Tsukahara Yasunori, Kamatani Takayuki, Iino Atsushi, Suzuki Takayoshi, Kaizaki Sumio
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
Inorg Chem. 2002 Aug 26;41(17):4363-70. doi: 10.1021/ic011282m.
Two new series of each of four Cr(III) and Ni(II) imino nitroxide complexes with various kinds of beta-diketonates, [Cr(beta-diketonato)(2)(IM2py)]PF(6), and [Ni(beta-diketonato)(2)(IM2py)] (IM2py = 2-(2'-(pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy)) have been synthesized, and their structures and magnetic and optical properties have been examined. The X-ray analysis demonstrated that a IM2py ligand coordinated to Cr(III) and Ni(II) acts as a five-membered bidentate chelate. The variable-temperature magnetic susceptibility measurements indicated the antiferromagnetic and ferromagnetic interaction of Cr(III) and Ni(II) with IM2py, respectively, giving a variety of the magnetic coupling constant J values with varying the beta-diketonato ligands. The UV-vis shoulders around (19-20) x 10(3) and (17-18) x 10(3) cm(-)(1) for the Cr(III) and Ni(II) complexes, respectively, characteristic of the IM2py complexes were assigned to the metal-ligand charge-transfer transitions, Cr(t(2g))-SOMO(pi*) and Ni(e(g))-SOMO(pi*) MLCT in terms of the resonance Raman spectra and the variable-temperature absorption spectra. The absorption components centered around (13-14) x 10(3) cm(-1) for the Cr(III) and Ni(II) complexes were due to the formally spin-forbidden d-d transition within the t(2g) and e(g) subshells, associated with the intensity enhancement. The spectroscopic behavior with varying the beta-diketonato ligands is discussed in connection with the antiferromagnetic or ferromagnetic coupling constant J values on the basis of the exchange mechanism along with the coligand effect.
已合成了四个系列的含各种β - 二酮配体的Cr(III)和Ni(II)亚氨基氮氧化物配合物，分别为[Cr(β - 二酮)(2)(IM2py)]PF(6)和[Ni(β - 二酮)(2)(IM2py)]（IM2py = 2-(2'-(吡啶基)-4,4,5,5 - 四甲基 - 4,5 - 二氢 - 1H - 咪唑 - 1 - 氧基），并对其结构、磁性和光学性质进行了研究。X射线分析表明，与Cr(III)和Ni(II)配位的IM2py配体充当五元双齿螯合物。变温磁化率测量表明，Cr(III)和Ni(II)与IM2py分别存在反铁磁和铁磁相互作用，随着β - 二酮配体的变化给出了各种磁耦合常数J值。Cr(III)和Ni(II)配合物分别在(19 - 20)×10(3)和(17 - 18)×10(3) cm(-)(1)附近的紫外可见肩峰，这是IM2py配合物的特征峰，根据共振拉曼光谱和变温吸收光谱，被归属于金属 - 配体电荷转移跃迁，即Cr(t(2g)) - SOMO(π*)和Ni(e(g)) - SOMO(π*) MLCT。Cr(III)和Ni(II)配合物以(13 - 14)×10(3) cm(-1)为中心的吸收成分是由于t(2g)和e(g)子壳层内形式上自旋禁阻的d - d跃迁，伴有强度增强。基于交换机制以及共配体效应，结合反铁磁或铁磁耦合常数J值，讨论了随着β - 二酮配体变化的光谱行为。
