Substituted nick el pyrazole and palladiumpyruzolyl complexes as catalyst precursors for ethylene polymeization
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Date
2003
Authors
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Journal ISSN
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Publisher
University of the Western Cape
Abstract
This study concerns the synthesis of pyrazole and substituted pyrazole nickel
complexes of the type [(3,5-R,R',pz)2NiB rz ( Pz : pyrazole; R = R' = cHr (1), tBu
(a)l and of the type [(3,5-R,R'pz)aNiBrz R: H, R' : CHr (2)] R: R' :H (3)l' These
complexes were synthesized by reacting (DME)NiBrz and the appropriate pyrazole
or substituted pyrazole in dichloromethane. The products were obtained in moderate
to good yields. All the complexes isolated were charac teizedby a combination of IR
spectroscopy, tH NNm. spectroscopy and elemental analysis' Complexes I and 2
were further characteri zedby single crystal X-ray crystallography. Complex 1 was
found to have a tetrahedral geometry and complex 2 has an octahedral geometry' In
addition to the pyrazole nickel complexes, new pyr.volyl ligands with alkane-o'oldione linkers tRpzC(OXCHz),C(O)pzR); R: CHr' n: 0 (A1)' n:2 (A2)'n:3 (A3)
and R: tBu, n = 3 (A4)] were synthesized. These new ligands were charactenzed by
IR spectroscopy, ,H NNfi, "C NNffi. spectoscopy and elemental analysis' They
were further reacted with (cHrCN)2PdCl2 in attempts to obtain a'obis(3'5-
Rzpyrazolyl)alkane-cr,rodione palladium chloride complexes' These ligands tend to
undergo hydrolysis when they are reacted wittr (CHTCN)zPdClz as confirmed by tH
NMR spectral analysis. one complex, 1,5.bis(3,5.Mezpz)pentane-1,5-dione
palladium chloride was successfully prepared under very dry solvent conditions' The
1,5-bis(3,5-Mezpz)pentane-1,Sdione palladium chloride complex was characteized
by 'HNMR spectroscoPY.
Description
>Magister Scientiae - MSc
Keywords
Nickel pyrazole, Palladiumpyruzolyl, Catalyst precursor, Ethylene polymeization