144717-67-9Relevant academic research and scientific papers
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].
Hydrogen bonding in transition metal complexes: Synthesis, dynamics, and reactivity of platinum hydride bifluoride complexes
Jasim, Naseralla A.,Perutz, Robin N.
, p. 8685 - 8693 (2007/10/03)
Platinum hydride bifluoride (FHF) complexes trans-[Pt(PR3)2H(FHF)] (R = Cy, iPr) were prepared from the reaction of the corresponding trans-dihydride complexes with NEt3?3(HF) in THF. They were also formed in C-F activation reactions of the same precursors with C6F6 in the presence of [Me4N]F. The low-temperature NMR spectra exhibit a complete network of coupling between the spin 1/2 nuclei, 1H, 31P, 19F, and 195Pt. At higher temperatures, fluxional behavior is observed which is principally associated with intermolecular exchange of HF between platinum centers. However, satisfactory simulation of the spectra also requires inclusion of intermolecular exchange of the distal fluoride. Addition of [Bu4N]FHF results in coalescence of the bifluoride proton resonance of the complex and the added bifluoride, demonstrating that the bifluoride ligand can exchange with free bifluoride, FHF-. The IR spectrum of trans-[Pt(PCy3)2H(FHF)] shows two broad bands at 2604 and 1832 cm-1 assigned to the H-F stretching modes and a sharp band at 2272 cm-1 for the Pt-H stretching mode. Bifluoride is a weakly coordinated ligand which can be replaced to give trans-[Pt(PCy3)2(H)X] complexes where X = N3, OTf. Hydrogen fluoride may be removed from trans-[Pt(PCy3)2H-(FHF)] by treatment with CsOH in the presence of [NMe4]F, yielding trans-[Pt(PCy3)2(H)F]. In addition, these bifluoride complexes fluorinate organic compounds, such as CH3I, CH3COCl, and C6H5COCl, to give CH3F, CH3COF, and C6H5COF together with trans-[Pt(PCy3)2(H)X] (X = Cl, I). Reactions with PPh3 and pyridine yield trans-[Pt(PCy3)2(PPh3)H]FHF and trans-[Pt(PCy3)2(C5H5N)H]FHF.
Electron transfer reactions involving trans- and fluorinated benzonitriles
Hintermann, Samuel,Pregosin, Paul S.,Rueegger, Heinz,Clark, Howard C.
, p. 225 - 234 (2007/10/02)
The complex trans- reacts with activated benzonitriles such as 4-R-C6F4CN (R=F, H, CN, OCH3) bearing electron-withdrawing substituents to give the new platinum(II) aryl complexes trans-(PCy3)2>, which have been isolated and fully characterized, and a hydridofluoride trans-, where F is either F or HF2, which has been detected in solution.These complexes and related by-products from the reaction have been characterized by one- and two-dimensional multinuclear NMR spectroscopy.A reaction mechanism involving rate-determining electron transfer from the dihydride complex to the organic substrate is postulated on the basis of (i) the relative reaction rates for the nitriles (p-C6F4(CN)2 > C6F5CN > p-C6HF4CN > p-C6F4(OCH3)CN > o,o-C6H3F2CN), which parallel their electron affinities, and (ii) the observation of a radical by ESR spectroscopy after spin-trapping with PBN.
