Four-component relativistic computational NMR study of ferrous, cobalt and nickel bisglycinates

The equilibrium structures of ferrous(II), cobalt(III) and nickel(II) bisglycinates were optimized at the DFT level using eight functionals, and their ¹H, ¹³C, ¹⁵N and ¹⁷O NMR chemical shifts were evaluated at both non-relativistic and four-component relativistic levels. Essential deshielding relativistic corrections were observed for nitrogen and oxygen, while they were found to be small for carbons and protons. Solvent corrections for chemical shifts noticeably increased with the dielectric constant of a solvent for nitrogen and carbon, and they were negligibly small for protons.