Dicationic 1-Germa and 1-Stannavinylidenes: Synthesis, Structure, and Reactivity

Abstract

The synthesis of heteronuclear vinylidene analogues containing heavier group 14 elements (R₂C═E:, E = Si, Ge, Sn) has been a challenging task due to their inherent instability. In this study, we report the synthesis of dicationic 1-germavinylidene (3Ge) and 1-stannavinylidene (3Sn) by using sym-bis(2-pyridyl)-tetraphenylcarbodiphosphorane (CDPPy₂) as a donor ligand. Both 3Ge and 3Sn have been characterized by single-crystal X-ray diffraction analysis, NMR spectroscopy, and high-resolution mass spectrometry. The structural analysis, supported by the results of theoretical calculations, confirms that 3Ge and 3Sn feature a polarized C═E double bond and a lone pair of electrons located at the E atom (E = Ge and Sn). The reactions of 3Ge with IDippMCl (M = Cu, Ag, Au) give the M–Cl bond addition products. Mechanistic studies on the activation of the Au–Cl bond by 3Ge demonstrate its ambiphilicity. This work represents an example of the utilization of a carbone ligand as both an σ and π donor for the synthesis of heavier heteronuclear vinylidene analogues.