Do High-Spin Topology Rules Apply to Charged Polyradicals? Theoretical and Experimental Evaluation of Pyridiniums as Magnetic Coupling Units
作者:Anthony P. West、Scott K. Silverman、Dennis A. Dougherty
DOI:10.1021/ja9527941
日期:1996.1.1
Ab initio calculations on pyridine and pyridinium analogues of m-xylylene indicate that the neutral heterocycle is essentially equivalent to benzene as a ferromagnetic coupling unit, while the cationic pyridiniums behave much differently. Depending on the substitution pattern, a protonated pyridine can serve as a ferromagnetic coupling unit or an antiferromagnetic coupling unit. Both valence bond and
对间二甲苯的吡啶和吡啶鎓类似物的从头算计算表明,中性杂环基本上等同于苯作为铁磁耦合单元,而阳离子吡啶鎓的行为则大不相同。根据取代模式,质子化吡啶可以用作铁磁耦合单元或反铁磁耦合单元。价键和分子轨道论证都为这些结果提供了定性合理化。为了测试理论预测,合成了吡啶和吡啶鎓双自由基的双(三亚甲基甲烷)类似物,并通过电子顺磁共振光谱进行了分析。获得了对理论预测的普遍支持。