Analysis of 1H NMR Data for Arene-Metal Complexes Using Extended Huckel Calculations

1998 ◽  
Vol 63 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Adelino M. Galvão ◽  
João L. Ferreira da Silva
Keyword(s):  
Metal Complexes ◽  
Molecular Orbital ◽  
Chemical Shifts ◽  
Arene Complexes ◽  
Group Vi ◽  
H Nmr ◽  
Nmr Data ◽  
Extended Hückel ◽  
Electronic Densities ◽  
Extended Hückel Calculations

This work reports the use of extended Hückel molecular orbital (EHMO) calculations to correlate pz electronic densities of aromatic carbons in group VI metal-bis(η6-arene) complexes with the respective 1H NMR chemical shifts. The effect of delocalization on the acceptor properties and stabilization of ligand orbitals is analyzed comparing complexes of naphthalene, biphenyle and fluorene.

Characterization of the 2,2′-bipyridine chelates of lanthanum(III) in acetonitrile. A 1H, 13C, 17O, and 139La NMR study

1993 ◽  
Vol 71 (3) ◽  
pp. 377-383 ◽  
Author(s):  
Monique Fréchette
Keyword(s):  
Coordination Sphere ◽  
Chemical Shifts ◽  
Complexation Reaction ◽  
Complex Species ◽  
H Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Close Proximity ◽  
Coordinated Water

We have investigated the reaction between La(NO3)3•6H2O and 2,2′-bipyridine (bipy) in acetonitrile by means of 139La, 17O, 13C, and 1H NMR spectroscopy. The 139La spectra show up to three different sites with variable intensities attributed to solvated La(III) ions and to two complex species with one or two bipy moieties in the La(III) coordination sphere. 17O NMR indicates that during the complexation reaction, the coordinated water is totally displaced from the coordination sphere whereas the nitrate groups remain coordinated. Proton NMR data confirm the water expulsion. In addition, the proton chemical shifts of bipy, in comparison with the 13C NMR data, clearly show an anisotropic shielding when two bipy are coordinated to La(III). Therefore, the two bipy molecules are in close proximity in the coordination sphere. From the NMR results it has been shown that, during the complexation process, five different La(III) species are formed: [La(NO3)3(CH3CN)4], [La(NO3)3(CH3CN)3(H2O)], [La(NO3)3(bipy)(CH3CN)2], [La(NO3)3(bipy)(CH3CN)-(H2O)], and [La(NO3)3(bipy)2]. Each La(III) complex has a coordination member of 10, with NO3− and bipy acting as chelating ligands. Furthermore, the structure of the La(NO3)3(bipy)2 complex in solution shows similarities with the solid state compound. Finally, comparisons are made with the La(III) complexes previously obtained with 1,10-phenanthroline.

Reaktion von 1.4-Dienen mit Metallkomplexen, I Darstellung und Röntgenstrukturanalyse eines π-enyl-Komplexes der Zusammensetzung (C8H13PdCl)2/ Reaction of 1,4-Dienes with Metal Complexes, I Synthesis and X-ray Structure Determination of a π-enyl Complex of Composition (C8H18PdCl)2

1976 ◽  
Vol 31 (4) ◽  
pp. 455-462 ◽  
Author(s):  
Peter Feldhaus ◽  
Richard Ratka ◽  
Hermann Schmid ◽  
Manfred L. Ziegler
Keyword(s):  
Metal Complexes ◽  
Structure Determination ◽  
Three Dimensional ◽  
Fourier Methods ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Reaction of (C6H5CN)2PdCl2 and 1,3-dimethylenecyclohexane led to an exocyclic π-enyl complex of formula (C8H13PdCl)2-bis(η3-2-methylene-6-methylcyclohexyl)(di-µ-chloro)-dipalladium. IR and 1H NMR data are in agreement with this formulation.The compound is monoclinic, with unit cell dimensions α = 499.97 ± 0.08, b =1342.26 ± 0.19, c =1379.60 ± 0.20 pm, β = 99.43 ± 0.02°, space group C5h2-P21/C, Ζ = 2, dX-ray = 1.83 g/cm3.The structure was determined from three-dimensional X-ray data by Patterson and Fourier methods. Least squares refinement by use of 1045 independent reflections has reached R1 = 5.6%.

A Further Contribution to the Triterpenoid Constituents of Glycyrrhiza glabra L

1990 ◽  
Vol 45 (9-10) ◽  
pp. 937-941 ◽  
Author(s):  
M. H. A. Elgamal ◽  
F. K. Abdel Hady ◽  
A. G. Hanna ◽  
G. H. Mahran ◽  
H. Duddeck
Keyword(s):  
Chemical Shifts ◽  
Glycyrrhiza Glabra ◽  
Spectroscopic Methods ◽  
Pentacyclic Triterpenoids ◽  
Minor Constituents ◽  
Stereochemical Configuration ◽  
H Nmr ◽  
Nmr Data ◽  
Glycyrrhiza Glabra L

Abstract Pentacyclic Triterpenoids, G lycyrrhiza glabra, 1H and 13C Chemical Shifts Five pentacyclic triterpenoids have been isolated from the minor constituents of local liquorice roots, one of them (8) has not been isolated before from liquorice root. Their struc­ tural formulae and stereochemical configuration was determined by spectroscopic methods. 13C and 1H NMR data have been compiled.

scholarly journals Cinnamoylphenethylamine 1H-NMR Chemical Shifts: A Concise Reference for Ubiquitous Compounds

2010 ◽  
Vol 5 (8) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Hans A. Pedersen ◽  
Stine K. Steffensen ◽  
Carsten Christophersen
Keyword(s):  
Natural Products ◽  
1H Nmr ◽  
Spectroscopic Data ◽  
Uv Light ◽  
Chemical Shifts ◽  
Rapid Identification ◽  
Upfield Shift ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Data

1H-NMR data of 25 cinnamoylphenethylamine derivates were recorded and compared in order to assign signals unequivocally without additional spectroscopic data. The spectra provide a key for the rapid identification of these ubiquitous natural products. The compounds isomerize rapidly in UV light, producing a characteristic upfield shift of the olefinic protons consistent with distorted planarity of the Cis cinnamate, and this requires special attention during preparative work.

Identification of acyl groups occurring in sesquiterpene lactones: Proton and carbon-13 NMR study

1987 ◽  
Vol 52 (2) ◽  
pp. 453-475 ◽  
Author(s):  
Miloš Buděšínský ◽  
David Šaman
Keyword(s):  
Chemical Shifts ◽  
Sesquiterpene Lactones ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Nmr Study ◽  
C Nmr

Characteristic 1H NMR parameters of 88 acyl groups, hitherto found as ester substituents in natural sesquiterpenic lactones, were determined from the measured spectra as well as literature data. Characteristic 13C NMR chemical shifts for 45 acyl groups were obtained in the same way; for the remaining acyls with hitherto unknown 13C NMR data the values were calculated on the basis of semiempirical relationships.

scholarly journals Optisch aktive Übergangsmetall-Komplexe, LVII [1] (+)- und (-)-C5H5M(CO)(P∅2R*)X mit M = Fe, 57Fe und X = I, COCH3, CH3 / Optically Active Transition Metal Complexes, L VII [1] (+)- and (-)-C5H5M(CO)(P∅2R*)X with M = Fe, 57Fe, and X = I, COCH3, CH3

1978 ◽  
Vol 33 (4) ◽  
pp. 407-411 ◽  
Author(s):  
Henri Brunner ◽  
Manfred Muschiol ◽  
Wilfried Nowak
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Fractional Crystallization ◽  
Iron Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Optically Active ◽  
H Nmr ◽  
Active Transition

In the reaction of C5H5Fe(CO)2l and C5H5Fe(CO)2CH3, respectively, with S-(+)-(C6H5)2PN(CH3)CH(CH3)(C6H5) (abbreviated P∅2R*) the complexes C5H5Fe(CO)(P∅2R*)I (1), C5H5Fe(CO)(P∅2R*)COCH3 (2), and C5H5Fe(CO)(P∅2R*)CH3 (3) are formed as pairs of diastereoisomers the components of which differ only in the configu­ration at the iron atom. CsH5Fe(CO)(P∅2R*)CH3 (3) can be obtained in higher yield by photochemical decarbonylation of C5H5Fe(CO)(P∅2R*)COCH3 (2). The (+)365- and (-)365-diastereoisomers of each pair exhibit different chemical shifts in the 1H NMR spectra. Diastereoisomer separation can be achieved by fractional crystallization.Starting with 57Fe metal (-)365-C5H557Fe(CO)(P∅2R*)I was prepared via 57Fel2, 57Fe(CO)4l2, C5H557Fe(CO)2l, and C5H557Fe(CO)(P∅2R*)I in order to demonstrate optical activity of a 57Fe compound in the y region by Mössbauer polarimetry in later experiments to be reported elsewhere.

The Correlation of 13C Chemical Shifts of Steroids with Atomic Charges Calculated by the Extended Hückel Molecular Orbital Method

1974 ◽  
Vol 29 (8) ◽  
pp. 1172-1178
Author(s):  
Helmar Repmann
Keyword(s):  
Molecular Orbital ◽  
Chemical Shifts ◽  
Linear Regression Analysis ◽  
Orbital Method ◽  
Molecular Orbital Calculations ◽  
Atomic Charges ◽  
Methyl Group ◽  
Extended Hückel ◽  
Hückel Theory ◽  
Steroidal Hormones

13C chemical shifts of several of the sterols and steroidal hormones which have been investigated by Reich et al. (J. Amer. Chem. Soc. 91, 7445 [1969]) are compared with the atomic charges derived from extended Hückel molecular orbital calculations for these molecules. The linear regression analysis of 126 observations for aliphatic carbons gives a correlation coefficient of 0.81, and a standard error of estimate of 8.2 ppm. The largest discrepancies arise for carbons in the neighbourhood of methyl groups, which cannot be attributed to deficiencies of the extended Hückel theory. The corrections for carbons in the α, β, and γ positions to a methyl group amount to + 11.75, - 6.44, and +4.45 ppm, respectively. The results are discussed in relation to the structural analysis of steroids.

Preparation, properties and structure of some intermediate nido- and arachno-monocarbaboranes

1981 ◽  
Vol 46 (10) ◽  
pp. 2345-2353 ◽  
Author(s):  
Karel Baše ◽  
Bohumil Štíbr ◽  
Jiří Dolanský ◽  
Josef Duben
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Nmr Spectra ◽  
Liquid Ammonia ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Starting Compound

The 6-N(CH3)3-6-CB9H11 carbaborane reacts with sodium in liquid ammonia with the formation of 6-CB9H12- which was used as a starting compound for preparing the 4-CB8H14, 9-L-6-CB9H13 (L = (CH3)2S, CH3CN and P(C6H5)3), 1-(η5-C5H5)-1,2-FeCB9H10-, and 2,3-(η5-C5H5)2-2,31-Co2CB9H10- carboranes. The 4-CB8H14 compound was dehydrogenated at 623 K to give 4-(7)-CB8H12 carborane. Base degradation of 6-N(CH3)3-6-CB9H11 in methanol resulted in the formation of 3,4-μ-N(CH3)3CH-B5H10. The structure of all compounds was proposed on the basis of their 11B and 1H NMR spectra and X-ray diffraction was used in the case of the transition metal complexes.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

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