A tetranuclear nickel(II) cluster: bis[μ3-2,6-bis(methylamino)pyridine(2-)-κ4N2:N1,N6:N6]bis[μ3-2,6-bis(methyl-amino)pyridine(1-)-κ3N1:N2:N2]-dichloridotetranickel(II)

The title compound, [Ni-4(C7H9N3)(2)(C7H10N3)(2)Cl-2], was obtained from a reaction in which 2,6-dimethylaminopyridine, in the presence of methyllithium used to deprotonate the organic ligand precursor, was added to NiCl2 during an attempt to synthesize a linear trinuclear nickel chain. During this reaction, two equivalents of the amine were fully deprotonated, forming dianions, and the three N atoms coordinate to Ni centers. The other two equivalents of the amine were only partially deprotonated, giving monoanions in which only two N atoms coordinate to Ni centers. In this tetranuclear complex, two of the four Ni atoms have square-planar coordination and are bonded to four N donors, while the other two are in a distorted tetrahedral geometry, with three coordination sites occupied by N donors and the fourth by a Cl atom. The molecule is noncentrosymmetic but the crystal structure is racemic.