Acetonitrile Activation Promoted by Divalent Nickel Species with Bicyclic Guanidinate Ligands

Three compounds are described from reactions of divalent nickel species and bicyclic guanidinate ligands. These compounds encompass a variety of nuclearities with one being triangular and having an hour-glass shape and the formula Ni₃(tbn)₆·2LiCl, 1, where tbn is a bicyclic guanidinate anion with fused 5/6 membered rings. A dinuclear compound (??²-Imeth)Ni(??-tbo)]₂Cl₂, 2, contains two fused 5/5 membered rings (tbo) that bridge two divalent nickel atoms and also contains a chelating unit in each metal center. The neutral Imeth (1-(2,3,5,6-tetrahydro-1H-imidazo1,2-a]imidazol-1-yl)ethanimine) is an imino-containing ligand produced by the Ni(II) catalyzed reaction of tbo with acetonitrile. A mononuclear species, (??²-hpp)Ni(hpp)(Hhpp)]Cl, 3, is obtained from reaction of NiCl₂ with the bicyclic guanidinate ligand with two fused six-member rings in contact with moisture. In all compounds each of the Ni atoms has a local square-planar arrangement common in d⁸ species.