Synthesis and Characterisation of Iodobismuthates Containing N-substituted 1,4-Diazabicyclo[2.2.2]octane

Two new hybrid iodobismuthates, [C8H17N2][C10H22N2][BiI6] (1) and [C6H12N2](0.5)[C10H22N2](3.5)[Bi2I10][Bi2I9] (2), have been prepared by solvothermal synthesis in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) and ethanol. Both compounds have been characterized by single-crystal and powder X-ray diffraction, infrared and UV-Vis spectroscopies and thermogravimetric analysis. Structure determination reveals that the crystal structure of 1 contains mononuclear [BiI6](3-) anions, whilst 2 contains an unusual combination of dinuclear anions, [Bi2I9](3-) and [Bi2I10](4-), consisting of two edge- and two face-sharing [BiI6](3-) octahedra, respectively. Mono- and diethylated derivatives of DABCO, which are formed in situ under solvothermal conditions, act as countercations and are located between the discrete anions. The optical band gaps of 1 and 2, which are 2.29(1) and 2.03(2) eV respectively, are consistent with the red color of these compounds, and are comparable to the band gaps measured for other iodobismuthates containing discrete anions. [GRAPHICS] .