From Spirocyclic Germanium Alkoxides to their Fluorido Germanates

The synthesis of 4,4′‐di‐ tert ‐butyl‐4 H ,4′ H ‐2,2′‐spirobi[benzo[ d ][1,3,2]dioxagermine] ( 1 ) and 4,4′,8,8′‐tetra‐ tert ‐butyl‐4 H ,4′ H ‐2,2′‐spirobi[benzo[ d ][1,3,2]dioxagermine] ( 2 ) being the first representatives of spirocyclic germanium salicyl alcoholates is reported. The reaction of these compounds with potassium fluoride in the presence of 18‐crown‐6 gives the alkoxido fluorido germanates [K(CH 2 CH 2 O‐) 6 ][GeF{OC 6 H 4 (CH t BuO)‐2} 2 ] ( 3 ) and [K(CH 2 CH 2 O–) 6 ][GeF{OC 6 H 3 (CH t BuO)‐2‐ t Bu‐6} 2 ] ( 4 ). All compounds are characterized including single crystal X‐ray diffraction analysis, nuclear magnetic resonance spectroscopy [ 1 H, 13 C{ 1 H}, 1 H– 13 C{ 1 H} heteronuclear single quantum coherence, and 19 F ( 3 and 4 )], infrared spectroscopy, and thermal analyzes. Single crystal X‐ray diffraction analyzes unveil a change of chirality in the salicyl alcoholate moieties of 3 with respect to the dominant (≈66%) stereoisomer of 1 upon crystallization as a result of fluoride‐induced ligand exchange equilibria. Reactivity studies of the compounds 1 and 2 are discussed in comparison with structurally related silicon‐based twin monomers.