ◽  
Judith A. K. Howard ◽  
Mauricio Fuentealba
Keyword(s):  
Hydrogen Bonding ◽  
Acetic Anhydride ◽  
Room Temperature ◽  
Molecular Structures ◽  
Hydroxyl Groups ◽  
Acylating Agent ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Crotonyl Chloride

Temperature-dependent regioselectivity between amino and hydroxyl groups mediated by hydrogen bonding was observed in the reaction of acetic anhydride with 2-(2,3-dimethoxyphenyl)- 4-(2-hydroxyphenyl)-2,3-dihydro-1H-1,5-benzodiazepine (1), obtaining 1-acetyl-2-(2,3-dimethoxyphenyl)- 4-(2-hydroxyphenyl)-2,3-dihydro-1H-1,5-benzodiazepine (1a), when these were reacted at room temperature, and 4-(2-acetoxyphenyl)-1-acetyl-2-(2,3-dimethoxyphenyl)-2,3-dihydro-1H-1,5- benzodiazepine (1b), when they were refluxed (148 - 150 °C). Acylation of the less hindered analog 4-(2-hydroxyphenyl)-2-phenyl-2,3-dihydro-1H-1,5-benzodiazepine (2) via crotonyl chloride (a bulky acylating agent compared with acetic anhydride) afforded by refluxing only 1-crotonyl-4- (2-hydroxyphenyl)-2-phenyl-2,3-dihydro-1H-1,5-benzodiazepine (2a). All compounds were characterized spectroscopically, and the molecular structures of compounds 1a and 2a were determined by X-ray diffraction analysis.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

scholarly journals The Isomorphous Structures of Ammonium trans-Diiodobis(ethanedial-dioximato-(1–)-N,N′)cobaltate(III) and Ammonium trans-Diiodobis(ethanedial-dioximato-(1–)-N,N′)rhodate(III): Extended Metaloximate Chains with a Novel ···I–M–I···I–M–I··· Zigzagged Structure

1990 ◽  
Vol 45 (11) ◽  
pp. 1508-1512 ◽  
Author(s):  
Michel Mégnamisi-Bélombé ◽  
Bernhard Nuber
Keyword(s):  
Room Temperature ◽  
Ammonium Salts ◽  
Monoclinic Space Group ◽  
Hydroxyl Groups ◽  
Coordination Geometry ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anionic Complexes ◽  
Complex Anions

The ammonium salts of the complex anions trans-diiodobis(ethanedial-dioximato)-cobaltate(III), [Col2(GH)2]-, and trans-diiodobis(ethanedial-dioximato)rhodate(III), [RhI2(GH)2]- (GH- = ethanedial dioximate or glyoximate), have been synthesized and their structures determined from single crystal X-ray diffraction data at room temperature. The crystals of the two salts are monoclinic, space group C2/c. NH4[CoI2(GH)2] (I) crystallizes as dark-brown prisms with a greenish reflectance; its crystal data are: C4H10Col2N5O4, Mr = 504.90; a = 8.910(6), b = 11.700(9), c = 11.691(6) Å; β = 93.55(5)°; V = 1216.4 Å3; Z = 4; Dc = 2.78 Mg m-3. NH4[RhI2(GH)2] (II) crystallizes as yellow-brown blocks with crystal data: C4H10I2N5O4Rh, Mr = 548.88; a = 9.038(4), b = 11.949(5), c = 11.770(3) Å; β = 95.54(3)°; V = 1265.16 A3; Z = 4; Dc = 2.87 Mg m-3. The two structures were refined to a final RW = 0.045 for 1209 observed independent reflections and 95 parameters for I, and to a final RW = 0.040 for 1922 observed independent reflections and 87 parameters for II. The coordination geometry around Co or Rh in the anionic complexes is a distorted (4 + 2) octahedron of four equatorial chelating N atoms and two apical iodides. The H atoms of the hydroxyl groups are involved, as usual, in intramolecular O—H—O bridges with uniform Ο···Ο separations of 2.582 Å for I, and 2.713 Å for II. The rectilinear I—Co—I or I—Rh—I triads form “infinite” zigzag chains extending parallel to the ab plane, with a weak I—I contact of 3.988 Å for I, and 4.010 Å for II.

Lyotropic Phase Behaviour and Structural Parameters of Monosaccharide and Disaccharide Guerbet Branched-Chain β-D-Glycosides

2014 ◽  
Vol 895 ◽  
pp. 111-115 ◽  
Author(s):  
Hairul A.A. Hamid ◽  
Rauzah Hashim ◽  
John M. Seddon ◽  
Nicholas J. Brooks
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
Structural Parameters ◽  
Phase Behaviour ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Branched Chain ◽  
Optical Polarizing Microscopy ◽  
Water Contents

The phase behaviour and self-assembly structural parameters of a pair of monosaccharide and disaccharide Guerbet branched-chain β-D-glycosides, namely 2-octyldodecyl β-D-glucoside (β-Glc-C12C8) and 2-octyldodecyl β-D-maltoside (β-Mal-C12C8), have been studied by means of optical polarizing microscopy (OPM) and small-angle X-ray diffraction at room temperature (25°C). These compounds are sugar-based glycolipid surfactants having a total chain length of C20, and differ based on the increasing number of hydroxyl groups of the sugar headgroup (glucose and maltose). The repeat spacings obtained by X-ray diffraction as a function of water content have been used to determine the limiting hydration for the two glycosides. At room temperature, β-Glc-C12C8 and β-Mal-C12C8 have limiting hydrations of 22 wt% and 25 wt%, corresponding to 8 10 and 10 12 water molecules per glycoside, respectively. At all water contents between 5 and 29 wt % water, these compounds adopt inverse hexagonal (HII) or fluid lamellar (Lα) phases. The structural parameters of these phases have been determined from the diffraction data, from the X-ray repeat spacings, densities and concentration of the glycosides.

A temperature-dependent structure study of gem-quality hibonite from Myanmar

2010 ◽  
Vol 74 (5) ◽  
pp. 871-885 ◽  
Author(s):  
M. Nagashima ◽  
T. Armbruster ◽  
T. Hainschwang
Keyword(s):  
Room Temperature ◽  
Structure Study ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Trigonal Bipyramidal ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Length Distortion

AbstractThe structure of hibonite from Myanmar (space group P63/mmc, Z = 2, at room temperature a = 5.5909(1), c = 21.9893(4) Å), with simplified formula CaAl12O19 and composition (Ca0.99Na0.01)Σ1.00 was investigated between temperatures of 100 K and 923 K by single-crystal X-ray diffraction methods. Structure refinements have been performed at 100, 296, 473 and 923 K. In hibonite from Myanmar, Ti substitutes for Al mainly at the octahedral Al4 site and, to a lesser degree, at the trigonal bipyramidal site, Al2. The Al4 octahedra build face-sharing dimers. If Ti4+ substitutes at Al4, adjacent cations repulse each other for electrostatic reasons, leading to off-centre cation displacement associated with significant bond-length distortion compared to synthetic (Ti-free) CaAl12O19. Most Mg and smaller proportions of Zn and Si are assigned to the tetrahedral Al3 site. 12-coordinated Ca in hibonite replaces oxygen in a closest-packed layer. However, Ca is actually too small for this site and engages in a ‘rattling-type’ motion with increasing temperature. For this reason, Ca does not significantly increase thermal expansion coefficients of hibonite. The expansion of natural Ti,Mg-rich hibonite between 296 and 923 K along the x and the z axes is αa = 7.64×10–6 K–1 and αc = 11.19×10–6 K–1, respectively, and is thus very similar to isotypic, synthetic CaAl12O19 and LaMgAl11O19 (LMA).

X-ray study of the α–β transformation of berlinite (AlPO4)

1976 ◽  
Vol 54 (6) ◽  
pp. 638-647 ◽  
Author(s):  
H. N. Ng ◽  
C. Calvo
Keyword(s):  
Room Temperature ◽  
Translational Motion ◽  
Fold Axis ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Atomic Displacements ◽  
Β Phase ◽  
Four Corners ◽  
Dauphiné Twinning

The α–β transformation of berlinite (AlPO4) at 586 °C was studied by X-ray diffraction. Atomic displacements were obtained from results of least-squares refinement of data taken between room temperature and 600 °C using reflections whose intensity is unaffected by Dauphiné twinning. The results suggest a rotational motion of the PO4 and AlO4 tetrahedra around the two-fold axis together with a translational motion along the same axis as the transition is approached from below. The vibrational amplitudes of the atoms increase with temperature and have exceeded half of the separation between Dauphiné twin-related configurations at 500 °C. The final β-phase configuration is not achieved by this twinning due to the mismatch of the two configurational potential minima in the a direction. Analysis of the intensity vs. temperature data favours a single minimum model for the β phase configuration over an order–disorder model. The β-AlPO4 structure consists of alternate PO4 and AlO4 tetrahedra sharing all four corners with P—O and Al—O distances 1.505 and 1.694 Å respectively. The results are correlated with those obtained from temperature dependent studies by Raman scattering and by EPR on Fe3+-doped AlPO4.

Structures of Energetic Acetylene Derivatives HC≡CCH2ONO2, (NO2)3CCH2C≡CCH2C(NO2)3 and Trinitroethane, (NO2)3CCH3

2013 ◽  
Vol 68 (5-6) ◽  
pp. 719-731 ◽  
Author(s):  
Thomas M. Klapötke ◽  
Burkhard Krumm ◽  
Richard Moll ◽  
Alexander Penger ◽  
Stefan M. Sproll ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Room Temperature ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Polar Solvents ◽  
X Ray ◽  
Nmr Study ◽  
Acetylene Derivatives

The molecular structures and relative ratios of the two conformers (anti and gauche) of HCCCH2ONO2 detected in the gas phase at room temperature have been determined by electron diffraction. The results are discussed on the basis of quantum chemical calculations. The molecular structures of (NO2)3CCH2C≡CCH2C(NO2)3 and (NO2)3CCH3 have been determined by X-ray diffraction. A109Ag NMR study was performed for silver trinitromethanide Ag[C(NO2)3] in various polar solvents.

Polymorphism of naphthazarin and its relation to solid-state proton transfer. Neutron and X-ray diffraction studies on naphthazarin C

1985 ◽  
Vol 399 (1817) ◽  
pp. 295-319 ◽  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Model Comparison ◽  
Molecular Model ◽  
Molecular Formula ◽  
X Ray Diffraction ◽  
X Ray

The crystal structure of naphthazarin C has been determined by neutron diffraction at 60 and 300 K (λ ═ 0.895 Å; 1 Å ═ 10 -10 m ═ 10 -1 nm) and X-ray diffraction at 300 K. The space group is Pc at 60 K, but P 2 1 /c at 300 K. There are small but significant differences in cell dimensions at the two temperatures: a ═ 7.664 (7.915), b ═ 7.304 (7.262), c ═ 15.16 (15.284) Å; β ═ 114.60 (114.20)°; Z ═ 4; U ═ 771.6 (801.3) Å 3 (values at 300 K in parentheses). Neutron diffraction shows that the Pc and P 2 1 /c structures are related by an order-disorder transition at 110±1 K. Structure analysis (1771 reflections; R F ═ 0.035; R W ═ 0.036) showed that the hydroxyl hydrogens are largely ordered at 60 K, the appropriate molecular formula being 5, 8-dihydroxy-1, 4-naphthadione. Neutron diffraction measurements at 300 K (1769 reflections; R F ═ 0.052) indicated a disordered molecular model with one-half of an hydrogen atom attached to each oxygen. X -ray diffraction measurements on naphthazarin C at 300 K (two independent sets of intensity measurements, one with CuKα and the other with MoKα) support this disordered model. The molecular dimensions for naphthazarin A and B also fit this model. Comparison of the crystal structure of naphthazarin C with those of the A and B polymorphs shows that only the former has intermolecular O─H • • • O hydrogen bonding. The diffraction results combined with the available solid-state n. m. r. data show that there is at room temperature a rapid intramolecular exchange of hydroxylic protons between each pair of oxygen atoms in all three naphthazarin polymorphs. Many 1, 3-diketones exist in an enol form in the solid. These enol forms have been reported to be disordered for about twenty molecules at room temperature (this total includes one molecule studied at 108 K, and four amino-imino systems) and ordered systems have been reported for about fifteen molecules. Intermolecular hydrogen bonding occurs only in a few of these crystals.

Energetic Materials: The Preparation and Structural Characterization of Three Biguanidinium Dinitramides

1997 ◽  
Vol 53 (3) ◽  
pp. 504-512 ◽  
Author(s):  
A. Martin ◽  
A. A. Pinkerton ◽  
R. D. Gilardi ◽  
J. C. Bottaro
Keyword(s):  
Hydrogen Bonding ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Energetic Materials ◽  
Room Temperature ◽  
Asymmetric Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths

Three biguanidinium salts of the energetic dinitramide anion have been prepared and structurally characterized from room-temperature X-ray diffraction data. Biguanidinium mono-dinitramide, (BIGH)(DN), triclinic, P\overline 1, a = 4.3686 (4), b = 9.404 (2), c = 10.742 (1) Å, \alpha = 83.54 (1), \beta = 80.386 (9), \gamma = 79.93 (1)°, V = 426.8 (1) Å3, Z = 2, D x = 1.62 g cm−3. Biguanidinium bis-dinitramide, (BIGH2)(DN)2, monoclinic, C2/c, a = 11.892 (2), b = 8.131 (1), c = 13.038 (2) Å, \beta = 115.79 (1)°, V = 1135.1 (3) Å3, Z = 4, D x = 1.84 g cm−3. Biguanidinium bis-dinitramide monohydrate, (BIGH2)(DN)2.H2O, orthorhombic, P212121, a = 6.4201 (6), b = 13.408 (1), c = 14.584 (2) Å, V = 1255.4 (4) Å3, Z = 4, D x = 1.76 g cm−3. All three structures are characterized by extensive hydrogen bonding. Both the mono- and diprotontated cations consist of two planar halves twisted with respect to each other. The dinitramide anion has a surprisingly variable and asymmetric structure. The two halves of the anion are twisted with respect to each other; however, the twist varies from 5.1 to 28.9°. In addition, the two ends of the anion have significantly different geometries, e.g. the `equivalent' N—N bond lengths differ by up to 0.045 Å.

Addition der schweren Chalkogen-Atome und Halogenonium-Ionen an Carbodiphosphorane / Addition of the Heavy Chalkogen Atoms and Halogenonium Ions to Carbodiphosphoranes

1985 ◽  
Vol 40 (10) ◽  
pp. 1293-1300 ◽  
Author(s):  
H. Schmidbaur ◽  
Chr. Zybill ◽  
D. Neugebauer ◽  
G. Müller
Keyword(s):  
Room Temperature ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Molar Ratios ◽  
Structure Factors ◽  
Elemental Iodine

Hexaphenylcarbodiphosphorane Ph3P=C=PPh3 (1) forms deeply coloured, crystalline 1:1 ad- ducts with elemental sulfur, selenium and tellurium (2, 3 and 7, respectively). A superior method of synthesis for 7 is the reaction of Na2Te with (Ph3P)2CCl⊕Cl⊖. All three compounds are thermally unstable and decompose at or below room temperature. A selenium adduct 5 was also obtained with Me3P = C = PPh, (4). The compounds 2 and 3 can be alkylated at the chalkogen atoms using MeOSO2F or PhCH2Cl. Oxydation of 3 leads to Se - Se coupling.Addition of elemental iodine to 1 in molar ratios 1:1. 2:3 and 1:2 affords salt-like products composed of the (Ph2P)2Cl⊕ cation associated with I⊖ and/or I3⊖ anions (8a-c).The crystal and molecular structures of 3 and 8b have been determined by single crystal X-ray diffraction. 3′, containing one half equivalent of disordered tetrahydrofuran, crystallizes in the monoclinic space group P21/n (a = 10.848(6), b = 17.433(8). c = 16.848(9) Å, β = 91.51(5)°. V = 3185.07 Å3, ϱx = 1359 gcm-3, Z = 4). Based on 3488 structure factors, the final R value was 0.103. The selenium is attached to the ylidic carbon atom without major changes of the Ph3P=C=PPh3 skeleton (C - Se = 1.99 Å). 8b crystallizes in the triclinic space group P1̄ (a = 9.935(2). b = 11.507(2), c = 16.646(3) Å, α = 90.91(1), β = 112.00(1), γ = 96.60(1)°, V = 1749.15 A3, ϱx = 1.741 gcm-3, Z = 2). Refinement of 382 parameters on 5096 structure factors converged at R = 0.043. The molecular structure shows close similarities to the selenium adduct 3 (C-I = 2.12 Å).

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