Synthesis, crystal structure, magnetic behavior and thermal property of three polynuclear complexes: [M(dca)2(H2O)2]n · (hmt)n [M = Mn(II), Co(II)] and [Co(dca)2(bpds)]n [dca, dicyanamide; hmt, hexamethylenetetramine; bpds, 4,4′-bipyridyl disulfide]

Three μ1,5-dicyanamide bridged Mn(II) and Co(II) complexes having molecular formula [Mn(dca)2(H2O)2]n · (hmt)n (1), [Co(dca)2(H2O)2]n · (hmt)n (2) and [Co(dca)2(bpds)]n (3) [dca = dicyanamide; hmt = hexamethylenetetramine; bpds = 4,4′-bipyridyl disulfide] have been synthesized and characterized by single crystal X-ray diffraction study, low temperature (300–2 K) magnetic measurement and thermal behavior. The X-ray diffraction analysis of 1 and 2 reveals that they are isostructural, comprising of 1D coordination polymers [M(dca)2(H2O)2]n [M = Mn(II), Co(II) for 1 and 2, respectively] with uncoordinated hmt molecules located among the chains. The [M(dca)2(H2O)2]n chains and the lattice hmt molecules are connected through H-bonds resulting in a 3D supramolecular architecture. The octahedral N4O2 chromophore surrounding the metal ion forms via two trans located water oxygens and four nitrogens from four nitrile dca. Complex 3 is a 1D chain formed by two μ1,5-dca and one bridging bpds. The octahedral N6 coordination sphere surrounding the cobalt ions comprises four nitrogens from dca and two from bpds. Low temperature magnetic study indicates small antiferromagnetic coupling for all the complexes. Best fit parameters for 1: J = −0.17 cm−1, g = 2.03 with R = 6.1 × 10−4; for 2, J = −0.50 cm−1, and for 3, J = −0.95 cm−1.