Nitridometalates and related compounds
Nitridometalates and metalide-nitrides of d as well as main-group metals M represent interesting classes of solid state phases, which contain nitrogen as isolated N3– anions or feature complex anions [MxNyz–] of different dimensionality with coordination numbers of M by nitrogen typically between two and four and oxidation states of the transition metals being comparatively low. Whereas the bonding within these complex anions and frameworks is essentially covalent, nitridometalates (e.g. (Sr6N)[Mn10N10]2) are stabilized by predominantly ionic bonding through counterions of electropositive metals like alkali or alkaline-earth cations. In contrast, bonding in metalide-nitrides (e.g. LiSr3Ga2N) is dominated by metallic and ionic interactions. The nitride research group also focusses on exploratory work on related compounds also containing carbon (e.g. Sr3[Co(CN)3], Ba5[TaN4][C2N]) prepared under reducing (very small amounts of nitrogen) as well as strong oxidizing conditions with a large nitrogen excess.
It is our primary goal to provide sound results in fundamental research on these generally rather neglected but chemically and structurally interesting and experimentally challenging systems. Both standard and highly sophisticated bulk preparation techniques are designed, refined, and employed for preparation of single phase samples as well as large single crystals of these extremely air and moisture-sensitive phases. Low oxidation states and exciting chemical, electronic, and magnetic properties are expected.
The products will be characterized in cooperation with other departments primarily by chemical analysis, X-ray diffraction, and IR as well as Raman spectroscopy. For complete evaluation of physical properties, electric conductivity, magnetic susceptibility as well as electron microscopy and spectroscopy are available accompanied by quantum-chemical bonding analysis.