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

Luinstra, Gerrit A.; Teuben, Jan H.; Brintzinger, Hans‐Herbert

doi:10.1016/0022-328x(89)85112-5

Cited by 6 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We hoped to observe the v (Ti–H) band in the 1600 cm −1 region by analogy to the strong band observed at 1605 cm –1 for Cp* 2 Ti(H)Cl. 46 However, rapid gas evolution disrupted the operation of the IR detector of the spectrometer. It is noteworthy that gas evolution was rapid even when the reaction was carried out at –40 °C.…”

Section: Resultsmentioning

confidence: 99%

“…Finally, several attempts were made to observe Cp 2 Ti(H)Cl, generated according to Scheme , using in situ infrared spectrometry. We hoped to observe the ν(Ti–H) band in the 1600 cm –1 region by analogy to the strong band observed at 1605 cm –1 for Cp* 2 Ti(H)Cl . However, rapid gas evolution disrupted the operation of the IR detector of the spectrometer.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl

et al. 2018

View full text Add to dashboard Cite

The role of Cp2Ti(H)Cl in the reactions of Cp2TiCl with trisubstituted epoxides has been investigated in a combined experimental and computational study. Although Cp2Ti(H)Cl has generally been regarded as a robust species, its decomposition to Cp2TiCl and molecular hydrogen was found to be exothermic (ΔG = −11 kcal/mol when the effects of THF solvation are considered). In laboratory studies, Cp2Ti(H)Cl was generated using the reaction of 1,2-epoxy-1-methylcyclohexane with Cp2TiCl as a model. Rapid evolution of hydrogen gas was demonstrated, indicating that Cp2Ti(H)Cl is indeed a thermally unstable molecule, which undergoes intermolecular reductive elimination of hydrogen under the reaction conditions. The stoichiometry of the reaction (Cp2TiCl:epoxide = 1:1) and the quantity of hydrogen produced (1 mole per 2 moles of epoxide) is consistent with this assertion. The diminished yield of allylic alcohol from these reactions under the conditions of protic versus aprotic catalysis can be understood in terms of the predominant titanium(III) present in solution. Under the conditions of protic catalysis, Cp2TiCl complexes with collidine hydrochloride and the titanium(III) center is less available for “cross-disproportionation” with carbon-centered radicals; this leads to by-products from radical capture by hydrogen atom transfer, resulting in a saturated alcohol.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Having characterized the isotopologue 4 - d 1 , we then photolyzed it to (NPN’)(PN)Ti(D) ( 5 - d 1 ) and monitored the reaction by 31 P NMR spectroscopy via its comparison to unlabeled 5 . Despite multiple attempts, however, 2 H NMR spectral data of 5 - d 1 was still ambiguous and did not clearly reveal the characteristic Ti–D (or Ti–H) resonance at lower fields, − akin to those reported for a few examples of titanium hydrides. However, it cannot be ruled out that such a hydride resonance might be broadened due to both 31 P and 14 N coupling.…”

Section: Results and Discussionmentioning

confidence: 87%

Pursuit of an Electron Deficient Titanium Nitride

et al. 2021

View full text Add to dashboard Cite

The nitride salt [(PN) 2 Ti≡N{μ 2 -K(OEt 2 )}] 2 (1) (PN − = (N-(2-P i Pr 2 -4-methylphenyl)-2,4,6-Me 3 C 6 H 2 ) can be oxidized with two equiv of I 2 or four equiv of ClCPh 3 to produce the phosphinimide-halide complexes (NPN'), respectively. In the case of 2, H 2 was found to be one of the other products; whereas, HCPh 3 and Gomberg's dimer were observed upon the formation of 3. Independent studies suggest that the oxidation of 1 could imply the formation of the transient nitridyl species [(PN) 2 Ti(≡N•)] (A), which can either oxidize the proximal phosphine atom to produce the Ti(III) intermediate [(NPN')(PN)Ti] (B) or, alternatively, engage in H atom abstraction to form the parent imido (PN) 2 Ti≡NH (4). The latter was independently prepared and was found to photochemically convert to the titanium-hydride, (NPN')(PN)Ti(H) (5). Isotopic labeling studies using (PN) 2 Ti≡ND (4-d 1 ) as well as reactivity studies of 5 with a hydride abstractor demonstrate the presence of the hydride ligand in 5. An alternative route to putative A was observed via a photochemically promoted incomplete reduction of the azide ligand in (PN) 2 Ti(N 3 ) (6) to 4. This process was accompanied by some formation of 5. Frozen matrix X-band EPR studies of 6, performed under photolytic conditions, were consistent with species B being formed under these reaction conditions, originating from a low barrier N-insertion into the phosphine group in the putative nitridyl species A. Computational studies were also undertaken to discover the mechanism and plausibility of the divergent pathways (via intermediates A and B) in the formation of 2 and 3, and to characterize the bonding and electronic structure of the elusive nitrogen-centered radical in A.

show abstract

Ring‐Opening Reactions of Epoxides With Titanium(III) Reagents

RajanBabu¹,

Nugent²,

Halder³

2022

Organic Reactions

View full text Add to dashboard Cite

The ring‐opening reactions of epoxides with titanium(III) reagents such as Cp 2 TiCl are critically reviewed, including the scope, limitations, and mechanism of these synthetically useful transformations. The initial reaction proceeds by single‐electron transfer to give a carbon‐centered β‐titanoxy radical. The resulting radical can be terminated by a number of different reaction pathways, including epoxide deoxygenation, reduction to the alcohol, intermolecular addition to activated olefins, and intramolecular addition (cyclization). The literature is surveyed from the first reported examples in 1988 through October, 2021.

show abstract

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

Cited by 6 publications

References 9 publications

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl

Pursuit of an Electron Deficient Titanium Nitride

Ring‐Opening Reactions of Epoxides With Titanium(III) Reagents

Contact Info

Product

Resources

About

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

Cited by 6 publications

References 9 publications

Demystifying Cp2Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp2TiCl

Demystifying Cp2Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp2TiCl

Pursuit of an Electron Deficient Titanium Nitride

Ring‐Opening Reactions of Epoxides With Titanium(III) Reagents

Contact Info

Product

Resources

About

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl

Demystifying Cp₂Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp₂TiCl