A Base-Stabilized 2‑Silaallene

The reaction of [CH2(PPh2S)2]
(1) with 2 equiv of MeLi in Et2O followed
by addition of 0.5 equiv of SiCl4 afforded the base-stabilized
2-silaallene [(PPh2S)2CSiC­(PPh2S)2] (2). It has been characterized by X-ray crystallography,
NMR spectroscopy, and theoretical studies. The results show that compound 2 comprises a C¯–Si2+–C¯ ylidic skeleton with a negative charge at the Cmethanediide atoms and two positive charges at the Si atom.
The reaction of 2 with excess PriNCNPri in refluxing toluene gave the thiophosphinoyl-stabilized
silene [(PPh2S)2C–Si+(NPri)2CC­(PPh2S)2] (3).