15003-43-7Relevant academic research and scientific papers
A Study of Polarization and Directing Effects of Unsymmetrical Alkynes Using Regioselective Pd-Catalyzed Bromoallylation
Topolov?an, Nikola,Hara, Shuto,Císa?ová, Ivana,To?ner, Zdeněk,Kotora, Martin
supporting information, p. 234 - 240 (2020/01/22)
Herein is disclosed the first comprehensive study of factors that affect the regioselectivity of PdBr2(PhCN)2-catalyzed bromoallylation of unsymmetrically substituted internal alkynes. The study was performed on a wide array of electronically and structurally diverse alkynes with aryl-aryl, aryl-ferrocenyl, and aryl-alkyl substitutions. The regioselective formation of bromoallylation products was mostly driven by the polarization of the triple bond in aryl-aryl and aryl-ferrocenyl-substituted ethynes. On the other hand, directing effect, which arises from the presence of a directing group in the side-chain of aryl-alkyl-substituted alkynes, was the dominating factor that determined the regioselectivity of these reactions.
Crystal structures and coordination-site exchange reactions of palladium(II) and platinum(II) complexes containing tris[2-(tert-butylthio)ethyl]amine
Nakajima, Kiyohiko,Kajino, Tomohiro,Nonoyama, Matsuo,Kojima, Masaaki
, p. 67 - 73 (2008/10/08)
Palladium(II) and platinum(II) complexes, [PdX(NS31Bu)]BPh4 (X = Cl, Br, I; NS31Bu = tris[2-(tert-butylthio)ethyl]amine) and [PtCl(NS31Bu)]BPh4, were prepared, and their structures were determined by X-ray analyses. The geometry around the palladium and platinum atoms is square planar. The NS31Bu ligand functions as a tridentate ligand and one sulfur atom is not coordinated to the metal. The 1H NMR spectrum of [PdCl(NS31Bu)]BPh4 in acetone-d6 exhibited a dynamic behavior. At 20°C the spectrum showed a singlet signal at 1.60 ppm that can be assigned to tert-butyl protons, whereas at -70°C three singlet signals were observed at 1.36, 1.61, and 1.70 ppm with an intensity ratio of 1: 0.25: 2. The signals at 1.36 and 1.70 ppm are assigned to the tert-butyl protons in the square-planar structure, and these signals are consistent with the X-ray structure. The signal at 1.61 ppm can be assigned to the tert-butyl protons in a trigonal-bipyramidal structure where the three tert-butyl groups are magnetically equivalent. Thus, we concluded that the coordination-site exchange occurred via a trigonal-bipyramidal intermediate. The square-planar and trigonal-bipyramidal species of [PdCl(NS31Bu)]BPh4 are in equilibrium in acetone-d6. The equilibrium was shifted toward the square-planar species on decreasing the temperature. The 1H NMR spectra for [PdX(NS31Bu)]BPh4 (X = Cl, Br, and I) were similar to one another at the same temperature, suggesting that the site-exchange process is insensitive to the kind of coexisting halogen ligand. The site exchange reaction of [PtCl(NS31Bu)]BPh4 seems to occur more slowly than that of the palladium(II) analogue.
Bis(benzonitrile)palladium(II) dihalides: Structures and cocrystallization of the cubic cluster Pd6Cl12 with (E)-stilbene and with bis(benzonitrile)palladium(II) dichloride
Olmstead, Marilyn M.,Wei, Pin-Pin,Ginwalla, Arwa S.,Balch, Alan L.
, p. 4555 - 4559 (2008/10/08)
Crystals of the planar, trans complexes, bis(benzonitrile)palladium(II) dichloride and bis(benzonitrile)palladium(II) dibromide, suitable for single-crystal X-ray diffraction studies are obtained by growth from solutions in benzonitrile and their structures determined. While bis(benzonitrile)palladium(II) dichloride readily loses benzonitrile to form the cubic cluster Pd6Cl12, which cocrystallizes with a variety of planar aromatic hydrocarbon molecules, the much less soluble complex bis(benzonitrile)palladium(II) dibromide does not act as a source of the so far unknown cluster Pd6Br12. Attempts to prepare the hypothetical bis(benzonitrile)palladium(II) diiodide by reaction of PdI2 with benzonitrile were not successful. A solution of bis(benzonitrile)palladium(II) dichloride in p-xylene on standing produces crystals of Pd6Cl12·(PhCN)2PdCl2·p-xylene, which contain columns of alternating Pd6Cl12. and (PhCN)2PdCl2 molecules in face-to-face orientations along with similar columns in which Pd6Cl12 and p-xylene molecules are interleaved in face-to-face arrays. A solution of bis(benzonitrile)palladium(II) dichloride and (E)stilbene in benzene solution leads, not to coordination of palladium to the olefin, but to deposition of crystals of the ternary molecular compound, Pd6Cl12·0.5((E)-stilbene)·2(benzene). In this solid, two Pcl6Cl12 clusters make face-to-face contact with phenyl rings on opposite sides of the (E)-stilbene molecule, but the olefinic portion is far from the palladium cluster. Additionally, one of the two benzene rings abuts the Pd6Cl12 cluster in a face-to-face fashion.
