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.

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.

scholarly journals SYNTHESIS AND SPECTRAL CHARACTERISTICS OF PERSPECTIVE NANOSIZED CARBON QUANTUM DOTS FOR ADSORPTION AND CATALYTIC PROCESSES

2020 ◽  
Vol 86 (1) ◽  
pp. 3-11
Author(s):  
Volodymyr Ogenko ◽  
Svitlana Orysyk ◽  
Ljudmila Kharkova ◽  
Oleg Yanko
Keyword(s):  
Quantum Dots ◽  
Bathochromic Shift ◽  
Spectral Characteristics ◽  
Carbon Quantum Dots ◽  
Hypsochromic Shift ◽  
Absorption Bands ◽  
Rhodium Chloride ◽  
Electron Transitions ◽  
Trivalent State ◽  
Adsorption Processes

Processes of interaction between carbon quantum dots (CQDs) and solutions of rhodium, ruthenium and palladium chlorides in the surface layer have been investigated by electron and IR spectroscopy. When rhodium chloride is added to a solution of CQDS, a bathochromic shift of the β- and p-absorption bands (ABs) at 48725 and 41711 cm-1 as well as hypsochromic shift of the α-AB at 28935 cm-1 indicate that rhodium adsorption occurs on the surface of CQDs. The bathochromic shift of the absorption bands at 22400 сm1 together with the hypsochromic shift of ABs corresponding to d-d electron transitions in the metal ions indicates the formation of rhodium with CQDs. When ruthenium and palladium chlorides are added to an aqueous solution of CQDs, the intensive of ABs characterizing the complex anions [RuCl6]3-, [RuCl6]2- or [PdCl4]2- are absent in the UV-Vis spectra. This indicates the passage of adsorption processes of metals on the surface of CQDs.  The present of ABs (at 27055 and 25125 сm-1) indicate the trivalent state of ruthenium ion; the p-ABs bathochromic shift as well as α-ABs hypsochromic shift indicates the probable complex formation of CQDs with Ru3+ ions. The change in the position of the absorption bands of d-d electron transitions (at 25448 сm1) together with the bathochromic shift of p-ABs and hypsochromic shift of α-ABs indicates a change in coordination environment in the palladium ion with the possible formation of Pd → N bond. The IR-spectra data of CQDs showed the presence of a number of characteristic ABs for functionalized CQDs: ν(N–H) at 3260 сm1, (C=O) at 1830, 1840 and 1850 сm1, –С=O(NH) at 1770 сm1, ν(C=N) at 1680 and δ(N–H) at 1640 сm1, which confirms the coordination of metals on the surface of CQDs.

Schwingungs-und Elektronenspektren der bindungsisomeren Hexakis(thiocyanato(N)-thiocyanato(S))-osmate(III) und (IV) / Vibrational and Electronic Spectra of Bond-Isomeric Hexakis(thiocyanato(N)-thiocyanato(S))osmates(III) and (IV)

1988 ◽  
Vol 43 (4) ◽  
pp. 371-381 ◽  
Author(s):  
K. Bütje ◽  
W. Preetz
Keyword(s):  
Charge Transfer ◽  
Vibrational Spectra ◽  
Near Infrared ◽  
Bathochromic Shift ◽  
Infrared Region ◽  
Hypsochromic Shift ◽  
Linkage Isomers ◽  
Near Infrared Region ◽  
Ir And Raman ◽  
Metal Ligand

AbstractWell-resolved IR and Raman spectra of the two sets of all 10 isomeric complexes [Os(NCS)n(SCN)6-n]3-/2-, n = 0-6, have been recorded. For both series, νCS(N) > νCS(S) and δNCS > δSCN; for the Os(III) complexes, vCN(N) ~ vCN(S) and vOsN ≥ vOsS while for the Os(IV) compounds, vCN(N) < vCN(S) and vOsN ~ vOsS. The vibrational spectra of the n = 0 and n = 6 members of both sets are assigned according to D3d and Oh point symmetry, respectively. For the mixed linkage isomers the band pattern is strongly influenced by pseudo-octahedral coupling wherever frequencies of N- and S-bonded groups coincide. The metal-ligand stretching region is therefore assigned according rather to pseudo-Oh, pseudo-D3d and pseudo-D4h symmetry than to D4h, C4v, C3v and C2v microsymmetry. The charge-transfer spectra of both series are similar, showing a parallel hypsochromic shift with increasing n value. Upon oxidation, a bathochromic shift of the CT bands by an average of 5400 cm-1 is observed, and the intensity increases by a factor 2-2.5. Weak absorptions in the near infrared region are assigned to intraconfigurational transitions.

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 on the Hydrolysis of p-Substituted Benzonitriles in Sulfuric Acid Solutions at (25.0± 0.1) °C

2008 ◽  
Vol 63 (9) ◽  
pp. 603-608 ◽  
Author(s):  
Khamis A. Abbas
Keyword(s):  
Sulfuric Acid ◽  
Rate Constants ◽  
Inductive Effect ◽  
Substituent Effects ◽  
Acid Solutions ◽  
Rate Determining Step ◽  
Inductive Effects ◽  
High Concentrations ◽  
Sulfuric Acid Solutions ◽  
Hydrolysis Of

The rate constants of the hydrolysis of p-substituted benzonitriles with sulfuric acid solutions (18.2 M to 10 M) have been determined spectrophotometrically at (25.1±0.1) °C. It was found that the catalytic activity of sulfuric acid was strongly inhibited by water. The logarithms of the observed rate constants were correlated with different substituent inductive (localized) and resonance (delocalized) constants. The results of the correlation studies indicated that the rate-determining step of the hydrolysis of benzonitriles in 18.2 M sulfuric acid was the addition of a nucleophile, and the hydrolysis was clearly enhanced by the electron-withdrawing inductive effect, while the rate-determining step of the hydrolysis of p-substituted benzonitriles in 10.0 M sulfuric acid was most probably the protonation of benzonitriles, and the rate constants increased by both electron-donating resonance and inductive effects. A mixture of the two mechanisms most probably occurred in 15.3 to 17.0 M sulfuric acid. HSO4 − rather thanwater most probably acted as nucleophile in the hydrolysis of benzonitriles especially at high concentrations of sulfuric acid solutions.

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.

Substituent effects in naphthalene. II. The strengths of the 4, 5, 6, 7, and 8-substituted 2-naphthoic acids

1965 ◽  
Vol 18 (9) ◽  
pp. 1365 ◽  
Author(s):  
PR Wells ◽  
W Adcock
Keyword(s):  
Electrostatic Interactions ◽  
Aqueous Ethanol ◽  
Substituent Effects ◽  
Simple Expression ◽  
Dipole Orientation ◽  
Aromatic Substituent ◽  
Resonance Effects ◽  
Naphthoic Acid ◽  
Inductive Effects ◽  
Substituted 1

The apparent pKa values of 44 substituted 2-naphthoic acids, six substituted 1-naphthoic acids, and the unsubstituted naphthoic acids have been determined for 50% v/v aqueous ethanol at 25�. The ΔpK values are examined in terms of Dewar and Grisdale's simple expression for aromatic substituent effects. This expression proves to be fairly satisfactory, but takes no account of substituent dipole orientation, secondary resonance effects, nor π-inductive effects. A survey of the naphthoic acid strengths demonstrates the importance of these factors. In particular, unambiguous evidence for the important role played by direct electrostatic interactions is obtained.

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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