The impact of the π-electron conjugation on15N,13C and1H NMR chemical shifts inpush–pull benzothiazolium salts. Experimental and theoretical study

2007 ◽  
Vol 45 (11) ◽  
pp. 942-953 ◽  
Author(s):  
Peter Hrobárik ◽  
Branislav Horváth ◽  
Ivica Sigmundová ◽  
Pavol Zahradník ◽  
Olga L. Malkina
Keyword(s):  
Theoretical Study ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts ◽  
The Impact

scholarly journals 29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1646 ◽  
Author(s):  
Ilia Ponomarev ◽  
Peter Kroll
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Density Functional ◽  
Chemical Shifts ◽  
29Si Nmr ◽  
Hydrogenated Silicon ◽  
Nmr Chemical Shifts ◽  
Nmr Data ◽  
29Si Nmr Spectra ◽  
The Impact

We investigate 29Si nuclear magnetic resonance (NMR) chemical shifts, δiso, of silicon nitride. Our goal is to relate the local structure to the NMR signal and, thus, provide the means to extract more information from the experimental 29Si NMR spectra in this family of compounds. We apply structural modeling and the gauge-included projector augmented wave (GIPAW) method within density functional theory (DFT) calculations. Our models comprise known and hypothetical crystalline Si3N4, as well as amorphous Si3N4 structures. We find good agreement with available experimental 29Si NMR data for tetrahedral Si[4] and octahedral Si[6] in crystalline Si3N4, predict the chemical shift of a trigonal-bipyramidal Si[5] to be about −120 ppm, and quantify the impact of Si-N bond lengths on 29Si δiso. We show through computations that experimental 29Si NMR data indicates that silicon dicarbodiimide, Si(NCN)2 exhibits bent Si-N-C units with angles of about 143° in its structure. A detailed investigation of amorphous silicon nitride shows that an observed peak asymmetry relates to the proximity of a fifth N neighbor in non-bonding distance between 2.5 and 2.8 Å to Si. We reveal the impact of both Si-N(H)-Si bond angle and Si-N bond length on 29Si δiso in hydrogenated silicon nitride structure, silicon diimide Si(NH)2.

Spirocyclic tin salicyl alcoholates – a combined experimental and theoretical study on their structures, 119Sn NMR chemical shifts and reactivity in thermally induced twin polymerization

2019 ◽  
Vol 48 (1) ◽  
pp. 220-230
Author(s):  
Philipp Kitschke ◽  
Ana-Maria Preda ◽  
Alexander A. Auer ◽  
Sebastian Scholz ◽  
Tobias Rüffer ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Chemical Shifts ◽  
Molecular Structures ◽  
Thermally Induced ◽  
Nmr Chemical Shifts ◽  
119Sn Nmr

Studies on a series of spirocyclic tin salicyl alcoholates regarding their molecular structures and their reactivity in twin polymerization are presented.

1H NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study

2013 ◽  
Vol 78 (4) ◽  
pp. 1504-1507 ◽  
Author(s):  
Marija Baranac-Stojanović ◽  
Milovan Stojanović
Keyword(s):  
1H Nmr ◽  
Theoretical Study ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts

Theoretical study on metal NMR chemical shifts: niobium complexes

1992 ◽  
Vol 96 (11) ◽  
pp. 4375-4381 ◽  
Author(s):  
Manabu Sugimoto ◽  
Mamoru Kanayama ◽  
Hiroshi Nakatsuji
Keyword(s):  
Theoretical Study ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts ◽  
Niobium Complexes

scholarly journals Theoretical study on 31P NMR chemical shifts of phosphorus-modified CHA zeolites

2020 ◽  
Vol 294 ◽  
pp. 109908 ◽  
Author(s):  
Pei Zhao ◽  
Bundet Boekfa ◽  
Toshiki Nishitoba ◽  
Nao Tsunoji ◽  
Tsuneji Sano ◽  
...  
Keyword(s):  
31P Nmr ◽  
Theoretical Study ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts
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