Fulvene–Ruthenium and Cp–Ruthenium Complexes via [2 + 2 + 1] Cyclotrimerization of Phenylacetylene with [RuCl(Tp)(1,5-cod)]

Abstract

The complex [RuCl(Tp)­(1,5-cod)], which bears the labile 1,5-cod ligand, was prepared from a high-yielding route involving the reaction of [RuCl2­(1,5-cod)­(CH3CN)2] with KTp (Tp = HB(pz)3). The reaction of [RuCl(Tp)­(1,5-cod)] with phenylacetylene in either ethanol or methanol gave anti-Markovnikov alkoxide-adduct complexes [Ru(Tp)­(η6-C5H2Ph2-CH(Ph)R)] (R = OMe, OEt). These adducts were formed by [2 + 2 + 1] cyclotrimerization reactions of phenylacetylene mediated by the precursor complex, [RuCl(Tp)­(1,5-cod)]. The ruthenium(II)–fulvene complex, [Ru(Tp)­(η6-C5H2Ph2-CH(Ph))]+, involved in these transformations was successfully isolated in the presence of NH4PF6. These complexes were fully characterized by 1H NMR, 13C NMR, DEPT, HSQC, IR, and ESI-MS spectroscopy. The molecular structures of [Ru(Tp)­(η6-C5H2Ph2-CH(Ph)R)] (R = OMe/OEt) and [Ru(Tp)­(η6-C5H2Ph2-CH(Ph))]PF6 have been determined by X-ray single-crystal diffraction. These complexes have piano-stool structures around the ruthenium center where half of the coordination sites are occupied by the pyrazole ligand while the remaining sites are occupied by either the π-bonded cyclopentadiene (Cp) or fulvene ligand.

Ruthenocene Precursors for Ruthenium-Containing Thin-Film Deposition: An Example of Solvent Nucleophilic Attack on Fulvene

“…Previous reports in the literature described the use of alcohols as reaction solvents, yielding zerovalent ruthenium complexes. ,, However, in our hands the solvents used (alcohols/amines) acted as nucleophiles, attacking the positively charged exocyclic carbon of fulvene (as shown in resonance form II). In the available literature on ruthenium chemistry, a similar nucleophilic attack by alcoholic solvents on the exocyclic carbon atom of fulvene ligands is described leading to products such as [Ru­(Tp)­(η 5 -C 5 H 2 Ph 2 -CH­(Ph)­OMe)] (Tp = tris­(pyrazolyl)­hydridoborato, HB­(pz) 3 ) and [Ru­(Tp)­(η 5 -C 5 H 2 Ph 2 -CH­(Ph)­OEt)] . In addition, various nucleophilic addition reactions to the exocyclic carbon of a fulvene before coordination to metal have been reported, especially including the field of metallocene catalysts .…”

Accessing Monosubstituted Cyclopentadienyl Rhodium(I) and Iridium(I) Complexes by a Simultaneous Nucleophilic Addition-Metalation Approach to Fulvenes

“…Indeed, the substitution proceeded smoothly, affording the corresponding complex in high yield, indicating II is a competent intermediate for the reaction. This is reminiscent of Ugi’s ferrocene-assisted elimination of acetate to form a relatively stable ferrocenyl carbonium ion, , which is subsequently trapped by a nucleophile. We therefore suggest that the substitution of II follows a similar pathway.…”

“…Meijboom reported a TpRu-catalyzed [2+2+1] trimerization of phenylacetylene, leading to a bound fulvene that is then trapped by an alcoholic solvent nucleophile, providing Tp Cp ruthenium complexes. 22 Perekalin reported a Rh(I)-catalyzed [2+2+1] trimerization of tert-butylacetylene, affording a cationic rhodium species coordinated to a fulvene which in turn is reduced to the Cp complex. 5i A general exploitation of the reactivity concept tailored to access libraries of complexes with utility in catalysis remains so far elusive.…”

“…The suggested mechanism involves a coordinated fulvene intermediate which subsequently undergoes a nucleophilic addition or an alkoxy transfer from the rhodium alkoxy ligand to form rhodonocenes. Meijboom reported a TpRu-catalyzed [2+2+1] trimerization of phenylacetylene, leading to a bound fulvene that is then trapped by an alcoholic solvent nucleophile, providing Tp Cp ruthenium complexes . Perekalin reported a Rh­(I)-catalyzed [2+2+1] trimerization of tert- butylacetylene, affording a cationic rhodium species coordinated to a fulvene which in turn is reduced to the Cp complex .…”

First preparation of low band gap fulvene-modified polynorbornene via ring-opening metathesis polymerization

“…The broad Ð obtained is likely a result from either competitive coordination between the fulvene and the double bond of the norbornene moiety or from steric effects imposed by the bulky diphenylfulvene. Since fulvenes are known to coordinate to metals, 26,27 including ruthenium, 28,29 equimolar mixtures of 1,3-diphenyl-6-isopropylfulvene (5) and G3 were analyzed via 1 H-NMR to investigate the possibility of fulvene coordination without interference from additional olefins. The resulting spectra had no discernible differences in the chemical shifts for either the exocyclic proton of the fulvene (6.33 ppm) or the alkylidene proton (19.20 ppm) on the catalyst, indicating an apparent lack of significant coordination effects (Fig.…”