Appreciable Ni⋯O interactions at distances almost equal to the sum of the van der Waals radii of the two atoms

Two new entities [Co(NiL)2(SCN)2]n (1) and [Mn(NiL)2(NCS)2]n (2) were prepared by using a macrocyclic oxamido mononuclear complex ligand NiL, and characterized by X-ray single crystal analyses. L denotes the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Ni⋯O contacts (3.092 Å) almost equal to the sum of the van der Waals radii of the two atoms were observed both in 1 and 2, and IR spectra support that appreciable coordination occurs at such long contacts. 1 and 2 are 1D coordination polymers incorporating bimetallamacrocycles with the very long Ni⋯O coordination bonds as a kind of linking interaction.