Oxidative Addition of Phenylacetylene through CH Bond Cleavage To Form the Mg^II–dpp‐bian Complex: Molecular Structure of [Mg{dpp‐bian(H)}(CCPh)(thf)₂] and Its Diphenylketone Insertion Product [Mg(dpp‐bian)^.−{OC(Ph₂)CCPh}(thf)]

Abstract

The use of a rigid bidentate ligand allows oxidative addition of an acetylene derivative to a non‐transition‐metal complex, not through oxidation of the metal atom, but through σ‐bond metathesis from ML: and HC to form HL⋅⋅⋅MC (see scheme; Ar=2,6‐iPr2C6H3).

Shedding New Light on ZnCl2‐Mediated Addition Reactions of Grignard Reagents to Ketones: Structural Authentication of Key Intermediates and Diffusion‐Ordered NMR Studies

“…Also noteworthy in 3, is the fact that the desired resulting addition product, the alkoxide {OC(Et)Ph 2 } À forms part of a magnesiate anion, instead of a neutral magnesium compound, [36] which can be an advantage to its further functionalisation, since, in general, magnesiates display an enhanced nucleophilicity than vis-a-vis relevant neutral species. The structural authentication of 3 also highlights the importance of the inorganic salt MgCl 2 (here provided by the alkylating reagent 1 but in other in situ methodologies, such as the one reported by Ishihara and coworkers, present in solution as a side product of the RMgCl/ ZnCl 2 metathesis), which not only provides a solvation anchor for the benzophenone (due to its high Lewis acidity) that will activate it towards the nucleophilic attack of the zincate anion, but also supplies structural support for the resulting alkoxide product (MgCl 2 is not only part of the cation in 3 but it also participates in the anionic moiety).…”

Reductive Isopropyl Radical Elimination from (dpp‐bian)Mg‐iPr(Et2O)

“…{[M] + n [(dpp‐bian)] n – (L) x } (M = Li, Na; n = 1–4; L = Et 2 O, THF)6a,6b and {[M] 2+ [(dpp‐bian)] 2– (THF) x } (M = Mg, Ca, Ge) 6c,6d,6e. Up to this time the aryl‐bian system was mainly used in transition metal chemistry,7 but we have demonstrated that the magnesium complex (dpp‐bian)Mg(THF) 3 is also a powerful reagent in organic synthesis 6e,8a,8b. Thus, the electron transfer from this complex to Ph 2 CO affords the pinacol coupling product, while its reaction with 9‐(10H)‐anthracenone yields the antryloxymagnesium derivative 8a…”

Redox‐Active Ligand‐Assisted Two‐Electron Oxidative Addition to Gallium(II)

“…The reactivity of two representative examples (dpp‐bian)Mg(THF) 3 ( 1 ) and (dpp‐bian)Ga−Ga(dpp‐bian) ( 2 ) has been studied thoroughly. We observed the following reactivity modes for compound 1 : 1) addition of substrates through the one‐electron oxidation of the ligand, which results in a magnesium–substrate bond, 2) addition of organic halides R−X to both the ligand and metal to afford L −R and M−X bonds, and 3) addition of terminal alkynes, nitriles, and enols by protonation of dianionic dpp‐bian ligand, which results in magnesium acetylenides, keteniminates, and enolates –. In contrast, compound 2 reacts with different alkynes to form cycloadducts that liberate “coordinated” alkyne upon heating .…”