New cadmium(II) halides modified by N-heterocyclic molecules

• Structure types of 1:1 adducts of MX2 and N,N′-donor ligands were studied.
• Structures of dabco-templated halo(pseudohalo)cadmates were investigated.
• Factors of controlling protonated degree of N-heterocyclic molecules were discussed.
• Photoluminescence behavior of [CdI2(bpp)] was investigated.

Under the solvothermal condition, the reaction of CdI2, bpp and KI at pH = 8 afforded compound [CdI2(bpp)] (bpp = 1,2-bis(4-pyridyl)propane) 1, while at the ambient conditions, the reactions of CdX2, dabco and KX at pH = 4–5 produced compounds [H2(dabco)][CdBr4]·H2O (dabco = 1,4-diazabicyclo[2,2,2]octane) 2 and [(Hdabco)CdI3] 3. X-ray single-crystal diffraction analysis reveals that (i) compound 1 possesses a one-dimensional (1-D) zigzag chain structure. The large volume bpp molecule controls the Cd2+ ion to adopt a tetrahedral geometric configuration; (ii) both compounds 2 and 3 are mononuclear. Interestingly, in the same pH environments, dabco was in situ diprotonated in compound 2, while dabco was in situ monoprotonated in compound 3. The templating effect as well as the X− ion maybe plays a key role in the protonated degree for dabco in an acidic environment. The photoluminescence analysis indicates that compound 1 emits the strong green light, which should be attributed to a combination of two types of charge transfers: the charge transfer between Cd2+ and I−; the charge transfer between Cd2+ and bpp.

Structural characterization of three new Cd(II) compounds were reported including 1:1 adduct of CdI2 and bpp, and dabco-templated bromocadmate and iodocadmate.Figure optionsDownload as PowerPoint slide