Organometallic chemistry of fullerenes: η2- and η5-(π)complexes

The reactivity of the fullerenes is primarily a function of their strain, as measured by the pyramidalization angle or curvature of the conjugated carbon atoms. A consideration of the orientation of the π-orbitals shows that η²-complexation reactions lead to reaction products with the fullerenes that are very similar to those obtained from unstrained alkenes. Furthermore, a large amount of strain energy is released in this reaction, so it is clear just why this reaction is important in fullerene chemistry. On the other hand, it is shown that the π-orbitals of C₆₀ are poorly oriented for overlap with an exohedral metal atom centered over the five- or six-membered rings, but well disposed for overlap with an endohedral metal atom centered under the five- or six-membered rings. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 139–143, 1998     

Improved Synthesis of the [Ru(η6‐p‐cymene)Cl3] Anion: Facile Isolation under Mild Conditions

Reaction of [Ru(η⁶‐p‐cymene)Cl₂]₂ with two equivalents of [Ph₄P][Cl] in CH₂Cl₂ yields [Ph₄P][Ru(η⁶‐p‐cymene)Cl₃], containing a trichlororuthenate(II) anion. In solution, an equilibrium between the product and [Ru(η⁶‐p‐cymene)Cl₂]₂ is observed, which in CDCl₃ is nearly completely shifted to the dimer, whereas in CD₂Cl₂ essentially a 1:1‐mixture of the two ruthenium species is present. Crystallization from CH₂Cl₂/pentane yielded two different crystals, which were identified by X‐ray analysis as [Ph₄P][Ru(η⁶‐p‐cymene)Cl₃] and [Ph₄P][Ru(η⁶‐p‐cymene)Cl₃]·CH₂Cl₂.     

Chromium Tricarbonyl η6-Complexes of (η5-Cyclopentadienyl)(η4-1,3-Diphenylcyclobutadiene)Cobalt

The reaction of (η⁵-cyclopentadienyl)(η⁴-1,3-diphenylcyclobutadiene)cobalt ( I ) with excess Cr(CO)₃py₃ in BF₃OEt₂ yielded two identified heterometallic compounds. Compounds II and III with one and two phenyl rings complcxed with Cr(CO)₃ fragment(s), respectively. These compounds were characterized by mass, infrared, ¹H and ¹³C NMR spectra and elemental analysis. The crystal structure of II was determined. The Cr(CO)₃ fragment bends inward toward the cyclobutadicne ring due to its electron-withdrawing ability, in accord with Hunter's postulate. A sharp line due to the non-complexed phenyl ring was observed in the ¹HNMR spectrum, which implies that five protons are magnetically equivalent. The chemical shifts of two protons of the cyclobutadiene ring decreased from I to II then to III , possibly because of diminished deshielding effect from the phenyl ring in (arene)Cr(CO)₃.     

Die photochemische synthese von μ-(1-2-η:2-3-η-allen)-octacarbonyldimangan(0)

Novel dihydroiridium(III) complexes containing mono- and bi-dentate sulfur ligands have been isolated. The cationic complexes [Ir(COD)L₂]ClO₄ (COD = 1,5-cyclooctadiene, L = tetrahydrothiophene (tht) or trimethylene sulfide (tms); L₂ = (CH₃S)₂(CH₂)₃ (dth)), [Ir(COD)(L-L)]₂(ClO₄)₂ (L-L = 1,4-dithiacyclohexane (dt) or (t-BuS)₂(CH₂)₂ (tmdto)) and [Ir(CO)₂(tmdto)]₂-(ClO₄)₂ react with H₂ to give the corresponding iridium(III) dihydrides: [IrH₂COD)L₂]ClO₄ (Ia: L = tht, Ib: L = tms, Ic: L₂ = dth), [IrH₂(COD)-(L-L)]₂(ClO₄)₂ (IIa: L-L = tmdto, IIb: L-L = dt) and [IrH₂(CO)₂(tmdto)]₂-(ClO₄)₂ (III). The ¹H NMR chemical shifts and ν(IrH) data are discussed.