New Outcomes of Beryllium Chemistry: Lewis Base Adducts for Salt Elimination Reactions

Abstract

A range of mono- and bis-adducts of beryllium dichloride with cyclic (alkyl)­(amino)­carbenes (CAAC), cyclic diamidocarbene (DAC), and carbodiphosphorane (CDP) are prepared, and their reactions with nucleophiles are studied. Salt elimination with Yamashita and Nozaki’s lithium diazaborolide reagent led to the isolation of an unsymmetrical beryllium diazaborolyl complex and a base-stabilized diazaborolyl beryllium chloride. From structural and spectroscopic analyses, the Be–B bonding in these compounds was determined to be polar covalent in character. In addition, the nucleophilic addition of magnesium anthracenediyl to one of the adducts resulted in the isolation of an interesting tetracyclic beryllium-bridged molecule.

N-Heterocyclic Carbene-Supported Aryl- and Alk- oxides of Beryllium and Magnesium

“…Additionally, the carbene C−Be bond of 1 is longer than those of (CDC)BeCl2 (1.748 Å ) [57], and (CDP)BeCl2 (1.742 Å ) [58]. Compound 1 is structurally similar to the recently reported (PMe3)2BeCl2 and (NHC)2BeCl2 complexes [50,59]. Molecular structure of 1 (thermal ellipsoids at 50% probability; H atoms and toluene solvent molecules omitted for clarity).…”

“…The beryllium atom is featured in a distorted tetrahedral environment with the widest bond angle being C1−Be1−Cl1 at 118.13(6) • , with two NHC ligands bound to BeCl 2 ( Figure 1). The carbene C−Be bond distance of 1 is 1.849(3) Å falls within the range of other carbene C−Be bonds (1.779-1.856(4)) [49][50][51][52][53][54][55][56]. Additionally, the carbene C−Be bond of 1 is longer than those of (CDC)BeCl 2 (1.748 Å) [57], and (CDP)BeCl 2 (1.742 Å) [ Colorless crystals of compound 1 were obtained from toluene at −37 °C .…”

Recent Contributions to the Coordination Chemistry of Beryllium

“…Through salt metathesis reactions, the chloride atoms of the carbene-BeCl 2 adducts can be substituted by alkyl groups. Either lithium or magnesium organyls can be used, giving complexes 30 [43] and 31, [39] respectively.H owever,a na nalogous approach with LiBH 4 as ah ydride source results in the formation of complex 32.T his compound exhibits ah ighly unusual fivefold-coordination geometry at the beryllium center and can be regardeda sN HC-stabilized monomeric beryllium borohydride. This compound is surprisingly air stable.…”

“…Beryllium organyls, beryllium-carbenea nd carbodiphosphorane complexes (Mes = 2,4,6-Me 3 C 6 H 2 ;dipp = 2,6-iPr 2 C 6 H 3 ). [25,26,38,39,41,44] Chem.E ur.J. 2019, 25,12018 -12036 www.chemeurj.org bond order of 1.5.…”

“…[49] Similarly,m onodiazaborolyls 47 and 48 can be obtained through salt metathesis of lithium diazaborolide with CAAC adducts 27 or Cp*BeCl (Cp* = C 5 Me 5 )r espectively. [39]…”