Jiang Changcheng, Young Philip J, Brown-Xu Samantha E, Kender William T, Hamilton Ewan J M, Gallucci Judith C, Chisholm Malcolm H
Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210, United States.
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, U.K.
Inorg Chem. 2017 Aug 21;56(16):9660-9668. doi: 10.1021/acs.inorgchem.7b01164. Epub 2017 Aug 7.
The interligand charge dynamics of the lowest singlet metal-to-ligand charge-transfer states (MLCT S states) of a series of quadruply bonded trans-Mo(NN)(OC-X) paddlewheel compounds are investigated, where NN is a π-accepting phenylpropiolamidinate ligand and OC-X (X = Me, Bu, TPB, or CF) is an auxiliary carboxylate ligand. The compounds show strong light absorption in the visible region due to MLCT transitions from the Mo center to the NN ligands. The transferred electron density was followed by femtosecond time-resolved infrared (fs-TRIR) spectroscopy with vibrational reporters such as the ethynyl groups on the NN ligands. The observed fs-TRIR spectra show that these compounds have asymmetric MLCT S excited states where the transferred electron mainly resides on a single NN ligand. The presence of interligand electron transfer (ILET) is suggested to explain the shape of the ν(C≡C) bands and the influence of auxiliary ligands and solvents on the interligand electronic coupling. The ILET in the MLCT S state is shown to be sensitive to the functional groups on the auxiliary ligands while being less responsive to changes in solvents.
研究了一系列四重键合的反式 - Mo(NN)(OC - X)桨轮化合物最低单重态金属到配体电荷转移态（MLCT S态）的配体间电荷动力学，其中NN是一个π - 接受型苯丙炔脒配体，OC - X（X = 甲基、丁基、TPB或CF）是一个辅助羧酸酯配体。由于从Mo中心到NN配体的MLCT跃迁，这些化合物在可见光区域表现出强烈的光吸收。通过飞秒时间分辨红外（fs - TRIR）光谱，利用诸如NN配体上的乙炔基等振动报告基团跟踪转移的电子密度。观察到的fs - TRIR光谱表明，这些化合物具有不对称的MLCT S激发态，其中转移的电子主要位于单个NN配体上。配体间电子转移（ILET）的存在被认为可以解释ν(C≡C)带的形状以及辅助配体和溶剂对配体间电子耦合的影响。MLCT S态中的ILET对辅助配体上的官能团敏感，而对溶剂变化的响应较小。
