67805-67-8Relevant articles and documents
Iron Complexes of Square Planar Tetradentate Polypyridyl-Type Ligands as Catalysts for Water Oxidation
Wickramasinghe, Lanka D.,Zhou, Rongwei,Zong, Ruifa,Vo, Pascal,Gagnon, Kevin J.,Thummel, Randolph P.
, p. 13260 - 13263 (2015)
The tetradentate ligand, 2-(pyrid-2′-yl)-8-(1″,10″-phenanthrolin-2″-yl)-quinoline (ppq) embodies a quaterpyridine backbone but with the quinoline C8 providing an additional sp2 center separating the two bipyridine-like subunits. Thus, the four
Fe and Co Complexes of Rigidly Planar Phosphino-Quinoline-Pyridine Ligands for Catalytic Hydrosilylation and Dehydrogenative Silylation
Basu, Debashis,Gilbert-Wilson, Ryan,Gray, Danielle L.,Rauchfuss, Thomas B.,Dash, Aswini K.
supporting information, p. 2760 - 2768 (2018/09/10)
Co and Fe dihalide complexes of a new rigidly planar PNN ligand platform are prepared and examined as precatalysts for hydrosilylation of alkenes. Lithiation of Thummel's 8-bromo-2-(pyrid-2′-yl)quinoline followed by treatment with (i-Pr)2PCl and (C6F5)2PCl afforded the phosphine-quinoline-pyridine ligands, abbreviated RPQpy for R = i-Pr and C6F5, respectively. These ligands form 1:1 adducts with the dichlorides and dibromides of iron and cobalt. Crystallographic characterization of FeBr2(iPrPQpy), FeBr2(ArFPQpy), CoCl2(iPrPQpy), CoBr2(iPrPQpy), and CoCl2(ArFPQpy) confirmed that the M-P-C-C-N-C-C-N portion of these complexes is planar within 0.078 ? unlike previous generations of PNN complexes where deviations from planarity were ~0.35 ?. Bond distances as well as magnetism indicate that the Fe complexes are high spin and the cobalt complexes are high spin or participate in spin equilibria. Also investigated were the NNN analogues of the RPQpy ligands, wherein the phosphine group was replaced by the mesityl ketimine. The complexes FeBr2(MesNQpy) and CoCl2(MesNQpy) were characterized crystallographically. Reduction of MX2(RPQpy) complexes with NaBHEt3 generates catalysts active for anti-Markovnikov silylation of simple and complex 1-alkenes with a variety of hydrosilanes. Catalysts derived from MesNQpy exhibited low activity. Fe-RPQpy derived catalysts favor hydrosilylation, whereas Co-RPQpy based catalysts favor dehydrogenative silylation. Catalysts derived from CoX2(iPrPQpy) convert hydrosilanes and ethylene to vinylsilanes. Related experiments were conducted on propylene to give propenylsilanes.
Cooperative or Oxidative Hydrogen Addition to 2-Hydroxypyridonate Iridium Complexes: Dependence on Oxidation State
Forrest, Sebastian J. K.,Manojveer, Seetharaman,Johnson, Magnus T.
, p. 3239 - 3243 (2017/07/22)
Iridium(III)–pyridone complexes are commonly found to react in a cooperative and redox-neutral manner with dihydrogen and alcohols. In this work, the reactivity preferences of IrI–pyridone complexes were investigated under a variety of conditions. We have found that, in contrast to IrIII–pyridones, IrI–pyridone complexes display a strong preference to react non-cooperatively. With a new chelating 2-hydroxy-8-diphenylphosphinoquinoline ligand that does not dissociate after hydrogen addition, oxidative addition is still preferred. In the preparation of mono- and bidentate neutral and anionic pyridone ligands, Vaska's complex was used as a point of reference. We expect these findings to have implications for catalyst development in the field of metal–ligand cooperation.