A Series of 4- and 5‑Coordinate Ni(II) Complexes: Synthesis, Characterization, Spectroscopic, and DFT Studies
journal contributionposted on 03.07.2018, 16:22 authored by Jack Ghannam, Talal Al Assil, Trey C. Pankratz, Richard L. Lord, Matthias Zeller, Wei-Tsung Lee
A series of four- and five-coordinate Ni(II) complexes CztBu(PyriPr)2NiX (1–3 and 1·THF–3·THF), where X = Cl, Br, and I, were synthesized and fully characterized by NMR and UV–vis spectroscopy, X-ray crystallography, cyclic voltammetry, and density functional theory calculations. The solid-state structures of 1–3 reveal rare examples of seesaw Ni(II) complexes. In solution, 1–3 bind reversibly to a THF molecule to form five-coordinate adducts. The electronic transitions in the visible region (630–680 nm), attributed to LMCT bands, for 1 → 3 exhibit a bathochromic shift. The thermochromic tendency of the five-coordinate complexes implies the loss of THF coordination at elevated temperatures. Finally, the electronic properties of all Ni(II) complexes were studied by time-dependent density functional theory calculations to characterize the nature of the excited states.