41016-40-4Relevant academic research and scientific papers
In Situ Generation of ArCu from CuF2 Makes Coupling of Bulky Aryl Silanes Feasible and Highly Efficient
Delpozo, Juan,Casares, Juan A.,Espinet, Pablo
supporting information, p. 4274 - 4284 (2016/03/16)
A bimetallic system of Pd/CuF2, catalytic in Pd and stoichiometric in Cu, is very efficient and selective for the coupling of fairly hindered aryl silanes with aryl, anisyl, phenylaldehyde, p-cyanophenyl, p-nitrophenyl, or pyridyl iodides of conventional size. The reaction involves the activation of the silane by CuII, followed by disproportionation and transmetalation from the CuI(aryl) to PdII, upon which coupling takes place. CuIII formed during disproportionation is reduced to CuI(aryl) by excess aryl silane, so that the CuF2 system is fully converted into CuI(aryl) and used in the coupling. Moreover, no extra source of fluoride is needed. Interesting size selectivity towards coupling is found in competitive reactions of hindered aryl silanes. Easily accessible [PdCl2(IDM)(AsPh3)] (IDM = 1,3-dimethylimidazol-2-ylidene) is by far the best catalyst, and the isolated products are essentially free from As or Pd (2: In the Cu-promoted Hiyama process, CuF2 plays the role of two reagents to provide full conversion into the fluoride and copper is also required to transform bulky trialkoxysilanes in situ into CuAr. CuAr immediately transmetalates to Pd, which makes the otherwise inaccessible Pd-catalyzed coupling of bulky arylsilanes feasible and highly efficient.
η5-Cyclopentadienylpalladium(II) complexes: Synthesis, characterization and use for the vinyl addition polymerization of norbornene and the copolymerization with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene
Blank, Frederik,Vieth, Jana K.,Ruiz, José,Rodríguez, Venancio,Janiak, Christoph
, p. 473 - 487 (2011/02/28)
Dinuclear complexes of palladium(II), containing two bridging halogen (Cl or Br) ligands, [NnBu4]2[(X5C 6)2Pd(μ-Cl)2Pd(C6X 5)2] and [(X5C6)(L)Pd(μ-Y) 2Pd(C6X5)(L)] (X = F, Cl; Y = Cl, Br), readily react with cyclopentadienylthallium, C5H5Tl, to give the corresponding air stable half-sandwich, pseudo-trigonal η5- cyclopentadienylpalladium complexes, [NnBu4] [(η5-C5H5)Pd(C6X 5)2] (X = F 1, Cl 2) and (η5-C 5H5)Pd(C6X5)(L) (X = F, L = CNBut 3, PPh3 4, PMe2Ph 5, PEt3 6, AsPh3 7, SbPh3 8; X = Cl, L = PMe2Ph 9, PEt3 10), respectively. With tetraphenylcyclopentadienylthallium, C5Ph4HTl or pentabenzylcyclopentadienylthallium, C 5Bn5Tl (Bn = CH2Ph) the air stable half-sandwich complexes (η5-C5Ph4H) Pd(C6F5)(AsPh3), 12 and (η5- C5Bn5)Pd(C6F5)(AsPh3), 13 are synthesized accordingly. The molecular structures were verified by NMR-spectroscopy, X-ray crystallography (7, 12, 13) and electron impact-mass spectrometry (EI-MS). The precatalysts 4 and 7 can be activated with methylalumoxane (MAO) for the homopolymerization of norbornene (NB) and 5-ethylidene-2-norbornene (ENB) and for the copolymerization of NB with 5-vinyl-2-norbornene (VNB) or ENB with activities of more than 106 gPNB/(molPd·h). The higher activity of 7/MAO over 4/MAO towards NB homopolymerization was reversed when the olefin-substituted VNB or ENB were added. Then, the more strongly bound PPh3 ligand of 4 (versus AsPh3 of 7) can compete with the olefin functionality of VNB or ENB and assume a directing role for the insertion of the ring double bond. As a consequence 4/MAO shows almost the same activity in NB and ENB homopolymerization.
Syntheses and properties of tetrakis(pentafluorophenyl)tellurium, Te(C6F5)4, and related compounds - (See abstract)
Naumann, Dieter,Tyrra, Wieland,Herrmann, Rudolf,Pantenburg, Ingo,Wickleder, Mathias S.
, p. 833 - 842 (2008/10/08)
Te(C6F5)4 was prepared from the reactions of TeCl4 or Te(C6F5)2Cl2 with Grignard reagents or AgC6F5 in moderate to good yields. Substitution reactions with Me3SiX (X = Cl, Br, OSO2CF3), with equimolar amounts of Br2, with AgNO3 and with H[BF4] or BF3·OEt2 yielded the Te(C6F5)3X derivatives (X = Cl, Br, OSO2CF3, NO3, BF4). Oxidation reactions of Cd, Hg, and Pd0 complexes led to Te(C6F5)2 and the corresponding bis(pentafluorophenyl) derivatives M(C6F5)2 (M = Cd, Hg, Pd) and with InBr to In(C6F5)2Br. From very slow hydrolysis of Te(C6F5)4 the oxide Te(C6F5)2O was prepared. The thermal decomposition, the NMR and mass spectra of the partially new compounds are discussed. The crystal structures of Te(C6F5)3Br (monoclinic, P21/a, Z = 4), [Te(C6F5)3][OSO2CF3] (monoclinic, P21/n, Z = 16) and [Te(C6F5)2O]2 (triclinic, P1, Z = 2) were determined.
Synthesis and reactivity of binuclear bis(μ-aryloxo) complexes of palladium and platinum. Crystal structure of [NBu4][Pt(C6F5)2(OC 6H4NO2-p)(CO)]
Ruiz, Jose?,Rodri?guez, Venancio,Lo?pez, Gregorio,Chaloner, Penny A.,Hitchcock, Peter B.
, p. 1662 - 1668 (2008/10/08)
The hydroxo complexes [NBu4]2[{M(C6F5) 2(μ-OH)}2] (M = Pd, Pt) react with phenols ROH (1:2 molar ratio) to give the bis(μ-aryloxo) complexes [NBu4]2[{M(C6F5) 2(μ-OR)}2] (M = Pd, Pt; R = C6H5, p-MeC6H4, p-NO2C6H4, C6F5). The reaction of bis(μ-aryloxo) complexes with PPh3 (1:2 molar ratio) gives the aryloxo monomer complexes [NBu4][M(C6F5)2(OR)(PPh 3)] (M = Pd, Pt; R = p-NO2C6H4, C6F5). The platinum monocarbonyl complexes [NBu4][Pt-(C6F5)2(OR)(CO)] (R = p-NO2C6H4, C6F5) have also been prepared by reaction of the corresponding bis(μ-aryloxo) complexes with carbon monoxide at room temperature and normal pressure. [NBu4][Pd(C6F5)3(CO)] is isolated in low yield from the reaction of [NBu4]2Pd(C6F5) 2(μ-OC6H4NO2-p)] with CO in the presence of water. The identity of the isolated complexes has been established by partial elemental analyses, conductance measurements, and spectroscopic (IR, 1H, 19F, 31P) methods. A single-crystal diffraction study of [NBu4][Pt(C6F5)2(OC 6H4NO2-p)(CO)] showed that coordination about platinum was approximately square-planar with the aryl rings tilted to avoid steric crowding.
