Synthesis and design of paramagnetic metal complexes containing stable radicals and their spectroscopic study

本研究旨在通过对金属配合物与自由基间的交换耦合、配位场与自由基间的电、磁相互作用以及自由基络合物在溶液中的反应性等方面的通用性和微调来研究含自由基顺磁性金属配合物的合成和设计。首先，我们揭示了由于配位场的微妙变化而引起的行为或d电子态，如核磁共振和溶致变色的溶剂效应以及由于各向异性的pi键导致的反常三角场分裂。此外，我们还探讨了由于氢键和CH/pi相互作用等分子内弱相互作用而产生的空间效应。这些研究是考察金属与自由基配位键的重要基础信息，特别是d轨道和pi^*轨道之间的配位键(SOMO)，顺磁性的铬(III)、镍(II)金属的自由基络合物如[Cr(acac)_2(NIT2-py)]+or[Ni(dbm)_2(NIT2-py)](dbm=dibenzoylmethane)，以及反磁性的Co(III)的自由基络合物如反式[Co(Acac)_2(X)(nit4+py)]^n(X=PPh_3：n=1+；NO_2&lt；-2&GT；：n=0))和反式[Co(Acac)_2(P(Ph_3))(4-NH_2Tempo)]+。考察了它们的稳定性和磁光性质，如自旋禁戒跃迁的强度增强。X-射线结构分析证实了反式[Co(Acac)_2(PPh_3)(NIT4-py)]+的吡啶配位方式。这些数据将是实现这一目的的重要线索，并对自由基络合物的化学有价值。

This research aims at versatility and fine-tuning of the exchange coupling between metal complexes and radical ligands together with electronic and magnetic interaction between the ligand field and radicals as well as the reactivity of radical complexes in solutions for the primary purpose of synthesis and design of paramagnetic metal complexes containing radical ligands.Firstly, we have revealed the behavior or the d electron state due to the subtle change of the ligand field such as the solvent effects as observed for the NMR and solvatochromism as well as anomalous trigonal field splitting due to anisotropic pi bonding. Furthermore, we explored the steric effect due to weak intramolecular interactions such as hydrogen bond and CH/pi interaction. These studies are the important and basic information to examine the coordination bond between the metal and radical, especially between the d orbital and pi^* orbital (SOMO)Secondarily, radical complexes of paramagnetic Cr(III) and Ni(II) metal such as [Cr(acac)_2(NIT2-py)]+or[Ni(dbm)_2(NIT2-py)](dbm=dibenzoylmethane) and those of diamagnetic Co(III) metal such as trans-[Co(acac)_2(X)(NIT4+py)]^n(X=PPh_3 : n=1+ ; NO_<-2> : n=0)) and trans-[Co(acac)_2(P(Ph_3))(4-NH_2tempo)]+have been prepared. Their stability and magneto-optic properties such as the intensity enhancement of the spin-forbidden transitions were examined. The X-ray structure analysis of trans-[Co(acac)_2(PPh_3)(NIT4-py)]+confirmed the pyridine coordination mode. These data will be an important clue to accomplish the present purpose and valuable for the chemistry for radical complexes.