Iron phenanthrolines: A density functional theory study

A comprehensive DFT study on the most extensive series of 1,10-phenanthroline iron complexes, to date, is reported here. Results have relevance to fields of active research; amongst others that of metal-to-ligand charge transfer complexes and of redox indicators. ADF geometry optimizations at the BP86/TZP level for a series of twenty-four iron complexes with substituted phenanthrolines for which electrochemical data is available, were obtained. Visible light excitations in these MLCT complexes involve transitions from the upper three metal based HOMO's to the lower five ligand based LUMO's. With high accuracy calculated HOMO energies, ionization potentials and Mulliken electronegativities are linearly correlated with experimentally obtained redox data from different studies. Molecular orbital renderings and TDDFT computed oscillators are illustrated to closely predict and explain experimental data. As part of the establishment of a larger data base, also for iron phenanthrolines an experimentally vindicated basis is now presented by which its chemical properties may theoretically be ascertained before embarking on more demanding experimental procedures. (C) 2017 Elsevier B.V. All rights reserved.