The fluxionality and crystal structures of [Fe3(CO)10L2] (L2 = dppm, (Ph2P)2NH, {(EtO)2P}2O) and [Fe3(CO)9(dppm){P(OMe)3}]

2001 ◽  
Vol 79 (5-6) ◽  
pp. 760-774 ◽  
Author(s):  
Harry Adams ◽  
Sylvana C Agustinho ◽  
Krystyna Chomka ◽  
Brian E Mann ◽  
Stephen Smith ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Nmr Spectra ◽  
Bidentate Ligand ◽  
Axial Position ◽  
Iron Carbonyls ◽  
C Nmr ◽  
Closing Mechanism

The crystal structures of [Fe3(CO)10L2] (L2 = dppm, (Ph2P)2NH, {(EtO)2P}2O) and [Fe3(CO)9(dppm){P(OMe)3}] (dppm = (Ph2P)2CH2) have been determined. [Fe3(CO)10L2] (L2 = dppm, (Ph2P)2NH, {(EtO)2P}2O) adopt a stereochemistry in the crystal with the bidentate ligand across an unbridged Fe-Fe edge, resulting in one phosphorus ligand being unusually in the axial position. In contrast, [Fe3(CO)9(dppm){P(OMe)3}] adopts a stereochemistry in the crystal with the bidentate ligand across the bridged Fe-Fe edge. The structures of the [Fe3(CO)10L2] (L2 = dppm, (Ph2P)2NH, {(EtO)2P}2O) support the Mann concerted bridge - opening bridge - closing mechanism of carbonyl fluxionality rather than the Johnson libration mechanism. The fluxionality of the compounds in the 13C NMR spectra is explained by a combination of the concerted bridge - opening bridge - closing, merry-go-round, and trigonal twist mechanisms, and ΔG‡ values were determined.Key words: iron carbonyls, crystal structures, 13C NMR spectroscopy, fluxionality, mechanisms.

Komplexe des Typs [MCl4(SEt2)2] mit M = Mo und W. Kristallstrukturen, NMR-Spektren und magnetisches Verhalten/[MCl4(SEt2)2] Complexes with M = Mo and W. Crystal Structures, NMR Spectra, and Magnetic Behaviour

1995 ◽  
Vol 50 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Peter Dierkes ◽  
Gerlinde Frenzen ◽  
Sigrid Wocadlo ◽  
Werner Massa ◽  
Stefan Berger ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Nmr Spectra ◽  
Magnetic Behaviour ◽  
Triclinic Space Group ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Metal Atoms ◽  
Ray Methods ◽  
C Nmr

The crystal structures of the thioether complexes [MCl4(SEt2)2] with M = Mo and W have been solved by X-ray methods. Both compounds crystallize isotypically in the triclinic space group P1̄ with two formula units per cell unit. The metal atoms are octahedrally coordinated by four chlorine atoms and by the two sulfur atoms of the thioether molecules in transposition (symmetry Ci) with bond lengths (average): Mo-Cl 233.1, Mo-S 253.4, W-Cl 233.1, and W-S 251.7 pm. Both complexes were also characterized by 1H and 13C NMR spectroscopy as well as by measurement of the magnetic susceptibilities in the temperature range from 1.8 to 350 K.

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

[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.

13C-Chemische Verschiebungen von Aminosäuren und Peptiden / 13C-NMR Chemical Shifts of Amino Acids and Peptides

1971 ◽  
Vol 26 (3) ◽  
pp. 213-222 ◽  
Author(s):  
Wolfgang Voelter ◽  
Günther Jung ◽  
Eberhard Breitmaier ◽  
Ernst Bayer
Keyword(s):  
Amino Acids ◽  
Fourier Transform ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Analytical Tool ◽  
Reasonable Time ◽  
C Isotopes ◽  
Direct Recording ◽  
C Nmr

Pulse - Fourier - Transform-13C-NMR spectroscopy allowed the direct recording of 13C-NMR spectra of amino acids and peptides with natural abundance of 13C isotopes within a reasonable time. The 13C-signals of more than 50 free and protected amino acids and several peptides were assigned. 13C-NMR spectroscopy gives valuable information about the carbon skeleton, thus offering a new analytical tool for the study of biopolymers and their constituents.

Hochauflösungs-13C-NMR-Spektroskopie, VI [1]. Strukturabhängigkeit der 13C,H-Kopplungskonstanten in 6.6-disubstituierten Fulvenen / High Resolution 13C NMR Spectroscopy, VI [1]. Structure Dependence of the 13C,H Coupling Constants in 6,6-Disubstituted Fulvenes

1980 ◽  
Vol 35 (12) ◽  
pp. 1572-1574 ◽  
Author(s):  
Siegmar Braun ◽  
Ulrich Eiehenauer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
High Accuracy ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Structure Parameters ◽  
Structure Dependence ◽  
C Nmr

In order to study the structure dependence of the 13C,H couplings in the fulvene system the 1H-coupled 13C NMR spectra of 6,6-disubstituted fulvenes (R = R′ = C6H5, CH3, cyclopropyl and N(CH3)2) were recorded and the interesting couplings determined with high accuracy by complete analysis. They have values typical for unsaturated five membered rings with vastly localised double bonds like cyclopentadiene-1,3 and spiro[2.4]heptadiene- 4,6 and show characteristic correlations with structure parameters.

scholarly journals A study of [Au(ethylenediamine)Cl2]Cl interaction with L-methionine and DL-seleno-methionine by1H and13C NMR spectroscopy

2010 ◽  
Vol 24 (5) ◽  
pp. 567-575 ◽  
Author(s):  
Bassem A. Al-Maythalony ◽  
Mohamed I. M. Wazeer ◽  
Anvarhusein A. Isab ◽  
Saeed Ahmad
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chloride Ligands ◽  
C Nmr

The interaction of [Au(en)Cl2]Cl with L-methionine (Met) and DL-seleno-methionine (Se-Met) was carried out in D2O solution at ∼pH 3.8.13C NMR spectra were interpreted by comparison with the spectra recorded after the reaction of Met or Se-Met with HAuCl4and also after oxidation by H2O2. Reactions of [Au(en)Cl2]Cl with Met and Se-Met were found to proceed through the exchange of chloride ligands from complex with Met or Se-Met. Gold(III) reduction takes place during the reaction andenligand was released from [Au(en)Cl2]Cl complex.

9-Silyl(-Germyl,-Stannyl) Substituted Derivatives of 1-(9-Fluorenyl)- germatranes. Synthesis, Characterisation, and Crystal Structures

1998 ◽  
Vol 53 (11) ◽  
pp. 1247-1254 ◽  
Author(s):  
Galina S. Zaitseva ◽  
Sergey S. Karlov ◽  
Bettina A. Siggelkow ◽  
Evgeni V. Avtomonov ◽  
Andrei V. Churakov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Elemental Analyses ◽  
Derivatives Of ◽  
C Nmr

9-Trimethylsilyl- and 9-trimethylgermyl substituted derivatives of 1-(9-fluorenyl)germatranes C13H8(R)Ge(OCH2CH2)3N (1 - 3) (1: R = H; 2: R = Me3Si; 3: R = Me3Ge) were prepared by the reaction of 9-tribromogermyl derivatives of fluorene C13H8(R)GeBr3 (4 - 6) with N(CH2CH2OSnAlk3)3 (7: Alk = Et; 8: Alk = Bu). 1-(9-Trimethylstannyl- 9-fluorenyl)germatrane (14) was synthesised by the reaction o f the germatrane (1) with Me3SnNMe2 . Formulas and structures were established by elemental analyses, (1H, 13C) NMR spectroscopy and mass spectrometry; crystal structures of 2 and 14 are reported.

Synthesis, spectroscopic characterization, and structural studies of organogermanium tri- and monothiocarbonates. Crystal structures of Me2Ge[S2CSEt]2, Ph3Ge[SCO2Me], Ph3Ge[SCO2(i-Pr)], and Ph2Ge[SCO2Me]2

1998 ◽  
Vol 76 (3) ◽  
pp. 319-334 ◽  
Author(s):  
John E Drake ◽  
Jincai Yang
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Sodium Salt ◽  
Variable Temperature ◽  
Spectroscopic Characterization ◽  
Structural Studies ◽  
Cell Parameters ◽  
Derivatives Of ◽  
C Nmr

Two series of S-alkyl trithiocarbonate derivatives of imethylgermane, Me2Ge[S2CSR]2, and halodiphenylgermane, Ph2GeX[S2CSR], where R = Me, i-Pr, n-Pr, n-Bu and X = Cl, Br, and three series of O-alkyl monothiocarbonate derivatives of triphenylgermane, Ph3Ge[SCO2R], diphenylgermane, Ph2Ge[SCO2R], and trimethylgermane, me3Ge[SCO2R], where R = Me, i-Pr, and n-Pr, have been prepared in 73-92% yields by the reaction of the potassium or sodium salt of the appropriate tri- or monothiocarbonic acid with dichlorodimethyl-, chlorotriphenyl-, dichlorodiphenyl-, and chlorotrimethylgermane. The compounds were principally characterized by infrared, Raman, and 1H and 13C NMR spectroscopy, including some variable temperature studies, as well as by mass spectrometry. Me2Ge[S2CSEt]2, 1: P21/m (No. 11) with cell parameters a = 6.647(4) Å, b = 7.423(2) Å, c = 16.290(4) Å, β = 91.07(3)°, V = 803.6(4) Å3, Z = 2, R = 0.0484,Rw = 0.0485. Ph3Ge[SCO2Me],13: P1bar (No. 2) with cell parameters a = 9.970(4) Å, b = 10.660(3) Å, c = 9.853(2) Å, α = 101.78(2)°, β = 109.98(2)°, γ = 89.76(3)°, V = 961.0(5) Å3, Z = 2, R = 0.0534, Rw = 0.0451. Ph3Ge[SCO2(i-Pr)], 14: P 1bar (No. 2) with cell parameters a = 14.386(7) Å, b = 18.598(6) Å, c = 9.223(3) Å, α = 102.85(3)°, β = 94.58(3)°, γ = 108.13(3)°, V = 2256(1) Å3, Z = 2, R = 0.0545, Rw = 0.0552. Ph2Ge[SCO2Me]2, 16: Cc, (No. 9) with cell parameters a = 11.790(4) Å, b = 13.696(5) Å, c = 23.232(6) Å, β = 92.26(3)°, V = 3748(2) Å3, Z = 8, R = 0.0563, Rw = 0.0512. The immediate environment about Ge is that of tetrahedral but the orientations of the thiocarbonate groups display interesting features.Key words: structure, germanium, phenyl, methyl, thiocarbonates.

Reassignment of the structure of M3(CO)12(Cl)(SnCl3) (M = Ru, Os)

1989 ◽  
Vol 67 (7) ◽  
pp. 1236-1238 ◽  
Author(s):  
Anna Becalska ◽  
Roland K. Pomeroy ◽  
William A.G. Graham
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Quantitative Yield ◽  
Nmr Spectrum ◽  
C Nmr

Reaction of M3(CO)12 (M=Ru, Os) with SnCl4 in benzene at room temperature affords M3(CO)12(Cl)(SnCl3) in essentially quantitative yield. The 13C nmr spectra of these complexes indicate they have a ClM3(SnCl3) arrangement of atoms with the Cl ligand cis and the SnCl3 group trans to a linear Os3 chain. This is contrary to previously proposed structures for these compounds. The 13C nmr spectrum of Os3(CO)12(I)2 which has the iodo ligands cis to the Os3 chain is also reported for comparison. Keywords: ruthenium–tin, osmium–tin, osmium–iodine, l3C nmr spectroscopy.

Substituent Influences on the Keto-Enol Tautomerism in 1-(2-Hydroxyphenyl)-3-α-and -β-naphthylpropane-1,3-diones Monitored by 1H and 13C NMR Spectroscopy

2000 ◽  
Vol 55 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Jorge L. Jios ◽  
Helmut Duddeck
Keyword(s):  
Nmr Spectroscopy ◽  
Long Range ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
1H And 13C Nmr ◽  
Tautomeric Equilibria ◽  
Hmbc Correlation ◽  
C Nmr

Synthesis of 18 1-(2-hydroxyphenyl)-3-α- and -β-naphthylpropan-1,3-diones is described. Their 1H and 13C NMR spectra were completely and unambiguously assigned using a combination of both homo- and heteronuclear (gs-COSY ), 1H -detected heteronuclear one-bond (gs-HMQC ) and long-range (gs-HMBC) correlation experiments. Substituent and conformation effects on the tautomeric equilibria were identified and interpreted in terms of steric and electronic contributions.

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