Nanoscale insight into C-C coupling on cobalt nanoparticlesElectronic supplementary information (ESI) available: Experimental methods; dI/dV spectra identifying the surface species; STM images of high-coverage, reactively formed biphenyl on Co/Cu(111). See DOI: 10.1039/c4cc03678f

The Ullmann coupling of bromobenzene to biphenyl on Co nanoparticles proceeds below room temperature via an intermediate in which phenyl groups are bound directly to metallic Co. A similar surface-bound benzyl intermediate is observed for coupling of benzylbromide to bibenzyl on Co. A molecular-scale view of efficient and selective homocoupling of both aryl and benzyl groups on cobalt nanoparticles.