High-frequency EPR study of reduced diruthenium and dirhenium polypyridine complexes based on the 1,2,4,5-tetrazine radical bridge
作者:Biprajit Sarkar、St�phanie Frantz、Wolfgang Kaim、Carole Duboc
DOI:10.1039/b407611g
日期:——
The radical complexes (μ-L)[Ru(bpy)2]2}˙3+, (μ-bmtz)[Ru(cym)Cl]2}˙+ and (μ-L)[Re(CO)3Cl]2}˙−, where L are 3,6-disubstituted 1,2,4,5-tetrazines such as 3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine (bmtz) and cym =
p-cymene, were studied by X-band EPR in fluid solution and by 285 GHz EPR in glassy frozen solution. A comparison with other transition metal complexes (Cu, Rh, Os, Ir, Pt) involving tetrazine radical ligands reveals that the g anisotropy reflects (i) the π acceptor effect of the tetrazine substituents, (ii) the competition from ancillary π acceptor ligands for back donation from the metal, and (iii) the spin–orbit coupling contributions from the transition metal.
研究了在流体溶液中通过X波段EPR、在玻璃态冷冻溶液中通过285 GHz EPR的激进复合物(μ-L)[Ru(bpy)2]2}˙3+,(μ-bmtz)[Ru(cym)Cl]2}˙+ 和 (μ-L)[Re(CO)3Cl]2}˙−,其中L是3,6-双取代的1,2,4,5-四嗪,如3,6-双(2-嘧啶基)-1,2,4,5-四嗪(bmtz),cym =对伞花烃。与其他涉及四嗪激进配体的过渡金属复合物(Cu, Rh, Os, Ir, Pt)的比较表明,g各向异性反映了(i)四嗪取代基的π受体效应,(ii)辅助π受体配体与金属的反向捐赠竞争,以及(iii)过渡金属的轨道自旋耦合贡献。