No abstract

Reported N2 complexes of cobalt do not have substantial weakening of the N−N bond. Using diketiminate ligands to enforce three-coordinate geometries, we have synthesized several novel CoNNCo complexes. In formally univalent complexes, cobalt is poorer than iron at weakening the N−N bond, but in formally zerovalent complexes, cobalt and iron give similar N−N weakening. The weakening is due to cobalt-to-N2 π-backbonding, and potassium cations pull more electron density into N2. These results show that the low coordination number of a trigonal-planar geometry is impetus enough to make even the electronegative cobalt weaken the N−N bond of N2.