A study of Fe3O4@ Si18O27 catalyst through Statistical-Nucleus Independent Chemical Shifts(S-NICS) method

• Published in: Oriental journal of chemistry 2016, Vol.32 (5), p.2327-2345
• Main Authors: Soofi, Neda, Monajjemi, Majid
• Format: Article
• Language: English
• Subjects: Aromaticity; Asymmetry; Benzene; Carbon; Catalysis; Catalysts; Chemical synthesis; Hydrocarbons; Iron oxides; Magnetic fields; Mathematical analysis; Naphthalene; NMR; Nuclear magnetic resonance; Organic chemistry; Parameters; Physical chemistry; Physics; Shielding; Silicon dioxide
• ISSN: 0970-020X; 2231-5039
• DOI: 10.13005/ojc/320504

There are no theoretical or mathematical reports of a statistical approach in NMR shielding and nucleus independent chemical shifts, while the asymmetry (η) and skew (κ) parameters are fluctuated in short distances and are alternative in long distances. In the case of axially symmetric tensor, σ22 equals either σ11 or σ33, skew is κ= ±1 and by changing asymmetry between 0 ≤ η ≤ +1 skew will be changed between -1 ≤ κ ≤ +1 , meanwhile the parameter “κ” is zero when σ22 = σiso. In this work, we have investigated a statistical method by computing of Nucleus-Independent Chemical Shifts (S-NICS) in point of probes motions in a sphere of shielding and deshielding spaces of SiO2 rings. Monajjemi in the previous work [24], has investigated a new method as the name “ S-NICS” which this method is suitable for calculation the aromaticity in the non-benzene rings such as SiO2 rings which is a famous catalyst for organic chemical synthesize and reaction. Although S-NICS values for some molecules such as benzene, borazine and naphthalene can be indicated as the aromaticity criterion, for other cases such as BnNnHx and their hydrogenated derivatives, these values indicate electromagnetic index. Finally, we have introduced a schematic diagram of statistical-nucleus independent chemical shifts for ab-initio calculations in Gaussian program, Games or other software.