Crystal Growth, Structural Motifs, and Optical Properties of Molecular and Polymeric Cerium Halide Materials

A series of seven compounds, Ce2Br6(CH3OH)8 (1), Ce2Br6(C2H5OH)8 (2), CeCl3(CH3OH)2(H2O) (3a), CeCl3(CH3OH)2(H2O) (3b), CeBr3((CH3)2CHOH)2(H2O) (4), Ce4Br10((CH3)2CHOH)10 (H2O)2(OH)2 (5), and CeCl3((CH3)2CHOH)2(H2O) (6) were synthesized via slow evaporation of CeBr3 or CeCl3 dissolved in an alcohol. This series structurally consists of two dimers, four polymeric chains, and one tetramer. The presence of water and/or hydroxide ions during synthesis profoundly affects the product structure by enhancing the formation of bridging halides, thus leading to polymeric rather than molecular structures. Each of the polymeric chains (3a, 3b, 4, 6) formed in response to the presence of water, to which cerium will preferentially coordinate over an alcohol. The tetrameric compound 5 formed in response to the presence of both water and hydroxide ions. These seven compounds, six of which are new compounds, demonstrate the diversity of these seemingly simple materials, which are described herein and were analyzed for their general trends in structure preferences and bond distances. The luminescent properties of compounds 1 and 2 are discussed and contrasted with that of CeBr3.