Snapshots of sequential polyphosphide rearrangement upon metallatetrylene addition.

Insertion and functionalization of gallasilylenes [LSi-Ga(Cl)L] (L = PhC(NBu); L = [{2,6-iPrCHNCMe}CH]) into the -E rings of [CpFe(-E)] (Cp = -CMe; E = P, As) are reported. Reactions of [CpFe(-E)] with gallasilylene result in E-E/Si-Ga bond cleavage and the insertion of the silylene in the -E rings. [(LSi-Ga(Cl)L){(-P)FeCp}], in which the Si atom binds to the bent -P ring, was identified as a reaction intermediate. The ring-expansion products are stable at room temperature, while isomerization occurred at higher temperature, and the silylene moiety further migrates to the Fe atom, forming the corresponding ring-construction isomers. Furthermore, reaction of [Cp*Fe(-As)] with the heavier gallagermylene [LGe-Ga(Cl)L] was also investigated. All the isolated complexes represent rare examples of mixed group 13/14 iron polypnictogenides, which could only be synthesized by taking advantage of the cooperativity of the gallatetrylenes featuring low-valent Si(ii) or Ge(ii) and Lewis acidic Ga(iii) units/entities.