Synthesis, structure, and reactivity of an organogermanium lewis acid

The 8-Ge-4 spirogermanacycle 3 was prepared from hexafluorocumyl alcohol and its structure determined by X-ray crystallography. The distortion of the internal O‒Ge‒C angles leads to an enhanced Lewis acidity, which was illustrated by the promotion of pericyclic reactions involving activation of aldehyde carbonyl groups. Four 10-Ge-5 anionic complexes were prepared, and X-ray crystallographic analysis of the n-butyl adduct 4b showed a trigonal-bipyramidal geometry.