Heterobimetallic Hydrides with a Germanium(II)-Zinc Bond

Abstract

In the presence of TMEDA (TMEDA=N,N,N',N'-tetramethylethylenediamine), zinc dihydride reacted with germanium(II) compounds (BDI-H)Ge (1) and [(BDI)Ge][B(3,5-(CF₃ )₂ C₆ H₃ )₄ ] (3) (BDI-H = HC{(C=CH₂ )(CMe)(NAr)₂ }, BDI = [HC(CMeNAr)₂ ]; Ar = 2,6-ⁱ Pr₂ C₆ H₃ ) by formal insertion of the germanium(II) center into the Zn-H bond of polymeric [ZnH₂ ]_n to give neutral and cationic zincagermane with a H-Ge-Zn-H core [(BDI-H)Ge(H)-(H)Zn(tmeda)] (2) and [(BDI)Ge(H)-(H)Zn(tmeda)][B(3,5-(CF₃ )₂ C₆ H₃ )₄ ] (4), respectively. Compound 2 eliminated [ZnH₂ ] giving diamido germylene 1 at 60 °C. Compound 2 and deuterated analogue 2-d₂ exchanged with [ZnH₂ ]_n and [ZnD₂ ]_n in the presence of TMEDA to give a mixture of 2 and 2-d₂ . Compounds 2 and 4 reacted with carbon dioxide (1 bar) at room temperature to form zincagermane diformate [(BDI-H)Ge(OCHO)-(OCHO)Zn(tmeda)] (5) and formate bridged digermylene [({BDI}Ge)₂ (μ-OCHO)]⁺ [B(C₆ H₃ (CF₃ )₂ )₄ ] (6) along with zinc formate [(tmeda)Zn(μ-OCHO)₃ Zn(tmeda)][B(C₆ H₃ (CF₃ )₂ )₄ ] (7), respectively. The hydridic nature of the Ge-H and Zn-H bonds in 2 and 4 was probed by reactions with Brönsted and Lewis acids.

Keywords: germanium; germylene; heterobimetallics; hydrides; zinc.