Ethylenediamine complexes of the beryllium halides and pseudo-halides

The suitability of ethylenediamine (en) as an alternative solvent to liquid ammonia in beryllium chemistry was evaluated. Therefore, BeF2, BeCl2, BeBr2, BeI2, [Be(NH3)4](N3)2, [Be(NH3)4](CN)2 and [Be(NH3)4](SCN)2 were reacted with ethylenediamine and analysed via NMR and IR spectroscopy. Additionally single crystal structures of [BeF2(en)]n, [Be(en)3]Cl2, [Be(en)3]Br2, [Be(en)2]I2·en, [Be(en)2](N3)2·en, [Be(en)2]4(SCN)7Cl and [Be3(OH)3(en)3][C2H9N2](SCN)4 were obtained. The anions were found to have a distinct influence on the solubility as well as on the species present in solution and the solid state, while ethylenediamine can act as mono- and bidentate ligand or as a crystal solvent.

Speciation of Be2+ in acidic liquid ammonia and formation of tetra- and octanuclear beryllium amido clusters

The hexa-μ₂-amido-tetraammine-tetraberyllium compounds [Be₄(NH₂)₆(NH₃)₄]X₂ (X = Cl, Br, I, CN, SCN, N₃) have been prepared from beryllium metal and NH₄X or [Be(NH₃)₄]X₂ in liquid ammonia at ambient temperature. The obtained compounds feature an adamantyl shaped complex cation, which was examined via X-ray diffraction, IR, Raman and NMR spectroscopy. The speciation in solution was studied via¹⁵N labeling experiments supplemented with quantum chemistry. Hereby, the intermediates [Be₂(NH₂)(NH₃)₆]³⁺ and [Be₃(NH₂)₃(NH₃)₆]³⁺ were identified. Reactivity studies provided bis(N-acetimidoylacetamidinato-N,N′)-beryllium(ii), when [Be₄(NH₂)₆(NH₃)₄]²⁺ was treated with acetonitrile. While the unprecedented octa-nuclear complex cation [Be₈O(NH₂)₁₂(C₅H₅N)₄]²⁺ was received from pyridine. This cluster proves that the [Be₄O]⁶⁺ core can be stabilized without bidentate O-donor ligands.

The boundaries of beryllium metal oxidation in acidic ammonia have been explored. This enabled the isolation of the tetra- and octa-nuclear beryllium amide complexes. The latter exhibits a completely new structural motive in coordination chemistry.

Theoretical predictions of aromatic Be–O rings

We have carried out a theoretical investigation of benzene substituted with BeO to assess stability and aromatic properties (with 1–3 BeO units in a six-membered ring); C₄H₄BeO, C₂H₂Be₂O₂, and Be₃O₃.