Introduction of bulky substituents at the bridgehead position of a 9-silatriptycene: Pentacoordinate hydridoorganylsilicates as intermediates

The reaction of 10-phenyl-10-germa-9-silatriptycene (1b) with phenyllithium in THF/HMPA produced 9,10-diphenyl-10-germa-9-silatriptycene (1a), which h ad hitherto not been accessible. The reaction proceeds by attack of the phe nyl anion on 1b via the intermediate silicate anion 7, which was identified by Si-29 NMR spectroscopy. The structure of 1a was confirmed by X-ray crys tallography. As a model reaction, the attack of phenyllithium on triphenyls ilane (8) and diphenylsilane (14) was investigated by Si-29 NMR spectroscop y, revealing the formation of a number of novel hydridosilicates analogous to 7.