Syntheses, structures and properties of two pentacoordinated μ1,5 bridged dinuclear metal(II)-dicyanamide (Mdca; M = Cu and Cd) compounds containing a tailored tetradentate bifunctional polyamine

Two pentacoordinated dinuclear compounds of the type [M2(dca)(L)2](ClO4)3·H2O [M = Cu (1), Cd (2); L = N,N′-bis(3-aminopropyl)-1,2-ethanediamine; dca = dicyanamide] have been prepared and characterized on the basis of microanalytical, spectroscopic and other physicochemical properties. Structures of 1 and 2 are solved by single crystal X-ray diffraction measurements. Structural study reveals that in both compounds each pentacoordinated metal(II) center adopts a distorted square pyramidal geometry with an MN5 chromophore coordinated by four N atoms of the polyamine (L) in the basal plane and nitrile N atom of single μ1,5 bridged dca in the apical position. The dinuclear units in 1 and 2 are engaged in weak intermolecular O–H⋯O, N–H⋯O, N–H⋯N and C–H⋯O hydrogen bondings resulting in 3D network structures in which the crystalline water molecules and counter ions are embedded. Variable-temperature magnetic susceptibility measurement of 1 indicates weak antiferromagnetic interactions among the metal centers.

► Compounds of the type [M2(dca)(L)2](ClO4)3·H2O [M = Cu (1), Cd (2)] are isolated.
► Two M(II) centers bound by four N atoms of L are linked through μ1,5 dca bridge.
► Versatile intermolecular hydrogen bonds play an important role in 3D crystal packing.
► TG-DTA analyses show their thermal stabilities and decomposition patterns.
► 1 shows small antiferromagnetic interactions mediated through μ1,5 dca bridge.