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Intramolecular coordination systems at platinum and palladium

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Patel, Jim 2000 , 'Intramolecular coordination systems at platinum and palladium', PhD thesis, University of Tasmania.

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Abstract

This thesis describes studies into the synthesis, characterisation and reactivity of
organometallic complexes of the nickel triad elements containing intramolecular coordination
systems based on N-heterocyclic donor groups.
Oxidative addition of the bromoarene 2,6-bis{(3,5-dimethylpyrazol-1
yl)methyl}bromobenzene to [PtMez(SEt)2 ]2 gives the platinum(IV) complex PtBrMe2{2,6
(3,5-Me2pzCH2)2C6H3} in which the NCN ligand coordinates in a facial manner. The reagent
reacts differently with [Pt(p-tolyl)z(SEt)2 ]2 to give the platinum(II) complex PtBr{2,6-(3,5
Me2pzCH2)2C6H3} and 4,4'-bitolyl. The method used to obtain the platinum(II) complex
represents a new synthetic route to the platinum(II) NCN kernel and is shown to be applicable
to other NCN ligand systems. Activation of both C(sp2)-H and C(sp3)-H bonds by palladium(II)
acetate is used to
generate aryl- and alkylpalladium(II) NCN complexes. Arylpalladium complexes are prepared
with pyrazol-1-yl based donor groups and alkylpalladium complexes with pyrazol-1-yl,
pyridin-2-yl and N-methylimidazol-2-yl donor groups. A hexametallic complex bearing six
palladated NCN units at its periphery is obtained on palladation of the ligand hexakis{3,5
bis[(pyrazol-1-yl)methyl]phenyl} benzene.
Oxidative addition of the bromoarene reagents 2,6-bis{ (pyrazol-1
yl)methyl} bromobenzene and 2,6-bis{ (3,5-dimethylpyrazol-1-yl)methyl} bromobenzene to
the nickel(O) reagents affords nickel(II) NCN complexes.
Cationic platinum, palladium and nickel NCN aqua complexes of the type [M(OH2){2,6
(3,5-Me2pzCH2)2C6H3} ][BF4], are found to catalyse the Michael addition of α-cyano
carboxylates to methyl vinyl ketone. The palladium and nickel complexes are found to be
more active catalysts than the platinum complex.
Platinum(IV) and palladium(IV) complexes containing CN intramolecular coordination
systems have been prepared. Ionic complexes of the type [PdR1R2{(pz)2BH2} ]K {(R1, R2)
= (Me, Me), (Me, Ph), (Me, p-tolyl), (CH2CMe3, p-tolyl)} react with 8-(bromomethyl)quinoline
to give the first isolable palladium(IV) complexes containing an intramolecular coordination
system, Pd(CH2C9H6N-C,N)R1Rz{(pz)2BH2}. Structural studies of the complexes
Pd(CH2C9H6N-C,N)Me2{(pz)2BH2} and Pd(CH2C9H6N-C,N)MePh{(pz)2BH2} reveal C-N
intramolecular coordination of the 8-methylquinolinyl groups and include the first structural
analysis of an arylpalladium(IV) complex. The palladium(IV) complexes show high thermal
stability in solution but decompose in refluxing acetone by reductive elimination, with low
selectivity in C-C coupling.
The platinum complex Pt(CH2C9H6N-C,N)Me2{(pz)2BH2} has been prepared and found to
be isostructural with Pd(CH2C9H6N-C,N)Me2{(pz)2BH2}, with the M-N bonds significantly
longer for the palladium complex but the M-C bonds slightly shorter.
Complexes containing bis(pyrazol-1-yl)borate in the absence of an intramolecular
coordination system have also been studied, and include the structural characterisation of
PtMe3 { (pz)2BH2} (py) and the detection of PdMe3 { (pz)2BH2} (PMePh2), the first example of a
neutral palladium(IV) complex containing a phosphorus donor ligand.

Item Type: Thesis - PhD
Authors/Creators:Patel, Jim
Keywords: Organometallic compounds, Organopalladium compounds, Organoplatinum compounds, Coordination compounds
Copyright Holders: The Author
Copyright Information:

Copyright 2000 the author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2001. Includes bibliographical references

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