Reactions of Halides and (Pseudo)Halidometallates of V, Cr, Mn, Fe, Co, and Ni in liquid, anhydrous Ammonia

• Applicant: Professor Dr. Florian Kraus
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524000768

While the chemistry of the hydroxides and the oxides can be considered intensively researched - some even call it completed - there are still gaps in the "ammonium system" even today. This is particularly noticeable in the case of the transition metals, with regard to homo- and heteroleptic ammine, amido and imido complexes as well as ammoniates of these metal compounds. We use the term "ammoniate" analogously to "hydrate". The term ammoniate is used to describe compounds that contain more weakly bound "crystal ammonia molecules", i.e. that do not act as ligands of a central atom. Higher ammoniates are generally not stable at room temperature, so they have rarely been studied in more detail in the past. Mononuclear ammine complexes of certain elements, such as those of Cr, Co, Pt, etc., are often quite stable and have therefore naturally been studied particularly intensively. They founded and shaped coordination chemistry as "Werner complexes". We do not consider main group metal or organometallic compounds in this project, nor do we want to deal with the 4d and 5d metals here. We likewise exclude at this point the compounds of Sc, Ti, Cu, and Zn. Copper is to be studied in a separate project of "Coin and Platinum Metals in Ammonia", zinc is already dealt with in other ongoing projects, Sc and Ti we want to deal with elsewhere. Similarly, the binary and ternary nitrides of the 3d metals, which are already quite well studied, are not the target of our experiments. For reasons stated below, we also do not consider azides, nitrates, hydroxides, aquocomplexes, or hydrates. We want to investigate how the (pseudo)binary and (pseudo)ternary halides and pseudohalides of the 3d metals V, Cr, Mn, Fe, Co and Ni, respectively their metallate complexes, react with and in anhydrous ammonia (anhydrous NH3, aNH3) in the temperature range from circa -78 °C to +70 °C under autogenous NH3 pressure, in the ammonoacidic, -neutral and -basic range and optionally in the presence of foreign ions, and which products, mononuclear and polynuclear homo- and heteroleptic amine, amido, imido and (pseudo)halide complexes and their ammoniaates, are formed.

• DFG Programme: Research Grants