Understanding electronic effects on carboxylate-assisted C–H activation at ruthenium: the importance of kinetic and thermodynamic control

2019 ◽  
Vol 220 ◽  
pp. 386-403 ◽  
Author(s):  
Raed A. Alharis ◽  
Claire L. McMullin ◽  
David L. Davies ◽  
Kuldip Singh ◽  
Stuart A. Macgregor
Keyword(s):  
Substituent Effects ◽  
Kinetic Control ◽  
Thermodynamic Control ◽  
Electronic Effects ◽  
Reaction Conditions ◽  
Opposite Trend

C–H activation processes may show contradictory substituent effects depending on the reaction conditions: under kinetic control ligands with electron-releasing substituents are favoured, whereas the opposite trend is seen under thermodynamic control.

Ambident nucleophilic reactivity in σ-complex formation. Part 5. Reaction of 1-phenyl-2,4,6-trinitrobenzene with methoxide and phenoxide ions

1984 ◽  
Vol 62 (3) ◽  
pp. 534-539 ◽  
Author(s):  
Erwin Buncel ◽  
Suresh Kumar Murarka ◽  
Albert Richard Norris
Keyword(s):  
Complex Formation ◽  
Kinetic Control ◽  
Thermodynamic Control ◽  
Electronic Effects ◽  
Strain Relief ◽  
Methanol Solutions ◽  
Nucleophilic Reactivity

The reactions of 1-phenyl-2,4,6-trinitrobenzene (4) with methoxide and phenoxide ions in DMSO and DMSO–methanol solutions have been investigated. MeO− gives rise to a 1,3 adduct through kinetic control and a 1,1 adduct through thermodynamic control. These processes persist also in the reaction of 4 with potassium phenoxide in DMSO–methanol. However, reaction of 4 with potassium phenoxide in DMSO gives rise to a 1,3 adduct as the only observed species in which phenoxide is bonded to the nitroaromatic moiety via the para phenoxy carbon, in accord with previous observations on the ambident reactivity of phenoxide ion. The results are considered in terms of various steric and electronic effects and it is concluded that F-strain, relief of steric compression, and delocalizability considerations play dominant roles in accounting for the observed reaction course.

scholarly journals Substituent Effects on EI-MS Fragmentation Patterns of 5-Allyloxy-1-aryl-tetrazoles and 4-Allyl-1-aryl-tetrazole-5-ones; Correlation with UV-Induced Fragmentation Channels

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3282
Author(s):  
Alina Secrieru ◽  
Rabah Oumeddour ◽  
Maria L. S. Cristiano
Keyword(s):  
Theoretical Calculations ◽  
Substituent Effects ◽  
Radical Cations ◽  
Electronic Effects ◽  
Diverse Range ◽  
The Matrix ◽  
Electron Impact Mass ◽  
Fragmentation Patterns ◽  
Tetrazole Derivatives ◽  
Impact Mass

1,4- and 1,5-disubstituted tetrazoles possess enriched structures and versatile chemistry, representing a challenge for chemists. In the present work, we unravel the fragmentation patterns of a chemically diverse range of 5-allyloxy-1-aryl-tetrazoles and 4-allyl-1-aryl-tetrazolole-5-ones when subjected to electron impact mass spectrometry (EI-MS) and investigate the correlation with the UV-induced fragmentation channels of the matrix-isolated tetrazole derivatives. Our results indicate that the fragmentation pathways of the selected tetrazoles in EI-MS are highly influenced by the electronic effects induced by substitution. Multiple pathways can be envisaged to explain the mechanisms of fragmentation, frequently awarding common final species, namely arylisocyanate, arylazide, arylnitrene, isocyanic acid and hydrogen azide radical cations, as well as allyl/aryl cations. The identified fragments are consistent with those found in previous investigations concerning the photochemical stability of the same class of molecules. This parallelism showcases a similarity in the behaviour of tetrazoles under EI-MS and UV-irradiation in the inert environment of cryogenic matrices of noble gases, providing efficient tools for reactivity predictions, whether for analytical ends or more in-depth studies. Theoretical calculations provide complementary information to articulate predictions of resulting products.

scholarly journals Effects of substituents on the 1H-NMR chemical shifts of 3-methylene-2-substituted-1, 4-pentadienes

2003 ◽  
Vol 68 (7) ◽  
pp. 525-534 ◽  
Author(s):  
Natasa Valentic ◽  
Gordana Uscumlic
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Effects ◽  
Resonance Effects ◽  
Charge Densities ◽  
Linear Free Energy ◽  
Energy Relationships ◽  
Consistent Picture ◽  
Vinyl Group ◽  
Proton Chemical Shifts

The principle of linear free energy relationships was applied to the 1H chemical shifts of the ?-vinyl proton atoms of 3-methylene-2-substituted-1,4-pentadienes. The correlations of the proton chemical shifts with Swain and Lupton substituent parameters provide a mutually consistent picture of the electronic effects in these compounds. The overall pattern of proton chemical shifts can be largely accounted for by a model of substituent effects based on field, resonance and ? polarization effects. Owing to the particular geometric arrangement of the vinyl group in 3-methylene-2-substituted-1,4-pentadienes, the ?-vinyl protons HB and HC have different sensitivities to polar and resonance effects. The different sensitivities of the 1H chemical shifts to resonance effects reveals some effects not predicted by the model outlined above. Evidence is presented that demonstrates that both the 1H and 13C chemical shifts for these compounds reflect their ground-state charge densities.

Ring-opening copolymerization of epoxide and dianhydride in the presence of manganese(III) asymmetrical bis-Schiff base catalysts

2014 ◽  
Vol 92 (11) ◽  
pp. 1098-1105 ◽  
Author(s):  
Deng-Feng Liu ◽  
Lu-Qun Zhu ◽  
Jing Wu ◽  
Li-Ying Wu ◽  
Xing-Qiang Lü
Keyword(s):  
Schiff Base ◽  
Ring Opening ◽  
Monomer Conversion ◽  
Structure Design ◽  
Steric Effects ◽  
Chain Growth ◽  
Electronic Effects ◽  
Reaction Conditions ◽  
Base Catalysts ◽  
Electronic And Steric Effects

Based on a series of asymmetrical bis-Schiff base H2Ln (n = 1–4) ligands with different electronic and steric effects, a series of [Mn(Ln)Cl] complexes 1–4 are obtained and shown to be effective catalysts in ring-opening copolymerization of epoxides and dianhydrides. Through the structure design, the input of electron-withdrawing bromine substituent para to the phenoxide group of the complexes is considerately beneficial to the improved activities. Moreover, steric and electronic effects of the suitable MeO substituent at the ortho orientation on the phenoxide group may both play a role in the formation of alternating ring-opening copolymers under the identical reaction conditions. In three cocatalysts tested, n-Bu4NBr is positive to monomer conversion and chain growth of polymer.

scholarly journals Tuning the electronic effects of aromatic phosphorus heterocycles: an unprecedented phosphinine with significant P(π)-donor properties

2014 ◽  
Vol 50 (64) ◽  
pp. 8842-8844 ◽  
Author(s):  
Antonia Loibl ◽  
Iris de Krom ◽  
Evgeny A. Pidko ◽  
Manuela Weber ◽  
Jelena Wiecko ◽  
...  
Keyword(s):  
Substituent Effects ◽  
Electronic Effects ◽  
Phosphorus Heterocycles ◽  
First Time

Substituent effects in phosphinine chemistry have been studied systematically and for the first time considerable π-donor properties of the aromatic phosphorus heterocycles have been revealed.

Substituent effects of two isophthalate derivatives on the construction of cadmium coordination polymers incorporating a dipyridyl ligand

2018 ◽  
Vol 74 (8) ◽  
pp. 894-900 ◽  
Author(s):  
Lin Wang ◽  
Qian-Kun Zhou ◽  
Yun Xu ◽  
Ni-Ya Li
Keyword(s):  
Coordination Polymers ◽  
Self Assembly ◽  
Three Dimensional ◽  
Substituent Effects ◽  
Dicarboxylic Acids ◽  
Two Dimensional ◽  
Reaction Conditions ◽  
Thermal Stabilities ◽  
Coordination Network ◽  
Potential Applications

In recent years, the design and construction of crystalline coordination complexes by the assembly of metal ions with multitopic ligands have attracted considerable attention because of the unique architectures and potential applications of these compounds. Two new coordination polymers, namely poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ2 N:N′](μ3-5-methylisophthalato-κ4 O 1,O 1′:O 3:O 3′)cadmium(II)], [Cd(C9H6O4)(C12H11N3)] n or [Cd(5-Me-ip)(2-NH2-3,4-bpe)] n , (I), and poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ2 N:N′](μ2-5-hydroxyisophthalato-κ4 O 1,O 1′:O 3:O 5)cadmium(II)], [Cd(C8H4O5)(C12H11N3)] n or [Cd(5-HO-ip)(2-NH2-3,4-bpe)] n , (II), have been prepared hydrothermally by the self-assembly of Cd(NO3)2·4H2O and trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene (2-NH2-3,4-bpe) with two similar dicarboxylic acids, i.e. 5-methylisophthalic acid (5-Me-H2ip) and 5-hydroxyisophthalic acid (5-HO-H2ip). The coordination network of (I) is a two-dimensional sql net parallel to (101). Adjacent sql nets are further linked to form a three-dimensional supramolecular framework via hydrogen-bonding interactions. Compound (II) is a two-dimensional (3,5)-connected coordination network parallel to (010) with the point symbol (63)(55647). As the other reactants and reaction conditions are the same, the structural differences between (I) and (II) are undoubtedly determined by the different substituent groups in the 5-position of isophthalic acid. Both (I) and (II) exhibit good thermal stabilities and photoluminescence properties.

scholarly journals Substituenteneinflüsse auf die 13C–NMR-chemischen Verschiebungen cis- und trans-konfigurierter Trimethincyanine / Substituent Effects on the 13C NMR Chemical Shifts of Trimethincyanines with cis and trans Configuration

1976 ◽  
Vol 31 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
Walter Grahn
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron Systems ◽  
Coupling Constant ◽  
Electronic Effects ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes ◽  
Cis And Trans ◽  
C Nmr

The 13C NMR chemical shifts of fifteen 6 substituted 2,3-dihydro-1,4-diazepinium salts (cis trimethincyanines) (1) and twelve 2 substituted bis(dimethylamino)trimethinium salts (trans trimethincyanines) (2) have been determined. A comparison of the substituentinduced shifts (13C SCS) of 1 and 2 allows no distinction between steric and electronic effects. In the three 6 п-electron systems 1, 2 and monosubstituted benzenes the 13C SCS are similar for the substituent bearing carbon atoms. A surprisingly large 4JFCCNC coupling constant has been observed.

scholarly journals Substituent effects on the spectral behavior and synthesis of mercury 1,5-diarylthiocarbazonates

1981 ◽  
Vol 59 (4) ◽  
pp. 679-687 ◽  
Author(s):  
Nori Y. C. Chu ◽  
Steven A. Goldstein ◽  
Philip M. Keehn
Keyword(s):  
Bathochromic Shift ◽  
Substituent Effects ◽  
Spectral Shift ◽  
Spectral Studies ◽  
Hypsochromic Shift ◽  
Electronic Effects ◽  
Activated State ◽  
Mercury Complexes ◽  
Inductive Effects ◽  
Methoxy Substituent

Symmetric and unsymmetric substituted 1,5-diarylthiocarbazones, and their mono- and bismercury complexes, were synthesized for spectral analysis. The first singlet–singlet transition of the mercury complexes was determined and the spectral shift produced by trifluoromethyl substitution was compared with that caused by different substituents in similar complexes. The large magnitude of the hypsochromic shift produced by the trifluoromethyl substituent can be explained by concerted steric and inductive effects, while the smaller bathochromic shift induced by the methoxy substituent is a result of opposing steric and electronic effects. In the trifluoromethyl substitution, a hypsochromic shift caused by steric influences was found to be 500 cm−1 in the photochromic unactivated state, and 250 cm−1 in the photochromic activated state. A similar shift caused by inductive influences was found to be 750 cm−1 in the photochromic unactivated state, and 600 cm−1 in the photochromic activated state. The smaller spectral shift observed in the photochromic activated state is consistent with the elucidated structure of the unsymmetric 1,5-diarylthiocarbazone, 6d, which was shown that the trifluoromethyl substitution was on the phenylazo portion of the molecule by chemical and spectral studies.

Metal complexes as ligands. X. Investigation of valency and substituent effects in binuclear complexes derived from tetradentate salicylaldimines

1972 ◽  
Vol 25 (1) ◽  
pp. 45 ◽  
Author(s):  
S Kokot ◽  
CM Harris ◽  
E Sinn
Keyword(s):  
Metal Complexes ◽  
Substituent Effects ◽  
Nickel Complexes ◽  
Magnetic Interactions ◽  
Binuclear Complexes ◽  
Electronic Effects ◽  
Metal Chlorides ◽  
Limited Sampling ◽  
Phenyl Rings ◽  
The Difference

A series of binuclear complexes has been formed by using planar copper(11) complexes (CUTSB) of tetradentate Schiff bases (TSB) as ligands to coordinate with metal chlorides. The binuclear complexes, (CuTSB)MCln (M = Cu11, Fe111, Mn11; n. = 2, 3), all exhibit pairwise antiferromagnetic interactions. The nickel complexes (NitsB)Mcln (M = FeIII, MnII) can be formed similarly, but the nickel atoms are diamagnetic so that no significant magnetic interactions are expected. The effect of 5-Cl, 5-Br, and 5,6-benzo substituents in the phenyl rings of the TSB groups on the strength of the antiferromagnetic interactions was examined in the complexes (CUTSB)CuCl2. Although the presence of a substituent usually increases the strength of the interaction, this trend is not systematic and there is no reason to attribute it to electronic effects of ring substituents. In (CUTSB)MCln, the main difference between the complexes with M = Fe111 and M = Mn11 is the difference in the valencies of the two d5 metals. In our limited sampling (one complex of each type), the interaction is stronger between iron(111) and copper(11) than between the manganese(11) and copper(11). These complexes form as hydrates, and since iron(111) and manganese(11) prefer octahedral environments, it is probable that one and two molecules of water respectively are coordinated to these metals. In the case where M = FeIII, N�ssbauer measurements indicate that this is so.

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