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Planar 1,3λ 4 δ 2 ,2,4‐Benzodithiadiazine and Its Nonplanar 5,6,7,8‐Tetrafluoro Derivative: Gas‐Phase Structures Studied by Electron Diffraction and Ab Initio Calculations
Author(s) -
Blockhuys Frank,
Hinchley Sarah L.,
Yu. Marakov Alexander,
Gatilov Yuri V.,
Zibarev Andrey V.,
Woollins J. Derek,
Rankin David W. H.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010817)7:16<3592::aid-chem3592>3.0.co;2-8
Subject(s) - planarity testing , electron diffraction , ab initio , ab initio quantum chemistry methods , gas phase , derivative (finance) , crystallography , diffraction , chemistry , molecule , phase (matter) , computational chemistry , physics , organic chemistry , financial economics , optics , economics
Abstract The gas‐phase molecular structures of 1,3λ 4 δ 2 ,2,4‐benzodithiadiazine and 5,6,7,8‐tetrafluoro‐1,3λ 4 δ 2 ,2,4‐benzodithiadiazine have been investigated by ab initio calculations and electron diffraction using the SARACEN method of structural analysis. Important structural parameters ( r h1 structure) for the parent compound were found to be: < r (S=N)>1.546(3), r (S−N) 1.697(5), r (C−S) 1.784(5), and r (C−N) 1.393(6) Å. For the tetrafluoro derivative, these are ( r h1 structure): < r (S=N)>1.552(3), r (S−N) 1.723(8), r (C−S) 1.812(9), and r (C−N) 1.396(7) Å. Furthermore, the GED experiment (Gas Electron Diffraction) quite convincingly demonstrates the nonplanarity of the former and the planarity of the latter in agreement with DFT calculations; but the results contradict calculations at the MP2 level. The effect of the fluorine atoms on the conformations of the molecules is discussed.