Tetravalent Cerium Alkyl and Benzyl Complexes

Abstract

High-valent cerium complexes of alkyl and benzyl ligands are unprecedented due to the incompatibility of the typically highly oxidizing Ce 4+ ion and the reducing alkyl or benzyl ligand. Herein we report the synthesis and isolation of the first tetravalent cerium alkyl and benzyl complexes supported by the tri-tert-butyl imidophosphorane ligand, [NP( t Bu) 3 ] 1− . The Ce 4+ monoiodide complex, [Ce 4+ I(NP(tert-butyl) 3 ) 3 ] (1-CeI), serves as a precursor to the alkyl and benzyl complexes, [Ce 4+ (Npt)(NP(tert-butyl) 3 ) 3 ] (2-CeNpt) (Npt = neopentyl, CH 2 C(CH 3 ) 3 ) and [Ce 4+ (Bn)(NP(tert-butyl) 3 ) 3 ] (2-CeBn) (Bn = benzyl, CH 2 Ph). The bonding and structure of these complexes are characterized by single-crystal XRD, NMR and UV−vis−NIR spectroscopy, cyclic voltammetry, and DFT studies.

Catalytically Relevant Organocopper(III) Complexes Formed through Aryl-Radical-Enabled Oxidative Addition

“…The electron density leaning toward the Cu center in the σ­(Cu–CH 2 ) bond could be reflected by the 1 H NMR chemical shifts of the CH 2 groups of these formal Cu III complexes. Methylene protons in M–CH 2 R groups typically show chemical shifts at low frequencies, such as 1.43 ppm for a recently reported tetravalent [Ce IV –CH 2 C­(CH 3 ) 3 ] complex . Contrastingly, in complexes 5 and 5b – 5f , the CH 2 groups resonate at higher frequencies, e.g., 4.08 and 3.45 ppm for 5 and 5d , respectively.…”

Elucidating the Impact of Rare Earth or Transition Metal Identity on the Physical and Electronic Structural Properties of a Series of Redox-Active Tris(amido) Complexes

“…Evans and co-workers have successfully isolated a series of divalent lanthanide complexes and explored their unique electronic properties . Additionally, exploration of high-valent lanthanide complexes (such as Ce 4+ , Pr 4+ , and Tb 4+ ) has been undertaken by the La Pierre, Schelter, and Mazzanti groups, among others. ,,− While the renaissance of nonaqueous lanthanide chemistry continues to expand, the use of harsh reductants and oxidants is normally needed to access these redox states in lanthanide complexes. − …”