Beryllium Dichloride Coordination by Nitrogen Donor Molecules

Abstract

The reaction of anhydrous beryllium chloride with nitrogen donors L in diethylether as a solvent under mild conditions affords 1:2 complexes of the type L2BeCl2 [L = benzonitrile (1), pyridine (2), 3,5-dimethylpyridine, pyrrolidine, piperidine (8), and diethylamine (10)]. Structural studies of compounds 1, 2, 8 (CHCl3), and 10 have shown that the complexes have the beryllium centers N2Cl2- tetracoordinated with a distorted tetrahedral geometry of the core unit. In crystals of 8 and 10 these molecules are associated to form helical strings via distinct N-H-Cl hydrogen bonding. The reaction of the weak donor pyrazole (pyz) with (Et2O)2BeCl2 at low temperature gives the mixed complex [(Et2O)(pyz)BeCl2] (4), in which one diethylether molecule is retained in the inner coordination sphere of the metal. In tetrahydrofuran (thf) solution, no reaction is observed with pyrazole, indicating that tetrahydrofuran is the stronger donor as compared to pyrazole, and the (thf)2BeCl2 solvate remains intact. By contrast, with the strong base pyrrolidine (pyrr) the same reaction leads to substitution of one chloride ligand to give the ionic product [(pyrr)3BeCl]+Cl−, (7). Both products (4, 7) have been structurally characterized. At room temperature the reactions with pyrazole or piperidine lead to ether cleavage as a side-reaction which may even become dominant at long reaction times and more forcing conditions. Dinuclear complexes of the type [LBeCl(μ2-OR)]2 are formed, the structures of which have also been determined. The results suggest that hydrogen bonding may assist in the ether cleavage process, since this reaction is not observed for ligands devoid of N-H functions.

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

“…In the 9 Be NMR spectra ( Figure S8 in the Supporting Information), we always observed a triplet at 1.5 ppm with 1 J BeF = 35 Hz, which shows that two fluorine atoms are bound to the beryllium atom. In the 19 F NMR spectra ( Figure S9 in the Supporting Information), a quartet at À164.5 ppm was observed, which is due to the 3 = 2 spin of 9 Be. The 1 J FBe coupling constant was found to be 34 Hz.…”

“…Both calculated values agree well with the experimentally observed value. The chemical shift of 19 F was calculated to be À192 and À169 ppm at the PBE0/TZVP and CCSD(T)/cc-pVTZ levels of theory, respectively. 3 or ND 3 , respectively, showed N À H/D stretching vibrations in the expected regions (Table S3 in the Supporting Information), which are redshifted relative to free NH 3 /ND 3 due to the coordination of NH 3 /ND 3 to Be 2 + and NÀH/D···F hydrogen bonding.…”

“…[19][20][21][22][23][24][25][26][27][28][29][30] Comprehensive studies have been conducted in recent years by the groups of Dehnicke, Schmidbaur, Weller, and Mederos, and extensive results are available in reviews. [1,14,[31][32][33] The [BeA C H T U N G T R E N N U N G (H 2 O) 4 ] 2 + cation has long been known from studies of the aqueous solution chemistry of beryllium.…”

Acidity enhancement of unsaturated bases of group 15 by association with borane and beryllium dihydride. Unexpected boron and beryllium Brønsted acids

“…Although these complexes may not be very stable, two of them, namely H 2 CvCHPH 2 : BH 3 and HCuCPH 2 : BH 3 , have already been synthesized and spectroscopically characterized, 35,36 and some rather stable complexes between N-bases and BeCl 2 have also been reported. 37 In our study we will consider not only the possibility of losing the proton from the XH 2 group but also from the BH 3 or BeH 2 ones. Since, it would be interesting to know whether unsaturation has some significant effect on the phenomena to be investigated, we have also included a series of saturated ethyl derivatives as a suitable reference.…”

Three‐Coordinate Ligand for Physiological Beryllium Imaging by Fluoresence

“…[13][14][15][16][17][18] Recent work has suggested that Be binding occurs through the displacement of strong hydrogen bonds. [19] Strong hydrogen bonds occur when the distance between the two heteroatoms, typically OÀH···O or OÀH···N, is shorter than the sum of the van der Waals radii and the energy barrier to hydrogen transfer between two atoms is on the order of the O À H vibrational zero-point energy.…”