More than 80 years after Paneth's report of dimethyl bismuth, the first monomeric Bi(II) radical that is stable in the solid state has been isolated and characterized. Reduction of the diamidobismuth(III) chloride Bi(NON(Ar))Cl (NON(Ar)=[O(SiMe2NAr)2](2-); Ar=2,6-iPr2C6H3) with magnesium affords the Bi(II) radical ˙Bi(NON(Ar)). X-ray crystallographic measurements are consistent with a two-coordinate bismuth in the +2 oxidation state with no short intermolecular contacts, and solid-state SQUID magnetic measurements indicate a paramagnetic compound with a single unpaired electron. EPR and density functional calculations show a metal-centered radical with >90% spin density in a p-type orbital on bismuth.

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Bismuth diphenylphosphanides Bi(NON )(PPh ) (NON =[O(SiMe NR) ], R=tBu, 2,6-iPr C H , Aryl) undergo facile decomposition via single-electron processes to form reduced Bi and P species. The corresponding derivatives Bi(NON )(PCy ) are stable. Reaction of the isolated Bi radical Bi(NON ) with white phosphorus (P ) proceeds with the reversible and selective activation of a single P-P bond to afford the bimetallic μ,η -bicyclo[1.1.0]tetraphosphabutane compound.

Bismuth(iii) TEMPOxide compounds have been synthesized from the coupling of Bi(ii) species with the TEMPO˙ radical. The steric profile of the supporting bis(amido)disiloxane ligand promotes different fluxional behaviour in solution, and DFT calculations suggest variation in the Bi-O bond character. These compounds are active catalysts for oxidative coupling of TEMPO and silane substrates, believed to proceed via metathesis of Bi-O and Si-H bonds followed by decomposition of bismuth-hydride intermediate species.