Durch sterische Blockierung und/oder Einbau in fünfgliedrige Ringsysteme stabilisierte Germylene, X2Ge, reagieren mit Azidoverbindungen, YN3, in Abhängigkeit von der Raumerfüllung der Substituenten X und Y zu Iminogermanen X2 Ge=NY (1, 2), Azidogermanen, X2Ge(N3)NY2 (6′8), Tetrazagermolen, X2Ge‐(–NY–N=)2 (10–16), bzw. Hexaazadigermadispirododecanen, [(NRCH2CH2NR )Ge(μ‐NY–)]2 (17, 18). NMR‐(1H, 13C, 14N, 15N und 29Si), MS‐Daten und Röntgenstrukturanalysen für die Verbindungen 8, 9, 16 und 18 sind angegeben.

Using a set of pyrazolate-based dinucleating ligands with thioether sidearms and a set of different carboxylates, seven tetranuclear nickel(II) complexes of types [L2Ni4(N3)3(O2CR)2](ClO4) (1) and [L2Ni4(N3)(O2CR)4](ClO4) (2) featuring an unprecedented central mu4-1,1,3,3-azide could be isolated and fully characterized. X-ray crystal structures are discussed for 1a,b,e and 2b. The mu4-1,1,3,3-azide is symmetric in all cases except 1a but exhibits distinct binding modes with significantly different Ni-N(azide)-Ni angles and Ni-NNN-Ni torsions in type 1 and 2 complexes, which indicates high structural flexibility of this novel bridging unit. Also, IR-spectroscopic signatures and magnetic properties are distinct for type 1 and 2 complexes. Magnetic data for 1a,b,d,e and 2a,b were investigated and analyzed in a three-J approach. The only model that gave a satisfactory fit for all type 1 complexes includes one dominant antiferromagnetic coupling and two ferromagnetic interactions (one large and one smaller), indicating some degree of frustration. On the basis of magneto-structural correlations for end-on and end-to-end azide linkages, it is reasonable to assign the antiferromagnetic interaction to the intradimer exchange along the pyrazolate and the end-to-end linkage of the mu4-azide. Overall, the magnitude of the coupling constants differs significantly for the two distinct types of compounds, 1 or 2, and depends on the individual geometric details of the Ni4 array and the mu4-1,1,3,3-azide.

The synthesis of a new bioinspired dinucleating ligand scaffold based on a bridging pyrazolate with appended bis[2-(1-methylimidazolyl)methyl]aminomethyl chelate arms is reported. This ligand forms very stable copper complexes, and a series of different species is present in solution depending on the pH. Interconversions between these solution species are tracked and characterized spectroscopically, and X-ray crystallographic structures of three distinct complexes that correspond to the species present in solution from acidic to basic pH have been determined. Overall, this provides a comprehensive picture of the copper coordination chemistry of the new ligand system. Alterations in the protonation state are accompanied by changes in nuclearity and pyrazolate binding, which cause pronounced changes in color and magnetic properties. Antiferromagnetic coupling between the copper(II) ions is switched on or off depending on the pyrazole binding mode.

Three new germaimines have been synthesized and two of them characterized by X-ray diffraction; the Ge=N bond lengths agree well with an ab initio prediction for H2Ge=NH.