Substituent Effects on Reductive Elimination from Disubstituted Aryl Hydride Complexes: Mechanistic and Thermodynamic Considerations

1995 ◽  
Vol 14 (12) ◽  
pp. 5677-5685 ◽  
Author(s):  
Anthony D. Selmeczy ◽  
William D. Jones ◽  
Robert Osman ◽  
Robin Perutz
Keyword(s):  
Substituent Effects ◽  
Reductive Elimination ◽  
Hydride Complexes

Hydrido(acylphenolato)cobaIt(III)-Verbindungen mit Trimethylphosphan-Liganden / Hydrido(acylphenolato)cobalt(III) Compounds Containing Trimethylphosphane Ligands

1998 ◽  
Vol 53 (5-6) ◽  
pp. 587-598 ◽  
Author(s):  
Hans-Friedrich Klein ◽  
Stefan Haller ◽  
Hongjian Sun ◽  
Xiaoyan Li ◽  
Thomas Jung ◽  
...  
Keyword(s):  
Chelate Ring ◽  
Molecular Complexes ◽  
Reductive Elimination ◽  
Hydride Complexes ◽  
Salicylaldehyde Derivatives ◽  
Chelate Ligands ◽  
Oxidative Substitution

Abstract Salicylaldehyde derivatives and related β-hydroxo aldehydes CHO-CR=CR′-OH react with CoMe(PMe3)4 via oxidative substitution to form low-spin d6 complexes mer-CoH(CO-CR=CR-O)(PMe3)3. Reductive elimination of acyl and hydride functions from cis positions at the metal is less favourable than in carbonyl cobalt intermediates through a pronounced stabilization by neutral phosphane σ-donor and dianionic acylenolato chelate ligands. Reactions of the hydride complexes with iodomethane or with protic acids HX afford octahedral molecular complexes mer-CoX(CO-CR=CR′-O)(PMe3)3 (X =I, OAc) and mer-CoX(CO-CR=CR′-O)(PMe3)2 (X = OAc, O-CR′=CR-CHO) without opening of the acylenolato chelate ring.

The importance of cyclopentadienyl substituent effects in group 4 metallocene dinitrogen chemistry

2005 ◽  
Vol 83 (4) ◽  
pp. 286-295 ◽  
Author(s):  
Jaime A Pool ◽  
Paul J Chirik
Keyword(s):  
Alkali Metal ◽  
Substituent Effects ◽  
Reductive Elimination ◽  
Sandwich Complex ◽  
Group 4 ◽  
Dinitrogen Complexes ◽  
The Future ◽  
Elimination Reactions

This article highlights some of our recent efforts and presents new data on the importance of cyclopentadienyl substituent effects on group 4 metallocene dinitrogen chemistry. Reactions such as the coordination of N2 to an isolated titanium sandwich complex, alkali-metal reductions of zirconocene dihalide complexes, alkane reductive elimination reactions, and the hydrogenation of zirconium dinitrogen complexes are all extremely sensitive to the groups present on the cyclopentadienyl rings. These results are promising for the future of N2 fixation, as the reactivity of a specific metallocene can be dramatically altered by subtle manipulations in ligand substituents.Key words: cyclopentadienyl, zirconium, dinitrogen, ammonia, sandwich.

Substituent effects and solvents

1992 ◽  
Vol 89 ◽  
pp. 1567-1571
Author(s):  
O Pytela ◽  
M Ludwig
Keyword(s):  
Substituent Effects

Reversible Oxidative-Addition and Reductive-Elimination of Thiophene from a Titanium Complex and Its Thermally-Induced Hydrodesulfurization Chemistry

2019 ◽  
Author(s):  
Alejandra Gomez-Torres ◽  
J. Rolando Aguilar-Calderón ◽  
Carlos Saucedo ◽  
Aldo Jordan ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Thiophene Ring ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Thermally Induced ◽  
Titanium Complex

<p>The masked Ti(II) synthon (<sup>Ket</sup>guan)(<i>η</i><sup>6</sup>-Im<sup>Dipp</sup>N)Ti (<b>1</b>) oxidatively adds across thiophene to give ring-opened (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti[<i>κ</i><sup>2</sup>-<i>S</i>(CH)<sub>3</sub><i>C</i>H] (<b>2</b>). Complex <b>2</b> is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate <b>1</b> – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from <b>2</b>. Finally, pressurizing solutions of <b>2 </b>with H<sub>2</sub> (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti(S) (<b>3</b>) and butane. </p>

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