Density functional computations of transition metal NMR chemical shifts: dramatic effects of Hartree-Fock exchange

The theoretical description of the 103Rh chemical shift range of a number of organorhodium complexes is significantly better when the B3LYP hybrid functional is used instead of pure density functionals: the slope of the linear regression line of computed versus experimental δ(103Rh) shifts is 0.80, 0.90 and 0.97 with the SOS-DFPT-IGLO, GIAO-BPW91 and GIAO-B3LYP methods, respectively, using a large basis set and optimized geometries. For 57Fe chemical shifts of several organoiron complexes, the improvement is even more dramatic: the corresponding slopes with the same methods are 0.55, 0.65, and 0.97, respectively. Inclusion of Hartree-Fock exchange has thus a huge effect on the computed transition metal chemical shifts.