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Single-atom Co–N–C catalyzes nitroarene azo coupling
A self-supporting Co–N–C single-atom catalyst with a CoN4C8-1-2O2 site hydrogenatively couples nitroarenes to azo compounds.
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What Co site structure did XANES/DFT assign?
CoN4C8-1-2O2: Co coordinated to four pyridinic N with two weakly adsorbed axial oxygens.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
How was the self-supporting Co–N–C made?
Pyrolyze Co(phen)2(OAc)2 on Mg(OH)2 at 700 °C, then leach MgO with nitric acid.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What Co loading and Mg residue were measured?
3.6 wt% Co and 0.09 wt% Mg.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What Co atom density was estimated?
About 0.55 Co atoms per nm².
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What oxidation state is Co at 500–700 °C pyrolysis?
Co2+; 900 °C instead forms metallic Co.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What EXAFS Co–N coordination was fitted?
CN 3.7 at 1.88 Å.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What isolated azo yield was obtained under optimized conditions?
97%.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What TOF did the Co–N–C catalyst afford?
35.9 h–1, near Au/Mg4Al at 41.8 h–1.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
How does 3-nitrostyrene behave?
Nitro groups reduce without detectable alkene hydrogenation.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
What iodo-azo yield was obtained without dehalogenation?
94%.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified
How reusable is the catalyst?
Recovered by filtration and reused at least 5 times with selectivity/yield retained if time is extended.
Source: Single-atom dispersed Co-N-C catalyst: structure identification and performance for hydrogenative coupling of nitroarenes · DOI · quote verified