Abstract/Summary

Single crystals of (C9H7N2)3Bi2I9, tris(2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepin-1-ium) tris(μ2-iodo)-bis(tri-iodobismuth(III)), were prepared by a solvothermal method, heating a mixture of BiI3, KI, 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) and ethanol at 170°C for six days. The asymmetric unit of the title compound, which crystallises in the monoclinic space group P21/c, contains one [Bi2I9]3- anion and three protonated DBUH+ moieties. The dinuclear [Bi2I9]3- anions, which are composed of face-sharing BiI6 3- octahedra, are packed in columns parallel to the [010] direction, and separated by protonated DBUH+ moieties. The optical band gap of (C9H7N2)3Bi2I9 is 2.1 eV.