The reactions of anionic aluminium or gallium nucleophiles
{K[E(NON)]}2 (E = Al, 1; Ga, 2; NON = 4,5-bis(2,6-diisopropylanilido)-2,7-ditert-butyl-9,9-dimethylxanthene) with beryllocene (BeCp2)
led to the displacement of one cyclopentadienyl ligand at
beryllium and the formation of compounds containing Be–Al or
Be–Ga bonds (NON)EBeCp (E = Al, 3; Ga, 4). The Be–Al bond in the beryllium–aluminyl complex
[2.310(4) Å] is much shorter than that found in the small number
of previous examples [2.368(2) to 2.432(6) Å], and quantum chemical
calculations suggest the existence of a non-nuclear attractor (NNA)
for the Be–Al interaction. This represents the first example
of a NNA for a heteroatomic interaction in an isolated molecular complex.
As a result of this unusual electronic structure and the similarity
in the Pauling electronegativities of beryllium and aluminium, the
charge at the beryllium center (+1.39) in 3 is calculated
to be less positive than that of the aluminium center (+1.88). This
calculated charge distribution suggests the possibility for nucleophilic
behavior at beryllium and correlates with the observed reactivity
of the beryllium–aluminyl complex with N,N′-diisopropylcarbodiimidethe electrophilic carbon center of
the carbodiimide undergoes nucleophilic attack by beryllium, thereby
yielding a beryllium–diaminocarbene complex.
The behavior of a variety of Lewis bases toward diphenylberyllium has been investigated, demonstrating the high Lewis acidity and electron deficiency of diphenylberyllium. A range of monodentate donors with vastly different steric and electronic properties were used, namely, pyridine, NEt 3 , THF, THT, and PMe 3 . The Be-donor bond strength was investigated through application of vacuum, and transformations between the mono-and disubstituted beryllium centers were investigated through stoichiometric addition of additional BePh 2 . Strong electron donors (Nheterocyclic carbenes) with vastly different steric profiles were then investigated, highlighting that steric interactions are more dominant than electronics. Adducts of bidentate ligands with O-, N-, and Pdonating sites were also produced.
It is common knowledge
that metal-to-ligand π back-donation
requires filled atomic orbitals at the metal center. However, we show
through a combined experimental and theoretical approach that Be(II)→N-heterocyclic
carbene (NHC) π back-donation is present in the two carbene
adducts [(iPr)BeBr2] (1) and [(iPr)2BeBr2] (2) (iPr = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene).
These complexes were characterized with NMR, IR, and Raman spectroscopy
as well as with single-crystal X-ray diffractometry. The unusual bonding
situation is understood from the results of energy decomposition analysis
in combination with natural orbital for chemical valence and quantum
theory of atoms-in-molecules analysis. The obtained findings shed
light on the unusually high Be–C bond strength in carbene adducts to beryllium compounds
and rationalize their geometry and reactivity.
The thioether diadducts [(SMe2)2BeCl2], [(SMe2)2BeBr2] and [(SMe2)2BeI2] have been prepared and converted to the corresponding μ2‐halido bridged monoadducts [(SMe2)BeCl2]2, [(SMe2)BeBr2]2 and [(SMe2)BeI2]2. These complexes have been characterized with IR and NMR spectroscopy as well as X‐ray crystallography. Furthermore, their long term stability in chlorinated solvents was tested, which yielded beryllate salts containing the [SMe3]+ cation.
Treatment of the new methanediide-methanide complex [Dy(SCS)(SCSH)(THF)] (1Dy, SCS = {C(PPh2S)2}2-) with alkali metal alkyls and auxillary ethers produces the bis-methanediide complexes [Dy(SCS)2][Dy(SCS)2(K(DME)2)2] (2Dy), [Dy(SCS)2][Na(DME)3] (3Dy) and [Dy(SCS)2][K(2,2,2-cryptand)] (4Dy). For...
Delicious deprotonations: The scrumptiously tantalising diphenylberyllium Brønsted‐base bratwurst can be combined with an enticing selection of Brønsted‐acid sauces to result in the formation of dreamy beryllium compounds, such as an XRD‐confirmed homoleptic beryllium alkoxide and an NHC‐stabilised beryllium Grignard. More information can be found in the Research Article by M. R. Buchner and co‐workers (DOI: 10.1002/chem.202200851).
The bonding situation in the tricoordinated beryllium phenyl complexes [BePh3]−, [(pyridine)BePh2] and [(trimethylsilyl‐N‐heterocyclic imine)BePh2] is investigated experimentally and computationally. Comparison of the NMR spectroscopic properties of these complexes and of their structural parameters, which were determined by single crystal X‐ray diffraction experiments, indicates the presence of π‐interactions. Topology analysis of the electron density reveals elliptical electron density distributions at the bond critical points and the double bond character of the beryllium‐element bonds is verified by energy decomposition analysis with the combination of natural orbital for chemical valence. The present beryllium‐element bonds are highly polarized and the ligands around the central atom have a strong influence on the degree of π‐delocalization. These results are compared to related triarylboranes.
The synthesis of beryllium halide etherates and the solution behavior in benzene, dichloromethane, and chloroform was studied by NMR, IR, and Raman spectroscopy. Mononuclear units of [BeX
2(L)2] (X = Cl, Br, I; L = Et2O, thf) were identified as the favorably formed species in solution. Treatment of the mononuclear diethyl ether beryllium halide adduct with one equivalent beryllium halide formed the dinuclear compounds [BeX
2(OEt2)]2 (X = Cl, Br, I). The solid-state structures of [BeCl2(thf)2] and [BeBr2(thf)2] have been determined by single crystal X-ray diffraction analysis. [BeI2(thf)2] decomposed in all solvents. In CD2Cl2 the salt [Be(thf)4]I2 was formed, whereas in C6D6 and CDCl3, BeI2 precipitated and [BeI(thf)3]+, [Be(thf)4]2+ together with the thf ring-opening product [Be(μ
2-O(CH2)4I)I(thf)]2 were observed in solution.
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