Simulation of 59Co NMR Chemical Shifts in Aqueous Solution

✍ Scribed by Michael Bühl; Sonja Grigoleit; Hendrik Kabrede; Frank T. Mauschick

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 197 KB
• Volume: 12
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200500285

✦ Synopsis

Abstract

^59^Co chemical shifts were computed at the GIAO‐B3LYP level for [Co(CN)~6~]^3−^, [Co(H~2~O)~6~]^3+^, [Co(NH~3~)~6~]^3+^, and [Co(CO)~4~]^−^ in water. The aqueous solutions were modeled by Car–Parrinello molecular dynamics (CPMD) simulations, or by propagation on a hybrid quantum‐mechanical/molecular‐mechanical Born–Oppenheimer surface (QM/MM‐BOMD). Mean absolute deviations from experiment obtained with these methods are on the order of 400 and 600 ppm, respectively, over a total δ(^59^Co) range of about 18 000 ppm. The effect of the solvent on δ(^59^Co) is mostly indirect, resulting primarily from substantial metal–ligand bond contractions on going from the gas phase to the bulk. The simulated solvent effects on geometries and δ(^59^Co) values are well reproduced by using a polarizable continuum model (PCM), based on optimization and perturbational evaluation of quantum‐mechanical zero‐point corrections.