Wautelet Pascale, Le Moigne Jacques, Videva Vladimira, Turek Philippe
Institut Charles Sadron, UPR 022 CNRS, Université Louis Pasteur, 67083 Strasbourg Cedex, France.
J Org Chem. 2003 Oct 17;68(21):8025-36. doi: 10.1021/jo034723n.
A series of bis-iminonitroxide diradical derivatives of different lengths and geometry have been prepared that incorporate a conjugated phenylene-ethynylene bridge as a rigid spacer. This paper describes the synthesis of these new components and their main characterizations. An unexpected singlet ground state and substituent effects on the singlet-triplet gap have been found for substituted "m-phenylene"-based diradicals. The effects of the pi-conjugation on the intramolecular through-bond spin coupling have been investigated by changing the length of the spacer within linear derivatives. The EPR studies demonstrate the intramolecular magnetic coupling between the radical spins within all compounds. This result is very attractive and unusual, given the large distance between the radicals from 15 A in the dimer to 36 A in the pentamer.
我们制备了一系列不同长度和几何结构的双亚氨基氮氧双自由基衍生物，其中包含一个共轭亚苯基 - 乙炔基桥作为刚性间隔基。本文描述了这些新化合物的合成及其主要表征。对于取代的基于“间亚苯基”的双自由基，发现了意外的单重态基态以及取代基对单重态 - 三重态能隙的影响。通过改变线性衍生物中间隔基的长度，研究了π共轭对分子内通过键的自旋耦合的影响。电子顺磁共振（EPR）研究表明所有化合物内自由基自旋之间存在分子内磁耦合。鉴于自由基之间的距离较大，从二聚体中的15埃到五聚体中的36埃，这一结果非常引人关注且不同寻常。
