title: Pacman and hangman metal tetraazamacrocycles.
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.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.
authors.forename: Chang Hoon
authors.initials: CH
authors.lastname: Lee
authors.forename: Dino
authors.initials: D
authors.lastname: Villágran
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Cook
authors.forename: Jonas C
authors.initials: JC
authors.lastname: Peters
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Nocera
mesh_terms: D002384:Catalysis; D004563:Electrochemistry; D006859:Hydrogen; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry
chemical_list: D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D010165:Palladium; D006859:Hydrogen
keywords: cobalt; electrochemistry; homogeneous catalysis; hydrogen; palladium