Tetrapyridin-Beryllium-Polyiodid. Synthese und Kristallstruktur von [Be(Py)4]2(I3)2(I4)

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.

Synthesis and crystal structures of β-[Be(DMF)4]I2, [Be(Pyr)4]I2, [Be(NMP)4]I2 and [BeI2(Lut)2]

Four solvent complexes of beryllium iodide were prepared by dissolving BeI2 in N,N-dimethyl formamide (DMF), pyridine (Pyr), N-methyl pyrrolidone (NMP) and 2,6-dimethyl pyridine (2,6-lutidine, Lut). Their crystal structures were established from single crystal X-ray diffraction. For [Be(DMF)4]I2 a new modification is reported (monoclinic, space group P21/c, a = 12.491(2), b = 11.593(2), c = 15.310(3) Å, β = 94.7073(6)°). In [Be(Pyr)4]I2 (monoclinic, space group C2/c, a = 17.8799(13), b = 7.6174(5), c = 18.2611(14) Å, β = 113.508(4)°) and [Be(NMP)4]I2 (orthorhombic, space group Pbca, a = 13.941(5), b = 15.754(3), c = 24.634(7) Å) homoleptic tetrahedral complex cations are formed, while the sterically demanding solvent ligand Lut yields a neutral complex with covalently bound iodine ligands [BeI2(Lut)2] (monoclinic, space group P21/c, a = 7.8492(9), b = 24.265(3), c = 27.037(3) Å, β = 97.076(3)°). Their electrochemical stability with respect to their application as beryllium electrolytes for deposition of beryllium from solution is discussed.

Preparation and crystal structures of the beryllium ammines [Be(NH3)4]X2 (X = Br, I, CN, SCN, N3) and Be(NH3)2X'2 (X' = Cl, Br, I)

Tetraammineberyllium halides and pseudo-halides [Be(NH₃)₄]X₂ (X = Cl, Br, I, CN, SCN, N₃) as well as Be(NH₃)₂F₂ have been prepared from beryllium metal and NH₄X or NH₄F in liquid ammonia at ambient temperature, respectively. Diammineberyllium halides Be(NH₃)₂X'₂ (X' = Cl, Br, I) were synthesized at 300 °C from Be and NH₄X'. The obtained compounds were characterised via X-ray diffraction, and IR and Raman spectroscopy and their thermal decomposition was studied by TGA.

Factors affecting charge transfer in tetraiodide dianions

Thirty-one examples of crystal structures containing discrete tetraiodide I₄²⁻dianions were identified from the Cambridge Structural Database (CSD) and analyzed in detail in order to find the factors influencing the geometry of this rare fragment. The intermolecular interactions are at least partially responsible for the changes in the geometry of the dianion.

Two iodine-rich (dimethylphosphoryl)methanaminium iodides

The reaction of

Bis(μ-diisopropyl-hydoxylaminato)-κ(2) O:N;κ(2) O:O-bis-[(diisopropyl-hydoxylaminato-κO)beryllium]

The title compound, [Be₂(C₆H₁₄NO)₄], was prepared from a solution of BeCl₂ in diethyl ether and two equivalents of O-lithia­ted N,N-diisopropyl­hydoxyl­amine. The mol­ecular structure is composed of a dinuclear unit forming a central five-membered planar Be—O—Be—O—N ring (sum of inter­nal angles = 540.0°; r.m.s. deviation from planarity = 0.0087 Å). Both Be atoms show the unusual coordination number of three, with one Be atom coordinated by three O atoms and the other by two O atoms and one N atom, both in distorted trigonal–planar environments. The Be—O distances are in the range 1.493 (5)–1.600 (5) Å and the Be—N distance is 1.741 (5) Å.