14024-02-3Relevant academic research and scientific papers
A new mechanism of nucleophilic vinylic substitution and unexpected products in the reaction of chlorotrifluoroethylene with [Re(CO)5]Na and [CpFe(CO)2]K
Sazonov,Artamkina,Lyssenko,Beletskaya
, p. 2346 - 2357 (2007/10/03)
The mechanism of chloride substitution in CF2{double bond, long}CFCl with [Re(CO)5]- and [CpFe(CO)2]- anions is investigated experimentally and theoretically. The substitution reaction begins with the nucleophile addition to CF2{double bond, long}CFCl producing the carbenoid anion [MCF2CFCl]- (A) (M = Re(CO)5, CpFe(CO)2). This is shown by trapping the intermediate A with electrophiles - proton donor (t-BuOH) to give MCF2CFClH or with CF2{double bond, long}CFRe(CO)5 to give acylmetallate III, and by the formation of the substitution products CF2{double bond, long}CFM from the anion A, generated by the deprotonation of MCF2CFClH with t-BuOK. 1,2-Shift of metal carbonyl group concerted with the α-elimination of chloride anion is proposed as the transformation pathway of carbenoid A into CF2{double bond, long}CFM. A competing process of carbene insertion into Fe-C{triple bond, long}O bond is proposed to explain the formation of {A figure is presented} (XI). The feasibility of these two pathways is confirmed by DFT (B3LYP/SDD and 6-31G*) calculations of the carbenes [MCF2CF:] and carbenoid anions [MCF2CFCl]-. Transition states (TS) for 1,2-shift (+3.2 kcal/mol) and for nucleophilic addition at C{triple bond, long}O ligand (+5.4 kcal/mol) are located for [(CO)5ReCF2CFCl]-, but only one TS corresponding to carbene insertion into Fe-C{triple bond, long}O bond (+2.1 kcal/mol) is located for [(CO)2CpFeCF2CFCl]-. The formation of other newly observed products, F(CO)CHFRe(CO)5 (V) and Cp(CO)2FeC{triple bond, long}CFeCp(CO)2 (VIII) is also discussed.
