Influence of Peripheral Substituents

The effects of substitution are not unlike those observed for silicon. Electron donation shortens the Ge-O contact, viz. 25-29. Note that the ketone derivatives 32 and 33 show Ge-O distances intermediate between the carboxylic acid or ester compounds 25-27 and the amides 28-31. The larger anellated ring in 21 as com- 

The name metallatrane applies to molecules 34, which may be considered as five-coordinate metal complexes of triply deprotonated triethanolamine. We use the term for analogous triphenolamine complexes 35 as well. Unlike the molecules described before, silatranes have three electronegative equatorial O-atoms. Because of the tricyclic nature of the molecules, the amine nitrogen atom is forced into an axial position. The Si - N distance may thus serve to probe the nature of the second axial ligand X. The atrane family of compounds is even more akin than the lactams discussed above because differences in connectivity are essentially confined to the ligand X. 

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