Metal-organic framework supported single-site nickel catalysts for butene dimerization

•Experimental and theoretical study of Ni sites at under-coordinated nodes of UiO-66.•Single Ni cations and oxo complexes with few cations catalyze 1-butene dimerization.•Monomeric Ni sites are active and selective to linear and mono-branched C8 isomers.•Aggregated Ni cations show lower activity and lead to oligomerization of C8 isomers.•Theoretical, kinetic, and spectroscopic analyses indicate a Cossee-Arlman mechanism.