Intramolecular Interligand Charge Transfer in Hexacoordinate Silicon Complexes

The linking of amide and imine ligands in the coordination sphere of octahedral silicon complexes opens access to new compounds with intense interligand charge transfer. In these novel complexes the highest occupied MOs are located around the amide nitrogen atoms, while the imine moieties significantly contribute to the formation of LUMO and LUMO+1 and the hexacoordinate silicon atom plays an important role in bridging these donor and acceptor sites. Regarding the intensity of the CT, the architecture of the silicon coordination sphere plays a dominant role:  the trans situation between the amide and imine ligand donor atoms provides a much more favored CT than is found in a trans-(imine, imine)-cis-(imine, amide) complex.