Substitution kinetics of Cr(CO)(5)(eta(2)-Z-cyclooctene) with tetracyanoethylene

Date

2002-09-16

Author

Kozanoglu, F
Saldamli, S
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

211
views

0
downloads

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. The observed rate constant, k(obs), was determined at four different temperatures and five different concentrations of the entering ligand tcne in the range of 0.033-0.33 M. From the evaluation of kinetic data a possible reaction mechanism was proposed in which the rate-determining step is the cleavage of metal-olefin bond in the complex Cr(CO)(5)(eta(2)-zco). A rate law was derived from the proposed reaction mechanism. From the dependence of k(obs) on the entering ligand concentration, the rate constant k(1) for the rate determining step was estimated at all temperatures. The activation enthalpy (DeltaHdegrees = 100 +/- 3kJ(.)mol(-1)) and the activation entropy (DeltaSdegrees = 59 +/- 3 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 chromium-olefin 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/11511/45993

Journal

JOURNAL OF ORGANOMETALLIC CHEMISTRY

DOI

https://doi.org/10.1016/s0022-328x(02)01698-4

Collections

Department of Chemistry, Article

Suggestions

OpenMETU
Core

Substitution kinetics of W(CO)(5)(eta(2)-bis(trimethylsilyl)ethyne) with triphenylbismuthine Bayram, Ercan; Özkar, Saim (Elsevier BV, 2006-07-15) 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. T...
Thermal polymerization of bis(4-fluoro-2,6-dibromophenolato)bis(pyridine)copper(II) complex in solution and in solid state Kisakurek, D; Akbas, M; Bilir, N (Wiley, 1998-02-01) The synthesis of the bis(4-fluoro-2,6-dibromophenolato)bis(pyridine)copper(II) complex was achieved from aqueous solution, and its characterization was performed by means-of IR and CHN elemental analysis. Thermal polymerization of this complex was carried out in toluene and in solid state. The structural analysis of the polymers was performed with H-1 NMR, C-13 NMR and FTIR analysis; the glass transition temperature was found to be at 160 degrees C. 4-Fluoro-2,6-dibromophenolate, with the non-chelating liga...
Insertion of Fischer Carbene Complexes into the Carbon-Carbon Bond of 1,2-Diphenylcyclopropenone: Formation of Cyclobutenones and o- and p-Methoxyphenol Derivatives Zora, Metin (American Chemical Society (ACS), 1994-08-01) Thereactionbetween1,2-diphenylcyclopro-penoneandFischercarbenecomplexeshasbeeninves-tigated.Thereactionproducedamixtureofdipheny-lacetyleneandcyclobutenones.Whena,ß-unsaturatedcarbenecomplexeswereemployed,benzannulationprod-uctsanddiphenylacetylenewereproduced.Amecha-nisminvolvingmetallacyclobutenoneformation,followedbyeithercarbeneinsertionandreductiveeliminationorfragmentationhasbeenproposed.Recently,wereportedthatcarbon—carbonbondin-sertionisthemajorreactionpathwaywhenFischercarbenecomplexesreactwith1,2-...
SYNTHESIS AND STEREOCHEMISTRY OF PENTACARBONYL(PHOSPHOLE)METAL(0) AND TETRACARBONYLBIS(PHOSPHOLE)METAL(0) COMPLEXES OF 6B ELEMENTS OZER, Z; Özkar, Saim (Informa UK Limited, 1992-01-01) Pentacarbonylphospholemetal(0) and cis-tetracarbonylbis(phosphole)metal(0) complexes were synthesized from the thermal reaction of M(CO)5(THF) and M(CO)4(COD) (M: Cr, Mo, W) with corresponding phosphole (1-phenyl-3,4-dimethylphosphole, 1-phenyl-3-methylphosphole, and 1-phenylphosphole). These complexes were isolated as orange crystals by column chromatography on silicagel at 253 K and crystallization from n-hexane at 223 K and characterized by means of IR and NMR (H-1, C-13, and P-31). Spectroscopic data sh...
Stereoconvergent Generation of a Contrasteric syn-Bicyclopropylidene (=syn-Cyclopropylidenecyclopropane) by Stille-Like Coupling GÜNEY, MURAT; Essiz, Selcuk; DAŞTAN, Arif; Balcı, Metin; De Lucchi, Ottorino; ŞAHİN, Ertan; Fabris, Fabrizio (Wiley, 2013-05-01) Stereoisomerically pure endo- and exo-7-halo-7-(trimethylstannyl)benzonorcar-3-enes (=endo- and exo-(1-halo-1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalen-1-yl)trimethylstannane) 4 and 6 were selectively obtained by lithiumtin or magnesiumtin transmetalation in good yields (Scheme2 and 3). The reaction of these compounds with copper(I) thiophene-2-carboxylate (CuTC) produced in both cases the corresponding CS-symmetric bicyclopropylidene (=cyclopropylidenecyclopropane) syn-1, a single diastereoisomer (Sche...

Citation Formats

F. Kozanoglu, S. Saldamli, and S. Özkar, “Substitution kinetics of Cr(CO)(5)(eta(2)-Z-cyclooctene) with tetracyanoethylene,” JOURNAL OF ORGANOMETALLIC CHEMISTRY, pp. 274–280, 2002, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/45993.