A quantum chemical study on the mechanism of S-coordinated tetrazole-thiolato formation by the reaction of organic isothiocyanates with metal azido complexes of Pt(II), Pd(II), and Sn |
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Authors: | Kunhye Lee |
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Affiliation: | Department of Chemistry, Kangnung National University, Gangnung, Gangwon-do 210-702, Korea |
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Abstract: | The mechanism of the reaction of isothiocyanates with metal-azido complexes of Pt(II), Pd(II), and Sn as well as hydrazoic acid is studied using the density functional theory method. The relative stability between two possible product isomers (S-coordinated tetrazole-thiolato and N-coordinated tetrazolato complexes) does not directly relate to the experimentally synthesized product. The overall reaction proceeds via three steps. The first step is the approach of the S-atom of the organic isothiocyanate to the central metal atom followed by the nucleophilic attack of the coordinated N-atom of the azido group to the C-atom of the isothiocyanate. The activation barrier of this step is 22-24 kcal mol−1, and the resulting intermediate has the imidoyl azide form. In the second reaction step, electrophilic attack of the terminal N-atom of the azido group to the N-atom of the isothiocyanate transforms the intermediate to the S-coordinated tetrazole-thiolato product with a barrier of about 11 kcal mol−1. The N-coordinated tetrazole could be made from the S-coordinated tetrazole-thiolato complex only after the third step, in which the metal coordination migrates from the S- to the N-atom. |
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Keywords: | S-coordinated tetrazole-thiolato Metal azido complexes Isothiocyanates Hydrazoic acid Reaction mechanism |
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