An Ylide-like Phosphasilene and Striking Formation of a 4π-Electron, Resonance-Stabilized 2,4-Disila-1,3-diphosphacyclobutadiene
journal contributionposted on 09.03.2011, 00:00 by Shigeyoshi Inoue, Wenyuan, Wang, Carsten Präsang, Matthew Asay, Elisabeth Irran, Matthias Driess
The first N-donor-stabilized phosphasilene LSi(SiMe3)PSiMe3 (L = PhC(NtBu)2) has been synthesized in 87% yield through 1,2-silyl migration of the (Me3Si)2P-substituted, N-heterocyclic silylene [LSi−P(SiMe3)2]. Remarkably, the latter reacts with dichlorotriphenylphosphorane Ph3PCl2 to give the unprecedented 4π-electron Si2P2-cycloheterobutadiene [(LSi)2P2] with two-coordinate phosphorus atoms. The striking molecular structures as well as the 29Si and 31P NMR spectroscopic features of both products indicate the presence of zwitterionic SiP bonds which is also in accordance with results by DFT calculations.