Oral Presentation Royal Australian Chemical Institute National Congress 2026

Structure/function Dependence of Homogeneous Cobalt Catalysts for Selective Reduction of NOx- ions (137198)

Tony F Masters 1 2 , Alexander Frisina 1 , Christopher Barnett 1 , Alexander K L Yuen 1 , Thomas Maschmeyer 1
  1. Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University of Sydney, NSW, Australia
  2. Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, The University Of Sydney, NSW, Australia

There is only one homogeneous Co complex catalyst that has been reported to convert both NO3- and NO2- into NH3 with perfect selectivity without the aid of a proton shuttle, [Co(DIM)Br2]+ (DIM = 2,3-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,3-diene).[1] Its non-innocent ligand and amino protons are suggested to be critical to its function.[1, 2] The geometry of the active catalytic species, the doubly reduced complex, has been calculated to be planar [Co(DIM)]+, although this has not been observed experimentally. In this project, we aim to test whether similar, perhaps simpler (at least synthetically), electronic and structural features offer the same selectivity in non-macrocyclic complexes, while varying the coordination of the complex. Inspired by established syntheses of coordinatively analogous complexes, the new complex [Co(bpy)(dien)Cl]2+ (bpy = 2,2’-bipyridine, dien = diethylenetriamine) has been prepared and tested for NOx- reduction.[3, 4] In aqueous electrolyte it shows selectivity towards NH3 but is only able to catalyse NO2- reduction. This observation supports the importance of the non-innocent ligand and amino protons for NOx- reduction by Co complexes, while it also suggests the possible importance of a more rigid ligand system, as without it activity is restricted to NO2- reduction.


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