Synthesis of the germanium(II) calixarene {p-Bu8tcalix[8]arene}Ge4 and its reaction with Fe2(CO)9: Generation of the germanium(II)/iron(0) complex {p-Bu8tcalix[8]arene}Ge4[Fe(CO)4]2

An uncommon germanium(II) calixarene species {p-Bu8tcalix[8]arene}Ge4 (1) was synthesized from Ge[N(SiMe3)2]2 and p-Bu8tcalix[8]arene in 94% yield. Complex 1 reacts with Fe2(CO)9 to yield the germanium(II) macrocyclic complex {p-Bu8tcalix[8]arene}Ge4[Fe(CO)4]2 (2), which contains two neutral Fe(CO)4 fragments, in 77% yield. The X-ray crystal structures of 1 and 2 were determined and each species contain two Ge2O2 rhombi having two germanium(II) centers and bridging aryloxide ligands from the calix[8]arene framework. The Ge2O2 rhombi are also connected to the calix[8]arene framework by terminal germanium–aryloxide bonds. Complexes 1 and 2 were also characterized by NMR spectroscopy and their 1H NMR spectra have been correlated with their solid state structures.

Graphical abstractThe germanium(II) calix[8]arene complex {p-Bu8tcalix[8]arene}Ge4 was synthesized from Ge[N(SiMe3)2]2 and {p-Bu8tcalix[8]arene}. This complex reacts with Fe2(CO)9 to yield {p-Bu8tcalix[8]arene}Ge4[Fe(CO)4]2, which contrasts with the reactivity of the related species {calix[8]arene}Ge4 with Fe2(CO)9.Figure optionsDownload full-size imageDownload as PowerPoint slide