Intermediates and products of the reaction of Zn(ii) organyls with tetrel elementZintlions: Cluster extensionversuscomplexation

The discovery of low-valent Zn compounds resulted in the renaissance of organometallic Zn complexes. Polyhedral clusters of tetrel elements can interact with Zn atoms either as Lewis donors or by incorporation of the Zn atoms as additional cluster vertices. Herein we report the reactions of ZnR₂(R = ethyl (Et), pentamethylcyclopentadiene (Cp*), phenyl (Ph) and 1,3,5-trimethylbenzene (Mes)) withZintlions of the types [E₄]^4-(E = Ge, Sn) and [Ge₉]^4-in liquid ammonia. Besides the desiredZintlion complexes, intermediates were isolated that give insight into the reaction of organo Zn compounds in liquid ammonia. Three ions, [(?³:?³-Ge₄)(ZnEt)₂]^2-(1a), [(?²-Sn₄)Zn(?²-Sn₄)]^6-(2a) and [(?⁴-Ge₉)(ZnEt)]^3-(3a), were obtained and characterized by means of single crystal X-ray diffraction analysis. Furthermore, amides [(ZnPh₂)₂(µ₂-NH₂)₂]^2-(4a) and {[Zn(µ₂-NH₂)₄][(ZnEt)₂(µ₂-NH₂)₂]₂}^2-(5a) were formed during the reactions, together with the addition products [ZnPh₃]^-(6a) and [ZnMes₃]^-(7a) and an anion [Cp*]^-(8a), suggesting the following reaction sequence: in liquid ammonia theZintlanions form amides, which then serve as ligands for ZnR₂molecules.