Synthesis and characterization of tetracarbonylpyrazinetrimethylphosphitetungsten (0) complexes

Download

index.pdf

Date

2004

Author

Alper, Fatma

Metadata

Show full item record

Item Usage Stats

209
views

90
downloads

In this study, the effect of a donor ligand on the stabilization of a carbonyl pyrazine tungsten complex was studied. The pentacarbonylpyrazinetungsten(0) complex could be formed from the photolysis of hexacarbonyltungsten(0) in the presence of pyrazine and could be isolated as crystalline solid. However, the complex was found to be unstable in solution, being converted to a bimetallic complex, (CO)5W(pyz)W(CO)5 and free pyrazine molecule. Two complexes exist in solution at equilibrium. The equilibrium constant could be determined by 1H-NMR spectroscopy and found to be 0.0396 at 25°C. To test whether the introduction of a second pyrazine ligand might provide stability for the carbonyl-pyrazine-tungsten complex, W(CO)4(pyz)2 was attempted to be synthesized. The cis-W(CO)4(pyz)2 complex could be generated from the thermal substitution reaction of cis-W(CO)4(piperidine)2 with excess pyrazine in dichloromethane. However, this complex could not be isolated because of the lack of stability. The complex could only be identified by IR spectroscopy in solution. To stabilize the pentacarbonylpyrazinetungsten(0) complex, trimethylphosphite was introduced to the complex as a donor ligand. For this purpose, cis-W(CO)4[P(OCH3)3](thf), photogenerated from W(CO)5[P(OCH3)3] in tetrahydrofuran (thf), was reacted with pyrazine. The replacement of tetrahydrofuran with pyrazine (pyz) yielded cis-W(CO)4[P(OCH3)3](pyz). The complex could be isolated from the reaction solution and characterized by means of IR, 1H-, 13C-, 31P-NMR, and Mass spectroscopies. The introduction of P(OCH3)3 has proved that a donor ligand will strengthen the metal-pyrazine bond and thus stabilizes the complex. As a result of this stabilization, the complex could be isolated as the first example of tungsten pyrazine complexes that contain a donor ligand.

Subject Keywords

Inorganic Chemistry.

URI

http://etd.lib.metu.edu.tr/upload/12605569/index.pdf
https://hdl.handle.net/11511/14910

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Rhodium(0) nanoparticles supported on hydroxyapatite: preparation, characterization and catalytic use in hydrogen generation from hydrolysis of hydrazine borane and ammonia borane Çelik, Derya; Özkar, Saim; Department of Chemistry (2012) This dissertation presents the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite, and investigation of their catalytic activity in hydrogen generation from the hydrolysis of hydrazine-borane and ammonia-borane. Rh+3 ions were impregnated on hydroxyapatite by ion-exchange; then rhodium(0) nanoparticles supported on hydroxyapatite were formed in-situ during the hydrolysis of hydrazine-borane at room temperature. The rhodium(0) nanoparticles supported on hydroxyapatite we...
Synthesis of beta-chloro-alpha-aminophosphonate derivatives via the regioselective ring opening of unactivated aziridine-2-phosphonates Polat-Cakir, Sidika; BEKSULTANOVA, Nurzhan; Doğan, Özdemir (Informa UK Limited, 2018-12-02) A series of unactivated racemic and chiral aziridine-2-phosphonates were synthesized by modified Gabriel-Cromwell reaction. Ring opening reaction of the synthesized phosphonates by gaseous HCl provided access to a wide range of biologically interesting novel beta-chloro-alpha-aminophosphonates. All reactions toward each of the above-mentioned products can be conducted regioselectively in high yields.
Synthesis of Ti,Cr,Mn,Fe,Co,Ni,Cu,Zn sulfide by solid-gas reactions,investigation of structural and conducting properties Genişel, Mustafa Fatih; Yılmaz, Ayşen; Department of Chemistry (2005) In this study some of the first row transition metal oxides were transformed to metal sulfides by new solid gas reaction system. Transition metal sulfides have wide application area in industry and technology. Several techniques are known for the production of metal sulfides. Such as reactions between metal or metal oxide with H2S, precipitation in several liquid medium, reaction between metal and sulfur in closed vessel, chemical vapor deposition (CVD) technique. These techniques will have some disadvantag...
Synthesis of (3,6-dihydro-2H-pyran-2-yl)phosphonate derivatives and investigation of catalyst effect on frontier molecular orbitals using DFT method Hossain, Md Shakhawoat; POLAT ÇAKIR, SIDIKA; Ozpinar, Gul Altinbas; Nadeem, Said; Demir, Ayhan Sıtkı (Informa UK Limited, 2016-01-01) Hetero Diels-Alder (HDA) reactions between 2,3-dimethyl-1,3-butadiene and diethyl ester of aroyl phosphonates catalyzed by AlCl3 to afford (3,6-dihydro-2H-pyran-2-yl) phosphonate derivatives were investigated. Aroyl phosphonates with electron-withdrawing groups generally resulted in better isolated chemical yields. A stoichiometric amount of AlCl3 rather than a catalytic amount was necessary to activate the cycloaddition reaction. The amount of AlCl3 catalyst and its effect on LUMO of ethyl ester benzoyl ph...
Synthesis of ferrocenyl quinolines Zora, Metin (Elsevier BV, 2008-06-01) A convenient one-pot synthesis of ferrocenyl-substituted quinolines via a molecular iodine-catalyzed reaction of ferrocenylimines with enolizable aldehydes is reported. First, nucleophilic addition of the in situ generated enol to ferrocenylimine produces beta-anilinopropionaldehyde, which then undergoes intramolecular Friedel-Crafts reaction to give dihydroquinoline derivative. Finally, subsequent dehydration and aerobic oxidation affords ferrocenyl quinolines.

Citation Formats

F. Alper, “Synthesis and characterization of tetracarbonylpyrazinetrimethylphosphitetungsten (0) complexes,” M.S. - Master of Science, Middle East Technical University, 2004.