Dendocarbin A: a sesquiterpene lactone fromDrimys winteri

2014 ◽  
Vol 70 (11) ◽  
pp. 1007-1010 ◽  
Author(s):  
Cristian Paz Robles ◽  
Viviana Burgos ◽  
Sebastián Suarez ◽  
Ricardo Baggio
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Sesquiterpene Lactone ◽  
Natural Compound ◽  
Intermolecular Hydrogen Bonding ◽  
Screw Axis ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
First Time ◽  
Drimys Winteri

The natural compound dendocarbin A, C15H22O3, is a sesquiterpene lactone isolated for the first time fromDrimys winterifor var chilensis. The compound crystallizes in the orthorhombic space groupP212121and its X-ray crystal structure confirmed theS/Rcharacter of the chiral centres at C-5/C-10 and C-9/C-11, respectively. The α-OH group at C-11 was found to be involved in intermolecular hydrogen bonding, defining chains along the <100> 21screw axis.

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.

The molecular and crystal structure of [Pt(diethylenetriamine)(guanosine)](ClO4)2

1979 ◽  
Vol 57 (1) ◽  
pp. 57-61 ◽  
Author(s):  
R. Melanson ◽  
F. D. Rochon
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Least Squares ◽  
Platinum Atom ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
R Factor ◽  
Square Planar ◽  
Coordination Plane

The crystal structure of [Pt(diethylenetriamine)(guanosine)](ClO4)2 has been determined by X-ray diffraction. The crystals are orthorhombic, space group P212121, with a = 12.486(6), b = 13.444(7), c = 14.678(11) Å, and Z = 4. The structure was refined by block-diagonal least-squares analysis to a conventional R factor of 0.050 and a weighted Rw = 0.045.The coordination around the platinum atom is square planar. Guanosine is bonded to platinum through N(7). The purine planar ring makes an angle of 62.7° with the platinum coordination plane. The structure is stabilized by hydrogen bonding.

Synthese, Struktur und thermisches Verhalten von Thiophosphorsäuretriamid SP(NH2)3 [1] / Synthesis, Structure, and Thermal Behaviour of Phosphorothionic Triamide SP(ΝΗ2)3 [1]

1989 ◽  
Vol 44 (8) ◽  
pp. 942-945 ◽  
Author(s):  
Wolfgang Schnick
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Thermal Properties ◽  
Single Crystal ◽  
Melting Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Ray Methods ◽  
Single Bonds

Phosphorothionic triamide SP(NH2)3 is obtained by slow addition of SPCl3 dissolved in dry CH2Cl2 to a satured solution of NH3 in CH2Cl2 at —50°C. Ammonium chloride is removed from the resulting precipitate by treatment with HNEt2 followed by extraction with CH2Cl2. Coarse crystalline SP(NH2)3 is obtained after recrystallization from dry methanol. The crystal structure of SP(NH2)3 has been determined by single crystal X-ray methods (Pbca; a = 922.3(1), b = 953.8(1), c = 1058.4(2) pm, Z = 8). In the crystals the molecules show non-crystallographic point symmetry C8. The P—S bond (195.4(1) pm) is slightly longer than in SPCl3. From P—N bond lengths of about 166 pm a significant electrostatic strengthening of the P—N single bonds is assumed. Weak intermolecular hydrogen bonding interactions (N —H · · · N ≥ 329.5 pm; N — H · · · S ≥ 348.3 pm) are observed.Investigation of thermal properties shows a melting temperature of 115°C for SP(NH2)3. According to combined DTA/TG and MS investigations above this temperature the compound decomposes by evolution of H2S and NH3 to yield amorphous phosphorus(V)nitride.

7α-Acetoxydihydronomilin: isolation, spectra, and crystal structure

1978 ◽  
Vol 56 (7) ◽  
pp. 1020-1025 ◽  
Author(s):  
Farid R. Ahmed ◽  
Angs Ng ◽  
Alex G. Fallis
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Least Squares ◽  
Furan Ring ◽  
Lactone Ring ◽  
Direct Method ◽  
Membered Ring ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray ◽  
Twist Boat

Methanol extraction of the ground seeds of Uncaria Gambier Roxb. followed by chromatography afforded a crystalline C30H38O10 terpene. This has been shown by X-ray analysis to be 7α-acetoxydihydronomilin. The crystals are orthorhombic, P212121, a = 13.158(2), b = 17.092(2), c = 12.689(2) Å, Z = 4, dx = 1.300, do = 1.300 g cm−3. The structure has been determined by the direct method and Fourier syntheses, and refined by block-diagonal least-squares to R = 0.042 for 2621 observed reflexions. The molecule contains a seven-membered lactone ring A, three six-membered rings B, C, D, a three-membered ring E, a furan ring F, and two acetate groups. A and B are chair, C is twist-boat, D is 1,3-diplanar, while E and F are planar. The A/B, A/C, C/D junctions are trans, D/E is cis, and F is linked to D by an equatorial C—C bond. The two acetate groups are in axial positions on A and B and are cis to each other. The O atom forming the apex of the three-membered ring is wedged between two H atoms and their parent C atoms at short intramolecular distances O … H = 2.28(2) and 2.28(3), and O … C = 2.623(3) and 2.668(4) Å. No intermolecular hydrogen bonding is indicated.

A heterotrimetallic Ni(II)–Dy(III) bis(salamo)-based complex: synthesis, structure and fluorescent property

2018 ◽  
Vol 73 (5) ◽  
pp. 281-288
Author(s):  
Qing Zhao ◽  
Ying-Qi Pan ◽  
Xiao-Yan Li ◽  
Han Zhang ◽  
Wen-Kui Dong
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Supramolecular Structure ◽  
Fluorescence Spectra ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distorted Octahedral ◽  
Tricapped Trigonal Prism ◽  
Elemental Analyses

AbstractA discrete heterotrinuclear complex [{Ni2LDy(OAc)3(CH3OH)}2] · 2CH3OH · 3CH2Cl2, with a naphthalenediol-based acyclic bis(salamo) ligand H4L, has been synthesized and structurally characterized using elemental analyses, IR, UV/Vis and fluorescence spectra and single crystal X-ray diffraction. The crystal structure shows two crystallographically independent but chemically identical molecules (molecules I and II). All the Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries. The central Dy atoms are nona-coordinated with slightly distorted tricapped trigonal prism geometries. An infinite 3D supramolecular structure is formed via intermolecular hydrogen bonding and C–H…π interactions.

Synthesis of 2', 6'-Dihydroxychalcones by Using Tetrahydropyran-2-yl and Trialkylsilyl Protective Groups; the Crystal Structure Determination of 2',6'-Dihydroxy-2,4,6-trimethoxychalcone

1989 ◽  
Vol 42 (7) ◽  
pp. 1103 ◽  
Author(s):  
CO Miles ◽  
L Main ◽  
BK Nicholson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Silyl Ether ◽  
X Ray ◽  
Protective Groups ◽  
Intramolecular Hydrogen ◽  
First Time ◽  
Mild Acid

Two improved general routes to 2′,6′-dihydroxychalcones are described in which the final step is protective-group removal from O 2′ under mild acid conditions. The first involves base-catalysed condensation of benzaldehydes with 2′-hydroxy-6′-tetrahydropyran-2-yloxyacetophenone, the second ring-opening of 5-hydroxyflavanones with 1,8-diazabicyclo[5.4.0]undec-7-ene in the presence of a trialkylchlorosilane to trap out the chalcone as a bis silyl ether. Chalcones prepared by the first route are 2',6'-dihydroxychalcone (1), and its 4-methoxy (2), 3,4-dimethoxy (3), 3,4,5-trimethoxy (4), and 2,4,6-trimethoxy (5) derivatives. The 4-chloro derivative (6) and the chalcone from hesperetin are prepared by the second method. .The X-ray crystal structure of 2',6'-dihydroxy-2,4,6-trimethoxychalcone (5), the first for a 2',6′-dihydroxychalcone, is reported, the hydrogen involved in intramolecular hydrogen-bonding between the carbonyl and phenolic oxygens being located for the first time for any 2'-hydroxychalcone derivative. The O 6' involved in the intramolecular hydrogen-bonding is also hydrogen-bonded intermolecularly to the hydrogen of the other (2'-)hydroxy group of a neighbouring molecule in the lattice. 13C n.m.r. data are the first reported for a series of 2',6'-dihydroxychalcones.

Synthesis and X-ray Crystal Structure of the Novel Organotin Dication [n-Bu2Sn(H2O)4]2+:  A Lamellar Layered Structure Assisted by Intermolecular Hydrogen Bonding

2002 ◽  
Vol 21 (22) ◽  
pp. 4575-4577 ◽  
Author(s):  
Vadapalli Chandrasekhar ◽  
Ramamoorthy Boomishankar ◽  
Sanjay Singh ◽  
Alexander Steiner ◽  
Stefano Zacchini
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Layered Structure ◽  
Intermolecular Hydrogen Bonding ◽  
The Novel ◽  
X Ray

Preparation of Rhenium Diamino Dithiolate Complexes. The X-Ray Crystal Structure of Oxo(1,1,8,8-tetraethyl-3,6-diazaoctane-1,8-dithiolato)rhenium

1993 ◽  
Vol 46 (7) ◽  
pp. 1093 ◽  
Author(s):  
TW Jackson ◽  
M Kojima ◽  
RM Lambrecht
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dithiolate Complexes ◽  
Hydrogen Bonded

The complexes oxo (1,1,8,8-tetraethyl-3,6-diazaoctane-1,8-dithiolato)rhenium[ ReO ( tedadt )], oxo (1,1,8,8-tetraethyl-4,4-dimethyl-3,6-diazaoctane-1,8-dithiolato)rhenium [ ReO ( tedmdadt )] and (1,1,4,4,8,8-hexamethyl-3,6-diazaoctane-1,8-dithiolato) oxorhenium [ ReO ( hmdadt )] were prepared. The crystal structure of the complex ReO ( tedadt ) was determined by X-ray crystallography to be a hydrogen-bonded dimer . This is the first example of intermolecular hydrogen bonding in rhenium diamino dithiolate ( dadt ) complexes.

scholarly journals Zur Stereochemie des freien Elektronenpaares in AX6E-Systemen, IX+ Statisch verzerrtes Anion in [(CH3)2HN(C6H4)NH(CH3)2]TeCl6 / On the Stereochemistry of the Lone-Pair Electrons in AX6E-Systems, IX+ Statically Distorted Anion in [(CH3)2HN(C6H4)NH(CH3)2]TeCl6

1990 ◽  
Vol 45 (5) ◽  
pp. 573-578 ◽  
Author(s):  
André du Bois ◽  
Walter Abriel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Single Crystal ◽  
Lone Pair ◽  
Intensity Data ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Lone Pair Electrons ◽  
Symmetry Rules

Using 293 K diffractometer intensity data, the crystal structure of [(CH3)2HN(C6H4)NH(CH3)2]TeCl6 has been determined by single crystal X-ray technique and refined to a final Rw of 0.022. The yellow crystals are orthorhombic, space group Pna 21, with a = 17.565(2), b = 8.4496(6), c = 12.572(1) Å and Z = 4. The TeCl62- anions show a strong statical distortion with Te—Cl distances from min. 2.39 to max. 2.78 A. The symmetry rules for the stereochemistry of the lone pair electrons in AX6E-systems are confirmed. The influence of hydrogen bonding on the type of distortion is also discussed.

Strukturen und Schwingungsspektren des Tetramethylammonium -a -dodekawolframatosilikats und des Tetrabutylammonium-β-dodekawolframatosilikats / Structures and Vibrational Spectra of Tetramethylammonium a-Dodecatungstosilicate and Tetrabutylammonium β-Dodecatungstosilicate

1981 ◽  
Vol 36 (2) ◽  
pp. 161-171 ◽  
Author(s):  
Joachim Fuchs ◽  
Axel Thiele ◽  
Rosemarie Palm
Keyword(s):  
Crystal Structure ◽  
Vibrational Spectra ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Crystal Water ◽  
Space Group ◽  
X Ray ◽  
First Time

Abstract Dodecatungstosilicates free of crystal water were prepared for the first time by using tetraalkylammonium as cation. The crystal structure of the tetramethylammonium a-dodeeatungstosilicate [N(CH3)4]4SiW12O40 (1) and tetrabutylammonium) β-dodecatungstosilicate, [N(C4H9)4]4SiWi2040 (2) were solved by X-ray diffraction. (1) crystallizes tetragonal in the space group 14̅ with lattice parameters a = 14.642 Å; c= 12.706 Å; (2) orthorhombic, space group P212121 with a = 29.277 Å, b = 22.181 Å and c = 15.381 Å. The differences between the two isomeric heteropolyanions are discussed, especially the distances and angles between the tungsten atoms. Comparison of characteristic differences in the vibrational spectra permits the identification of the isomeric anions.

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