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

After single electron reduction of the dinitrogen complex L^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] ( I ) with KC₈, reaction of the resulting compound KL^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] ( II ) with sodium sand yields KNaL^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] ( 1 ), which contains two different alkali metal ions. Treatment of I with two equivalents of sodium sand leads to the symmetric complex Na₂L^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] ( 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 K₂L^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] ( III ), which contains two K⁺ ions. Thus, it became obvious that the nature of the alkali metal ion M in compounds M₂L^tBuNi(μ‐η¹:η¹‐N₂)NiL^tBu] 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 K₂L^tBuNi(CO)]₂ ( 4 ) and N₂. Reaction of the unreduced dinickel(I) complex I with CO leads to a more simple replacement of the N₂ ligand and formation of L^tBuNi(CO)] ( 3 ).