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'‐(azo bis)tetrazolide (ZT) were synthesized and structurally characterized. The dinuclear, isostructural compounds [Ce2(ZT)2CO3(H2O)12] · 4 H2O (1) and [Pr2(ZT)2CO3(H2O)12]·4H2O (2) were synthesized via two independent routes. Compound 1 was obtained after partial Lewis acidic decomposition of ZT by CeIV in aqueous solution of (NH4)2Ce(NO3)6 and Na2ZT. Compound 2 was obtained by crystallization from aqueous solutions of Pr(NO3)3, Na2ZT, and Na2CO3. 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 H2O ligands and one ZT ligand thus being ninefold coordinated.