Abstract: | The homologous series of parent octamethylcyclotetrasilazane (c‐NH‐SiMe2‐)4, ( 1 ), the lithium complex (THF)2Li2(c‐N‐SiMe2‐NH‐SiMe2‐)2]2, ( 2 ), containing the cyclic dianion, and (THF)2LiAl(c‐N‐SiMe2‐)4]2, ( 3 ), accommodating the unprecedented tetraanion Me2SiN]4‐ was synthesized to investigate the nature of the covalent Si‐N single bond in the presence of various metals. These model compounds show a wide diversity of Si‐N(H), Si‐N(M), Si‐N(H, M) and M‐N bonds and serve as bench‐mark systems to study polar bonds by high‐resolution low‐temperature X‐ray structure analysis. Experimental charge density studies reveal highly polar Si‐N bonds with remarkable ionic contribution, even in the non‐metallated starting material 1 . The Li‐N and Li‐O bonds have to be classified as almost purely ionic bonds with topological properties not far from those determined for NaCl. |