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

Abstract

Bismuth(III) oxidation of 3,5-di-substituted-1,2,4-triazolato anions afforded a paddlewheel 1,2,4-triazolato dibismuth complex [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) Å). The reaction involved the intermediates of the organobismuth radical [Bi(R₂tz)₂]˙ and neutral N-1,2,4-triazolyl radical [3,5-R₂tz]˙. The dimerization of the former produced the corresponding dibismuth complex while the latter was trapped by using 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.