Reactions of Beryllium Halides in Liquid Ammonia: The Tetraammineberyllium Cation [Be(NH₃)₄]²⁺, its Hydrolysis Products, and the Action of Be²⁺ as a Fluoride‐Ion Acceptor

Abstract

The first structural characterization of the text-book tetraammineberyllium(II) cation [Be(NH(3))(4)](2+), obtained in the compounds [Be(NH(3))(4)](2)Cl(4)⋅17NH(3) and [Be(NH(3))(4)]Cl(2), is reported. Through NMR spectroscopic and quantum chemical studies, its hydrolysis products in liquid ammonia were identified. These are the dinuclear [Be(2)(μ-OH)(NH(3))(6)](3+) and the cyclic [Be(2)(μ-OH)(2)(NH(3))(4)](2+) and [Be(3)(μ-OH)(3)(NH(3))(6)](3+) cations. The latter species was isolated as the compound [Be(3)(μ-OH)(3)(NH(3))(6)]Cl(3)⋅7NH(3). NMR analysis of solutions of BeF(2) in liquid ammonia showed that the [BeF(2)(NH(3))(2)] molecule was the only dissolved species. It acts as a strong fluoride-ion acceptor and forms the [BeF(3)(NH(3))](-) anion in the compound [N(2)H(7)][BeF(3)(NH(3))]. The compounds presented herein were characterized by single-crystal X-ray structure analysis, (9)Be, (17)O, and (19)F NMR, IR, and Raman spectroscopy, deuteration studies, and quantum chemical calculations. The extension of beryllium chemistry to the ammine system shows similarities but also decisive differences to the aquo system.

[Be(ND3)4]Cl2: Synthesis, Characterisation and Space‐Group Determination Guided by Solid‐State Quantum Chemical Calculations

“…The Be-N bond lengths of the [Be(ND 3 [12] for [Be(iPr-N=C=N-iPr) 4 ] 2+ at 1.734(6) Å, [13] for [Be(Me-Im) 4 ] 2+ (Me-Im = Nmethylimidazole) at 1.703(3) Å, [14] for [Be(SPh) 2 (py)(NH 3 )] 2 -(18-crown-6) at 1.724(4) and 1.731(4) Å, [15,16] and [Be(NH 3 ) 4 ] 2+ at 1.725(1)-1.733(3) Å. [8] The N-Be-N angles observed are close to the tetrahedral ones and are between 106.9 (10) (1) and 109.6(1)°. [8] The N-D distances are in the Table 4.…”

“…The formation of two liquid phases has been observed previously, [3] and it seems that traces of moisture lead to the phase separation. [8] Very temperature-and moisture-sensitive colourless crystals of the composition [Be(NH 3 ) 4 ] 2 Cl 4 ·17NH 3 were grown at -40°C from this liquid ammonia solution as evidenced by X-ray crystal structure analysis, Equation (1). [8] 2 [6,9] the N-H stretching vibrations are more redshifted by approximately 50 cm -1 .…”

“…[8] Very temperature-and moisture-sensitive colourless crystals of the composition [Be(NH 3 ) 4 ] 2 Cl 4 ·17NH 3 were grown at -40°C from this liquid ammonia solution as evidenced by X-ray crystal structure analysis, Equation (1). [8] 2 [6,9] the N-H stretching vibrations are more redshifted by approximately 50 cm -1 . The X-ray powder pattern of compound 1-H could be indexed to an orthorhombic unit cell with cell parameters a = 9.3878(3), b = 11.8965(4), c = 6.7637(3) Å and V = 755.39 (5) [4] However, our powder patterns do not support this statement and look completely different.…”

“…Up to now, only the crystal structure of the 12.5 ammoniate in the form of [Be(NH 3 ) 4 ] 2 Cl 4 ·17NH 3 [8] has been established in our previous works. Now we report on the synthesis, composition and crystal structure of [Be(NH 3 ) 4 ]Cl 2 (1-H) and the perdeuterated [Be(ND 3 ) 4 ]Cl 2 (1-D), respectively.…”

“…[6] Biltz and co-workers found BeCl 2 adducts with two, four, six and twelve molecules of ammonia by tensieudiometric measurements. [7] The latter was shown to be a 12.5 ammoniate in the form of [Be(NH 3 ) 4 ] 2 Cl 4 ·17NH 3 , [8] which contains the tetraammineberyllium(II) cation. We observed that this am-the assignment of proper crystallographic space groups in cases where the choice between centrosymmetry and noncentrosymmetry is not completely obvious, e.g.…”