Abstract
We report the synthesis and characterization of the nickelocenium cations [NiCp2]& sdot;+ and [NiCp2]2+ as their [F-{Al(ORF)3}2]- (Cp = C5H5; 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 ...
Abstract
We report the synthesis and characterization of the nickelocenium cations [NiCp2]& sdot;+ and [NiCp2]2+ as their [F-{Al(ORF)3}2]- (Cp = C5H5; 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 (0 -> 1) and +1.17 V (1 -> 2) vs Fc/Fc+. The 1H NMR of [NiCp2]2+ is a singlet at 8.6 ppm, whereas paramagnetic [NiCp2]& sdot;+ is significantly shifted upfield to -103.1 ppm. The synthesis and isolation of the first parent metallocene dication is reported. Nickelocene was twice deelectronated, i.e. single-electron oxidized, by [NO]+ in 1,2,3,4-tetrafluorobenzene. The [NiCp2]+ and [NiCp2]2+ cations were isolated as their [F-{Al(ORF)3}2]- salts and were fully characterized by NMR, CV and XRD analysis.image
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