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Contrasting reactivity of fluoropyridines at palladium and platinum: C-F oxidative addition at palladium, P-C and C-F activation at platinum

Jasim, N.A., Perutz, R.N., Whitwood, A.C., Braun, T., Izundu, J., Neumann, B., Rothfeld, S. and Stammler, H-G. (2004) Contrasting reactivity of fluoropyridines at palladium and platinum: C-F oxidative addition at palladium, P-C and C-F activation at platinum. Organometallics, 23 (26). pp. 6140-6149. ISSN 0276-7333

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Abstract

The divergent behavior of palladium(0) and platinum(0) is revealed in the reactivity of [M(PR3)2] (M = Pd or Pt; R = Cy or iPr) toward pentafluoropyridine and 2,3,5,6-tetrafluoropyridine. The palladium complexes react with pentafluoropyridine at 100 °C to yield the fluoride complexes trans-[Pd(F)(4-C5NF4)(PR3)2]. They do not react with 2,3,5,6-tetrafluoropyridine. The reaction of platinum(0) complexes [Pt(PR3)2] with pentafluoropyridine in THF at ambient temperature yields trans-[Pt(R)(4-C5NF4)(PR3)(PFR2)] complexes, whereas the reaction of [Pt(PCy3)2] with 2,3,5,6-tetrafluoropyridine results in C−H activation to form cis-[Pt(H)(4-C5NF4)(PCy3)2]; this complex may be converted to the trans isomer by photolysis. The cis-hydride also forms during the reaction of [Pt(PCy3)2] with C5NF5 in hexane. These reactions also contrast with earlier studies of the reactivity of the same substrates toward {Ni(PEt3)2}, which yield [Ni(F)(2-C5NF5)(PEt3)2] with pentafluoropyridine and [Ni(F)(2-C5NF4H)(PEt3)2] with tetrafluoropyridine. Thus palladium has different regioselectivity from nickel and is the least reactive. Platinum is capable of both C−F and C−H activation and is alone in the triad in undergoing rearrangement to the alkyl complex with the fluorophosphine ligand. Mechanisms for the rearrangement are proposed. The platinum dihydride complex trans-[Pt(H)2(PR3)2] reacts with pentafluoropyridine at room temperature, yielding a 1:1:1 mixture of trans-[PtH(FHF)(PR3)2], trans-[Pt(H)(4-C5NF4)(PR3)2], and trans-[Pt(R)(4-C5NF4)(PR3)(PFR2)]. Crystal structures are reported for trans-[Pd(F)(4-C5NF4)(PCy3)2]·H2O·C6H6, trans-[Pd(F)(4-C5NF4)(PiPr3)2], trans-[Pt(C6H11)(4-C5NF4)(PCy3)(PFCy2)]· CH2Cl2, and cis-[Pt(H)(4-C5NF4)(PCy3)2].

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Chemistry (York)
Depositing User: York RAE Import
Date Deposited: 12 Mar 2009 15:45
Last Modified: 12 Mar 2009 15:45
Published Version: http://dx.doi.org/10.1021/om049448p
Status: Published
Publisher: ACS American Chemical Society
Identification Number: 10.1021/om049448p
URI: http://eprints.whiterose.ac.uk/id/eprint/7114

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