Tertiary phosphine complexes of the cobalt(III) NN′-ethylenebis(salicylideneiminato) and bisdimethylglyoximato systems

1976 ◽  
Vol 54 (12) ◽  
pp. 1875-1883 ◽  
Author(s):  
C. W. Smith ◽  
G. W. Van Loon ◽  
M. C. Baird
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Ligand Field ◽  
Tertiary Phosphine ◽  
H Nmr ◽  
Phosphine Complexes ◽  
Salen Complexes ◽  
Inductive Effects ◽  
Ligand Field Parameters

Complexes of the types [CosalenPR3]X, [Cosalen(PR3)2]X, [Co(DH)2PPh3X], and [Co(DH)2(PR3)2]ClO4, many of them new, have been prepared and characterized with respect to 1H nmr spectra, ligand field parameters, and equilibrium constants for the formation of the 2:1 salen complexes. 1H chemical shifts appear to be dominated by anisotropic rather than inductive effects, while the relative tertiary phosphine ligand field strengths appear to correlate with the steric requirements of the phosphines as well as their expected σ donor strengths. Ease of formation of the 2:1 salen complexes is determined largely by steric effects, as are trans effects in the DH systems.

31P-NMR-und 57Fe-Mößbauer-spektroskopische Untersuchungen an Pentacyano(phosphan oder phosphit)ferraten(II) / 31P NMR and 57Fe Mössbauer Spectroscopic Studies on Pentacyano(phosphane or phosphite)ferrates(II)

1985 ◽  
Vol 40 (1) ◽  
pp. 22-25 ◽  
Author(s):  
Hidenari Inoue ◽  
Masahiro Sasagawa ◽  
Ekkehard Fluck
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
31P Nmr ◽  
Chemical Shifts ◽  
Spectroscopic Studies ◽  
57Fe Mössbauer ◽  
Mossbauer Spectra ◽  
H Nmr ◽  
Phosphine Complexes ◽  
Low Field

The 31P{1H}NMR spectra for a series of pentacyanoferrates(II) of the type Na3[Fe(CN)5L] (L = phosphine or phosphite) have been measured. A low field chemical shift range of 48.1-88.7 ppm for phosphine complexes and of 32.5-48.4 ppm for phosphite complexes is observed when one compares free vs. coordinated ligands. The correlation between chemical shifts in the 31P NMR spectra and isomeric shifts in the Mössbauer spectra is investigated and discussed

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.

Chemical shifts of charge-transfer complexes and Buckingham equation

1990 ◽  
Vol 55 (9) ◽  
pp. 2131-2137
Author(s):  
Mahboob Mohammad ◽  
Ather Yaseen Khan ◽  
Tariq Mahmood ◽  
Ismat Fatima ◽  
Riffat Shaheen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Charge Transfer Complex ◽  
Chemical Shifts ◽  
Charge Transfer Complexes ◽  
Aprotic Solvents ◽  
Reaction Field ◽  
H Nmr ◽  
Spherical Cavities ◽  
Dipolar Aprotic Solvents

The 1H NMR spectra of the charge-transfer complex of 1-ethyl-4-methoxycarbonylpyridinium iodide have been recorded in various dipolar aprotic solvents. An attempt is made to interpret the chemical shifts in terms of Buckingham's reaction field equation for spherical cavities. A linear dependence has been found between the δ(2,6) values and the square of dielectric function for a spherical cavity, which confirms the validity of the Buckingham equation for this class of compounds.

13C-NMR-Spektroskopie an polycyclischen Aromaten, II. Die 13C-NMR-Spektren von 1- und 2-Fluornaphthalin. Überprüfung der Signalzuordnung und Untersuchung der Substituenteneffekte auf die chemischen Verschiebungen / 13C NMR Spectroscopy of Polycyclic Aromatics, II. The 13C NMR Spectra of 1- and 2-Fluoronaphthalene. Reexamination of Signal Assignments and Investigation of Substituent Effects on Chemical Shifts

1975 ◽  
Vol 30 (9-10) ◽  
pp. 788-793 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Double Resonance ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Polycyclic Aromatics ◽  
H Nmr ◽  
Iterative Analysis ◽  
C Nmr

During a reinvestigation of the 13C NMR spectra of 1-fluoronaphthalene (1) and of 2-fluoronaphthalene (2) at 20 and 25.16 MHz, uncertainties that existed in the literature about signal assignments for 1 could be cleared. In the spectral analyses for 2 given so far, five out of ten signals were incorrectly assigned. The corrected assignment is supported by extensive 13C{1H} double resonance experiments, by recording of proton-coupled 13C and 13C{19F} spectra and by off-resonance 13C{1H} noise-decoupling. The results show a strong + M-effect of the fluorine substituents on 13C chemical shifts similar to the effects of OH and OCH3 groups. 1H NMR spectra of 1 and 2 could be partially assigned by decoupling of the 19F resonances and by iterative analysis.

scholarly journals Synthesis and Structural Studies of Transition Metal Complexes with Bidentate Schiff Base Derived from 3-Acetyl-6-methyl-(2H)-pyran-2,4(3H)-dione

2011 ◽  
Vol 8 (s1) ◽  
pp. S245-S252 ◽  
Author(s):  
Praveen S. Mane ◽  
Sanjiv M. Salunke ◽  
Balagi S. More
Keyword(s):  
Schiff Base ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Octahedral Geometry ◽  
Ligand Field ◽  
Schiff Base Ligands ◽  
H Nmr ◽  
Dehydroacetic Acid ◽  
Ligand Field Parameters

The solid complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with Schiff base ligands derived from heterocyclic compounds 3-acetyl-6-methyl-(2H)-pyran-2,4(3H)-dione (Dehydroacetic acid) ando-chloroaniline were synthesized and characterized by elemental analysis, conductance, magnetic, thermal, UV-Vis and1H-NMR spectroscopy. The ligand field parameters have been evaluated for Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) complexes which suggest an octahedral geometry for each of them. The magnetic moment and spectral data suggest the dimeric nature of Mn(II) complexes with octahedral geometry. The fungicidal activities of the ligands and their metal complexes have been screened in vitro againstAspergillus nigerand the percentage inhibition of the metal complexes is found to be increased considerably then that of their corresponding ligands and the order is Cu>Ni>Fe>Mn>Co.

Conformation of ring A in triterpenoid and 4,4-dimethylsteroid 3-ketones. Chemical shifts of methyl protons and lanthanide and benzene induced shifts

1990 ◽  
Vol 55 (3) ◽  
pp. 766-781 ◽  
Author(s):  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jarmil Světlý
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Methyl Groups ◽  
Pentacyclic Triterpene ◽  
H Nmr ◽  
Lanthanide Induced Shifts ◽  
Physical Data

Chemical shifts of signals due to methyl groups in position 10β (in CDCl3) and 4α and 4β (in C6D6) in 1H NMR spectra of pentacyclic triterpene 3-oxo derivatives (V, VIII, IX, and XII) are suitable for estimation of chair-boat equilibrium in the ring A. Benzene and lanthanide induced shifts of 4α and 4β-methyl protons were also used for this purpose. The results obtained with 2α-methyl-3-ketones (III, X) and 2β-methyl-3-ketones (IV, XI) as the respective chair and boat models agree well with those derived from other physical data (about 40% boat). The same methods were applied to 4,4-dimethylsteroid 3-ketones XV-XVII.

Dynamic NMR spectroscopy of 2,2′-dimethyl-1-picrylhydrazine in various solvents

2006 ◽  
Vol 84 (12) ◽  
pp. 1648-1657 ◽  
Author(s):  
K C Brown ◽  
M El-Bermani ◽  
Y Upadrashta ◽  
J A Weil
Keyword(s):  
Conformational Changes ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Activation Parameters ◽  
Detailed Comparison ◽  
Liquid Solution ◽  
Molecular Orbital Calculations ◽  
Dynamic Nmr ◽  
Hindered Rotation ◽  
H Nmr

We have studied the 1H NMR spectra of 2,2′-dimethyl-1-(2,4,6-trinitrophenyl)hydrazine at 300 and 500 MHz in seven liquid solvents, with a view to learning details of the internal conformational changes taking place as a function of temperature and of the solvent. These molecules in liquid solution occur as interconverting enantiomorphic pairs (atropisomers). Advanced techniques for obtaining the correct activation energies and pseudo-thermodynamic parameters have been utilized, and these parameters are listed and discussed. Our results point to a transformation between the pair of atropisomers that is not quite as complicated as one might have encountered in that the solvent does not affect ΔG‡ in any major fashion. Molecular orbital calculations clarified some of the chemical shifts observed for both 1H and 13C. One goal of this study was to enable a detailed comparison with similar results available for 2,2′-diphenyl-1-(2,4,6-trinitrophenyl)hydrazine.Key words: dynamic NMR, dimethylpicrylhydrazine, hindered rotation, atropisomers, activation parameters.

Ligand field parameters obtained from and chemical shifts observed at the CrL2,3edges

1999 ◽  
Vol 59 (12) ◽  
pp. 7931-7936 ◽  
Author(s):  
C. Theil ◽  
J. van Elp ◽  
F. Folkmann
Keyword(s):  
Chemical Shifts ◽  
Ligand Field ◽  
Ligand Field Parameters
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