Studies on the Chemistry of Tetraamminezinc(II) Dipermanganate ([Zn(NH 3 ) 4 ](MnO 4 ) 2 ): Low‐Temperature Synthesis of the Manganese Zinc Oxide (ZnMn 2 O 4 ) Catalyst Precursor

Tetraamminezinc(II) dipermanganate ([Zn(NH 3 ) 4 ](MnO 4 ) 2 ; 1 ) was prepared, and its structure was elucidated with XRD‐ Rietveld ‐refinement and vibrational‐spectroscopy methods. Compound 1 has a cubic lattice consisting of a 3D H‐bound network built from blocks formed by four MnO $\rm{ {_{4}^{-}}}$ anions and four [Zn(NH 3 ) 4 ] 2+ cations. The other four MnO $\rm{ {_{4}^{-}}}$ anions are located in a crystallographically different environment, namely in the cavities formed by the attachment of the building blocks. A low‐temperature quasi‐intramolecular redox reaction producing NH 4 NO 3 and amorphous ZnMn 2 O 4 could be established occurring even at 100°. Due to H‐bonds between the [Zn(NH 3 ) 4 ] 2+ cation and the MnO $\rm{ {_{4}^{-}}}$ anion, a redox reaction took place between the NH 3 and the anion; thus, thermal deammoniation of compound 1 cannot be used to prepare [Zn(NH 3 ) 2 ](MnO 4 ) 2 (contrary to the behavior of the analogous perrhenate (ReO $\rm{ {_{4}^{-}}}$ ) complex). In solution‐phase deammoniation, a temperature‐dependent hydrolysis process leading to the formation of Zn(OH) 2 and NH 4 MnO 4 was observed. Refluxing 1 in toluene offering the heat convecting medium, followed by the removal of NH 4 NO 3 by washing with H 2 O, proved to be an easy and convenient technique for the synthesis of the amorphous ZnMn 2 O 4 .