Synthesis, structure and luminescence behaviour of a mononuclear cadmium(II) dicyanamide and a coordination polymer of mercury(II) dicyanamide containing 2,2′-dipyridylamine (dpaH) as end-capping ligand/anion of dpaH as binucleating bridge. Variance in co

A mononuclear compound [Cd(dpaH)2(dca)2] (1) and a tetranuclear based 2D coordination polymer [Hg4(dpa)4(dca)4]n (2) [dpaH = 2,2′-dipyridylamine, dpa = anion of dpaH, dca = dicyanamide] have been synthesized and characterized. X-ray structural analyses reveal that cadmium(II) center in 1 has a distorted octahedral geometry with a CdN6 chromophore ligated through two bidentate neutral dpaH units along with two nitrile N atoms of two terminally bound dca units in mutual cis orientation. Each of the four independent mercury(II) centers in 2 adopts a distorted trigonal bipyramidal environment coordinated by two pyridine N atoms of two different anionic dpa ligands, two nitrile N atoms of two μ1,5 bridged dca units and the fifth position is occupied by the amide N of one dpa. Cooperative intermolecular N–H···N and C-H···N hydrogen bondings promote dimensionality in 1. The compounds display intraligand 1(π–π∗) fluorescence in DMF solutions at room temperature.