1,2,4-Triazolato paddlewheel dibismuth complexes with very short Bi(II)-Bi(II) bonds: bismuth(III) oxidation of 1,2,4-triazolato anions into neutral N-1,2,4-triazolyl radicals

Bismuth(III) oxidation of 3,5-di-substituted-1,2,4-triazolato anions afforded paddlewheel 1,2,4-triazolato dibismuthanes [L2(Bi–Bi)L2] (L = η1,η1-3,5-R2tz, R = Ph (3), iPr (4)) with very short Bi(II)-Bi(II) bonds (2.8650(4)2.8721(3) A). The reaction involved the intermediates of organobismuth radical [Bi(R2tz)2]• and neutral N-1,2,4-triazolyl radical [3,5-R2tz]•. The dimerization of the former produced the corresponding dibismuthane while the latter was trapped by spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) to give the radical adduct of {(3,5-R2tz)(DMPO)}• which was unambiguously evidenced by EPR analysis.