Reactions between N-Heterocyclic Carbene and Lutetium–Metallofullerenes: High Regioselectivity Directed by Electronic Effect in Addition to Steric Hindrance

2018 ◽  
Vol 84 (2) ◽  
pp. 606-612 ◽  
Author(s):  
Wangqiang Shen ◽  
Le Yang ◽  
Yongbo Wu ◽  
Lipiao Bao ◽  
Ying Li ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect

scholarly journals On the nature of the electronic effect of multiple hydroxyl groups in the 6-membered ring – the effects are additive but steric hindrance plays a role too

2017 ◽  
Vol 15 (5) ◽  
pp. 1164-1173 ◽  
Author(s):  
Christian Marcus Pedersen ◽  
Mikael Bols
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Membered Ring ◽  
Steric Effects ◽  
Hydroxyl Groups ◽  
Base Strength ◽  
Electronic And Steric Effects

Electronic and steric effects each play important roles in determining the base strength in piperidines.

Synthesis of Silyl Iron Dinitrogen Complexes for Activation of Dihydrogen and Catalytic Silylation of Dinitrogen

2021 ◽  
Author(s):  
Guoliang Chang ◽  
Peng Zhang ◽  
Wenjing Yang ◽  
Yanhong Dong ◽  
Shangqing Xie ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Dinitrogen Complexes ◽  
First Time

Three novel iron dinitrogen hydrides, [FeH(iPr-PSiMeP)(N2)(PMe3)] (1), [FeH(iPr-PSiPhP)(N2)(PMe3)] (2), and [FeH(iPr-PSiPh)(N2)(PMe3)] (3), supported by silyl ligand are synthesized for the first time by changing the electronic effect and steric hindrance...

scholarly journals A Theoretical Analysis of the Contributions to the Internal Rotation Barrier in N-Benzylideneanilines

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1199-1204
Author(s):  
K. Figueroa ◽  
M. Campos-Vallette ◽  
R. Contreras R.
Keyword(s):  
Total Energy ◽  
Internal Rotation ◽  
Steric Hindrance ◽  
Electronic Effect ◽  
Energy Surface ◽  
Rotation Barrier ◽  
Absolute Minimum ◽  
Internal Rotation Barrier ◽  
The Stability ◽  
Net Charges

Abstract An analysis, using CNDO wave functions, has been carried out on the different contributions to the internal rotation barrier in N-benzylideneaniline (1) and p-dimethylaminobenzylidene-p-nitro-aniline (2) in several conformations. The stability of the different structures has been expressed in terms of a partition of the total energy into electronic, net charges and steric hindrance contributions. Based on the shape of the total energy surface it appears that the barrier composition may be reasonably well described without approaching the absolute minimum. Rotation of the aniline group in both molecules is mainly governed by steric hindrance. Rotation of the benzylidene group shows a prevalent destabilizing electronic effect. The donor strength of the substituent in the benzylidene ring seems to play an important role in stabilizing a less nonplanar structure.

Steric effects in quaternizations. Alkylation of pyridine, thiazole, isothiazole and some benzologues with methyl, ethyl and isopropyl iodides

1976 ◽  
Vol 29 (8) ◽  
pp. 1745 ◽  
Author(s):  
LW Deady ◽  
DC Stillman
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Alkyl Halide ◽  
Steric Effects ◽  
Methyl Ethyl ◽  
Rate Retardation

Results of quaternization reactions in sulpholane at 65� are reported. A large steric hindrance is noted for quinoline relative to pyridine. A much smaller variation in rate with change in alkyl halide is seen in the benzothiazole/thiazole pair. Steric effects are very small and the rate retardation resulting from benzofusion is ascribed largely to an electronic effect. 2,l-Benzisothiazole reacts at essentially the same rate as isothiazole under these conditions.

Hexamethylazoxybenzene. Structure, Basicity, and Rearrangement

1973 ◽  
Vol 51 (18) ◽  
pp. 3143-3149 ◽  
Author(s):  
Robin A. Cox ◽  
Erwin Buncel
Keyword(s):  
Sulfuric Acid ◽  
Steric Hindrance ◽  
Reaction Mechanisms ◽  
Electronic Effect ◽  
Two Factors ◽  
Large Distortion ◽  
Concentrated Sulfuric Acid ◽  
Steric Inhibition Of Resonance

2,2′,4,4′,6,6′-Hexamethylazoxybenzene (1) has been prepared and characterized. The u.v. spectrum is indicative of large distortion from coplanarity. 1 is only slightly more basic than azoxybenzene despite expectations due to electronic effect of the methyl substituents. Two factors are considered responsible for this: steric inhibition of resonance in the unprotonated species and steric hindrance to hydration in the conjugate acid.Rearrangement of 1 in moderately concentrated sulfuric acid gives rise to the alcohol 4-hydroxymethyl-2,2′,4′,6,6′-pentamethylazobenzene (6). A Bamberger type phenolic product which would result from methyl migration is not observed. Possible reaction mechanisms are given.

Michael Additions of Benzotriazole-Stabilized Carbanions. A Review

1998 ◽  
Vol 63 (5) ◽  
pp. 599-613 ◽  
Author(s):  
Alan R. Katritzky ◽  
Ming Qi
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Steric Effects ◽  
Unsaturated Ketone ◽  
Electronic Effects ◽  
Michael Additions ◽  
Unsaturated Aldehydes ◽  
Michael Acceptor ◽  
Michael Acceptors ◽  
Electron Withdrawing Group

The 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors is reviewed. The selectivity between 1,4- and 1,2-addition depends significantly on the electronic effect of the carbanion (usually lithium is the counterion), the type of the Michael acceptor, and steric effects. Steric hindrance of the benzotriazolyl group probably enhances the regioselectivity. Normally, 1,4-additions to α,β-unsaturated ketone or ester are observed for carbanions stabilized by a benzotriazolyl group and an electron-withdrawing group (e.g. aryl, vinyl, carbonyl). For α,β-unsaturated aldehydes as Michael acceptors, 1,2-addition is more likely, except where electronic effects are very strong. A review with 39 references.

Steric hindrance influence of a diazo link upon mesogenic properties of some ligands and related copper complexes

1997 ◽  
Vol 94 ◽  
pp. 1695-1714 ◽  
Author(s):  
P Lesot ◽  
F Perez ◽  
P Judeinstein ◽  
JP Bayle ◽  
H Allouchi ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Copper Complexes
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