Low Valent Magnesium Chemistry with a Super Bulky β‐Diketiminate Ligand. Issue 2 (5th December 2018)

• Record Type: Journal Article
• Authors: Gentner, Thomas Xaver; Rösch, Bastian; Ballmann, Gerd; Langer, Jens; Elsen, Holger; Harder, Sjoerd
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 2(2019)
• Page Start: 607
• Page End: 611
• Publication Date: 2018-12-05
• Subjects: alkaline earth metal -- bulky ligand -- low valence -- magnesium -- metal-metal bonding; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201812051
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The steric bulk of the well‐known DIPP BDI ligand (CH[C(CH3 )N‐DIPP]2, DIPP=2, 6‐diisopropylphenyl) was increased by replacing isopropyl for isopentyl groups. This very bulky DIPeP BDI ligand could not stabilize the radical species ( DIPeP BDI)Mg . : reduction of ( DIPeP BDI)MgI with Na gave ( DIPeP BDI)2 Mg2 with a rather long Mg‐Mg bond of 3.0513(8) Å. Addition of TMEDA prior to reduction gave complex ( DIPeP BDI)2 Mg2 (C6 H6 ), which could also be obtained as its THF adduct. It is speculated that combination of a bulky spectator ligand and TMEDA prevents dimerization of the intermediate Mg I radical, which then reacts with the benzene solvent. Complex ( DIPeP BDI)2 Mg2 (C6 H6 ), which formally contains the anti ‐aromatic anion C6 H6 2−, reacted with t BuOH as a Brønsted base to 1, 3‐ and 1, 4‐cyclohexadiene and with H2 as a two electron donor to ( DIPeP BDI)2 Mg2 H2 and C6 H6 . It also reductively cleaved the C−F bond in fluorobenzene and gave ( DIPeP BDI)MgPh, ( DIPeP BDI)MgF, and C6 H6 . Abstract : Pepping up chemistry with DIPeP : Replacing the isopropyl groups in a commonly used β‐diketiminate ligand for isopentyl substituents gives the super bulky DIPeP BDI ligand. Its dinuclear Mg I complex, ( DIPeP BDI)2 Mg2, features a strongly elongated Mg−Mg bond. Attempted isolation of the radical ( DIPeP BDI)Mg . gave ( DIPeP BDI)2 Mg2 (C6 H6 ) in which the formally reduced benzene, C6 H6 2−, is a very strong reductant.