Substitution kinetics of W(CO)(5)(eta(2)-bis(trimethylsilyl)ethyne) with triphenylbismuthine

Date

2006-07-15

Author

Bayram, Ercan
Özkar, Saim

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

115
views

0
downloads

The labile complex W(CO)(5)(eta(2)-btmse) undergoes replacement of bis(trimethylsilyl)ethyne, btmse, by triphenylbismuthine in cyclohexane solution at an observable rate in the temperature range of 35-50 degrees C yielding almost solely W(CO)(5)(BiPh3) as the final product. The kinetics of this substitution reaction was studied in cyclohexane solution by quantitative FT-IR spectroscopy. The substitution reaction obeys a pseudo-first-order kinetics with respect to the concentration of the starting complex. The observed rate constant, k(obs), was determined at four different temperatures and three different concentrations of the entering ligand BiPh3 in the range 16.8-65.4 mM. From the evaluation of kinetic data a possible reaction mechanism was proposed in which the rate determining step is the cleavage of metal-alkyne bond in the complex W(CO)(5)(eta(2)-btmse). A rate law was derived from the proposed mechanism. From the dependence of kobs on the entering ligand concentration, the rate constant k(1) for the rate determining step was estimated at all temperatures. The activation enthalpy (106 +/- 2 kJ mol(-1)) and the activation entropy (111 +/- 6 J K-1 mol(-1)) were determined for this rate determining step from the evaluation of k(1) values at different temperatures. The large positive value of the activation entropy is consistent with the dissociative nature of reaction. The large value of the activation enthalpy, close to the calculated tungsten-alkyne bond dissociation energy, also supports this dissociative rate-determining step of the substitution reaction.

Subject Keywords

Physical and Theoretical Chemistry, Inorganic Chemistry, Organic Chemistry, Materials Chemistry, Biochemistry

URI

https://hdl.handle.net/11511/39498

Journal

JOURNAL OF ORGANOMETALLIC CHEMISTRY

DOI

https://doi.org/10.1016/j.jorganchem.2006.03.036

Collections

Department of Chemistry, Article

Suggestions

OpenMETU
Core

Carboligation reactions with benzaldehyde lyase immobilized on superparamagnetic solid support Sopaci, S. Betuel; Turan, Ilke Simsek; Tural, Bilsen; Volkan, Mürvet; Demir, Ayhan Sıtkı (Royal Society of Chemistry (RSC), 2009-01-01) Histidine-tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) was efficiently immobilized to surface-modified magnetic particles with affinity ligand binding. In addition to conventional benzoin condensation reactions, two important representative BAL-catalyzed carboligation reactions, were also performed with this magnetically responsive biocatalyst. The results obtained from the carboligation reactions that were performed with this simple and convenient heterogenous biocatalyst were comparable to tha...
PHOTOCHEMICAL-REACTIONS OF TRANSITION METAL-OLEFIN COMPLEXES .11. [4+6]-CYCLOADDITION OF TRICYCLO[6.3.0.0(2.7)]UNDECA-3,5-DIENE IN TRICARBONYL-ETA-6-1,3,5-CYCLOHEPTATRIENE-CHROMIUM(0) Özkar, Saim (Elsevier BV, 1985-01-01) The photochemical reaction of tricarbonyl-η6-1,3,5-cycloheptatriene-chromium(0) (I) with tricyclo[6.3.0.02,7]undeca-3,5-diene (II) in n-pentane at 248 K yields the [4 + 6]-cycloadduct tricarbonyl-η6-pentacyclo[7.6.2.110,15.02,8.03,7]octadeca-11,13,16-triene-chromium(0) (III). Detachment of the pentacyclic triene ligand from chromium can be achieved with trimethylphosphite. The constitutions of complex III and of the pentacyclic hydrocarbon IV were determined by spectroscopic means.
Mesoporous MnCo2O4 with efficient peroxidase mimetic activity for detection of H2O2 Vetr, Fahime; Moradi-Shoeili, Zeinab; Özkar, Saim (Elsevier BV, 2018-12-01) Mesoporous MnCo2O4 with hierarchical structures were synthesized from a dual-metal zeolitic-imidazolate framework (ZIF) as precursor. The corresponding heterometallic ZIF was synthesized by mixing manganese(II) and cobalt(II) ions in the presence of 2-methylimidazole as linker. Calcination of the intermediate ZIF in air affords the nanosized mesoporous manganese cobaltite with spinel crystal structure. The obtained nanomaterials were characterized by a combination of physico-chemical and spectroscopic techn...
Substitution kinetics of Cr(CO)(5)(eta(2)-Z-cyclooctene) with tetracyanoethylene Kozanoglu, F; Saldamli, S; Özkar, Saim (Elsevier BV, 2002-09-16) The weakly bound Z-cyclooctene (zco) ligand in Cr(CO)(5)(eta(2)-zco) is replaced by tetracyanoethylene (tcne) at an observable rate in the temperature range between - 5 and + 10 degreesC yielding the complex Cr(CO)(5)(eta(2)-tcne) as the final product The kinetics of this substitution reaction was studied in toluene solution containing 5% by volume zco by quantitative FTIR spectroscopy The substitution reaction obeys a pseudo-first order kinetics with respect to the concentration of the starting complex. Th...
Benzaldehyde lyase catalyzed enantioselective self and cross condensation reactions of acetaldehyde derivatives Ayhan, Peruze; Turan, Ilke Simsek; Cifci, Burce; Demir, Ayhan Sıtkı (Royal Society of Chemistry (RSC), 2011-01-01) Flexible protected 1,3,4-trihydroxy-2-butanone is synthesized in high enantiomeric excesses by using asymmetric homo- and cross- acyloin coupling of aliphatic aldehydes catalyzed by benzaldehyde lyase.

Citation Formats

E. Bayram and S. Özkar, “Substitution kinetics of W(CO)(5)(eta(2)-bis(trimethylsilyl)ethyne) with triphenylbismuthine,” JOURNAL OF ORGANOMETALLIC CHEMISTRY, pp. 3267–3273, 2006, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/39498.