Corcos Amanda R, Roy Michael D, Killian Michelle M, Dillon Stephanie, Brunold Thomas C, Berry John F
Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States.
Inorg Chem. 2017 Dec 4;56(23):14662-14670. doi: 10.1021/acs.inorgchem.7b02557. Epub 2017 Nov 15.
The electronic structures of the diruthenium compounds Ru(ap)Cl (1, ap = 2-anilinopyridinate) and Ru(ap)OTf (2) were investigated with UV-vis, resonance Raman, and magnetic circular dichroism (MCD) spectroscopies; SQUID magnetometry; and density functional theory (DFT) calculations. Both compounds have quartet spin ground states with large axial zero-field splitting of ∼60 cm that is characteristic of Ru compounds having a (π*, δ*) electron configuration and a Ru-Ru bond order of ∼2.5. Two major visible absorption features are observed at ∼770 and 430 nm in the electronic spectra, the assignments of which have previously been ambiguous. Both bands have significant charge-transfer character with some contributions from d → d transitions. MCD spectra were measured to enable the identification of d → d transitions that are not easily observable by UV-vis spectroscopy. In this way, we are able to identify bands due to δ → δ* and δ → π* transitions at ∼16 100 and 11 200-12 300 cm, respectively, the latter band being sensitive to the π-donating character of the axial ligand. The Ru-Ru stretches are coupled with pyridine rocking motions and give rise to observed resonance Raman peaks at ∼350 and 420 cm, respectively.
利用紫外可见光谱、共振拉曼光谱和磁圆二色性（MCD）光谱；超导量子干涉仪磁力测定法；以及密度泛函理论（DFT）计算，对二钌化合物Ru(ap)Cl（1，ap = 2-苯胺基吡啶酸盐）和Ru(ap)OTf（2）的电子结构进行了研究。这两种化合物都具有四重态自旋基态，轴向零场分裂约为60 cm，这是具有(π*, δ*)电子构型且Ru-Ru键级约为2.5的Ru化合物的特征。在电子光谱中，在约770和430 nm处观察到两个主要的可见吸收特征，其归属此前一直不明确。这两个吸收带都具有显著的电荷转移特征，并有一些d→d跃迁的贡献。测量了MCD光谱，以识别紫外可见光谱不易观察到的d→d跃迁。通过这种方式，我们能够分别识别出在约16100和11200 - 12300 cm处由δ→δ和δ→π跃迁引起的吸收带，后一个吸收带对轴向配体的π供体性质敏感。Ru-Ru伸缩振动与吡啶摇摆运动耦合，分别在约350和420 cm处产生观察到的共振拉曼峰。
