Thèse de Xuefei ZHAO (LPCNO), Novembre 2016

Titre : Modeling of the structure and reactivity of Sm(II) complexes

Abstract : This doctoral dissertation presents the study of the structure and reactivity of samarium(II) complex by mean of DFT methods. The major subject of this dissertation is the reactivity of Sm(II) iodide (SmI2) towards organic substrates. A brief introduction of SmI2 reagent has been included at the beginning to address general aspects of this important reducing reagent. After the presentation of theoretical chemistry used for modeling of organometallic reactivity, this dissertation is mainly arranged by the class of additives utilized to study the reactivity of SmI2 : (1) Lewis base-HMPA ; (2) Proton source-H2O. Mechanistic study of SmI2-HMPA mediated reactions is first presented and special emphasis is placed on samarium Barbier reaction. In light of previous evidence, new mechanism is suggested and the results provide basis for the selective reduction of alkyl halide over carbonyls by SmI2-HMPA. Then, the reactivity of SmI2-H2O mediated reduction of important functional groups is investigated. The role of H2O is uncovered in the electron transfer process. This study is then extended to the full reduction of valerolactone and aliphatic ester with SmI2-H2O and SmI2/H2O/Amine. The results show that the reduction proceeds through a bimetallic proton coupled electron transfer (BPCET) process. In particular, the activation of H2O in the first coordination shell by Sm center or the amine acting as a proton relay promotes the BPCET process.

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