Abstract

Sayyed Mostafa Habibi Khorassani*, Malek Taher Maghsoodlou, Ali Ebrahimi, Fatemeh Ghodsi and Razieh Doostmohammadi

In the present work, dynamic 1H NMR effects were investigated within a particular stable phosphorous ylide involving 4, 5-dihydrothiaZole-2-thiol around the carbon-carbon double bond (OCH₃-C?C-PPh₃) in the two Z- and E- rotational isomers. Activation parameters including ?H?, ?G?, ?S? were calculated in accord with dynamic 1H NMR data for the rotational process. In addition, theoretical studies were investigated on the same bond using ab initio calculation at HF level and B3LYP method with 6-31G(d, p) basis set. In this case, the Gibbs free energy barrier (?G? = 69.29 and 67.42 kj.mol-1) results were in a good agreement with the experimental data (?G? = 68.71 kj.mol-1) for interchangeable process of rotational isomers between the two 4-Ea and 4-Za

Dynamic 1H NMR; Abinitio method; 4; 5-dihydrothiaZole-2-thiol; Triphenylphosphine; Rotational energy barrier

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