Ten compounds of the IIB metal halide/pseudohalide-bipy system, β-[ZnBr 2 (4,4′-bipy)] n (1), [Cd 2 Br 5 (4,4′-bipyH) 2 ]-(CdBr 3 ) (2), [Cd 3 Br 6 (4,4′-bipy)] n (3), [CdI 2 (4,4′-bipy)] n (4), (HgI 2 ) 2 (4,4′-bipy) (5), [Hg(CN) 2 (4,4′-bipy)(H 2 O) 2 ] n (6), HgCl 2 (2,2′bipy) (7), [HgCl 2 (2,2′-bipy)]‚2HgCl 2 (8), [Hg 3 Br 6 (2,2′-bipy)]‚HgBr 2 (9), and [HgI 2 (2,2′-bipy)]‚HgI 2 (10), have been synthesized via hydro(solvo)thermal and solid-state reactions; except for 4, all the other compounds are reported for the first time. Compound 1 features a 1-D zigzag chain, based on tetrahedral zinc atoms bridged by 4,4′-bipy molecules and terminally coordinated by two bromine atoms. The chains are linked by hydrogen bonds and π‚‚‚π interactions to form a 2-D sheet. Compound 2 possesses dinuclear [Cd 2 Br 5 (4,4′-bipyH) 2 ] + cations and CdBr 3anions. Compound 3 has a 2-D layered structure, constructed from novel triple chains and bridging 4,4′-bipy ligands. The triple chains contain edge-shared CdBr 6 and CdBr 5 N octahedra. In 4, the layers are formed by monochains and bridging 4,4′-bipy molecules. The monochains contain edge-shared CdI 4 N 2 octahedra. Compound 5 features a discrete structure with a 4,4′-bipy ligand bridging two HgI 2 moieties. Compound 6 has a 1-D zigzag chain, containing octahedral mercury atoms and bridging 4,4′-bipy molecules. In 7 and 8, mercury atoms are tetrahedrally coordinated to two chlorine atoms and two nitrogen atoms. In 9, 2-, 3-, 4-, and 5-coordinated mercury atoms coexist, whereas in 10, the mercury atoms are only 2-and 4-coordinated. Photoluminescence investigations reveal that the compounds display strong emissions in the blue/green/yellow regions, which, in combination with the molecular orbital (MO) calculations of 1, 5, and 7, leads us to conclude that the emissions originate from a ligand-to-ligand charge-transfer (LLCT) transition. The solid-state diffuse reflectance spectra, IR, and TG-DTA are also presented.
