Structural studies on dioxan-2-ylium ions; intramolecular attack of an oxygen atom on a carbenium ion centre

1994 ◽  
Vol 72 (10) ◽  
pp. 2084-2093 ◽  
Author(s):  
Ronald F. Childs ◽  
Guogong J. Kang ◽  
Teresa A. Wark ◽  
Christopher S. Frampton
Keyword(s):  
Carbon Chain ◽  
Intramolecular Rearrangement ◽  
Carbon Chain Length ◽  
Monoclinic Crystal ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ether Oxygen ◽  
Carbenium Ion ◽  
C Nmr

As models for the ionization of orthoesters, a series of 1,3-dioxan-2-ylium salts have been prepared and characterized. The properties of 1,3-dioxan-2-ylium hexachloroantimonate 1, 5-ethoxymethyl-1,3-dioxan-2-ylium hexachloroantimonate 2, 2-methyl-5-ethoxymethyl-1,3-dioxan-2-ylium hexachloroantimonate 3, and 2-phenyl-5-ethoxymethyl-1,3-dioxan-2-ylium hexachloroantimonate 4, have been studied by 1H and 13C NMR spectroscopy. The structures of 3 and 4 have been determined using X-ray crystallography. Salts 3 and 4 both crystallize in monoclinic crystal systems. For 3, the space group is C2/c, with a = 30.192(4) Å, b = 9.613(2) Å, c = 12.742(2) Å, β = 109.71(1)°, V = 3482(1) Å3, and Z = 8. Complex 4 crystallizes in the space group P21/n, with a = 10.638(2) Å, b = 11.849(2) Å, c = 16.970(3) Å, β = 106.84(1)°, V = 2047(1) Å3, and Z = 4. The geometries of 3 and 4 are similar with the ether oxygen disposed over the dioxan-2-ylium ring. However, the interaction between the ether oxygen and the cationic centre is not significant due to the large internuclear distance observed. The cation 5, in which the carbon chain length between the ether oxygen and C(5) was increased, was prepared. This ion was found to undergo a reversible, intramolecular rearrangement resulting in the formation of 1-methyl-4-acetoxymethyl-tetrahydrofuranyl oxonium hexachloroantimonate 11.

Preparation and X-ray crystal structures of the arsenic pentafluoride adducts of benzo-2,1,3-thiadiazole and benzo-1,2,3-thiadiazole

1986 ◽  
Vol 64 (5) ◽  
pp. 849-853 ◽  
Author(s):  
Allen Apblett ◽  
Tristram Chivers ◽  
John F. Richardson
Keyword(s):  
Nitrogen Atom ◽  
Crystal Structures ◽  
Benzene Ring ◽  
Heterocyclic Ring ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
C Nmr

The reaction of arsenic pentafluoride with benzo-2,1,3-thiadiazole, 1, or benzo-1,2,3-thiadiazole, 2, in liquid SO2 gave 1:1 adducts that were characterized spectroscopically (infrared and 13C nmr) and by X-ray crystallography. Crystal data: for 1•AsF5, monoclinic, space group P21/n, a = 6.932(1), b = 9.113(1), c = 15.136(2) Å, β = 98.035(7)°, V = 946.8(2) Å3, Z = 4; for 2•AsF5, monoclinic, space group P21/a, a = 7.573(2), b = 13.101(2), c = 9.514(3) Å, β = 90.95(2)°, V = 943.9(4) Å3, Z = 4. The coordination of AsF5 to one of the nitrogen atoms in 1 introduces asymmetry in the heterocyclic ring, with the longer bond lengths being associated with the coordinated nitrogen atom, d(S—N) = 1.633(5) and 1.577(6) Å, d(C—N) = 1.364(7) and 1.339(8) Å. The quinonoid character of the benzene ring is still apparent in the adduct. In 2•AsF5, the AsF5 molecule is coordinated to the nitrogen atom that is bonded to carbon.

Unexpected beauty and diversity in the structures of three homologous 4,5-dialkoxy-1-ethynyl-2-nitrobenzenes: the subtle interplay between intermolecular C—H...O hydrogen bonds and alkyl chain length

2017 ◽  
Vol 73 (10) ◽  
pp. 814-819 ◽  
Author(s):  
Shalisa M. Oburn ◽  
Eric Bosch
Keyword(s):  
Nmr Spectra ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Triclinic Crystal System ◽  
Space Group ◽  
X Ray ◽  
Crystal System ◽  
C Nmr

The synthesis, 1H and 13C NMR spectra, and X-ray structures are described for three dialkoxy ethynylnitrobenzenes that differ only in the length of the alkoxy chain, namely 1-ethynyl-2-nitro-4,5-dipropoxybenzene, C14H17NO4, 1,2-dibutoxy-4-ethynyl-5-nitrobenzene, C16H21NO4, and 1-ethynyl-2-nitro-4,5-dipentoxybenzene, C18H25NO4. Despite the subtle changes in molecular structure, the crystal structures of the three compounds display great diversity. Thus, 1-ethynyl-2-nitro-4,5-dipropoxybenzene crystallizes in the trigonal crystal system in the space group R{\overline 3}, with Z = 18, 1,2-dibutoxy-4-ethynyl-5-nitrobenzene crystallizes in the monoclinic crystal system in the space group P21/c, with Z = 4, and 1-ethynyl-2-nitro-4,5-dipentoxybenzene crystallizes in the triclinic crystal system in the space group P{\overline 1}, with Z = 2. The crystal structure of 1-ethynyl-2-nitro-4,5-dipropoxybenzene is dominated by planar hexamers formed by a bifurcated alkoxy sp-C—H...O,O′ interaction, while the structure of the dibutoxy analogue is dominated by planar ribbons of molecules linked by a similar bifurcated alkoxy sp-C—H...O,O′ interaction. In contrast, the dipentoxy analogue forms ribbons of molecules alternately connected by a self-complementary sp-C—H...O2N interaction and a self-complementary sp 2-C—H...O2N interaction. Disordered solvent was included in the crystals of 1-ethynyl-2-nitro-4,5-dipropoxybenzene and its contribution was removed during refinement.

Solid state and solution stereochemistry of crown ethers and models. ortho-Dimethoxydiphenyl ether and related dibenzo-15-crown-5 and tetrabenzo-30-crown-10 ethers as studied by X-ray crystallography and 1H and 13C NMR spectroscopy

1994 ◽  
Vol 72 (5) ◽  
pp. 1218-1224 ◽  
Author(s):  
G. W. Buchanan ◽  
A. Rodrigue ◽  
K. Bourque ◽  
A. C. Chiverton ◽  
I. R. Castleden ◽  
...  
Keyword(s):  
Solid Phase ◽  
Direct Methods ◽  
13C Nmr Spectroscopy ◽  
Structural Features ◽  
X Ray Diffraction ◽  
1H And 13C Nmr ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
C Nmr

Solid phase 45.3 MHz 13C NMR spectra of ortho-dimethoxydiphenyl ether, 1, dibenzo[b,e]-15-crown-5- ether, 2, and tetrabenzo[b,e,q,t]-30-crown-10 ether, 3, have been obtained. Chemical shift trends are discussed in terms of the asymmetric units and structural features available from X-ray crystallographic data. Comparison with solution 13C spectra are made. The crystal structures of 1 and 3 were determined by X-ray diffraction at room temperature. 1 crystallizes in space group P21/a with a = 13.366(1), b = 8.230(1), c = 12.303(1) Å, β = 116.63(1)°, Z = 4. 3 crystallizes in space group P21/c with a = 7.903(1), b = 26.337(2), c = 7.852(1) Å, β = 97.28(1)°, Z = 2. The structures were solved by direct methods and refined by full-matrix least squares to residuals of 0.055 using 1727 reflections for 1 and of 0.042 using 2590 reflections for 3.

Crystal and solution structure of (E)-1,2-bis(ethylsulphonyl)cyclobutane-1,2-dicarbonitrile

1989 ◽  
Vol 54 (12) ◽  
pp. 3253-3259
Author(s):  
Jaroslav Podlaha ◽  
Miloš Buděšínský ◽  
Jana Podlahová ◽  
Jindřich Hašek
Keyword(s):  
Hydrogen Peroxide ◽  
Solution Structure ◽  
Peroxide Oxidation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nmr Study ◽  
Hydrogen Peroxide Oxidation ◽  
Unusual Product ◽  
C Nmr

The unusual product of the reaction of 2-chloroacrylonitrile with ethane thiol and following hydrogen peroxide oxidation was found to be (E)-1,2-bis(ethylsulphonyl)cyclobutane-1,2-dicarbonitrile by means of X-ray crystallography. 1H and 13C NMR study of this compound has proven the same conformation of the molecule in solution.

Supramoleküle aus Kronenethern und geminalen Sulfonen: Synthese von vier binären Komplexen und Kristallstruktur von (CH2CH2O)4·2H 2C(SO2C2H5)2/Supramolecules of Crown Ethers with Geminal Sulfones: Synthesis of Four Binary Complexes and Crystal Structure of (CH2CH2O )4·2H2C(SO2C2H5)2

1995 ◽  
Vol 50 (7) ◽  
pp. 1018-1024 ◽  
Author(s):  
Axel Michalides ◽  
Dagmar Henschel ◽  
Armand Blaschette ◽  
Peter G. Jones
Keyword(s):  
Monoclinic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Binary Complexes ◽  
Cyclic Polyethers ◽  
Adjacent Unit ◽  
Methylene Group

In a systematic search for supramolecular complexes involving all combinations of the cyclic polyethers 12-crown-4 (12C4), 15-crown-5 (15C 5), 18-crown-6 (18C 6) and dibenzo- 18-crown-6 (DB -18C6), and the geminal di- or trisulfones H2C(SO 2Me)2, H2C (SO2Et)2 and HC (SO2Me)3-n (SO2Et)n (n = 0 -3 ) , only the following four complexes could be isolated and unequivocally characterized by elemental analysis and 1H NMR spectroscopy: [(12C4){H2C (SO2Et)2}2] (3), [(18C6){H2C (S O2Me)2}] (4), [(DB -18C 6){H2C (SO2Et)2}] (5) and [(D B -18C 6)2{HC (SO2Me )(SO2Et)2}3] (6). The structure of 3 (triclinic, space group P1̄) consists of crystallographically centrosymmetric formula units, in which the disulfone molecules are bonded on each side of the ring by two C -H ··· O(crown) interactions originating from the central methylene group (H···O 213 pm) and from the methylene group of one EtSO2 moiety ( H ··· O 237 pm). Formula units related by translation are connected into parallel strands by a third type of reciprocal C -H ···O bond (H ···O 232 pm) between the second H atom of the central methylene group and a sulfonyl oxygen atom of the adjacent unit. The structure of 4 (monoclinic, space group C2/c) showed severe disorder of the crown ether and could not be refined satisfactorily. Compounds 5 and 6 crystallized as long and extremely thin fibres, indicative of linear-polymeric supramolecular structures; single crystals for X-ray crystallography were not available.

The Pyrolytic Rearrangement of 1-Alkynoyl-3-methylpyrazoles: Synthesis of Pyrazolo[1,5-a]pyridin-5-ols and Related Compounds

1994 ◽  
Vol 47 (6) ◽  
pp. 991 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon ◽  
SC Lee ◽  
RP Mcgeary
Keyword(s):  
Carbon Chain ◽  
Ring Structure ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Fused Ring ◽  
Related Compounds

Flash vacuum pyrolysis of 1-(alkyn-2′-oyl)-3-methylpyrazoles at 650°/0.03 mm forms pyrazolo[1,5-a]pyridin-5-ols, often in high yield, which may bear substituents at C2, C3 or C7. In the absence of a 3-methyl group in the precursor, N-ethynylpyrazoles are formed in low yield. The formation of both types of product is interpreted as involving 3-(N-pyrazolyl)propadienones formed by N1 → N2 migration of the N-alkynoyl group with inversion of the three-carbon chain. The fused-ring structure of 2-methylpyrazolo[1,5-a]pyridin-5-ol (25) was established by X-ray crystallography of the O-benzoyl derivative (27).

scholarly journals Base-enhanced catalytic water oxidation by a carboxylate–bipyridine Ru(II) complex

2015 ◽  
Vol 112 (16) ◽  
pp. 4935-4940 ◽  
Author(s):  
Na Song ◽  
Javier J. Concepcion ◽  
Robert A. Binstead ◽  
Jennifer A. Rudd ◽  
Aaron K. Vannucci ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Proton Transfer ◽  
Water Oxidation ◽  
Proton Acceptor ◽  
Half Time ◽  
X Ray ◽  
X Ray Crystallography ◽  
Buffer Base ◽  
Electron Proton Transfer ◽  
C Nmr

In aqueous solution above pH 2.4 with 4% (vol/vol) CH3CN, the complex [RuII(bda)(isoq)2] (bda is 2,2′-bipyridine-6,6′-dicarboxylate; isoq is isoquinoline) exists as the open-arm chelate, [RuII(CO2-bpy-CO2−)(isoq)2(NCCH3)], as shown by 1H and 13C-NMR, X-ray crystallography, and pH titrations. Rates of water oxidation with the open-arm chelate are remarkably enhanced by added proton acceptor bases, as measured by cyclic voltammetry (CV). In 1.0 M PO43–, the calculated half-time for water oxidation is ∼7 μs. The key to the rate accelerations with added bases is direct involvement of the buffer base in either atom–proton transfer (APT) or concerted electron–proton transfer (EPT) pathways.

Triazene derivatives of (1,x-)diazacycloalkanes. Part VI. 3-({5,5-Dimethyl-3-[2-aryl-1-diazenyl]-1-imidazolidinyl}methyl)-4,4-dimethyl-1-[2-aryl-1-diazenyl]imidazolidines — Synthesis, characterization, and X-ray crystal structure

2006 ◽  
Vol 84 (10) ◽  
pp. 1294-1300 ◽  
Author(s):  
Keith Vaughan ◽  
Shasta Lee Moser ◽  
Reid Tingley ◽  
M Brad Peori ◽  
Valerio Bertolasi
Keyword(s):  
Crystal Structure ◽  
Significant Degree ◽  
Ion Trapping ◽  
Published Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Diazonium Ion ◽  
Derivatives Of ◽  
C Nmr

Reaction of a series of diazonium salts with a mixture of formaldehyde and 1,2-diamino-2-methylpropane affords the 3-({5,5-dimethyl-3-[2-aryl-1-diazenyl]-1-imidazolidinyl}methyl)-4,4-dimethyl-1-[2-aryl-1-diazenyl]imidazolidines (1a–1f) in excellent yield. The products have been characterized by IR and NMR spectroscopic analysis, elemental analysis, and X-ray crystallography. The X-ray crystal structure of the p-methoxycarbonyl derivative (1c) establishes without question the connectivity of these novel molecules, which can be described as linear bicyclic oligomers with two imidazolidinyl groups linked together by a one-carbon spacer. This is indeed a rare molecular building block. The molecular structure is corroborated by 1H and 13C NMR data, which correlates with the previously published data of compounds of types 5 and 6 derived from 1,3-propanediamine. The triazene moieties in the crystal of 1c display significant π conjugation, which gives the N—N bond a significant degree of double-bond character. This in turn causes restricted rotation around the N—N bond, which leads to considerable broadening of signals in both the 1H and 13C NMR spectra. The molecular ion of the p-cyanophenyl derivative (1b) was observed using electrospray mass spectrometry (ES + Na). The mechanism of formation of molecules of type 1 is proposed to involve diazonium ion trapping of the previously unreported bisimidazolidinyl methane (13).Key words: triazene, bistriazene, imidazolidine, synthesis, X-ray crystallography, NMR spectroscopy.

Structural and vibrational studies of 1,1,3,3-tetracyanopropane and 2,2,4,4,6-pentacyanocyclohexenamine

1987 ◽  
Vol 65 (2) ◽  
pp. 261-270 ◽  
Author(s):  
R. A. Bell ◽  
B. E. Brown ◽  
M. Duarte ◽  
H. E. Howard-Lock ◽  
C. J. L. Lock
Keyword(s):  
Unit Cell ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
New Methods ◽  
Cell Dimensions ◽  
Cell Data ◽  
Unit Cell Data ◽  
Monoclinic Cell ◽  
C Nmr

1,1,3,3-Tetracyanopropane, 1, was prepared in low yields by a literature method with 2,2,4,4,6-pentacyanocyclohexenamine, 2, as a major by-product. The products were examined by X-ray crystallography. 1 has an orthorhombic space group, Pbcn (No. 60) with cell dimensions, a = 7.158(2), b = 10.510(3), c = 9.733(2) Å and has four formula units in the unit cell. 2 has a monoclinic cell, P21/c (No. 14) with cell dimensions a = 14.368(3), b = 6.626(1), c = 12.300(2) Å, β = 115.60(1)° and has 4 formula units in the unit cell. Data were collected with use of MoKα radiation and a Nicolet P3 diffractometer. The crystal structures were determined by standard methods and refined to Rw = 0.037 (1) and Rw = 0.040 (2) on the basis of 782 and 2108 unique reflections. Bond lengths and angles in the two compounds are normal. 2 has what has been considered to be the less likely tautomeric structure. Both compounds were examined by 1H, 13C nmr, vibrational spectroscopy, and mass spectroscopy. For 2 there was no evidence of the alternative tautomeric structure. New methods were developed for the preparation of both compounds and the mechanism of the original reaction rationalized.

[Zn(phen)2(CX3COO)]+, X = H orCl; Influence of X on the Coordination Mode of the Carboxylate Group (phen = 1,10-Phenanthroline)

2005 ◽  
Vol 60 (10) ◽  
pp. 1049-1053 ◽  
Author(s):  
Zeanab Talaei ◽  
Ali Morsali ◽  
Ali R. Mahjoub
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Coordination Mode ◽  
Bidentate Ligand ◽  
Carboxylate Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Coordinate Geometry ◽  
C Nmr

Two new ZnII(phen)2 complexes with trichloroacetate and acetate anions, [Zn(phen)2(CCl3COO)- (H2O)](ClO4) and [Zn(phen)2(CH3COO)](ClO4), have been synthesized and characterized by elemental analysis, IR, 1H NMR, 13C NMR spectroscopy. The single crystal X-ray data of these compounds show the Zn atoms to have six-coordinate geometry. From IR spectra and X-ray crystallography it is established that the coordination of the COO− group is different for trichloroacetate and acetate. The former acts as a monodentate whereas the latter acts as a bidentate ligand.

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