Sv. Kukharenko et al., ELECTRON-TRANSFER-INDUCED CHANGE OF DIRECTION OF INTERANNULAR HAPTOTROPIC ISOMERIZATION OF FLUORENYLTRICARBONYLCHROMIUM ANIONS, Russian chemical bulletin, 43(1), 1994, pp. 41-46
It has been shown by cyclic voltammetry in a THF medium in the tempera
ture range from -70 degrees C to +20 degrees C that one-electron elect
rochemical reduction of (eta(6)-C13H10)Cr(CO)(3) (1) to the correspond
ing 19-electron anion radical (1(-)) is accompanied by splitting off o
f a H atom to form the 18-electron carbon-centered anion (eta(6)-C13H9
)Cr(CO)(3)(-) ((-)2), which at room temperature undergoes intramolecul
ar haptotropic isomerization to the metal-centered (eta(5)-C13H9)Cr(CO
)(3)(-) ((-)3) anion. The reversible one-electron reduction of 3(-) to
the corresponding 19-electron radical dianion 3(2.-) induces eta(5)--
>eta(6) interannular isomerization. In contrast to the equilibrium shi
ft to the eta(5)-isomer in 18-electron complexes 2 and 3, in their 19-
electron analogs the equilibrium is shifted to the eta(6)-isomer.