The direct electrochemical synthesis of some metal derivatives of lapachol

1997 ◽  
Vol 75 (5) ◽  
pp. 499-506 ◽  
Author(s):  
E.H. De Oliveira ◽  
G.E.A. Medeiros ◽  
C. Peppe ◽  
Martyn A. Brown ◽  
Dennis G. Tuck
Keyword(s):  
Electrochemical Oxidation ◽  
Copper Atom ◽  
Electrochemical Synthesis ◽  
Acetonitrile Solution ◽  
Triclinic Space Group ◽  
X Ray ◽  
Metal Anode ◽  
X Ray Crystallography ◽  
Metal Derivatives ◽  
Derivatives Of

The electrochemical oxidation of a sacrificial metal anode (M = Zn, Cd, Cu) in an acetonitrile solution of 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone, lapachol, C15H14O3 (=HL) gives ML2. The results are in keeping with earlier work on direct electrochemical synthesis in related systems. Adducts with 2,2′-bipyridine (bpy) and N,N,N′,N′-tetramethylethanediamine (tmen) have also been prepared. The structure of the 2,2′-bipyridine adduct of Cu(lapacholate)2 has been established by X-ray crystallography. The parameters are triclinic, space group [Formula: see text], a = 12.748(59) Å, b = 13.859(49) Å, c = 11.770(59) Å, α = 108.30(4)°, β = 108.08(3)°, γ = 68.94(3)°, Z = 2, R = 0.059 for 2256 unique reflections. The copper atom is in a distorted CuN2O2O2′ environment. The mechanism of the formation of this Cu(lapacholate)2 is discussed. Keywords: electrochemical synthesis, lapachol, X-ray crystallography, copper(II) complex.

The direct electrochemical synthesis of some metal derivatives of 3-hydroxy-2-methyl-4-pyrone

1990 ◽  
Vol 68 (9) ◽  
pp. 1598-1605 ◽  
Author(s):  
Theodore A. Annan ◽  
Clovis Peppe ◽  
Dennis G. Tuck
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Synthesis ◽  
Electron Delocalization ◽  
Sacrificial Anode ◽  
Cadmium Complexes ◽  
X Ray ◽  
X Ray Crystallography ◽  
Metal Derivatives ◽  
Derivatives Of ◽  
C Nmr

The electrochemical oxidation of a metallic sacrificial anode (M = Zn, Cd, Sn, In, Cu) in a non-aqueous solution of 3-hydroxy-2-methyl-4-pyrone (= HL) yields the MLn complexes (M = Zn, Cd, Sn, Cu, n = 2; M = In, n = 3). Adducts of the type ML2•B (M = Zn, Cd, B = N,N,N′,N′-tetramethylethylenediamine (tmen); M = Cu, B = triphenylphosphine) were obtained by the reaction between the appropriate ligand (B) and the previously synthesized complexes (M = Zn, Cd), or by arranging for the initial electrolytic phase to include the base (M = Cu). The tin(II) compound shows the typical reactions of such low oxidation state species by reacting with iodine and ortho-quinones by oxidative addition. All compounds were characterized by elemental analysis and by IR, 1H and 13C nmr spectroscopy. The structure of CdL2•tmen was determined by X-ray crystallography, which identified the CdO4N2 kernel, and partial electron delocalization within the pyronate ring. Keywords: electrochemical synthesis, cadmium complexes, zinc complexes, tin(II) oxidation, 3-hydroxy-2-methyl-4-pyrone.

The direct electrochemical synthesis of thiolato complexes of cobalt and nickel, and the crystal structure of bis(phenylthiolato)bis(1,10-phenanthroline)cobalt(III) perchlorate

1988 ◽  
Vol 66 (9) ◽  
pp. 2151-2156 ◽  
Author(s):  
Raj K. Chadha ◽  
Rajesh Kumar ◽  
Jaime Romero Lopez-Grado ◽  
Dennis G. Tuck
Keyword(s):  
Crystal Structure ◽  
Electrochemical Oxidation ◽  
Electrochemical Synthesis ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Metal Anode ◽  
Aerial Oxidation ◽  
Perchlorate Salt ◽  
Cobalt And Nickel

Cobalt(II) and nickel(II) thiolates, M(SR)2, can be prepared in high yield by the electrochemical oxidation of a metal anode in an acetonitrile or acetone solution of RSH (R = C6H5, o-CH3C6H4, 2-C10H7, 2,3,4,5-C6F4H; not all combinations). When 2,2-bipyridine or 1,10-phenanthroline (=L) is added to the electrolyte phase, the products are the adducts M(SR)2L2. In the case of Co(SC6H5)2(phen)2, aerial oxidation leads to the formation of the cobalt(III) cation [Co(SC6H5)2(phen)2]+, isolated as the perchlorate salt. X-ray crystallographic analysis showed that this cation has a cis-CoS2(N2)2 kernel.

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.

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.

scholarly journals NMR and X-ray studies of apetalic acid isolated from Calophyllum brasiliense and of its chiral amides

2021 ◽  
Author(s):  
Marie-Rose Van Calsteren ◽  
Ricardo Reyes-Chilpa ◽  
Chistopher K Jankowski ◽  
Fleur Gagnon ◽  
Simón Hernández-Ortega ◽  
...  
Keyword(s):  
Antimycobacterial Activity ◽  
Side Chain ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Rain Forests ◽  
X Ray ◽  
X Ray Crystallography ◽  
Calophyllum Brasiliense ◽  
Derivatives Of

The tropical tree Calophyllum brasiliense (Clusiaceae) grows in the rain forests from Brazil to Mexico. Its leaves, as well as those of other Calophyllum species, are rich sources of chromanone acids, such as apetalic acid, isoapetalic acid, and their derivatives. Apetalic acid has shown significant antimycobacterial activity. The biological activity of apetalic acid has been related to the configuration of three asymmetric centers and the stereochemistry of the molecule; however, the C-19 configuration in the acidic side chain has not been fully resolved. For this reason, the unequivocal determination of the absolute configuration by means of X-ray crystallography in a sample of unique homogeneous apetalic acid stereoisomer was the most important point to start this study. We prepared some chiral amides using the carboxyl group. We determined the C-19 stereochemistry of apetalic acid, and its specific chiral derivatives, using NMR, X-ray diffraction methods, and molecular mechanics. Finally, we observed that steric hindrance in the side chain of apetalic acid leads to restriction of rotation around the pivotal link C-10 and C-19 establishing chiral centers at C2(R), C3(S), and C19(R). We were able to separate derivatives of these two high-rotatory-barrier conformers of apetalic acid by forming diastereoisomeric amides with phenylglycine methyl ester having a chiral center at C-2’. Our results allowed the conclusion of the existence of atropisomerism in the apetalic acid molecule.

Perchlorate and difluorophosphate coordination derivatives of rhenium carbonyl

1980 ◽  
Vol 33 (11) ◽  
pp. 2369 ◽  
Author(s):  
E Horn ◽  
MR Snow
Keyword(s):  
Heavy Atom ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
Triclinic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
Rhenium Carbonyl ◽  
Hydrolysis Of ◽  
Derivatives Of

The complexes Re(CO)5ClO4, Re(CO)5PO2F2, L2(CO)3Re(OClO3) and L2(CO)3Re(PO2F2), where L2 = 2,2?-bipyridyl (bpy), have been synthesized by bromide abstraction reactions from the respective rhenium carbonyl bromide precursors. The complexes were characterized by infrared and mass spectroscopy. The crystal structure of (bpy)(CO)3Re(PO2F2) has been determined from X-ray diffraction data by the heavy-atom technique. The crystals are triclinic, space group Pī with a 8.620(3), b 15.912(5), c 6.466(3) Ǻ, α 102.08(8), β 83.29(8), γ 95.08(4) and Z 2. The structure has been refined by full-matrix least-squares from 2829 reflections to R = 0.084, Rw = 0.088. The coordination geometry about rhenium is that of a distorted octahedron. Difluorophosphate coordinates to the metal centre by one of its oxygen atoms. Formation of the difluorophosphate by hydrolysis of hexafluorophosphate was shown by 31P n.m.r. spectra.

The Conformation of Some 1,6-Disulfide-Bridged D-Hexopyranoses

2005 ◽  
Vol 58 (3) ◽  
pp. 199 ◽  
Author(s):  
Ethan D. Goddard-Borger ◽  
Brian W. Skelton ◽  
Robert V. Stick ◽  
Allan H. White
Keyword(s):  
Nmr Spectroscopy ◽  
Single Crystal ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Similar Investigation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structure Determinations ◽  
Derivatives Of

The use of 1H NMR spectroscopy, in tandem with X-ray crystallography, has cast light on the conformation of the 1,6-disulfide-bridged derivatives of d-gluco-, d-manno-, d-allo-, d-galacto-, and d-talo-pyranose. A similar investigation was performed on the thiosulfinate derived from the d-gluco disulfide. Single-crystal X-ray structure determinations are reported for (1S,5S,6S,7S,8R)-6,7,8-tribenzoyloxy-9-oxa-2,3-dithiabicyclo[3.3.1]nonane, (1S,5S,6S,7R,8R)-6,7,8-tribenzoyloxy-9-oxa-2,3-dithiabicyclo[3.3.1]nonane, and (1S,2S,5S,6S,7S,8R)-6,7,8-triacetoxy-9-oxa-2,3-dithiabicyclo[3.3.1]nonane 2-oxide.

The Structures of the Decaphenylmetallocenium Cations of Chromium and Cobalt

1997 ◽  
Vol 50 (11) ◽  
pp. 1035 ◽  
Author(s):  
Leslie D. Field ◽  
Trevor W. Hambley ◽  
Taian He, ◽  
Anthony F. Masters ◽  
Peter Turner
Keyword(s):  
Methylene Chloride ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography

Decaphenylchromocenium and decaphenylcobaltocenium cations [M(η5-C5Ph5)2]+, M = Cr and Co, were synthesized by oxidation of the corresponding neutral decaphenylchromocene and decaphenylcobaltocene respectively with nitrosyl tetrafluoroborate. The complexes are air-stable and were fully characterized; decaphenylchromocenium tetrafluoroborate (1) and decaphenylcobaltocenium tetrafluoroborate (2) were structurally characterized by X-ray crystallography. Crystals of (1) (as a water/methylene chloride solvate), C70·5H50BClCrF4O0·5, M 1079·42, are triclinic, space group P -1 (No. 2), a 13·634(5), b 17·424(5), c 13·298(4) Å, α 106·45(2), β 101·83(3), γ 74·56(2)°, Z 2. Crystals of (2) (as a water/methylene chloride solvate), C70·5H50BClCoF4O0·5, M 1086·36, are triclinic, space group P-1 (No. 2), a 13·633(2), b 17·683(3), c 13·255(3) Å, α 107·95(1), β 102·71(1), γ 73·23(1)°, Z2.

New insights into chalcogen bonding provided by co-crystal structures of benzisoselenazolinone derivatives and nitrogen bases

CrystEngComm ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1539-1542 ◽  
Author(s):  
Thomas Fellowes ◽  
Jonathan M. White
Keyword(s):  
Crystal Structures ◽  
X Ray ◽  
Nitrogen Bases ◽  
X Ray Crystallography ◽  
Derivatives Of

A number of derivatives of benzisoselenazolinones, including the drug ebselen, have been synthesized, and their interactions with various nitrogen bases characterized through X-ray crystallography.

Application of the Variable Oxygen Probe to Determine the π-Electron Donor Ability of the Alkyne Group

2014 ◽  
Vol 67 (12) ◽  
pp. 1866 ◽  
Author(s):  
Benjamin L. Harris ◽  
Jonathan M. White
Keyword(s):  
Low Temperature ◽  
Electron Donor ◽  
Oxygen Probe ◽  
X Ray ◽  
X Ray Crystallography ◽  
Donor Ability ◽  
Structural Database ◽  
Derivatives Of ◽  
Electron Demand ◽  
Electron Donor Ability

Eight ester and ether derivatives of propargyl alcohol with varying electron demand were structurally characterised using low temperature X-ray crystallography, these were combined with seven derivatives obtained from the Cambridge Structural Database. Variable oxygen probe analysis of these derivatives provided evidence that the ethynyl substituent is a relatively weak π-electron donor, and is a slightly less effective donor than the C–C bond of an ethyl substituent.

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