N₂ Activation in Ni^I–NN–Ni^I Units: The Influence of Alkali Metal Cations and CO Reactivity

Abstract

Abstract After single electron reduction of the dinitrogen complex [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( I ) with KC 8 , reaction of the resulting compound K[L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( II ) with sodium sand yields KNa[L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( 1 ), which contains two different alkali metal ions. Treatment of I with two equivalents of sodium sand leads to the symmetric complex Na 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( 2 ). Complexes 1 and 2 were investigated by single crystal X‐ray diffraction analysis as well as by Raman spectroscopy, and the results were compared with the data of K 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( III ), which contains two K + ions. Thus, it became obvious that the nature of the alkali metal ion M in compounds M 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] has hardly any influence on the degree of NN bond activation. Furthermore, it was shown that treatment of the dinickel(I) complex III with CO leads to the dinickel(0) compound K 2 [L t Bu Ni(CO)] 2 ( 4 ) and N 2 . Reaction of the unreduced dinickel(I) complex I with CO leads to a more simple replacement of the N 2 ligand and formation of [L t Bu Ni(CO)] ( 3 ).