Structure determination of methyl nicotinate and methyl picolinate by gas electron diffraction combined with ab initio calculations

Hajime Kiyono, Ryosuke Tatsunami, Teruyo Kurai, Hiroshi Takeuchi, Toru Egawa, Shigehiro Konaka

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The molecular structures of isomers, methyl nicotinate and methyl picolinate, have been studied by gas electron diffraction. The samples were heated to 341-343 K by using a high-temperature nozzle to get enough vapor pressure. HF/6-31G* ab initio calculations were carried out, and structural constraints were taken from their results. Vibrational amplitudes and shrinkage corrections were calculated from the harmonic force constants given by normal coordinate analyses. The principal structural parameters of the s-trans conformer of methyl nicotinate are as follows (angle brackets mean averaged values): 〈rg(N-C)〉 = 1.337(7) Å; 〈rg(C-C)ring〉 = 1.402(3) Å; rg(Cring-C(=O)) = 1.480(12) Å; rg(C=O) = 1.199(7) Å; 〈rg(C-O)〉 = 1.380(11) Å; ∠αCNC = 119.0(14)°; 〈∠αNCC) = 122.8(11)°; ∠α(N=)C-Cring-C(=O) = 118.3(12)°; ∠αCring-C=O = 121.5(12)°; ∠αCring-C-O = 115.6(10)°. Those of the s-trans conformer of methyl picolinate are as follows: 〈rg(N-C)〉 = 1.344(7) Å; 〈rg(C-C)ring〉 = 1.398(4) Å; rg(Cring-C(=O)) = 1.497(11) Å; rg(C=O) = 1.209(7) Å; 〈rg(C-O)〉 = 1.380(11) Å; ∠αCNC = 117.2(12)°; 〈∠αNCC〉 = 123.9(12)°; ∠αN-C-C(=O) = 115.1(10)°; ∠αCring-C=O = 121.0(12)°; ∠αCring-C-O = 115.1(12)°. The structural parameters of the two isomers and methyl isonicotinate have been compared and their similarity and differences have been discussed.

元の言語English
ページ(範囲)1405-1411
ページ数7
ジャーナルJournal of Physical Chemistry A
102
発行部数8
DOI
出版物ステータスPublished - 1998 2 19

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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