| Popis: |
Stable carbonium ion salts of the type [(HCCC + R 1 R 2 )Co 2 (CO) 6 ]Z − (R 1 = R 2 = CH 3 , Z = SbF 6 ; R 1 = R 2 = C 6 H 5 , Z = SbF 6 ; R 1 = CH 3 , R 2 = H, Z = BF 4 ; R 1 = R 2 = H, Z = BF 4 ) were isolated upon treatment of the corresponding alcohol complexes with HF·SbF 5 or HBF 4 ·Et 2 O at −45°C. Extensive charge delocalization onto the Co 2 (CO) 6 moiety of the cations was evidenced in the IR by an increase in v (CO) and in the proton NMR spectra which exhibited very small downfield shifts relative to the alcohol precursors (Δδ). The p K R + values for the cations were essentially the same regardless of other substituents at the carbonium ion center and were approximately equal to that of the triphenylmethyl cation. |
