RESUMO
We report the synthesis and characterization of the nickelocenium cations [NiCp2 ]â + and [NiCp2 ]2+ as their [F-{Al(ORF )3 }2 ]- (Cp = C5 H5 ; RF =C(CF3 )3 ) salts. Diamagnetic [NiCp2 ]2+ represents the first example for the isolation of an unsubstituted parent metallocene dication. Both salts were generated by reacting neutral NiCp2 with [NO]+ [F-{Al(ORF )3 }2 ]- in 1,2,3,4-tetrafluorobenzene (4FB). The salts were characterized by single crystal X-ray diffraction (XRD), indicating shorter metal-ligand bond lengths for the higher charged salt. Powder XRD shows the salts to be phase pure, cyclic voltammetry in 4FB gave quasi reversible redox waves at -0.44 (0â1) and +1.17â V (1â2) vs Fc/Fc+ . The 1 Hâ NMR of [NiCp2 ]2+ is a singlet at 8.6â ppm, whereas paramagnetic [NiCp2 ]â + is significantly shifted upfield to -103.1â ppm.