Hydrogenation during ligand exchange reactions between ferrocene and pyrene

Abstract

. Can. J. Chem. 57,933 (1979).From ligand exchange reactions between ferrocene and pyrene, carried out in the presence of AIC13-AI, the q6-pyrene-q5-cyclopentadienyliron, q6-4,5-dihydropyrene-$-cyclopentadienyliron, and q6-4,5,9,10-tetrahydropyrene-q5-cyclopentadienyliron monocations (2, 3, and 4, respectively) as well as the q6-pyrene-trans-bis-$-cyclopentadienyliron and q6-4,5,9,10-tetrahydropyrene-trans-bis-~-cyclopentadienyIiron dications (5 and 7, respectively) were isolated and identified. A possible mechanism for the partial hydrogenation of the pyrene ligand is discussed.CHOI CHUCK LEE, KEN J. DEMCHUK et RONALD G. SUTHERLAND. Can. J. Chem. 57,933 (1979).A partir de rkactions d'tchange de ligands entre le ferrocene et le pyritne effectutes en presence de AI-AICI, on a pu identifier et caractkriser les monocations q6-pyrtneq5-cyclopentadiknylfer, q6-dihydro-4,5 pyritne q5-cyclopentadiknylfer et q6-tktrahydro-4,5,9,10 pyritne q5-cyclopentadiknylfer (respectivement 2, 3 et 4) ainsi que les dications q6-pyritne trans-bis-q5-cyclopentadiknylfer et q6-tktrahydro-4,5,9,10 pyritne trans-bis-q5-cyclopentadienylfer (respectivement 5 et 7). On discute d'un mkanisme possible pour I'hydrogtnation partielle du ligand pyritne.[ ' it was stated in a footnote that control experiments with naphthalene-AlC1,-A1-CrCl, in C6H5C1 as solvent gave bis(q6-tetralin)chromium(O) as the main product. On the basis of the observation of a stereospecific hydrogenation when 9,lO-dimethylanthracene was the aromatic ligand, a mechanism for the hydrogenation process has also been proposed recently (4). As an extension of these studies, the present work was undertaken on the ligand exchange reaction between ferrocene and pyrene in order to ascertain the extent of hydrogenation that might occur during ligand exchange with this tetracyclic aromatic system. In ligand exchange reactions between ferrocene and phenanthrene, effected in the presence of AIC1,-Al, hydrogenation could take place at the C-9,10 positions giving rise to q6-phenanthrene-q5-cyclo-, pentadienyliron and q6-9,l0-dihydrophenanthrene-1 q5-cy~lopentadien~liron monocations and q6-phenanthrene-trans-bis-q5-cyclopentadienyliron and q6-9,lO-dihydrophenanthrene-trans-bis-q5-cyclopentadienyliron dications (5). In similar reactions with pyrene (I), if analogous partial hydrogenations occur at C-4,5 and C-9,10, monocations 2, 3, and 4, and dications 5, 6, and 7, might be obtained. In the present work, attempts were made to isolate and characterize these cations. The extent of hydrogenation in ligand exchange reactions between ferrocene (FcH) and polycyclic arenes has been found to be highly dependent on reaction conditions such as the molar ratio of the reactants, the reaction temperature and the nature

Syntheses and Electrochemical Properties of [C5Me5Ru]+ Complexes with Polycyclic Arenes. Crystal Structure of[(C5Me5)Ru( μ6-chrysene)]PF6 · 0.5 Me2CO

“…In no case we observed a hydrogenation o f the arene atom s. H ydrogenation o f naphthalene, a n thracene and pyrene is well know n to occur w hen the [C pFe]+ fragm ent is being coordinated in solu tion in the presence o f A1C13/A1 [16].…”

First 17−18−19-Electron Triads of Stable Isostructural Organometallic Complexes. The 17-Electron Complexes [Fe(C5R5)(arene)]2+ (R = H or Me), a Novel Family of Strong Oxidants: Isolation, Characterization, Electronic Structure, and Redox Properties

“…The [M II Cp(arene)] + salts (M = Fe or Ru) are so robust toward oxidation of the M II center (by common oxidizing agents) that NMR studies of the Fe II complexes have been carried out in concentrated D 2 SO 4 , and it was commonly believed that these complexes could not be oxidized . In a preliminary communication, Solodovnikov et al reported in 1980 the low-temperature generation using SbCl 5 and ESR spectra of unstable oxidized species from [FeCp(arene)] + complexes bearing either an anisole or polyaromatic ligand 19a.…”