Geometric Analysis and DFT Study of 2,2′-Dipyridylamine-Stabilized First-Row Transition-Metal Complexes

A geometric analysis of first-row transition-metal complexes bearing 2,2 '-dipyridylamine (dpa) and halogen ligands has been performed using crystallographic data retrieved from the Cambridge Structural Database. The mononuclear complexes were found to exist in octahedral, square-planar, and tetrahedral geometries. Analysis of the bite angles shows clear deviations from the expected 109.5(degrees) for tetrahedral complexes which have observable consequences on the geometry and reactivity of these complexes. A density functional theoretical (DFT) study at the B3LYP/6-31+G-(d,p) level on a series of tetrahedrally coordinated cobalt-(II), nickel-(II), copper-(II), and zinc-(II) complexes bearing dpa and halogen ligands shows that the computed gas phase geometric parameters are remarkably close to those of the experimental values. DFT calculated global chemical reactivity descriptors (chemical hardness, chemical potential, electrophilicity, electron affinity, and ionization energy) show that the energy and reactivity of the tetrahedrally coordinated complexes can be fine-tuned with an appropriate halogen ligand for various applications.