Anion-dependent structural diversity of cadmium(II) complexes: synthesis, crystal structures, luminescence properties, and unusual C-H/σ supramolecular interactions involving σ-aromatic M 2 X 2 cores

The complexes are [Cd 2 (L) 2 (μ-Cl) 2 ](ClO 4 ) 2 ( 1 ), [Cd 2 (L) 2 (μ-Br) 2 ](ClO 4 ) 2 ( 2 ), [Cd(L)I](ClO 4 ) ( 3 ), and [Cd(L)(NCS) 2 ] ( 4 ). L exhibits the same coordination mode in 1 – 4 .

The radius of each anion plays a role in affecting the structures and luminescent intensities of the final products. CdCl 2 , CdBr 2 , and CdI 2 react with L to produce chloride or bromido-bridged binuclear complexes and mononuclear iodido complex, respectively, whereas an unusual mononuclear trigonal prismatic (TP) 4 is obtained when thiocyanate was used as a coligand. Photoluminescence properties of all the complexes show that the trend of fluorescence intensity is 1 > 4 > 2 > 3 .