Pseudozoanthoxanthins from gold coral

1979 ◽  
Vol 57 (13) ◽  
pp. 1707-1711 ◽  
Author(s):  
Robert E. Schwartz ◽  
Mark B. Yunker ◽  
Paul J. Scheuer ◽  
Tor Ottersen
Keyword(s):  
Deep Water ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Data ◽  
Derivatives Of ◽  
C Nmr

From a deep water Pacific zoanthid, Gerardia sp., we have isolated two new fluorescent nitrogenous pigments, derivatives of tetrazacyclopentazulene. The first was characterized by uv, 1H and 13C nmr data, and by X-ray diffraction; the second by interconversion.

β-Hydroxydithiozimtsäurederivate als Liganden. Synthese und Charakterisierung neuartiger 1,1-Ethendithiolato- und O,S-Chelatkomplexe / Derivatives of β -Hydroxydithiocinnamic Acids as Ligands. Syntheses and Characterisation of Novel 1,1-Ethenedithiolato and O,S-Chelate Complexes

2007 ◽  
Vol 62 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Karsten Schubert ◽  
Helmar Görls ◽  
Wolfgang Weigand
Keyword(s):  
Bidentate Ligand ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
H Nmr ◽  
Hexyl Ester ◽  
Elemental Analyses ◽  
Derivatives Of ◽  
C Nmr

Starting from 4-bromoacetophenone 1, the 4-bromo-β -hydroxydithiocinnamic acid 2 and the 4-bromo-β -hydroxydithiocinnamic acid hexyl ester 3 were prepared using carbon disulfide and potassium-tert-butylate as a base. Acting as a ligand, the acid gives 1,1-ethenedithiolato complexes with (Ph3P)2Pt(II) (4a), (Et3P)2Pt(II) (4b), dppePt(II) (4c), (Ph3P)2Pd(II) (4d), dppePd(II) (4e), and dppeNi(II) (4f). In contrast to the acid, the deprotonated ester 3 forms a monoanionic bidentate ligand. [O,S] Complexes of Pt(II) (5a), Pd(II) (5b) and Ni(II) (5c) were obtained. All complexes have been fully characterised using 1H NMR, 13C NMR and 31P NMR spectroscopy, mass spectrometry, infrared spectroscopy and elemental analyses. The molecular structures of the complexes 4b and 5a - 5c were determined by X-ray diffraction analyses.

The Structure And Tautomerism Of Cyameluric Acid*

2006 ◽  
Vol 61 (8) ◽  
pp. 975-978 ◽  
Author(s):  
Jörg Wagler ◽  
Nadia E. A. El-Gamel ◽  
Edwin Kroke
Keyword(s):  
Single Crystal ◽  
Keto Form ◽  
X Ray ◽  
Nmr Data ◽  
Almost All ◽  
Derivatives Of ◽  
Theoretical Results ◽  
C Nmr

The single crystal X-ray structure of the DMSO solvate of cyameluric acid C6N7O3H3 ·3DMSO, 2b’ has been determined. The results show that the most stable tautomer of solid cyameluric acid is the tri-keto form 2b with C3h symmetry. 1H and 13C NMR data indicate that this isomer is also present in solution, with slow interchange of the N-H protons. This confirms previous theoretical results although almost all derivatives reported in the literature are derivatives of the tri-hydroxy tautomer 2a

[(Dimethylamino)methyl]ferrocene as an Amine Ligand: Study of the Bonding and X-Ray Crystal and Molecular Structure of the Pentacarbonyl{[(dimethylamino)methyl]ferrocene}tungsten Complex

2002 ◽  
Vol 67 (2) ◽  
pp. 228-234 ◽  
Author(s):  
Axel Fischer ◽  
Frank T. Edelmann ◽  
Klaus Jacob ◽  
Ivan Pavlík ◽  
Martin Pavlišta
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Crystal And Molecular Structure ◽  
X Ray Diffraction ◽  
Amine Nitrogen ◽  
X Ray ◽  
Nmr Data ◽  
Amine Ligand ◽  
C Nmr

The heterodinuclear complex [W(CO)5(Me2NCH2Fc)] (Fc = ferrocenyl) (1) resulting from the reaction of [(dimethylamino)methyl]ferrocene (2) and [W(CO)6] was studied by single-crystal X-ray diffraction. Its molecular structure confirms the coordination of the amine nitrogen in 2 to tungsten (d(W-N) = 2.359(5) Å) and reveals its trans-influence in the W(CO)5 moiety. The structure is discussed in relation to several previously referred spectroscopic (IR, UV-VIS, 13C NMR) data.

Pd-catalyzed synthesis of C-C (Sonogashira, Suzuki, Heck, Stille), C-P and C-S linked products using gem -dibromovinyl BODIPY

2021 ◽  
pp. A-O
Author(s):  
Hasrat Ali ◽  
Brigitte Guérin ◽  
Johan E. van Lier
Keyword(s):  
Absorption Maximum ◽  
Palladium Catalysis ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Cross Coupling Reactions ◽  
Derivatives Of ◽  
C Nmr

The chemistry of gem-dibromovinyl derivatives has undergone a renaissance through the application of palladium catalysis and has been applied to pyrrole substituted gem-dibromovinyl BODIPY. gem-Dibromovinyl BODIPYs (substituted at either the [Formula: see text]-position of 8-phenyl or the [Formula: see text]-position of the pyrrole rings) were studied for cross-coupling reactions using Sonogashira, Suzuki, Heck and Stille conditions, and with phosphonates and thiols. The assigned structures were supported by MS and 1H NMR, [Formula: see text]C NMR, X-ray diffraction analysis as well as optical spectroscopy. The conjugates were investigated for their absorption, fluorescence and solvatochromic properties in different solvents. Substitution at the [Formula: see text]-position of 8-phenyl derivatives of gem-diethynyl BODIPYs did not induce any shift in the absorption maximum, while the [Formula: see text]-position pyrrole substituted derivatives showed a red shift. Aromatic compounds gave larger red shifts as compared to the aliphatic substituted analogs.

scholarly journals Studies of Dihydropyridines by X-Ray Diffraction and Solid State 13C NMR

2007 ◽  
Vol 62 (4) ◽  
pp. 549-555 ◽  
Author(s):  
Martha S. Morales-Ríos ◽  
Antonio Martínez-Richa ◽  
Zurisaddai Hernández-Gallegos ◽  
Angelina Hernández-Barragán ◽  
Ricardo Vera-Graziano ◽  
...  
Keyword(s):  
Solid State ◽  
Phenyl Ring ◽  
Chemical Shifts ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
Substitution Pattern ◽  
Trans Orientation ◽  
X Ray ◽  
Nmr Data ◽  
C Nmr

Fourteen dimethyl 4-aryl-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates (DHPs) were evaluated by means of single crystal X-ray diffraction in order to investigate the effects of the structure in the crystals on the solid state 13C NMR chemical shifts. These include the analysis of three DHPs containing two molecules per asymmetric unit. The chiral rotamer unit generated by the s-cis/s-trans orientation of the carbonyl groups, as well as by rotation of the 4-phenyl ring out of the bisecting plane containing the N1, C4, C7 atoms, resulted in a significant magnetic non-equivalence for the C2-CH3/C6-CH3 and the COOCH3 pairs of signals. The solid state 13C NMR data reveal that the substitution pattern of the phenyl ring has a marked effect on the extent to which the signals of the carbonyl carbon atoms and those of C-2/C-6 peaks are split.

Darstellung und Strukturelle Charakterisierung von cis-und trans- Dicyclohexyl-3,3′,4,4′-tetracarbonsäure-tetramethylestern / Preparation and Structural Characterization of cis- and trans-Tetramethyl Dicyclohexyl-3,3′,4,4′-tetracarboxylates

2001 ◽  
Vol 56 (2) ◽  
pp. 189-201
Author(s):  
Akinori Shiotani
Keyword(s):  
Catalytic Hydrogenation ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Trans Isomers ◽  
X Ray ◽  
Nmr Data ◽  
Methoxycarbonyl Group ◽  
Cis And Trans ◽  
C Nmr

Abstract In the catalytic hydrogenation of tetramethyl biphenyl-3,3′,4,4′-tetracarboxylate, tetramethyl dicyclohexyl-3,3′,4,4′-tetracarboxylates were obtained, from which we have isolated cis isomers as crystals. The base-catalyzed isomerization afforded the trans isomers. The structure of the products isolated was determined by single-crystal x-ray diffraction, which clearly reveals the axial and equatorial positions of the methoxycarbonyl group. The structures in solution are supported by 1H and 13C NMR data, and also by two-dimensional COSY techniques.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Darstellung, 11B-, 13C-, 29Si-NMR- und Schwingungsspektren von Trimethylsilylmethyl-hexahydro-closo-hexaborat, [B6H6(CH2Si(CH3)3)]- sowie Kristallstruktur von [P(C6H5)4][B6H6(CH2Si(CH3)3)] / Preparation, 11B, 13C, 29Si NMR and Vibrational Spectra of Trimethylsilylmethyl-hexahydro-clo-hexaborate, [B6H6(CH2Si(CH 3)3)]-and the Crystal Structure of [P(C6H5)4] [B6H6(CH2Si(CH3)3)]

1995 ◽  
Vol 50 (7) ◽  
pp. 1025-1029 ◽  
Author(s):  
J. Baurmeister ◽  
A. Franken ◽  
W. Preetz
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
29Si Nmr ◽  
X Ray Diffraction ◽  
Nmr Spectrum ◽  
X Ray ◽  
Quadrupole Coupling ◽  
Stretching Vibration ◽  
Ir And Raman ◽  
C Nmr

By reaction of [N(C4H9 )4]2 [B6H6] with iodomethyl-trimethylsilane in acetonitrile a solution with trimethylsilylm ethyl-closo-hexaborate(1-)anions, [B6H6 (CH2Si(CH3)3)]-, is formed. The crystal structure of [P(C6H5 )4][B6H6(CH2Si(CH3)3)] has been determined by single crystal X-ray diffraction analysis; monoclinic, space group P21/n with a = 16.140(2), b = 11.646(8), c = 16.731(3) Å, β 109.664(11)°. The 11B NMR spectrum reveals features of a mono hetero substituted octahedral B6 cage. The 13C NMR spectrum exhibits a quartet at +0.18 ppm with 1J(C,H) = 118 Hz for the three methyl groups and a weak multiplet at -0.65 ppm for the methylene bridge due to quadrupole coupling with the boron atoms. In the 29Si NMR spectrum a decet at +2.25 ppm with 2J(C,H ) = 6.9 Hz is observed. The B -C stretching vibration is observed at 1155 cm-1 in the IR and Raman spectrum.

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.

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