Synthesis and Characterization of Verdazyl Radicals Bearing Pyridine or Pyrimidine Substituents: A New Family of Chelating Spin-Bearing Ligands
作者:Christa L. Barr、Preston A. Chase、Robin G. Hicks、Martin T. Lemaire、Cecilia L. Stevens
DOI:10.1021/jo991198c
日期:1999.11.1
radical precursors, the corresponding 1,2,4,5-tetrazanes, were prepared by condensation of the bis(1-methylhydrazide) of carbonic acid with the appropriate aromatic aldehyde. Oxidation of 3-(4,6-dimethyl-2-pyrimidyl)-1,5-dimethyl-1,2,4,5-tetrazane 6-oxide (7) with sodium periodate afforded 1,5-dimethyl-3-(4,6-dimethyl-2-pyrimidyl)-6-oxoverdazyl (4), which could be isolated and stored without decomposition
描述了两个新的带有2-吡啶和4,6-二甲基-2-嘧啶环作为取代基的1,5-二甲基-6-氧过二氮杂基的合成和表征。通过将碳酸的双(1-甲基肼)与适当的芳族醛缩合来制备自由基前体,即相应的1,2,4,5-四氮烷。用高碘酸钠氧化3-(4,6-二甲基-2-嘧啶基)-1,5-二甲基-1,2,4,5-四氮烷6-氧化物(7)得到1,5-二甲基-3-( 4,6-二甲基-2-嘧啶基)-6-氧杂二唑(4),可以分离和储存而不会分解。相反,尝试用高碘酸盐氧化类似的3-(2-吡啶基)-1,5-二甲基-1,2,4,5-四氮烷6-氧化物(6)产生1,5-二甲基-3-( 2-吡啶基)-6-氧杂二唑(3),无法分离。然而,用苯醌将该四氮烷氧化,生成与氢醌为1:1配合物的吡啶基凡达基3。该络合物在固态中无限稳定,并提供了吡啶基凡达唑的长期储存方式。两种自由基的电子性质已通过EPR光谱,循环伏安法和MNDO计算得到了表征。自由基具有宽的电化学稳定性窗口(>