Syntheses, structures and magnetic properties of μ1,5 dicyanamide bridged coordination polymers of copper(II) and nickel(II) containing a tetradentate N-donor Schiff base

One neutral [Cu2(enbzpy)(dca)4]n (1) and one polycationic [Ni(enbzpy)(dca)]n(ClO4)n (2) [enbzpy = N,N′-(bis-(pyridin-2-yl)benzylidene)ethane-1,2-diamine; dca = dicyanamide] 1D coordination polymers are synthesized and characterized. X-ray structural analyses reveal each copper(II) center in 1 to adopt a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the Schiff base behaving as a binucleting bis(bidentate) ligand and three nitrile N atoms of one terminal and two single μ1,5 dca units leading to a 1D ladder structure. In 2, each nickel(II) center has a distorted octahedral coordination environment with an NiN6 chromophore bound by four N atoms of enbzpy through tetradentate chelation and two nitrile N atoms of two different single bridged μ1,5 dca units; the latter connects other neighboring metal centers in a non-ending fashion affording a 1D chain. Variable-temperature magnetic susceptibility measurements of 1 and 2 show weak antiferromagnetic interactions among the metal centers through μ1,5 dca bridges.