Density functional computation of 41Ti NMR chemical shifts

Ti-49 chemical shifts of TiX4 (X = Cl, Br, F), TiClnMe(4-n) (n = 0-3), Ti(C5H5)(2)X-2 (X = F, Cl, Br) and Ti(CO)(6)(2-) were computed, using geometries optimized with the gradient-corrected BP86 density functional, at the GIAO (gauge-including atomic orbitals)-Hartree-Fock, BPW91, and B3LYP levels. For this set of compounds, substituent effects on delta(Ti-49) are reasonably well described with all methods considered; judged from mean absolute deviations from experiment, B3LYP performs best. Zero-point corrections to the delta(Ti-49) values, evaluated from a perturbational approach based on vibrationally averaged effective geometries, turn out to be fairly small. Electric field gradients computed with the B3LYP functional do not correlate with trends in Ti-49 NMR linewidths. Attempts are reported to correlate the delta(Ti-49) values of Ti[YC(O)CHC(O)Y](2)Cl-2 (Y = H, Me, CF3, CN, F, Cl and Br) with the rate-limiting propagation barrier for ethylene polymerization using catalysts derived from these precursors. Copyright (C) 2004 John Wiley Sons, Ltd.