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Metallotropic rearrangements (itramolecular rearrangements involving the displacement of the transition metal atom) in chromium tricarbonyl $\pi$-complexes with polycyclic aromatic ligands were studied by FTIR spectroscopy. A novel $\eta 6\eta 5$ rearrangements have been found and studied for anions $\eta 6$-phenalenyl- (I) and $\eta 6$-(9- hydroanthracenyl) (II) tri***ar-bonychromium generated by deprotonation of corresponding neutral $\eta 6$-complexes with various bases (BuLi, $Ph3P=CH2$, proton sponges or t-BuOM, where $M=K,Cs$) at low temperatures. IR spectra in the $\nu (CO)$ range of the $\eta 6$- and $\eta 6$-anions with various counter-ions $(Li++K+$, and $Cs+$) in THF and dimethoxyethane solutions and in the presence of the solvating additive, dibenzo-18-crown-6, in a temperature region between -70 to $20\circ C$ showed that anionic complexes exist in solution as tight and solvent separated ion pairs or as their equilibrium mixture. The factors that influence the ion-pair equilibrium (solvent, the excess of the base, temperature, the nature of the counter-ion) have been studied. The results are compared with the NMR data. The work was supported by the Russian Foundation for Basic Research (grants 96-03-3241a and 96-03-34082a).