Speciation of Be(2+) in acidic liquid ammonia and formation of tetra- and octanuclear beryllium amido clusters

The hexa-μ(2)-amido-tetraammine-tetraberyllium compounds [Be(4)(NH(2))(6)(NH(3))(4)]X(2) (X = Cl, Br, I, CN, SCN, N(3)) have been prepared from beryllium metal and NH(4)X or [Be(NH(3))(4)]X(2) 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 via(15)N labeling experiments supplemented with quantum chemistry. Hereby, the intermediates [Be(2)(NH(2))(NH(3))(6)](3+) and [Be(3)(NH(2))(3)(NH(3))(6)](3+) were identified. Reactivity studies provided bis(N-acetimidoylacetamidinato-N,N′)-beryllium(ii), when [Be(4)(NH(2))(6)(NH(3))(4)](2+) was treated with acetonitrile. While the unprecedented octa-nuclear complex cation [Be(8)O(NH(2))(12)(C(5)H(5)N)(4)](2+) was received from pyridine. This cluster proves that the [Be(4)O](6+) core can be stabilized without bidentate O-donor ligands.