Exploring Differences between Bis(aldimino)- and amino-aldimino-<i>N</i>,<i>C</i>,<i>N</i>-Pincer-Stabilized Pnictinidenes: Limits of Synthesis, Structure, and Reversible Tautomerization-Controlled Oxidation

Two types of N,C,N-chelated pnictinidenes, i.e., [2-(RNHCH2)-6-(RN ═ CH)C6H3]E (1-E-R) and [2,6-(RN═CH)2C6H3]E (2-E-R, where E = As, Sb, Bi), are targeted in this study. 2-E-R could be obtained by simple reduction respective precursors [2,6-(RN═CH)2C6H3]ECl2 (i.e., (2-E-R)Cl2) with KC8 for or Bi R being tBu, Ad, Dipp. By contrast, the utilization a bulky hydride, K-selectride, allowed isolation 1-E-R As Sb Dipp, while other pincer ligands, tBu led only to mixtures both 2-E-R. For bismuth, even Dipp-substituted ligand provided mixture 1-Bi-Dipp 2-Bi-Dipp only. The structures chemical properties these sets compounds, 1-E-Dipp, 2-E-tBu, 2-E-Dipp, were compared using X-ray diffraction analysis, UV–vis spectroscopy including an extensive theoretical study, CV measurements. oxidation 2-E-Dipp (E Bi) air resulted formation complicated mixtures, 1-E-Dipp Sb) cleanly produces (1′-E-Dipp)OH as result tautomeric NH → OH shift at elusive oxides (1-E-Dipp)O under new E–N covalent bond. To examine potential such tautomerization-driven stabilization products, reactivity toward chalcogens is also reported,