Masahiko Hada
Tokyo Metropolitan University, Japan
Title: Vanadium NMR chemical shift in vanadium complex catalyst: a cooperation of QC calculation and MLR analysis
Biography
Biography: Masahiko Hada
Abstract
The vanadium complex catalysts play an important role in olefin polymerization. (imido)vanadium(V) complexes containing (2-anilidomethyl)pyridine ligands were presented notable catalytic activity and high selectivity in ethylene dimerization. In recent studies, Nomura and his coworkers found a good relationship between the catalytic activity and the vanadium chemical shift (51V-NMR) for the (imido)vanadium complex in ethylene polymerization. They deduced that the high catalytic reactivity originates from stabilization of the active site by electron-donating substituents. The trend of observed 51V-NMR chemical shifts was well reproduced by the LC-BLYP/cc-pVTZ method as shown in Figure 1. Calculated 51V NMR chemical shifts were analyzed by the multiple linear regression analysis (MLRA) method with a series of calculated molecular properties as shown in Figure 2. We showed an accurate correlation (R2=0.95) between 51V-NMR chemical shifts and natural charge (Q), HOMO-LUMO energy gap (Δε), and Wiberg bond index of V=N bond (ω).
Figure 1. Molecular Structure of Vanadium Complexes [ref. 3]
Figure 2. MLR analysis of V-NMR chemical shifts