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

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

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

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