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

Abstract

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.

Behavior of Lewis Bases toward Diphenylberyllium

“…36 However, the latter chemical shift has to be taken with caution since this shift range is otherwise only observed for cationic Ndonor complexes of beryllium like [(Py) 3 BeBr] + (6.2 ppm), 37 [(NH 3 ) 4 Be] 2+ (3.3 ppm), and [(NH 3 ) 4 Be 4 (NH 2 ) 6 ] 2+ (4.5 ppm). 38 We observe the resonance of tricoordinate [(THF)BePh 2 ] at 17.0 ppm by 9 Be NMR spectroscopy, which compares well to the signals observed for [O n Bu 2 ]BePh 2 ] (17.4 ppm), 30 [(OEt 2 )BePh 2 ] (20.0 ppm), 20 and [(OEt 2 )BeMe 2 ] (20.8 ppm). 35 Tetracoordinate [(THF) 2 BePh 2 ] shows a 9 Be NMR signal at 10.2 ppm, which is shifted significantly upfield compared to [(THF)BePh 2 ].…”

“…For [(Py) 2 BePh 2 ], the 9 Be NMR shift is observed at 10.0 ppm, which is in between the one found for [(NEt 3 )­BeCl 2 ] 2 (8.0 ppm) and [(NMe 3 ) 2 BeMe 2 ] (12.0 ppm), while the signal of (3,5-dimethylpyridine) 2 BeCl 2 is given as 1.7 ppm . However, the latter chemical shift has to be taken with caution since this shift range is otherwise only observed for cationic N-donor complexes of beryllium like [(Py) 3 BeBr] + (6.2 ppm), [(NH 3 ) 4 Be] 2+ (3.3 ppm), and [(NH 3 ) 4 Be 4 (NH 2 ) 6 ] 2+ (4.5 ppm) …”

“…The most closely related beryllium pyridine−nitrogen bond length is found in [(Py) 4 Be 8 (NH 2 ) 12 O] 2+ (1.828(4)−1.836(4) Å). 38 In general, the Be−N distances in neutral pyridine complexes of beryllium are longer than in corresponding neutral compounds with ammonia [(NH 3 ) 2 BeX 2 ] (1.70(2)−1.722(3) Å) 51 or in cationic ([(Py) 3 BeBr] + : 1.754(5) Å, 37 [(Py) 4 Be] 2+ : 1.72.3(8)−1.738(8) Å, 49,50 [(NH 3 ) 4 Be] 2+ : 1.707(3)− 1.744(4) Å) 51 or anionic ([(Py)BeCl 3 ] − : 1.765(6) Å, 52 [Be(NH 2 ) 3 ] − : 1.594(4)−1.616(4) Å, 53 [Be(NH 2 ) 4 ] 2− : 1.7382(7)−1.7710(8) Å) 53 beryllium nitrogen complexes.…”

Dimethylsulfide Adducts of the Beryllium Halides

“…We are interested in the speciation of beryllium compounds in solution [23–26] . For this reason, we have already investigated the beryllium halide adducts of O ‐donor solvents like carboxylic acid esters [27] and dimethylformamide [28] as wells as of the N ‐donor solvents ammonia, [29,30] ethylienediamine, [31] triethylamine [32] and acetonitrile [33] .…”

A Second Modification of Beryllium Bromide: β-BeBr2

“…Therefore, it was evident that recrystallization in solution at ambient temperature had to be employed. However, the choice of solvent was significantly reduced by the fact that BeBr 2 forms stable adduct complexes with oxygen- and nitrogen-donor solvents and ligands. , Chlorinated solvents are also capable of dissolving low amounts of beryllium halides. However, in the case of BeBr 2 and BeI 2 , exchange of the bromide and iodide against chloride can occur through activation of the C–Cl bonds .…”