Spin Density Distribution in Iron(II) and Cobalt(II) Alkyl Complexes Containing 1,3-Bis(2-pyridylimino)isoindolate Ligands

Iron­(II) and cobalt­(II) alkyl complexes using tridentate bis­(pyridylimino)­isoindolates as ancillary ligands have been synthesized from the pyridine alkyl precursor complexes [(py)₂Fe­(CH₂SiMe₃)₂] and [(py)₂Co­(CH₂SiMe₃)₂]. The extremely air- and moisture-sensitive compounds were structurally characterized in the solid state by X-ray diffraction as well as in solution by paramagnetic NMR spectroscopy. It is demonstrated that the paramagnetic shifts in the ¹³C NMR spectra are dominated by strong Fermi-contact interactions. All ¹³C NMR signals can be assigned by correlation with DFT-calculated spin-density distributions.