Kempgens Pierre, Elbayed Karim, Raya Jésus, Granger Pierre, Rosé Jacky, Braunstein Pierre
Laboratoire de RMN de la Matière Condensée (UMR 7177 CNRS), Université Louis Pasteur, Institut de Chimie, BP 296, F-67008 Strasbourg Cedex, France.
Inorg Chem. 2006 Apr 17;45(8):3378-83. doi: 10.1021/ic051544a.
Two-dimensional (2D) 59Co correlation spectroscopy (COSY)/double-quantum-filtered (DQF)COSY experiments are reported for three tetrahedral mixed-metal clusters HFeCo3(CO)11L with L = PPh3, P(OMe)3, and PCy3 (Cy = cyclohexyl) in which the L-substituted Co center is chemically different from the other two. The 2D 59Co COSY and DQFCOSY NMR spectra of these clusters in solution prove the existence of a scalar coupling constant between the 59Co nuclei. To determine this value for each cluster, 2D 59Co COSY and DQFCOSY NMR spectra have been simulated by numerical density-matrix calculations. The predicted spectra mimic well the features of the experimental spectra if a scalar coupling is introduced between the Co nuclei. It was initially observed that the scalar coupling constants between the Co nuclei obtained from the 2D COSY and DQFCOSY NMR spectra differed significantly. In contrast to the 2D COSY spectra, the diagonal and cross peaks are of comparable intensity in the 2D DQFCOSY spectra, which leads to a considerable increase in the accuracy of the determination of the scalar coupling constant.
报道了针对三个四面体混合金属簇HFeCo3(CO)11L（其中L = PPh3、P(OMe)3和PCy3（Cy = 环己基））的二维（2D）59Co相关光谱（COSY）/双量子滤波（DQF）COSY实验，在这些簇中，L取代的Co中心在化学性质上与另外两个不同。这些簇在溶液中的二维59Co COSY和DQFCOSY NMR光谱证明了59Co核之间存在标量耦合常数。为了确定每个簇的该值，通过数值密度矩阵计算模拟了二维59Co COSY和DQFCOSY NMR光谱。如果在Co核之间引入标量耦合，则预测的光谱能很好地模拟实验光谱的特征。最初观察到，从二维COSY和DQFCOSY NMR光谱获得的Co核之间的标量耦合常数有显著差异。与二维COSY光谱不同，二维DQFCOSY光谱中的对角峰和交叉峰强度相当，这导致标量耦合常数测定的准确性有相当大的提高。
