823790-00-7Relevant articles and documents
Contrasting reactivity of fluoropyridines at palladium and platinum: C-F oxidative addition at palladium, P-C and C-F activation at platinum
Jasim, Naseralla A.,Perutz, Robin N.,Whitwood, Adrian C.,Braun, Thomas,Izundu, Joseph,Neumann, Beate,Rothfeld, Sascha,Stammler, Hans-Georg
, p. 6140 - 6149 (2008/10/09)
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)(PR 3)2]. They do not react with 2,3,5,6-tetrafluorapyridine. The reaction of platinum(0) complexes [Pt(PR3)2] with pentafluoropyridine in THF at ambient temperature yields trans-[Pt(R)4-C 5NF4)(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-C 5NF4)(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 C5NF 5 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)(PEt 3)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-C 5NF4)(PR3)2], and trans-[Pt(R)(4-C5NF4)(PR3)(PFR2)]. Crystal structures are reported for trans-[Pd(F)(4-C5NF 4)-(PCy3)2]-H2O-C6H 6, trans-[Pd(F)(4-C5NF4)(PiPr 3)2], trans-[Pt(C6H11)(4-C 5NF4)(PCy3)(PFCy2)]-CH 2Cl2, and cis-[Pt(H)(4-C5NF4) (PCy3)2].
