Insights into Molecular Beryllium–Silicon Bonds

Abstract

We present the synthesis of two silyl beryllium halides HypSiBeX·(thf) (HypSi = Si(SiMe 3 ) 3 , X = Cl 2a, I 4a) and the molecular structure of 2a as determined by single crystal X-ray diffraction. Compounds 2a and 4a were characterized via multi-nuclear NMR spectroscopy ( 1 H, 9 Be, 13 C, 29 Si), and the bonding situation was further investigated using quantum chemical calculations (with the addition of further halides X = F 1b, Cl 2b, Br 3b, I 4b). The nature of the beryllium silicon bond in the context of these compounds is highlighted and discussed.The reaction of LiSi(SiMe 3 )·(thf) 2.6 with BeX 2 (X = Cl, I) in a 1:1 mixture of dry toluene/thf at 60 • C led to the formation of 2a and 4a after stirring for 16 h (Scheme 1), which was confirmed by 9 Be NMR spectroscopy. All volatiles were removed under reduced pressure, and the residue was dried for 2 h in an oil-pump vacuum. The residue was then dissolved in a small amount of dry toluene and filtrated, and the compounds were crystallized at −28 • C (yield: 2a 83%, 4a 87%). 2a and 4a were obtained as colorless crystalline solids, which dissolve easily in a number of typical coordinating (Et 2 O, THF) and non-coordinating solvents (hexane, cyclohexane, toluene) and were characterized by multi-nuclear NMR spectroscopy (

Recent Contributions to the Coordination Chemistry of Beryllium

“…With the additional help of quantum-chemical calculations it was demonstrated that the BeÀSi bond is mainly cova-lent in these compounds. [50] Monodentate phosphines proved to be rather good ligandsf or beryllium halides and the bisphosphine adduct [BeCl 2 (PMe 3 ) 2 ]( 50)w as obtained quantitatively by reactiono fB eCl 2 with PMe 3 in chlorinated or aromatic solvents. [51] Reaction of one equivalent of BeCl 2 with one equivalent of [Pd(PCy 3 ) 2 ]l eads to the formation of the relatedd inuclear species 51 through an unknown route.…”

“…Various beryllium compounds with Lewis bases. [21,24,50,[52][53][54][55] Scheme6.Di(n-butyl)beryllium synthesis utilizing PMe 3 as solubilizer. [51] Chem.…”

“…The conversion with BeI 2 results in the analogous iodo‐bridged dinuclear complexes. With the additional help of quantum‐chemical calculations it was demonstrated that the Be−Si bond is mainly covalent in these compounds . Monodentate phosphines proved to be rather good ligands for beryllium halides and the bis‐phosphine adduct [BeCl 2 (PMe 3 ) 2 ] ( 50 ) was obtained quantitatively by reaction of BeCl 2 with PMe 3 in chlorinated or aromatic solvents .…”

Behavior of Lewis Bases toward Diphenylberyllium

“…The beryllium atom is coordinated pseudotetrahedrally by two SMe 2 and two phenyl ligands. The S−Be−S, C−Be−C and C− Be−S angles are 99.60 (10), 120.20 (16), and 106.92(5)/ 110.65(5)°, respectively. These are comparable to the corresponding angles in [(SMe 2 ) 2 BeBr 2 ] (S−Be−S: 96.6(2)°, Br−Be−Br: 117.6(2)°, S−Be−Br: 106.92(3)−113.47(4)°), 41 while the S−Be−S angles in [(NH 3 )(Py)Be(SPh) 2 ] are significantly larger (124.6(2)−125.2(2)°).…”

“…In contrast to the ubiquity of organomagnesium reagents, organoberyllium chemistry is relatively unexplored due, at least in part, to the perceived toxicity of this element. − Indeed, although organoberyllium complexes were prepared as early as the 1920s, − the field has subsequently been relatively devoid of methodical, fundamental beryllium research. Recently, there has been renewed interest in the organometallic chemistry of beryllium, driven by a desire to understand the biotoxicity mechanisms of this element and exploit its unique electronic properties for chemical transformations. − Within the past five years, the first compounds containing formally zero- and monovalent beryllium centers, in addition to the first BeC and BeN bonds have all been reported. − …”