Synthesis and Crystal Structure of a Salt Containing 1{Zn[trans233-Ge9)]}2– Anions: A Polymer with Ge9 Zintl Clusters Bridged by Zn Atoms

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Abstract

The reaction of an ethylenediamine (en) solution of K4Ge9 with Zn2(Mesnacnac)2 {Mesnacnac = [(2,4,6-Me3C6H2)NC(Me)]2CH} in the presence of 18-crown-6 (18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane) leads to the formation of the new compound [K(18-crown-6)]2{Zn[trans233-Ge9)]}(en). A crystallographic structure determination revealed that the salt contains 1[Zn(Ge9)]2– polyanions in which each Zn atom bridges two Ge9 clusters by coordinating to opposite triangular faces of the Ge9 deltahedra. The polymeric chain can be formally described as consisting of a trans ZnII complex with two [η33-Ge9]4– ligands. 1H NMR spectroscopic investigations indicated that the protonation of the Mesnacnac ligand by the solvent ethylenediamine plays a crucial role in the disproportionation of the ZnI starting material and thus in the formation of the polymeric ZnII complex. In contrast, the reaction of ZnPh2 instead of Zn2(Mesnacnac)2 under the same conditions leads to the known complex [PhZn(η4-Ge9)]3–.

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