Controlling complexation behavior of early lanthanides via the subtle interplay of their Lewis acidity with the chemical stability of 5,5'-(azobis)tetrazolide

Two novel nitrogen-rich lanthanide compounds of 5,5'-(azobis)tetrazolide (ZT) were synthesized and structurally characterized. The dinuclear, isostructural compounds [Ce${}_2$(ZT)${}_2$CO${}_3$(H${}_2$O)${}_{12}$]·4H${}_2$O (1) and [Pr${}_2$(ZT)${}_2$CO${}_3$(H${}_2$O)${}_{12}$]·4H${}_2$O (2) were synthesized via two independent routes. Compound 1 was obtained after partial Lewis acidic decomposition of ZT by Ce${}^{IV}$ in aqueous solution of (NH${}_4$)${}_2$Ce(NO${}_3$)${}_6$ and Na${}_2$ZT. Compound 2 was obtained by crystallization from aqueous solutions of Pr(NO${}_3$)${}_3$, Na${}_2$ZT, and Na${}_2$CO${}_3$. By X-ray diffraction analysis at 200 K, it was found that the trivalent lanthanide cations are bridged by a bidentate carbonato ligand and each cation is further coordinated by six H${}_2$O ligands and one ZT ligand thus being ninefold coordinated. (© 2020 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley‐VCH GmbH)