2D Homologous Series SrFMBiS (M = Pb, AgBi; = 0, 1) and Commensurately Modulated SrFBiS.

We report three new mixed-anion two-dimensional (2D) compounds: SrFPbBiS, SrFAgBiS, and SrFBiS. Their structures as well as the parent compound SrFBiS were refined using single-crystal X-ray diffraction data, with the sequence of SrFBiS, SrFPbBiS, and SrFAgBiS defining the new homologous series SrFMBiS (M = Pb, AgBi; = 0, 1). SrFBiS has a different structure, which is modulated with a vector of 1/3* and was refined in superspace group 2/(0β0)00 as well as in the 1 × 3 × 1 superstructure with space group 2/ (with similar results). SrFBiS features hexagonal layers of alternating [SrF] and [BiS], and the modulated structure arises from the unique ordering pattern of Sr cations. SrFPbBiS, SrFAgBiS, and SrFBiS are semiconductors with band gaps of 1.31, 1.21, and 1.85 eV, respectively. The latter compound exhibits room temperature red photoluminescence at ∼700 nm.