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 ( TCHP 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 [( TCHP NON)Ca(D) n ] (D = THF, n = 2, 3; D = toluene, n = 1, 4). Reduction of 4 with 5% w/w K/KI under an N 2 atmosphere gave the first well-defined, hetero-bimetallic s-block complex of activated dinitrogen, [{K( TCHP NON)Ca} 2 (μ-η 2 :η 2 -N 2 )] 5, presumably via a transient calcium(I) intermediate.