Interpretation of substituent effects on 13C and 15N NMR chemical shifts in 6-substituted purines

2011 ◽  
Vol 13 (35) ◽  
pp. 15854 ◽  
Author(s):  
Stanislav Standara ◽  
Kateřina Bouzková ◽  
Michal Straka ◽  
Zuzana Zacharová ◽  
Michal Hocek ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
15N Nmr ◽  
Nmr Chemical Shifts

Chemometrical analysis of substituent effects on 13C and 15N NMR chemical shifts in 1-aroyl-3-substituted thioureas

1989 ◽  
Vol 54 (9) ◽  
pp. 2399-2407 ◽  
Author(s):  
Oldřich Pytela ◽  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
Latent Variables ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
The Other ◽  
15N Nmr ◽  
Nmr Chemical Shifts ◽  
Additional Constant ◽  
Substituent Constants ◽  
Derivatives Of ◽  
C Nmr

The methods of conjugated deviations and regression analysis have been used to study the substituent effects on 13C and 15N NMR chemical shifts of 12 derivatives of 1-aroyl-3-phenylthiourea and 1-aroyl-3-methylthiourea. The 13C NMR chemical shifts can be described by two latent variables, one univocally correlated with the Hammett substituent constants (r = 0.993) and the other reflecting the increased shielding of the nuclei due to overlap of the adjacent bond electrons as a consequence of electron-donor or electron-acceptor character of the substituents.This effect is less pronounced with the 15N nuclei. Application of dual substituent constants σR, σF with the additional constant σα describing the polarization has failed in giving sufficiently close correlations and explanation of the substituent effect found.

scholarly journals Predicting Heats of Explosion of Nitroaromatic Compounds through NBO Charges and 15N NMR Chemical Shifts of Nitro Groups

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Ricardo Infante-Castillo ◽  
Samuel P. Hernández-Rivera
Keyword(s):  
Cross Validation ◽  
Chemical Shifts ◽  
Quantitative Model ◽  
Nitroaromatic Compounds ◽  
Basis Set ◽  
15N Nmr ◽  
Prediction Ability ◽  
Heat Of Explosion ◽  
Nmr Chemical Shifts ◽  
Nbo Charges

This work presents a new quantitative model to predict the heat of explosion of nitroaromatic compounds using the natural bond orbital (NBO) charge and 15N NMR chemical shifts of the nitro groups (15NNitro) as structural parameters. The values of the heat of explosion predicted for 21 nitroaromatic compounds using the model described here were compared with experimental data. The prediction ability of the model was assessed by the leave-one-out cross-validation method. The cross-validation results show that the model is significant and stable and that the predicted accuracy is within 0.146 MJ kg−1, with an overall root mean squared error of prediction (RMSEP) below 0.183 MJ kg−1. Strong correlations were observed between the heat of explosion and the charges (R2 = 0.9533) and 15N NMR chemical shifts (R2 = 0.9531) of the studied compounds. In addition, the dependence of the heat of explosion on the presence of activating or deactivating groups of nitroaromatic explosives was analyzed. All calculations, including optimizations, NBO charges, and 15NNitro NMR chemical shifts analyses, were performed using density functional theory (DFT) and a 6-311+G(2d,p) basis set. Based on these results, this practical quantitative model can be used as a tool in the design and development of highly energetic materials (HEM) based on nitroaromatic compounds.

Correlation of 13C- and 15N-NMR Chemical Shifts of Ylidic Carbon and Nitrogen with Calculated Partial Charges in Pyridinium Dicyanomethylides

Heterocycles ◽  
1997 ◽  
Vol 45 (12) ◽  
pp. 2443 ◽  
Author(s):  
Kiyoshi Matsumoto ◽  
Hideki Katsura ◽  
Takane Uchida ◽  
Kinuyo Aoyama ◽  
Takahisa Machiguchi
Keyword(s):  
Chemical Shifts ◽  
15N Nmr ◽  
Nmr Chemical Shifts ◽  
Carbon And Nitrogen ◽  
Partial Charges

ChemInform Abstract: 15N-NMR CHEMICAL SHIFTS OF 2-SUBSTITUTED AZIRIDINES

1982 ◽  
Vol 13 (7) ◽  
Author(s):  
E. E. LIEPIN'SH ◽  
I. YA. KALVIN'SH ◽  
P. T. TRAPENTSIER
Keyword(s):  
Chemical Shifts ◽  
15N Nmr ◽  
Nmr Chemical Shifts

Substituent Effects on 31P NMR Chemical Shifts and 1JP–Se of triarylselenophosphates

2010 ◽  
Vol 185 (4) ◽  
pp. 772-784 ◽  
Author(s):  
Zaira Domínguez ◽  
Javier Hernández ◽  
Lorena Silva-Gutiérrez ◽  
Magali Salas-Reyes ◽  
Mario Sánchez ◽  
...  
Keyword(s):  
31P Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts

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 Prediction of 15N NMR chemical shifts for nitrogenated aromatic compounds

ARKIVOC ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 113-122
Author(s):  
Marcelo T. de Oliveira ◽  
Júlia M. A. Alves ◽  
Sara F. de A. Morais ◽  
Ataualpa A. C. Braga
Keyword(s):  
Aromatic Compounds ◽  
Chemical Shifts ◽  
15N Nmr ◽  
Nmr Chemical Shifts
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