open access

https://hdl.handle.net/2115/35489

Molecular structure of trans-cinnamaldehyde as determined by gas electron diffraction aided by DFT calculations

英語

DFT calculations

2008-12-15

Elsevier B.V.

Journal of Molecular Structure

892(1-3)

158-162

The molecular structure of trans-cinnamaldehyde ((E)-3-phenyl-2-propenal) was determined by means of gas electron diffraction. The nozzle temperature was 165 ℃. The results of B3LYP calculations with the 6-31G** basis set were used as supporting information. It was found that this molecule has two stable conformers, s-cis and s-trans, which differ in the orientation of the -CH=O group. Their abundances at 165 ℃ were determined to be 25±19% and 75%, for the s-cis and s-trans, respectively. This conformational composition is consistent with the prediction by the theoretical calculations. The determined structural parameters (rg and ∠α) of the more abundant conformer, s-trans, of trans-cinnamaldehyde are as follows: <r(C–C)ring> = 1.398(1) Å; r(C=C) = 1.348 Å (←); r(C1–C) = 1.470(8) Å; r(C–C(=O)) = 1.473(←) Å; r(C=O) = 1.225(6) Å; <r(C–H)> = 1.116(6) Å; ∠C6–C1–C2 = 118.6(3)°; ∠C1–C2–C = 121.0(←)°; ∠C–C6–C1 = 121.4(←)°; ∠C2–C1–C(=C) = 122.0(26)°; ∠C1–C=C = 128.3(26)°; ∠C=C–CO = 115.3(27)°; ∠C–C=O = 126.6(19)°. The C1, C2 and C6 atoms are on the ring with the C1 attached to the -CH=CH–CHO group, and the C2 and C6 are on the cis and trans sides to the C=C bond, respectively. Angle brackets denote average values; parenthesized values are the estimated limits of error (3σ) referring to the last significant digit; left arrows in the parentheses mean that the differences to the preceding parameters are fixed.

学術雑誌論文

Accepted Manuscript

0022-2860

0022-2860