Abstract
La~3~FMo~4~O~16~ crystallizes in the triclinic crystal system with space group P$\bar {1}$ [a = 724.86(2) pm, b = 742.26(2) pm, c = 1469.59(3) pm, Ξ± = 101.683(2)Β°, Ξ² = 102.118(2)Β°, Ξ³ = 100.279(2)Β°] with two formula units per unit cell. The three crystallographically independent La^3+^ cations show a coordination number of nine each, with one F^β^ and eight O^2β^ anions forming distorted monocapped square antiprisms. The fluoride anion is coordinated by all three lanthanum cations to form a nearly planar triangle. Besides three crystallographically independent tetrahedral [MoO~4~]^2β^ units, a fourth one with a higher coordination number (CN = 4 +1) can be found in the crystal structure, forming a dimeric entity with a formula of [Mo~2~O~8~]^4β^ consisting of two edgeβconnected square pyramids. Several spectroscopic measurements were performed on the title compound, such as infrared, Raman, and diffuse reflectance spectroscopy. Furthermore, La~3~FMo~4~O~16~ was investigated for its capacity to work as host material for doping with luminescent active cations, such as Ce^3+^ or Pr^3+^. Therefore, luminescence spectroscopic as well as EPR measurements were performed with doped samples of the title compound. Both the pure and the doped compounds can be synthesized by fusing La~2~O~3~, LaF~3~ and MoO~3~ (ratio 4:1:12; ca. 1β% CeF~3~ and PrF~3~ as dopant, respectively) in evacuated silica ampoules at 850 Β°C for 7 d.