Synthesis and Characterization of Substituted Phosphasilenes and its Rare Homologue Stibasilene >Si=Sb-

Herein we report the reduction of R-EX2 (E=P, Sb) with two equivalents of KC8 in the presence of silylene (LSiR; L=PhC(NtBu)(2)) to give Trip-P=SiL(C6H4PPh2) (1), Ph-Ter-P=(tBu)SiL (2) and Ph-Ter-Sb=(tBu)SiL (3). The last (3) belongs to a new class of heavier analogues of Schiff bases (>C=N-), containing a formal >Si=Sb- double bond. The theoretical calculations suggest that lone pairs on the dicoordinated group-15 centers are stabilized by hyperconjugative interactions resulting in pseudo-Si-P/Si-Sb multiple bonds which are highly reactive as indicated by the high first and second proton affinities.

Automated summary

In this study, the reduction of R-EX2 (E=P, Sb) with two equivalents of KC8 in the presence of silylene (LSiR; L=PhC(NtBu)(2)) has been reported, resulting in the formation of Trip-P=SiL(C6H4PPh2) (1), Ph-Ter-P=(tBu)SiL (2), and Ph-Ter-Sb=(tBu)SiL (3). Compound 3 belongs to a new class of heavier analogues of Schiff bases (>C=N-) and features a formal >Si=Sb- double bond. Theoretical calculations suggest that the pseudo-Si-P/Si-Sb multiple bonds are highly reactive due to the stabilization of lone pairs on the dicoordinated group-15 centers by hyperconjugative interactions, as evidenced by the high first and second proton affinities.