Ojwach S.O., Tshivhase M.G., Guzei I.A., Darkwa J., Mapolie S.F.
Furoyl and thiophene carbonyl linker pyrazolyl palladium(II) complexes - Synthesis, characterization, and evaluation as ethylene oligomerization catalysts
Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa; Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States
Ojwach, S.O., Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa; Tshivhase, M.G., Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa; Guzei, I.A., Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, United States; Darkwa, J., Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa; Mapolie, S.F., Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
Reactions of 2-furoyl chloride and 2-thiophene carbonyl chloride with substituted pyrazoles produced the modified pyrazolyl compounds: {(3,5-Me 2pzCO)-2-C4H3O} (L1), {(3,5-Me 2pzCO)-2-C4H3S} (L2), {(3,5-t-Bu 2pzCO)-2-C4H3O} (L3), {(3,5-t-Bu 2pzCO)-2-C4H3S} (L4), {(3,5-Ph 2pzCO)-2-C4H3S} (L5), and {(pzCO)-2-C 4H3O} (L6) in good yields. Reactions of these synthons with [Pd(NCMe)2Cl2] afforded the corresponding mononuclear palladium(II) complexes: [Pd(L1)2Cl2] (1), [Pd(L2) 2Cl2] (2), [Pd(L3)2Cl2] (3), [Pd(L4)2Cl2] (4), [Pd(L5)2Cl2] (5), and [Pd(L6)2Cl2] (6) in moderate to high yields. All compounds synthesized were characterized by a combination of 1H NMR, 13C NMR, and IR spectroscopy. Compounds L1, 1, and 2 were examined by single crystal X-ray crystallography. DFT theoretical studies at the B3LYP/6-31+G(d) level of theory with GAUSSIAN98 have been used to rationalize some of the results. When the complexes were activated with ethylaluminium dichloride (EtAlCl2), they catalysed the oligomerization of ethylene to mostly C10 and C12 oligomers. Oligomer distribution greatly depends on the oligomerization conditions; for example, an increase in temperature and pressure produced a higher percentage of C12 compared to C10. © 2005 NRC Canada.
Ethylene; Infrared spectroscopy; Nuclear magnetic resonance; Oligomers; Polymerization; Single crystals; X ray crystallography; Ethylene oligomerization; Furoyl and thiopene carbonyl linker pyrazolal compounds; Oligomerization; Pyrazoles; Thiopene; Palladium compounds; 2 furoyl chloride; 2 thiophene carbonyl chloride; aluminum derivative; carbon; carbonyl derivative; ethylaluminum dichloride; ethylene; furan derivative; furoyl derivative; palladium complex; pyrazole derivative; thiophene derivative; unclassified drug; article; carbon nuclear magnetic resonance; catalyst; chemical modification; chemical reaction; complex formation; density functional theory; evaluation; infrared spectroscopy; molecular size; oligomerization; pressure; proton nuclear magnetic resonance; synthesis; temperature; X ray crystallography