Solid-state NMR Fermi contact and dipolar shifts in organometallic complexes and metalloporphyrins

We have used density functional theory methods to investigate the solid-state "magic-angle" spinning (MAS) NMR and single-crystal NMR/ENDOR spectra of paramagnetic organometallic complexes and metalloporphyrins. The solid-state MAS NMR chemical shifts (including both diamagnetic and hyperfine contributions) are predicted with a slope of 1.007 and an R2 = 0.967, corresponding to a 28 ppm (or 6.3%) error over the entire 442 ppm range. Single-crystal ENDOR hyperfine values, including both isotropic Fermi contact and dipolar couplings, are predicted with a slope of 1.009 and an R2 = 0.998, corresponding to a 0.93 MHz (or 1.2%) error over the entire 78.37 MHz range. In addition, single-crystal NMR shifts (including both hyperfine terms) are predicted with an R2 = 0.961. The ability to compute solid-state MAS NMR and single-crystal NMR/ENDOR data should facilitate the use of these techniques in investigating paramagnetic metal complexes and should be of particular use in studying paramagnetic metalloproteins, where structures are less accurately known. Copyright © 2005 American Chemical Society.