Indenyl and fluorenyl transition metal complexes. VIII. Synthesis, structure and properties of metal carbonyl derivatives of azafluorenes, indole, carbazole and the corresponding anions

The interaction of indole, carbazole and aza-analogues of fluorene, 1-azafluorene (I), 2-azafluorene (II), 3-methyl-II (III), 3-azafluorene (IV), 4-azafluorene (V), 7-methyl-V (VI) and [2,3]benzo-V (VII) with Cr(CO)6 (diglyme/heptane, 140° C), and with (NH3)3Cr(CO)3 (boiling dioxan) and of II with [BrM(CO)5] [NEt4] (M Cr, Mo, W) has been studied. In all cases II and IV form only N-donor complexes of the LCr(CO)5 type, and the other heterocycles: arene-chromium tricarbonyl derivatives coordinated to the benzene, and not the heterocyclic, ring. The interaction of I and III with (NH3)3Cr(CO)3 results in the formation of a mixture of both types of complexes, predominantly arene ones. Reactions with (NH3)3Cr(CO)3 give appreciably higher yields than similar processes involving Cr(CO)6. Deprotonation of arenechromium tricarbonyl compounds (THF, t-BuOK) leads to η6-anions which reversibly isomerize in the case of complexes Ill, V and VI into η5-anions. These are new examples of metallotropic tautomerism in which the metal "slips" between the rings along the plane of the aromatic ligand. In the case of η6-anions of complexes of indole, carbazole, I and VII no such isomerization takes place. Alkylation of η6-anions yields 9-exo-alkyl compounds. These are also the only substances that can be isolated from the alkylation of tautomeric mixtures of anions obtained from XI, XIII and XXIV. © 1982.