Isolation and Characterization of the Homoleptic Nickel(I) and Nickel(II) Bis-benzene Sandwich Cations

Angew Chem Int Ed Engl. 2022 Dec 12;61(50):e202211555. doi: 10.1002/anie.202211555. Epub 2022 Nov 16.

Abstract

A stable salt of the metalloradical [Ni(C6 H6 )2 ]+ hitherto unknown in the condensed phase was synthesized from [Ni(CO)4 ]+ [WCA]- and benzene ([WCA]- =[F{Al(ORF )3 }2 ]- ; RF =C(CF3 )3 ). Single crystal XRD reveals a remarkable asymmetrically η3 ,η6 -slipped sandwich structure. The magnetic properties of the [Ni(C6 H6 )2 ]+ cation were determined in solution and in the gas phase. Oxidation with the synergistic Ag+ /0.5 l2 system led to the salt [Ni(C6 H6 )2 ]2+ ([WCA]- )2 . All products were fully characterized by means of IR, Raman, NMR/EPR, single crystal and powder XRD.

Keywords: Arene Ligands; Nickel; Sandwich Complexes; Transition Metals; Weakly Coordinating Anion (WCA).