Structural and magnetochemical studies of Ba5Mn3F19 and related compounds A(5)(II)M(3)(III)F(19)

Single crystal structure determinations by X-ray methods were performed at the following compounds, crystallizing tetragonally body-centred (Z = 4): S r5V3F19 (a = 1423.4(2), c = 728.9(1) pm), Sr5Cr3F19 (a = 1423.5(2), c = 728 .1(1) pm), Ba5Mn3F19 (a = 1468.9(1), c = 770.3(1) pm), Ba5Fe3F19 (a = 1483. 5(1), c = 766.7(1) pm), and Ba5Ga3F19 (a = 1466.0(2), c = 760.1(2) pm). Onl y Ba5Mn3F19 was refined in space group I4cm (mean distances for elongated o ctahedra Mn1-F: 185/207 pm equatorial/axial; for compressed octahedra Mn2-F : 199/182 pm), the remaining compounds in space group I4/m. In all cases th e octahedral ligand spheres of the M1 atoms showed disorder, the [M1F(6)] o ctahedra being connected into chains in one part of the compounds and into dimers in the other. The magnetic properties of the V, Cr and Mn compounds named above and of Pb5Mn3F19 and Sr5Fe3F19 as well were studied the results are discussed in context with the in part problematic structures.