Calculations of nuclear magnetic shielding in paramagnetic molecules

Abstract

Articles you may be interested inA fully relativistic method for calculation of nuclear magnetic shielding tensors with a restricted magnetically balanced basis in the framework of the matrix Dirac-Kohn-Sham equationa)Perturbational ab initio calculations of relativistic contributions to nuclear magnetic resonance shielding tensorsWe propose and evaluate first principles methods for calculating the nuclear shielding tensor in open-shell, paramagnetic molecules, dealing with the case of small spin-orbit coupling that, in turn, implies the best applicability to light, organic compounds. The formalism is consistent up to second order in the fine structure constant, and includes orbital, fully anisotropic dipolar, and isotropic contact contributions to the tensor. The proposed method is implemented within the ab initio singleand multiconfiguration self-consistent field as well as density functional theory frameworks. The applications include small main-group radicals and larger nitroxide radicals. The analysis of the results and comparison with the experimental nuclear magnetic resonance data, which are available for the latter compounds, indicate promising accuracy and applicability of the density functional theory method to chemically interesting problems.

Predicting the NMR Spectra of Paramagnetic Molecules by DFT: Application to Organic Free Radicals and Transition‐Metal Complexes

“…The results we have presented, which complement other studies, [18][19][20][22][23][24][25][26][27][28] show that DFT calculations should offer a major aid in understanding such spectra with minimal assumptions, for a wide variety of open-shell molecules. Indeed, we were able to show that some literature assignments can be easily corrected in this way.…”

Aromaticity in spin-polarized systems: Can rings be simultaneously alpha aromatic and beta antiaromatic?

“…36,37 These formulas contain the so-called orbital term present in the closed-shell expression 38,39 and several terms accounting for the spin-orbit effects that arise from the electron spin, such as the anisotropic dipolar and the isotropic contact contributions. These studies show that the orbital term of the chemical shielding in open-shell systems is calculated analogously to that in closed-shell systems.…”

Probing the C 60 triplet state coupling to nuclear spins inside and out

“…While the calculation of NMR properties of closed-shell, diamagnetic molecules is now widely used to aid structure determination [36][37][38][39]43], the corresponding computations for open-shell, paramagnetic species are comparatively less developed. Nevertheless, it has been shown that DFT methods can be used to predict NMR and EPR parameters for a variety of paramagnetic organic, organometallic and inorganic molecules [44][45][46][47][48][49][50][51][52][53][54][55][56].…”