Synthesis and characterization of divalent main group diamides and reactions with CO2

It is known that bulky Sn and Ge N-silylamides insert CO 2 to form either silyl isocyanides or silyl carbodiimides, albeit relatively slowly. As part of a research effort to eventually prepare 1 1 C-labelled radiophannaceuticals derived from 1 1 CO 2 , we have been interested in expanding the scope of this reaction by investigating other species that may react more rapidly. We have synthesized and structurally characterized a large variety of new diamides based on other metals such as Mg, Ca, Ba, and Zn, as well as new divalent Sn species with several new sterically-demanding, trimethylsilyl-containing ligands. Reactions of these species with CO 2 are discussed.