A series of four- and five-coordinate Ni(II) complexes Cz(tBu)(Pyr(iPr))(2)NiX (1-3 and 1 center dot THF-3 center dot 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.