Antiferromagnetische zweikernige (η5-Cyclopentadienyl)- und (Pentamethyl-η5-cyclopentadienyl)chrom(III)dihalogenide

doi:10.1016/0022-328X(89)87042-1

Journal of Organometallic Chemistry

Volume 365, Issue 3, 18 April 1989, Pages C15-C18

https://doi.org/10.1016/0022-328X(89)87042-1 Get rights and content

Abstract

The dinuclear chromium(III) half-sandwich molecules [Cp^★CrX₂]₂ (Cp^★ = C₅Me₅; X = Cl (1), Br (2), I (3) and [CpCrX₂]₂ (Cp = C₅H₅; X = Br, I) have been prepared starting from CrCl₃(THF)₃, [Cp^★Cr(CO)₂]₂ or chromocenes. When the latter were treated with HX in THF the intermediates Cp^★₂CrI, [Cp^★₂Cr][Cp^★CrI₃], [Cp₂Cr][CpCrX₃] (X = Br, I), Cp^★CrX₂(THF) (X = Cl, Br, I), and CpCrX₂(THF) (X = Br, I) could be established. The trans-isomer of 1 crystallizes in the space group P $1$ (Z = 2). cis- and trans-isomers were found for 3 in solution. The paramagnetic ¹H NMR data indicate that antiferromagnetic coupling is present in 1–3.

Literatur (9)

J.L. Robbins et al.
J. Am. Chem. Soc.
(1982)
F.H. Köhler et al.
Organometallics
(1987)
F.H. Köhler et al.
Z. Naturforsch. B
(1983)
D.B. Morse et al.
J. Am. Chem. Soc.
(1988)

There are more references available in the full text version of this article.

Cited by (44)

Synthesis and structural characterization of chromium(III) complexes bearing 3,5-dimethylpyrazolate ligand
2015, Polyhedron
Citation Excerpt :
The geometry of this molecule can be described as an edge-sharing bioctahedron with the Cp∗ ligand occupying one trigonal face of an octahedron, which is common to complexes containing the ‘Cp∗CrCl’ moiety [15c,16]. The Cr–OH bond distances are shorter than those found in the analogous chromium(III) complexes: [Cp∗Cr(μ-OMe)I]2 (1.973(3) Å) [9] and [CpCr(μ-OBut)X]2 (X = Cl, Br, and I) [17]. Further, the Cr–Cr distance of 3.022(1) Å is longer than those found in the mentioned preceding complexes.
The reaction of [Cp^∗CrCl₂]₂ with one or two equivalents of the 3,5-dimethylpyrazolate anion (pz^Me2) gave [Cp^∗CrCl(μ-pz^Me2)(μ-Cl)CrClCp^∗] or [Cp^∗CrCl(μ-pz^Me2)]₂ containing bridging 3,5-dimethylpyrazolate anions, respectively. However, with three equivalents of 3,5-dimethylpyrazolate anion, it afforded [Cp^∗Cr(pz^Me2)(μ-OH)]₂ containing two terminally bound 3,5-dimethylpyrazolate anions and two bridging hydroxide anions. With four equivalents of the 3,5-dimethylpyrazolate anion, the mononuclear complex [Cp^∗Cr(pz^Me2)₂(Hpz^Me2)] containing both the 3,5-dimethylpyrazolate and the neutral pyrazole ligands was isolated. Further, the [Cp^∗CrCl₂]₂ dimer is cleaved when treated with Hpz^Me2 to give the mononuclear [Cp^∗CrCl₂(Hpz^Me2)]. All these complexes are characterized by single crystal X-ray diffraction, magnetic moment, and IR methods.
Cyclopentadienyl and related complexes of the group 6 elements having metal-metal triple bonds: Synthesis, structure, bonding and reactivity
2013, Coordination Chemistry Reviews
Citation Excerpt :
There are also a few reports dealing with reactions of triply-bonded cyclopentadienyl complexes and nitrogen oxides and related species. [ Mo2Cp2(CO)4] was reported to react with NO2− or NO3− to give the nitrosyl derivative [MoCp(CO)2(NO)] along with several oxo complexes including [{MoCp(O)2}2O] [166], with the latter species being formed after an N–O bond activation. Remarkably, similar products were obtained from the photochemical reaction of the electron-precise hexacarbonyl [Mo2Cp2(CO)6] with NO2−, but in this case radical species seemed to be involved.
Ion pairs from redox reaction of decamethylchromocene with cyclopentadienyltitanium trichlorides
2012, Inorganic Chemistry Communications
Decamethylchromocene [Cr(η⁵-C₅Me₅)₂] reacted with cyclopentadienyltitanium trichlorides [Ti(η⁵-C₅H_5-nMe_n)Cl₃] (n = 0–5) in toluene to precipitate yellow finely crystalline ion pairs [Cr(η⁵-C₅Me₅)₂]⁺[Ti(η⁵-C₅H_5-nMe_n)Cl₃]⁻ (1–6). Evidence for the chromocenium cation and titanate anions was obtained by paramagnetic ¹H NMR spectra of 1–6 in CD₂Cl₂. The resonance of the cation was invariant at δ 6.9 ppm (Δν_1/2 ~ 0.4 kHz) whereas resonances of the titanate anions were shifting in response to the number of methyl groups (δ 10.5–8.4 ppm (CpMe) and δ 26.6–39.0 ppm (CpH)). The presence of toluene of crystallization in 1–6 was observed by ¹H NMR spectra, and in the crystal structure of 6. Crystallization of 6 from tetrahydrofuran afforded solvent-free crystals of 6A. In crystal structures of both 6 and 6A the [Ti(η⁵-C₅Me₅)Cl₃]^– titanate anion possessed shorter Ti–Cg distances and longer Ti–Cl bonds than the neutral species.
Synthesis, structure and catalytic properties of [Cp*Cr(C <inf>6</inf>F<inf>5</inf>)(Bn)(THF)] toward ethylene in the presence of AlEt<inf>3</inf>
2005, Journal of Organometallic Chemistry
Treatment of [Cp*CrCl(C₆F₅)]₂ with BnMgCl (Bn = benzyl) in Et₂O/THF affords [Cp*Cr(C₆F₅)(Bn)(THF)] (1) which has been isolated in 72% yield. This compound whose magnetic moment is equal to of 4.037 μ_B has been characterized by NMR and single crystal X-ray analysis. Compound 1 alone does not polymerize ethylene when dissolved in toluene. However, addition of excess AlEt₃ to a solution of 1 in toluene leads to a catalytically active system which readily oligomerizes ethylene under standard conditions. Oligomerization experiments carried out with [1] = 10⁻³ M and [AlEt₃] = 9 × 10⁻² M for 15 min lead to the production of ethylene oligomers with an activity of 280 kg mol Cr⁻¹ h⁻¹. The experimental molecular weight distribution observed at intermediate times during the reaction is satisfactorily accounted for by the Poisson distribution formula, which is indicative of a living polymerization system. These observations are in agreement with a catalytic cycle in which the growing alkyl chain is transferred from chromium to aluminum via a bimetallic complex in which the chromium and aluminum centers are bridged by an alkyl group and the growing polymer chain.
Synthetic, X-ray structural and protonation studies of CpCr(CO)<inf>2</inf>SPy and CpCr(CO)<inf>2</inf>SPym (SPy = C<inf>5</inf> H<inf>4</inf>NS, SPym = C<inf>4</inf>H<inf>3</inf>N<inf>2</inf>S)
2004, Journal of Organometallic Chemistry
The facile reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with one mole equivalent of 2,2′-dithiodipyridine ((C₅H₄NS)₂(SPy)₂) at ambient temperature led to the isolation of dark brown crystalline solids of CpCr(CO)₂(η²-SPy) (2) in ca. 72% yield. 2 undergoes quantitative conversion to CpCrCl₂(η¹-SPyH) (3) with HCl. The reaction 1 with one mole equivalent of 2-mercaptopyrimidine (C₄H₃N₂SHHSPym) at ambient temperature led to the isolation of reddish-brown crystalline solids of CpCr(CO)₂(η²-SPym) (4) and green solids of CpCr(CO)₃H (5) in yields of ca. 42% and 46%, respectively. Reaction of 4 with HCl and subsequent workup in acetonitrile resulted in the cleavage of the thiolate ligand, giving the 15-electron chromium(III) species CpCrCl₂(CH₃CN) (6) and free 2-mercaptopyrimidine. The complexes 2–4 have been determined by single X-ray diffraction analysis.
Substituted cyclopentadienylchromium(III) complexes containing neutral donor ligands. Synthesis, crystal structures and reactivity in ethylene polymerization
2004, Journal of Organometallic Chemistry
Lithium derivatives of substituted cyclopentadiene ligands reacted with CrCl₃(THF)₃ in THF solution to afford homodinuclear complexes of the type [{(η⁵-RCp)CrCl(μ-Cl) }₂] [R=SiMe₃ (1), CH₂C(Me)CH₂ (2)]. Complex 1 reacts with pyrazole (C₃H₄N₂) to yield the mononuclear half-sandwich complex [(η⁵-Me₃SiCp)CrCl₂(pyrazole)] (3). The similar complex [Cp*CrCl₂(pyrazole)] (4) was synthesised by reaction of [{Cp*CrCl(μ-Cl)}₂] with pyrazole. Complex 2 reacts with bidentate ligands to give binuclear complexes of the type [{(η⁵-CH₂C(Me)CH₂Cp)CrCl₂ }₂(μ-L-L)] [L-L=Ph₂PCH₂CH₂PPh₂ (5), trans-Ph₂P(O)CHCHP(O)Ph₂ (6)]. All complexes were structurally characterised by X-ray diffraction. After reaction with methylaluminoxane these complexes are active in the polymerization of ethylene. At 25 °C and 4 bar of ethylene, complex 3 yields polyethylene with a bimodal molecular weight distribution centred at 155,000 and 2000 g/mol. Complex 4 shows similar activity, yielding only the low molecular weight fraction. On the other hand, the binuclear complexes 5 and 6 under the same conditions were three times more active than mononuclear complexes. The melting point of the polymers indicates the formation of linear polyethylene.

View all citing articles on Scopus

View full text

Preliminary communicationAntiferromagnetische zweikernige (η5-Cyclopentadienyl)- und (Pentamethyl-η5-cyclopentadienyl)chrom(III)dihalogenide

Abstract

J. Am. Chem. Soc.

Organometallics

Z. Naturforsch. B

J. Am. Chem. Soc.

Preliminary communication
Antiferromagnetische zweikernige (η⁵-Cyclopentadienyl)- und (Pentamethyl-η⁵-cyclopentadienyl)chrom(III)dihalogenide