• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.457-460
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• 2010

The geometrical structures and energetics of positively doubly charged fullerene dimer $(C_{60})_2{^{2+}}$ conformers were studied using semiempirical PM3 and MNDO, Hartree-Fock (HF), and Hybrid B3LYP density functional methods. The shape of the HOMO-LUMO for the three conformers was also analyzed. The gauche conformer was the most stable of the three conformers. The anti conformer was more stable than the syn conformer.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3099-3102
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• 2014

• Bulletin of the Korean Chemical Society
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• 제20권10호
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• pp.1145-1148
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• 1999

1H NMR spectra of methyl-, ethyl-, propyl-, isopropyl-, butyl-, N-methylethyl-, N-methylpropyl-, and N-methylisopropylamine coordinated to the paramagnetic 11-tungstocobalto(II)silicate anion (SiW11Co) in dimethylsulfoxide-d6 or dimethylformamide-d7 are reported. For these complexes the ligand exchange is slow on the NMR time scale and pure 1H NMR signals have been observed at room temperature. No complex is detected in D2O. From the pseudocontact shifts of the CH2 and CH3 groups in ethylamine the energy of the gauche conformers with respect to the anti conformer is estimated. Two diastereotopic protons in the CH2 group of N-methylethylamine have quite different chemical shifts especially at low temperatures (e.g. 48.5 vs. 19.4 ppm at -10℃). This may be attributed mainly to the different positions of the two protons in the most stable (gauche) conformer.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.100-104
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• 2011

The structures of the conformers for 1,3-di-t-butyl-2,4-dinitro-tetramethoxysulfonylcalix[4]arene (1) and 1,2-di-t-butyl-3,4-dinitro-tetramethoxysulfonylcalix[4]arene (2) were optimized using DFT BLYP and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the total electronic and Gibbs free energies and the differences between the various conformations (cone, partial-cone (PC), 1,2-alternate, and 1,3-alternate) of 1 and 2. For both compounds, the 1,3-alternate (1,3-A) conformers were calculated to be the most stable, which correlate very well with the experimental results. The orderings of the relative stability of 1 and 2 that resulted from the mPW1PW91/6-31G(d,p) calculations are the following: 1: 1,3-A (syn) > PC (syn) > PC (anti) > 1,2-A (anti) > CONE (syn); 2: 1,3-A (anti) > PC (anti) > PC (syn) > 1,2-A (anti) > 1,2-A (syn) > CONE (syn). The BLYP/6-31G(d) calculated IR spectra of the most stable 1,3-A conformers of 1 and 2 are compared.