1625-68-9Relevant academic research and scientific papers
Synthesis and characterization of palladium(ii) complexes with new diphosphonium-diphosphine and diphosphine ligands. Production of low molecular weight alternating polyketones via catalytic CO/ethene copolymerisation
Bianchini, Claudio,Brueggeller, Peter,Claver, Carmen,Czermak, Georg,Dumfort, Alexander,Meli, Andrea,Oberhauser, Werner,Suarez, Eduardo J. Garcia
, p. 2964 - 2973 (2006)
The bis-cationic diphosphonium-diphosphine 6,7-di(di-2-methoxyphenyl) phosphinyl-2,2,4,4-tetra(di-2-methoxyphenyl)-2λ4, 4λ4-diphosphoniumbicyclo[3.1.1]heptane-bis(PF6) ((o-MeO-PCP)(PF6)2) and the diphosphine rac-2,4-bis((di-2-methoxyphenyl)phosphino)pentane (rac-o-MeO-bdpp) have been synthesized. Both ligands have been employed to coordinate PdCl2 and Pd(OAc)2 to give [PdCl2(o-MeO-PCP)](PF6) 2 (1a), PdCl2(rac-o-MeO-bdpp) (1b), [Pd(OAc) 2(o-MeO-PCP)](PF6)2 (2a) and Pd(OAc) 2(rac-o-MeO-bdpp) (2b). The ligands and complexes have been fully characterized in solution by multinuclear NMR spectroscopy. In addition, 1a and 1b have been authenticated by single crystal X-ray structure analyses. The PdII complexes 1a and 1b have been employed as catalyst precursors for the CO/ethene copolymerisation in water-acetic acid mixtures, while 2a and 2b have been tested in methanol in the presence of p-toluenesulfonic acid. Irrespective of the reaction media, perfectly alternating polyketones were obtained in excellent yields and with number-average molecular weights ranging from 7.1-13.9 kg mol-1 with the diphosphonium-diphosphine catalysts and from 37.2-48.2 kg mol-1 with the diphosphine catalysts. The Royal Society of Chemistry 2006.
Flexible molecules with defined shape XI[≠]. - Conformer equilibria in 2,4-disubstituted pentane derivatives
Hoffmann, Reinhard W.,Stenkamp, Dirk,Trieselmann, Thomas,G?ttlich, Richard
, p. 2915 - 2927 (2007/10/03)
2,4-Disubstituted penfanes are molecules which adopt essentially only two conformations. Substituents have been varied in order to find those which lead to a strong preference of the conformer equilibrium. Studying 2- substituted 4-methylpentanes 3 and 4-benzyloxypentanes 12, it has been shown that substituent effects on the conformer equilibria are not additive, as would be expected on the grounds of steric effects alone. Rather, interactions between polar groups reinforce the bias of the conformer equilibria. When applied to 2,4-disubstituted pentanes, substituents such as chloro or phthalimido shift the conformer equilibrium to the side of the gg conformer with preferences exceeding 90%.
