Showing papers by "Dino Villagrán published in 2013"
TL;DR: Mononuclear Fe(II) and Fe(III) complexes residing in a trigonal tris(ditox) (ditox = (t)Bu2(Me)CO(-)) ligand environment have been synthesized and characterized.
Abstract: Mononuclear Fe(II) and Fe(III) complexes residing in a trigonal tris(ditox) (ditox = tBu2(Me)CO–) ligand environment have been synthesized and characterized. The Fe(III) ditox complex does not react with oxidants such as PhIO, whereas NMe3O substitutes a coordinated tetrahydrofuran (THF) in the apical position without undergoing oxo transfer. In contrast, the Fe(II) ditox complex reacts rapidly with PhIO or Me3NO in THF or cyclohexadiene to furnish a highly reactive intermediate, which cleaves C–H bonds to afford the Fe(III)–hydroxide complex. When generated in 1,2-difluorobenze, this intermediate can be intercepted to oxidize phosphines to phosphine oxide. The fast rates at which these reactions occur is attributed to a particularly weak ligand field imparted by the tris(alkoxide) ancillary ligand environment.
27 citations
TL;DR: Electrochemical examination of the parent [Co(bapa)](2+) scaffold reveals it to be a catalyst for the hydrogen evolution reaction (HER) in acetonitrile, and studies of the Hangman complex appear to be obscured by trace amounts of residual palladium remaining from the Suzuki coupling reaction to provide a cautionary note for the use of such cross-coupling methodologies in the preparation of HER catalysts.
Abstract: Metal complexes of derivatized 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentane (bapa) ligands were prepared from 4-substituted diacetylpyridine derivatives by templated condensation with 3,3′-diaminodipropylamine in the presence of a metal halide or nitrate. The diacetylpyridine derivatives with Pacman and Hangman scaffolds are delivered from borylation of the 4-postion of diacetylpyridine and subsequent Suzuki coupling with the appropriate Hangman or Pacman backbone. Electrochemical examination of the parent [Co(bapa)]^(2+) scaffold reveals it to be a catalyst for the hydrogen evolution reaction (HER) in acetonitrile. Similar studies of the Hangman complex appear to be obscured by trace amounts of residual palladium remaining from the Suzuki coupling reaction to provide a cautionary note for the use of such cross-coupling methodologies in the preparation of HER catalysts.
15 citations