Reactions of Dicyclopentadienyltitanium(III) compounds with carbon monoxide

Boer, E.J.M. de; Cate, L.C. ten; Staring, A.G.J.; Teuben, Jan H.

doi:10.1016/s0022-328x(00)85737-x

Cited by 26 publications

(8 citation statements)

References 15 publications

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“…at -1.4 V, which generates tmen(CphTiC12 -and tmen(CphTiCl(THF) in THF solution, does not lead to formation of the dicarbonyl oxidation peak 1'. This is evidence that a CO-induced disproportionation of the solvated monochloride, analogous to that reported to take place with (Cp2TiClh and (C5(CH3)5hTiCl under CO [27,28], does not contribute to the formation of the dicarbonyl complex under the conditions of our study.…”

Section: (Fig 2)supporting

confidence: 87%

ansa-Metallocene derivatives

Schwemlein

Tritschler

Kiesele

et al. 1985

Journal of Organometallic Chemistry

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In the reduction of tetramethylethylene-bridged (CH3)4C2(CsH4hTiCI2 under argon, studied by cyclic voltammetry, a first reduction to the Ti III stage occurs at a potential of-0.92 V vs. SCE, close to that of (CsHshTiCI2, and a second reduction to the Ti II stage at a potential of-2.53 V, about 0.3 V more negative than in the corresponding reduction of the unbridged analogue. Decay of the tetramethylethylene-bridged Ti II product is considerably faster than that of its unbridged analogue. Changes induced by the presence of an N2 or H2 atmosphere indicate the occurrence of secondary reactions. In the presence of CO, reduction to (CH3)4C2(CsH4hTi(COh occurs at-2.0 V. This tetramethylethylene-bridged titanocene dicarbonyl complex, which is also formed by reduction of (CH3)4C2(CsH4hTiCI2 with Mg metal under CO, undergoes irreversible reduction and oxidation at-2.78 and-0.08 V, respectively. When the latter process is conducted in the presence of Cl-, the dichloride (CH3)4C2(CsH4hTiCI2 is regenerated.

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Section: (Fig 2)supporting

confidence: 87%

ansa-Metallocene derivatives

Schwemlein

Tritschler

Kiesele

et al. 1985

Journal of Organometallic Chemistry

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“…When 1 is treated with CO, disproportionation to Cp 2 TiCl 2 (3) and Cp 2 Ti(CO) 2 (2) (eq. 1) occurs [3]; this reaction is fast at room temperature and CO pressures of or above 1 bar. In contrast to the analogous reaction with (Cp 2 TiCl) 2 [2], the disproportionation is irreversible: Removal of the CO atmosphere does not lead to the disappearance of the 1 H NMR signals of 2 and 3 by comproportionation to 1.…”

Section: Characterisation Of Reaction Products and Intermediatesmentioning

confidence: 98%

“…The CO-induced disproportionation of (Cp 2 TiCl) 2 was recently reported [2] to proceed by a reaction between monomeric Cp 2 TiCl and its CO adduct Cp 2 TiClCO; in the rate-determining step the latter appears to transfer its chlorine ligand to the uncomplexed monomer. The object of the present study was to elucidate the mechanism for the CO-induced disproportionation of the closely related complexes Cp 2 TiX (Cp = η 5 -C 5 (CH 3 ) 5 ; X = Cl, Br, I) [3] and to determine in which way differences in electronic and steric properties of the Cp and halogen ligands [4] affect disproportionation and comproportionation reactions in reaction systems of this type.…”

Section: Introductionmentioning

confidence: 99%

IR studies at elevated gas pressures III. Kinetics of the CO induced disproportionation of (C5(CH3)5)2TiX (X = Cl, Br, I)

Luinstra

Teuben

Brintzinger

1989

Journal of Organometallic Chemistry

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The disproportionation of Cp 2 TiClCO (Cp = η 5-C 5 (CH 3) 5) (formed from Cp 2 TiCl and CO in toluene solution) into Cp 2 TiCl 2 and Cp 2 Ti(CO) 2 has been studied at CO pressures of between 2 and 90 bar. The rate of reaction was found to be inversely proportional to the CO concentration. The reaction order with respect to Cp 2 TiClCO changed from 1 to 1.4 with increasing CO pressure. The observations are explained in terms of a kinetic scheme in which Cp 2 TiCl, which is formed from Cp 2 TiClCO in a slow reaction, is an essential intermediate.

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“…As shown in Figure 3 (b) for L = 2-substituted pyridine, the orbitals concerned are perpendicular; for the in-plane overlap, a 90° rotation around the Ti-N bond is required, which is sterically prevented by the cyclopentadienyl groups. [7,26,27]. For nitriles, R'C N reductive dimerization of te ligand to Ti(IV) di-imine compounds follows the adduct formation [6].…”

Section: Chemistry Of Cp2tir (R = Alkyl Allyl Alkenyl Aryl)mentioning

confidence: 99%

“…For these reasons we started to explore Cp*2TiR chemistry a few years ago. Some of the preliminary results on synthesis and carbonylation of Cp*2TiCl have been published [27].…”

Section: Bis(pentamethylcyclopentadienyl)titanium (Iii) Compounds: Cpmentioning

confidence: 99%