scholarly journals What can NMR spectroscopy of selenoureas and phosphinidenes teach us about the π-accepting abilities of N-heterocyclic carbenes?

2015 ◽  
Vol 6 (3) ◽  
pp. 1895-1904 ◽  
Author(s):  
Sai V. C. Vummaleti ◽  
David J. Nelson ◽  
Albert Poater ◽  
Adrián Gómez-Suárez ◽  
David B. Cordes ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Heterocyclic Carbenes ◽  
Carbene Ligands ◽  
Nmr Chemical Shifts ◽  
The Relationship

The relationship between the NMR chemical shifts of phosphinidene and selenourea compounds and the π-accepting ability of the related carbene ligands has been investigated.

Preparation, 1H and 13C NMR, and ab initio/IGLO study of mono-O-protonated deltic acid and theoretical investigation of di-, tri-, and tetra-O-protonated deltic acids

1999 ◽  
Vol 77 (5-6) ◽  
pp. 525-529 ◽  
Author(s):  
GK Surya Prakash ◽  
Golam Rasul ◽  
George A Olah ◽  
Ronghua Liu ◽  
Thomas T Tidwell
Keyword(s):  
Nmr Spectroscopy ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
13C Nmr ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Molar Solution ◽  
Protonated Species ◽  
C Nmr

The hitherto elusive mono-O-protonated deltic acid C3O3H3+ was prepared by protolysis of di-tert-butoxy deltate in FSO3H-SO2ClF and in FSO3H:SbF5 (Magic Acid; 1:1 molar solution) in SO2ClF as solvent at -78°C and was characterized by 1H and 13C NMR spectroscopy. The structure and NMR chemical shifts were also calculated by the ab initio/IGLO method. No NMR evidence was found for persistent di-O-protonated deltic acid under these conditions, although a limited equilibrium with the mono-O-protonated species can be involved. Di-, tri-, and tetra-O-protonated deltic acids were also studied by ab initio/IGLO method.Key words: protonated deltic acid, aromaticity, superacids, NMR spectroscopy, ab initio and IGLO calculations.

scholarly journals Palladium complexes with simple iminopyridines as catalysts for polyketone synthesis

2016 ◽  
Vol 45 (37) ◽  
pp. 14609-14619 ◽  
Author(s):  
V. Rosar ◽  
D. Dedeic ◽  
T. Nobile ◽  
F. Fini ◽  
G. Balducci ◽  
...  
Keyword(s):  
Systematic Study ◽  
Chemical Shifts ◽  
Palladium Complexes ◽  
Nmr Chemical Shifts ◽  
The Relationship ◽  
Donor Capability ◽  
Catalytic Performances

A systematic study on iminopyridine palladium complexes demonstrates the relationship among NMR chemical shifts, ligand donor capability and catalytic performances.

Determining the π-Acceptor Properties of N-Heterocyclic Carbenes by Measuring the 77Se NMR Chemical Shifts of Their Selenium Adducts

2013 ◽  
Vol 32 (19) ◽  
pp. 5269-5272 ◽  
Author(s):  
Annika Liske ◽  
Kathrin Verlinden ◽  
Hannes Buhl ◽  
Klaus Schaper ◽  
Christian Ganter
Keyword(s):  
Chemical Shifts ◽  
Heterocyclic Carbenes ◽  
Nmr Chemical Shifts

scholarly journals Influence of Fluorine Substituents on the Electronic Properties of Selenium-N-Heterocyclic Carbene Compounds

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5161
Author(s):  
Mohamad Shazwan Shah Jamil ◽  
Nor Azam Endot
Keyword(s):  
Electronic Properties ◽  
Chemical Shifts ◽  
Organometallic Compounds ◽  
Heterocyclic Carbenes ◽  
Metal Centre ◽  
Ancillary Ligands ◽  
Nmr Chemical Shifts ◽  
Work Supports

N-heterocyclic carbenes (NHCs) are common ancillary ligands in organometallic compounds that are used to alter the electronic and steric properties of a metal centre. To date, various NHCs have been synthesised with different electronic properties, which can be done by modifying the backbone or changing the nitrogen substituents group. This study describes a systematic modification of NHCs by the inclusion of fluorine substituents and examines the use of selenium-NHC compounds to measure the π-accepting ability of these fluorinated NHC ligands. Evaluation of the 77Se NMR chemical shifts of the selenium adducts reveals that fluorinated NHCs have higher chemical shifts than the non-fluorinated counterparts, IMes and IPh. Higher 77Se NMR chemical shifts values indicate a stronger π-accepting ability of the NHC ligands. The findings of this study suggest that the presence of fluorine atoms has increased the π-accepting ability of the corresponding NHC ligands. This work supports the advantage of the 77Se NMR chemical shifts of selenium-NHC compounds for assessing the influence of fluorine substituents on NHC ligands.

NMR effective radius of hydrogen in XIV group hydrides evaluated by NMR spectroscopy

2017 ◽  
Vol 46 (41) ◽  
pp. 14094-14097 ◽  
Author(s):  
M. Benedetti ◽  
F. De Castro ◽  
A. Ciccarese ◽  
F. P. Fanizzi
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Effective Radius ◽  
Nmr Chemical Shift ◽  
Ionic Radii ◽  
Nmr Chemical Shifts

In the [ABrnIm] (A = C, Si, Ge, Sn; n + m = 4) compounds, with the heavier halido ligands bonded to the central IV group elements, the 13C, 29Si, 73Ge and 119Sn NMR chemical shifts were found to be linearly related to the bonded halides ionic radii overall sum, ∑(rh). The 207Pb NMR chemical shift of the unstable [PbH4] hydride could be calculated.

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