Synthetic, kinetic and electrochemical aspects of betadiketonato titanium(IV) complexes
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Date
2007-03
Authors
Tsotetsi, Tsietsi Abram
Journal Title
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Publisher
University of the Free State
Abstract
English: In this study, phenyl-containing β-diketones, phenyl-containing and biphen-containing titanium(IV) complexes were synthesised. Seven of these compounds are new and five are previously reported complexes.
The keto-enol isomerisation kinetics of β-diketone PhCOCH2COCH3 has been studied by 1H NMR spectroscopy in CDCl3.
The temperature study of the isomer distribution biphen-containing titanium(IV) Ti(ba)2biphen complex has been studied by 1H NMR spectroscopy in CDCl3.
Electrochemical studies were conducted in dichloromethane in the presence of [NBu4][B(C6F5)4] non-coordinating supporting electrolyte. Electrochemical studies in dichloromethane utilising cyclic voltammetry of both [Ti(β-diketonato)2Cl2] and [Ti(β-diketonato)2(biphen)] complexes revealed a chemical reversible Ti4+/Ti3+ couple. Electrochemically quasi-reversible behaviour was observed: for [Ti(β-diketonato)2Cl2] and for [Ti(β-diketonato)2(biphen)] with β-diketonato = acac, dbm, tfba and irreversible for Ti(PhCOCHCOCH3)2(biphen).
The substitution reaction of two Cl' ions with 2,2'-biphenyldiolato-2 from the [Ti(acac)2Cl2] is reported. The substitution reaction reveals a small negative value of entropy which suggests a dissociative mechanism.
Afrikaans: In hierdie studie is fenielbevattende β-diketone, asook fenielbevattende en bifeenbevattende titaan(IV) komplekse gesintetiseer. Sewe van hierdie verbindings was tot nog toe totaal onbekend. Die keto-enol isomerisasie kinetika van die β-diketoon PhCOCH2COCH3 is met behulp van 1H KMR spektroskopie in CDCl3 ondersoek bestudeer. Die gedrag van die bifeenbevattende titaan(N) Ti(ba)2bifeen kompleks is met behulp van 1H NMR spektroskopie in CDCl3 bestudeer. Elektrochemiese studies is in dichlorometaan in die tweenwoordigheid van [NBu4][B(C6F5)4] as nie-koordinerende ondersteuningselektroliet uitgevoer. Alle titaanbevattende komplekse vertoon chemiese en elektrochemiese omkeerbaarheid vir die Ti4+/Ti3+ koppels. [Ti(β-diketonato )2Cl2] en vir [Ti(β-diketonato)2(bifeen)] met β-diketonato = acac, dbm, ttba het elektrochemiese kwasiomkeerbaarheid vertoon, en Ti(PhCOCHCOCH3)2(bifeen) elektrochemiese onomkeerbaarheid. Die substitusie reaksie van twee chloride-ione met 2,2'-bifenieldiolato-2 vanaf die [Ti(acac)2Cl2] kompleks is gerapporteer. Die substitusiereaksie vertoon 'n klein negatiewe entropiewaarde wat 'n dissosiatiewe meganisme voorstel.
Afrikaans: In hierdie studie is fenielbevattende β-diketone, asook fenielbevattende en bifeenbevattende titaan(IV) komplekse gesintetiseer. Sewe van hierdie verbindings was tot nog toe totaal onbekend. Die keto-enol isomerisasie kinetika van die β-diketoon PhCOCH2COCH3 is met behulp van 1H KMR spektroskopie in CDCl3 ondersoek bestudeer. Die gedrag van die bifeenbevattende titaan(N) Ti(ba)2bifeen kompleks is met behulp van 1H NMR spektroskopie in CDCl3 bestudeer. Elektrochemiese studies is in dichlorometaan in die tweenwoordigheid van [NBu4][B(C6F5)4] as nie-koordinerende ondersteuningselektroliet uitgevoer. Alle titaanbevattende komplekse vertoon chemiese en elektrochemiese omkeerbaarheid vir die Ti4+/Ti3+ koppels. [Ti(β-diketonato )2Cl2] en vir [Ti(β-diketonato)2(bifeen)] met β-diketonato = acac, dbm, ttba het elektrochemiese kwasiomkeerbaarheid vertoon, en Ti(PhCOCHCOCH3)2(bifeen) elektrochemiese onomkeerbaarheid. Die substitusie reaksie van twee chloride-ione met 2,2'-bifenieldiolato-2 vanaf die [Ti(acac)2Cl2] kompleks is gerapporteer. Die substitusiereaksie vertoon 'n klein negatiewe entropiewaarde wat 'n dissosiatiewe meganisme voorstel.
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Keywords
Titanium, β-diketones, Temperature study, Electrochemistry, Organometallic compounds, Metallocenes, Dissertation (M.Sc. (Chemistry))--University of the Free State, 2007