ИСТИНА

1,2-Shift of a β-substituent is one of the primary stabilization pathways for carbene and carbenoid intermediates, in case of vinyl carbenoids also known as Fritsch-Buttenberg-Wiechell rearrangement. The migratory aptitude of hydrogen and carbon based organic groups was the subject of many detailed studies, both experimental and theoretical. However, little is known about the migration of substituents other than carbon. 1,2-Sift of the entering nucleophile is also relevant for nucleophilic substitution in vinylic and acetylenic systems, and actually has been postulated as a reaction mechanism in cases when substituents favor nucleophile addition in β-position to the leaving group. The mechanism with 1,2-shift of carbonylmetallate group as a key step allowed us to explain the substitution of chloride in the reactions of [Re(CO)5]- and [CpFe(CO)2]- carbonylmetallates with CF2=CFCl.