Metal-to-Ligand Ratio Effect on the Size of Copper Iodide and Copper Bromide Clusters in 1,4-Bis(cyclohexylthio)butane-Spanned Coordination Polymers

The CuX salts (X = Br, I) react with 1,4-bis(cyclohexylthio)butane, L2, in a 1:1 ratio to form the corresponding isostructural and weakly luminescent 1D coordination polymers [(Cu2X2)(mu-L2)(2)] (n) (X = Br, 4; X = I, 3) as determined by X-ray crystallography. The previously reported reaction of CuI with 1,4-bis(phenylthio)butane, L1, in a 2:1 metal-to-ligand ratio provides a 2D polymer [(Cu4I4)(mu-L1)(2)] (n) , 1 (Knorr et al., Dalton Trans 38:948-955, 2009), where the Cu4I4 unit exhibits the common cubane structure and an intense luminescence centered at 555 and 565 nm respectively at 298 and 77 K. When CuI reacts with L2 in a 2:1 metal-to-ligand ratio, a new material 2 is formed but no X-ray structure was obtained. The intense and characteristic luminescence of polymer 2 is strongly indicative of the formation of the cubane Cu4I4 unit. The new materials have been characterized by solid-state UV-Vis rasing-angle transmittance spectroscopy, luminescence spectroscopy and emission lifetime measurements.