A Flexible, Extremely Sterically Demanding Triazenide Ligand: Synthesis and Coordination Chemistry

Abstract

Seeking to further the investigation of extremely sterically congested main group metals, the synthesis of a new oligoaryl triazene (Dipp*2N3H) is reported. This was accessed by diazotization of Dipp*NH2 to access both Dipp*I and Dipp*N3 in high yield and with scalable preparations. These compounds are used as precursors to Dipp*2N3H, via a magnesium aryl, due to the difficulties in obtaining pure triazene via an aryl‐lithium species. Deprotonation of the triazene with both potassium and thallium tert‐butoxides gives the respective metal triazenides in high yield. The solid‐state structures of these complexes have been determined and three high hapticity metal arene‐π interactions, which sterically shield the metal centers, were observed in each case; spectroscopic C2v symmetry suggests these interactions are fluxional in solution. The variability of these interactions in the solid state as well as the changes in calculated steric demand of the ligand between metals point to an adaptive, flexible coordination mode.

Synthetic, Structural, and Computational Studies on Heavier Tetragen and Chalcogen Triazenide Complexes

“…Amidinates, guanidinates, and triazenides , are part of the wider family of monoanionic-heteroallylic ligands − and are extremely common ligands in coordination chemistry (Chart ). In main group chemistry, they are often used to kinetically stabilize coordinatively unsaturated and typically low-oxidation state complexes. − The attraction of these monoanionic, κ 2 -N,N coordinating systems is due to their relative ease of synthesis , and their variability with respect to steric and electronic properties. For heteroallylic ligands, such properties may be fine-tuned by the informed choice of substituents on either the terminal nitrogen atoms or the central heteroatom (Chart ).…”