Developing organo-Zintl deltahedral clusters as ligands for coordination to transition-metals via their organic tethers

Deltahedral Zintl ions Ge94- are disubstituted with organic fragments that have various functional groups. Some of the latter are appropriate for coordination to transition-metals to eventually form coordination compounds where the organo-Zintl species act as ligands. Examples of [Ge9R2]2- include R = –CHCH-Im(Me), –CHCH–C6H4–OMe, –CHCH-Fc, –CHCH–(CH2)4–CCH, –CHCH–C6H4–CCH, CHCH–C6H4–NH2, CHCH-Py, –CHCH–(CH2)3–CN, –CHCHCH(OEt)2, –C(CH3)2CCH. Furthermore, the reported coexistence of [Fe(en)3]2+ and [Ge9-(CHCH-Fc)2]2- in the structure of [Fe(en)3][Ge9-(CHCH-Fc)2]•3.5en shows that some transition metals in 2 + oxidation state may not oxidize the disubstituted clusters and could potentially coordinate to them.

Graphical abstractReported are reactions of addition of organic fragments to deltahedral nine-atom germanium clusters. The organic substituens have functional groups that may coordinate to 2 + transition metals and form netrual complexes where the organo-Zintl motif is one of the ligands as shown.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Several new organo-Zintl deltahedral clusters [Ge9R2]2- have been synthesized. ► The organic groups in [Ge9R2]2- are amines, imines, nitriles, ethers, and alkynes. ► Two of the new [Ge9R2]2- clusters were crystallographically characterized. ► The [Ge9-(CHCH-Fc)2]2- cluster can coexist with the complex [Fe(en)3]2+.