Hypercoordinate Silicon Complexes of (O,N,N′ vs. O,N,O′) Schiff Base Type N ‐(2‐Carbamidophenyl)imines: Examples of Exclusively O ‐Silylated Carbamides

Tridentate salphen‐type O,N,N′ chelators, upon acylation of the NH 2 group, are capable of engaging an O,N,O′ coordination mode in addition to their inherent O,N,N′ donor character. In six‐coordinate silicon complexes of the type SiL 2 [L = N ‐(2‐ c arbamidophenyl)imine], these ligands were found to exclusively form SiN 2 O 4 coordination spheres by engaging their tridentate O,N,O′ donor capability. Selected ligands L were also shown to preferably engage the O,N,O′ coordination mode when incorporated in five‐ and four‐coordinate silicon compounds of the type LSiPhX (X = Cl, F) and LSiPh 2 , respectively. The coordination modes of the herein presented six‐, five‐, and four‐coordinate silicon compounds represent the first examples of X‐ray structurally confirmed O ‐silylated carbamides, which hence adopt structural features of C‐siloxyimines.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)