A series of compounds were discovered which have the generalized formula . Examination of single crystals of showed it to have hexagonal symmetry with and . Five of the seven compounds studied (, , , , and ) were isostructural with , and the seventh, , had optical properties closely related to the group. With the exception of all of the compounds exhibited a broad band blue fluorescence, with an intensity maximum near 4800Aå, when excited by 2537Aå radiation. By contrast, showed a weak orange fluorescence, more easily excited by 3650Aå radiation. Emission, absorption, and excitation data are presented.