Cobalt–Magnesium and Cobalt–Calcium Heterotrimetallic Dinitrogen Complexes

Abstract

AbstractWe report the use of alkaline earth metals magnesium and calcium for the reduction of the cobalt(II) complex [ i Pr2NN]Co(μ-Cl)2Li(thf)2 [ i Pr2NN = 2,4-bis(2,6-diisopropylphenylimido)pentyl] that resulted in heterotrimetallic dinitrogen complexes with a rare example of a [Co–N2–M–N2–Co] core where M = Mg and Ca. The dinitrogen ligands in these new complexes showed weakened N–N bonds, as judged by infrared spectroscopy, and the crystal structures of the complexes were illustrated by X-ray crystallography. These cobalt complexes can be isolated as pure solids that are stable in solutions of non-coordinating solvents such as n-pentane or cyclohexane, as well as tetrahydrofuran. These results demonstrate the correlation between the binding mode of the Lewis acid and N–N weakening in heterotrimetallic dinitrogen complexes.