Spectroscopic studies and correlation analysis of substituent effects in arylplatinum(II) complexes: cis and trans influences of aryl ligands

1984 ◽  
Vol 23 (14) ◽  
pp. 2117-2124 ◽  
Author(s):  
Dennis P. Arnold ◽  
Martin A. Bennett
Keyword(s):  
Correlation Analysis ◽  
Substituent Effects ◽  
Spectroscopic Studies ◽  
Cis And Trans

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.

Resonance Raman labels: spectroscopic studies on cis- and trans-4-benzylidene-2-phenyl-Δ2 -oxazolin-5-one and an isotopically substituted analog

1978 ◽  
Vol 56 (2) ◽  
pp. 232-239 ◽  
Author(s):  
K. Kumar ◽  
D. J. Phelps ◽  
P. R. Carey
Keyword(s):  
Raman Spectra ◽  
Electronic Transition ◽  
Raman Band ◽  
Resonance Raman ◽  
Spectroscopic Studies ◽  
Trans Isomers ◽  
Absorption Bands ◽  
Cis And Trans Isomers ◽  
Raman Excitation Profiles ◽  
Cis And Trans

The absorption and preresonance Raman spectra of cis- and trans-4-benzylidene-2-phenyl-Δ2-oxazoIin-5-one are reported. Although steric considerations suggest that the π electron pathway in the cis isomer is considerably distorted compared to the trans isomer, the Raman and absorption spectra of the two isomers are strikingly similar. Preresonance Raman excitation profiles for the cis and trans isomers indicate that the main features in the Raman spectra owe their intensity to coupling to the 360 nm absorption band present in both isomers. It is proposed that both the electronic dipole transition responsible for this absorption and the vibrational modes giving rise to the intense Raman bands are localized in the —C=C—N=C—Ph part of the molecule. Thus the main Raman and absorption bands are insensitive to isomerization in the benzylidene portion. Support for a localized electronic transition, polarized along the —C=C—N=C—Ph long axis, comes from Raman depolarization ratio (ρ) measurements which show that ail intense Raman features in both cis and trans isomers have ρ ∼ 0.33. Further support comes from ir and resonance Raman spectra of trans-4-(4-dimethylamino-3-nitrobenzylidene)-2-phenyloxazolin-5-one substituted either with 13C in the 4 position, or with 15N, in the oxazolinone ring. These spectra indicate that the main Raman feature seen in all 4-benzylidene-2-phenyloxazolinonesat 1561 cm−1 is a symmetric stretching mode associated with the —C=C—N=C— chain and that this feature has some C=N stretching character. The substitution experiments also show that the weak 1654 cm−1 Raman band has a high degree of C=C stretching character and may represent an essentially antisymmetric mode from the C=C—N=C moiety. The preresonance Raman excitation profiles show that the intensity enhancement follows an FB2 type dependence. The utility of the Raman spectrum as a probe for the chromophore responsible for the electronic transition in a highly conjugated system is discussed.

Correlation analysis of31P NMR chemical shifts with substituent effects of phenols

1995 ◽  
Vol 33 (5) ◽  
pp. 375-382 ◽  
Author(s):  
Zhi-Hua Jiang ◽  
Dimitris S. Argyropoulos ◽  
Alessandro Granata
Keyword(s):  
Correlation Analysis ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts

Application of photoelectron spectroscopy to substituent effects. Conformational analysis of some flexible allylic ethers and alcohols

1979 ◽  
Vol 57 (14) ◽  
pp. 1890-1896 ◽  
Author(s):  
R. S. Brown ◽  
R. W. Marcinko ◽  
A. Tse
Keyword(s):  
Conformational Analysis ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Ionization Energy ◽  
Substituent Effects ◽  
Allylic Alcohol ◽  
Tert Butyl ◽  
Cis And Trans ◽  
Allylic Ethers

He(I) photoelectron (pe) spectroscopy is applied to determine the preferred gas phase conformations of a limited number of flexible allylic ethers and alcohols. Based on earlier observations that the π-ionization energy is increased more when the allylic C—O bond is coplanar (with the π-system) than when it is perpendicular, the pe spectrum of cis and trans-4-tert-butyl-2-cyclohexanol and their corresponding ethers, and 5α-hydroxy(and methoxy)-10α-Δ3-octalin have been determined. The results indicate that when a coplanar arrangement of the allylic C—O bond can be attained, it is preferred, leading to a favored conformation of the allylic alcohol or ether.

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