Reductive activation of N 2 using a calcium/potassium bimetallic system supported by an extremely bulky diamide ligand.

An extremely bulky xanthene bridged diamide ligand (NON = 4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene) has been developed and used to prepare two monomeric diamido-calcium complexes [(NON)Ca(D)] (D = THF, = 2, 3; D = toluene, = 1, 4). Reduction of 4 with 5% w/w K/KI under an N atmosphere gave the first well-defined, hetero-bimetallic s-block complex of activated dinitrogen, [{K(NON)Ca}(μ-η:η-N)] 5, presumably a transient calcium(I) intermediate.