Synthesis and characterization of alkylgermasesquioxanes

Alkyl(chloro)ethoxygermanes, RGe(OEt)nCl3−n (R=i-Pr, n=0; R=t-Bu, n=0–3; R=cyclo-C6H11, n=0) were hydrolyzed with aqueous NaOH in xylene at 130–140 °C to give cage hexakis(alkylgermasesquioxane)s, (RGe)6O9. These structures of cage (RGe)6O9 were fully confirmed by spectroscopic and X-ray diffraction methods. t-Butyldichloro(ethoxy)germane, t-BuGe(OEt)Cl2, was carefully treated with water at 5 °C for 3 h to afford cis, trans-1,3,5-tri-t-butyl-1,3,5-trichlorocyclotrigermoxane, (t-BuClGeO)3. Hydrolysis of (t-BuClGeO)3 at 5 °C for additional 33 h gave a tricyclic anti-form ladder 5,7-dichloro-1,3,5,7,9,11-hexa-t-butyltricyclo[7.3.1.13,7]hexagermoxanes, (t-BuGe)6O8Cl2. The tricyclic ladder (t-BuGe)6O8Cl2 was also prepared by hydrolysis of t-butyl(chloro)diethoxygermane, t-BuGe(OEt)2Cl, at 5 °C for 6 h, and its structure was determined by spectroscopic and X-ray diffraction analysis. The tricyclic ladder germoxane reacted with aqueous NaOH in xylene at 130–140 °C for 3 h to afford hexakis(t-butylgermasesquioxane), (t-BuGe)6O9. The formation mechanism of the germasesquioxane, (t-BuGe)6O9 from t-butyl(chloro)ethoxygermanes, t-BuGe(OEt)nCl3−n (n=0–3) is also discussed.