Barium Triphenylmethanide: An Examination of Anion Basicity

Abstract

Differences in anion basicity seem to be key for the formation of the first charge‐separated barium triphenylmethanide (see structure) versus a novel heteroleptic vinyl ether which results from cleavage of the attendant [18]crown‐6. Ba: green; O: red; P: yellow; N: blue.

Not Just Heavy “Grignards”: Recent Advances in the Organometallic Chemistry of the Alkaline Earth Metals Calcium, Strontium and Barium

“…This method takes advantage of the strong thermodynamic drive towards the formation of toluene (and/or substituted phenylmethanes), resulting in the facile metallation of a variety of acidic hydrocarbons [Equation (4)]. [52] (4) This method is particularly attractive as it forms simple hydrocarbons as the reaction products that can be easily removed from the reaction mixture. Again, similar pK a limitations as discussed above apply (see section 3.1), as well as the lack of flexibility in solvent selection for some of the heavier analogs.…”

“…Reaction of triphenylmethane and barium bis[bis(trimethylsilyl)]amide in the presence of 18-crown-6 in THF at low temperature did not afford the desired product; instead, cleavage of the crown ether and subsequent elimination of free amine led to the formation of the heteroleptic vinyl ether amide (21; Figure 13). [52] This heteroleptic barium amide exists as a dimer, with two slightly asymmetrically bridging alkoxide moieties connecting the two metal centers. The opposite face is filled by an amide ligand, and the vinyl ether wraps around the equator of the barium atom giving four additional metaloxygen interactions for a total coordination number of seven.…”

Low‐Coordinate Barium Boryloxides: Synthesis and Dehydrocoupling Catalysis for the Production of Borasiloxanes

“…In related cases of supported heteroleptic amido/alkoxo barium dimers, the dinuclear edifices are bridged through the O alkoxide atoms . The bonding situation in 3 reflects both considerable steric bulk of the boryloxide R 2 BO − and limited electronic density available at O boryloxide to bridge the two metals.…”

Intramolecular C–F and C–H bond cleavage promoted by butadienyl heavy Grignard reagents

“…Nevertheless, the organometallic chemistry of heavy Grignard reagents (RAeX, Ae ¼ Ca, Sr and Ba) is still in its infancy due to the rather inert heavy alkalineearth metals and extremely high ionicity and reactivity of Ae-C bonds [2][3][4][5][6][7] . The enormous reactivity of generated Ae-C bonds easily led to side reactions and obstructed the application of heavy Grignard reagents [8][9][10][11][12] .…”