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

Ein starrer zweizähniger Ligand ermöglicht die oxidative Addition eines Alkins an einen Hauptgruppenmetallkomplex. Hierbei wird nicht das Magnesiumzentrum oxidiert, sondern es findet eine σ‐Bindungsmetathese statt: Aus ML und HC wird HL⋅⋅⋅MC (siehe Schema; Ar= Ar=2,6‐iPr2C6H3).

Addition of Enolisable Ketones to (dpp‐bian)Mg(THF)3 [dpp‐bian =1,2‐Bis{(2,6‐diisopropylphenyl)imino}acenaphthene]

“…The long Mg–N(2)(amino) bonds are always to the N atoms in the axial positions. The differences between the N(amido)–metal and the N(amino)–metal distances correspond well with those found for 4 (2.355 and 2.045 Å), obtained by addition of phenylacetylene to 1 5b. The short amido Mg–N(1) bonds in 6 , 7 and 8 are close to the Mg–N bond lengths in the starting complex 1 (2.045 and 2.105 Å) 4c.…”

“…Owing to the Lewis basicity of 1 , it also adds phenylacetylene to give the phenylethynyl derivative [dpp‐bian(H)]Mg(C≡CPh)(THF) 2 ( 4 ) which in turn reacts with diphenyl ketone with insertion into the magnesium carbon bond, elimination of the N ‐bonded hydrogen and oxidation of the dianionic dpp‐bian ligand to the radical anion affording the carbonilate (dpp‐bian) · – Mg[OC(Ph 2 )CCPh](THF) ( 5 ) 5b …”

Sodium Cation Migration Above the Diimine π‐System of Solvent Coordinated dpp‐BIAN Sodium Aluminum Complexes (dpp‐BIAN=1,2‐Bis[(2,6‐diisopropylphenyl)imino]acenaphthene)

“…[11] Depending on the solvent used, the reduction of dpp-BIAN with aluminum in the presence of its halides gives…”

Single‐Electron‐Transfer Reactions of α‐Diimine dpp‐BIAN and Its Magnesium Complex (dpp‐BIAN)2–Mg2+(THF)3

“…Metallic magnesium easily reduces dpp‐BIAN to a dianion and provides the monomeric solvated complex (dpp‐BIAN)Mg(THF) 3 ( 1 ) 7. To some extent, this complex is related to Hauser bases because it readily deprotonates C–H acids,8 ketones,9 and nitriles 10. Reaction of 1 with diphenylketone provides, by SET, the pinacolate complex [(dpp‐BIAN) – · Mg] 2 (μ‐O 2 C 2 Ph 4 ) 11.…”