2001 EWR Steacie Award Lecture - The imido ligand in main group element chemistry

The imido group (NR) is a versatile ligand in main group chemistry. The high reactivity of multiply bonded (terminal) imido derivatives of p-block elements is used, for example, in the aza-Wittig reaction, allylic aminations, and in peptide synthesis. As a bridging ligand, the imido group provides a cornerstone for a wide variety of binary cluster structures. This review is primarily concerned with the synthesis, structures, reactions, and ligand behaviour of imido derivatives of the heavy chalcogens (selenium and tellurium) as exemplified by the tellurium diimide dimer t-BuNTe(mu-N-t-Bu)(2)TeN-t-Bu and the homoleptic trisimido-tellurite dianion [Te(N-t-Bu)(3)](2-). The synthesis and cluster structures of alkali metal and alkaline earth metal derivatives of heteroleptic imido-oxo anions of sulfur, e.g., [OxS(NR)(3-x)](2-) (x = 1, 2) and [O2S(mu-NPh)SO2](2-), are also discussed.