Density-functional computation of 53Cr NMR chemical shifts.
53Cr chemical shifts of CrO4(2-), Cr2O7(2-), CrO3X-, CrO2X2(X = F, Cl), and Cr(CO)5L (L = CO, PF3, CHNH2, CMeNMe2) are computed, using geometries optimized with the gradient-corrected BP86 density functional, at the gauge-including atomic orbitals (GIAO)-, BPW91-, and B3LYP levels. For this set of compounds, substituent effects on delta(53Cr) are better described with the pure BPW91 functional than with B3LYP, in contrast to most other transition-metal chemical shifts studied so far. For selected cases, 53Cr NMR line widths can be rationalized in terms of electric field gradients (EFGs) computed with the BPW91 functional, but in general other factors such as molecular correlation times appear to be dominating. 53Cr chemical shifts and EFGs are predicted for CrO3, Cr(C6H6)2, Cr(C6H6)CO3, and, with reduced reliability, for Cr2(mu2-O2CH)4.
Bühl
Michael
M
Max-Planck Institut für Kohlenforschung, Kaiser-Wilhelm Platz 1, D-45470 Mülheim an der Ruhr, Germany. buehl@mpi-muelheim.mpg.de