Indenyl and fluorenyl transition metal complexes. IV. Reactions of 2- and 4-azafluorenes with chromium hexacarbonyl

Reactions of 2- and 4-azafluorenes (I, II) and their methyl derivatives, 3-methyl-2-azafluorene (III) and 7-methyl-4-azafluorene (IV) with chromium hexacarbonyl in a 1 1 diglyme/heptane mixture at 140°C have been studied. A N-donor complex, C12H9NCr(CO)5 is formed in the reaction of I with Cr(CO)6. Compounds II-IV react to give arenechromiumtricarbonyl derivatives with benzene rather than pyridine ring bound to the metal. [η6-(4b,5,6,7,8,9b)-4-Azafluorene]chromiumtricarbonyl (VIII) gives the corresponding hydrochloride under the action of HCl. Methyl iodide decomposes VIII to produce 4-azafluorene iodomethylate. Deprotonation of VIII with BuLi in ether at -20°C followed by dilution with hexane leads to precipitation of the corresponding Li salt (Xb), having η6-structure. Methylation of Xb with methyl iodide proceeds stereospecifically to yield the exo-methyl derivative XII. Treatment of VIII with excess t-BuOK at 25°C in THF results in a mixture of η6-(Xa) and η5-anions (XI), the former predominating. © 1980.