1‑Phenyl-3-(pyrid-2-yl)benzo[e][1,2,4]triazinyl: The First “Blatter Radical” for Coordination Chemistry

A neutral air- and moisture-stable N,N′-chelating radical ligand, 1-phenyl-3-(pyrid-2-yl)­benzo­[e]­[1,2,4]­triazinyl (1) was synthesized and characterized by electron paramagnetic resonance spectroscopy, X-ray crystallography, and magnetic measurements. Subsequent reaction of 1 with Cu­(hfac)2·2H2O (hfac = hexafluoroacetylacetonate) under ambient conditions afforded the coordination complex Cu­(1)­(hfac)2 in which the radical binds to the metal in a bidentate fashion. Magnetic susceptibility data collected from 1.8 to 300 K indicate a strong ferromagnetic metal-radical interaction in the complex and weak antiferromagnetic radical···radical interactions between the Cu­(1)­(hfac)2 units. Detailed computational investigations support this assignment. Radical 1 is a new addition to the growing library of 1,2,4-triazinyl radicals and the first member of this family of paramagnetic species synthesized specifically for coordination purposes.

一种对空气与水汽稳定的中性N,N′-螯合自由基配体——1-苯基-3-(2-吡啶基)苯并[e][1,2,4]三嗪基（1），通过电子顺磁共振波谱、X射线晶体学以及磁学测试完成了合成与表征。随后在常温环境下，将配体1与Cu(hfac)₂·2H₂O（hfac=六氟乙酰丙酮根）进行反应，得到配位配合物Cu(1)(hfac)₂，该配合物中自由基以双齿配位模式与金属中心结合。在1.8至300 K区间采集的磁化率数据表明，该配合物内部存在较强的金属-自由基铁磁性相互作用，而不同Cu(1)(hfac)₂单元之间则存在较弱的自由基-自由基反铁磁性相互作用。详尽的理论计算研究佐证了这一指认。自由基1是日益壮大的1,2,4-三嗪基自由基库中的新增成员，同时也是这类顺磁性物种中首个专为配位合成目的而制备的成员。