Preparation and Structure Determination of SrMn 2 (PO 4 ) 2 and Redetermination of b ′‐Mn 3 (PO 4 ) 2

Pale rose single crystals of SrMn 2 (PO 4 ) 2 were obtained from a mixture of SrCl 2  · 6 H 2 O, Mn(CH 3 COO) 2 , and (NH 4 ) 2 HPO 4 after thermal decomposition and finally melting at 1100 °C. The new crystal structure of strontium manganese orthophosphate [P‐1, Z = 4, a = 8.860(6) Å, b = 9.054(6) Å, c = 10.260(7) Å, α = 124.27(5)°, β = 90.23(5)°, γ = 90.26(6)°, 4220 independent reflections, R1 = 0.034, wR2 = 0.046] might be described as hexagonal close‐packing of phosphate groups. The octahedral, tetrahedral and trigonal‐bipyramidal voids within this [PO 4 ] packing provide different positions for 8‐ and 10‐fold [SrO x ] and distorted octahedral [MnO 6 ] coordination according to a formulation Mn $^tbpy_1$ Mn $^tet_1$ Mn $^oct_2$ Sr $^oct_2$ (PO 4 ) 4 . Single crystals of β′‐Mn 3 (PO 4 ) 2 (pale rose) were grown by chemical vapour transport (850 °C → 800 °C, P/I mixtures as transport agent). The unit cell of β′‐Mn 3 (PO 4 ) 2 [P2 1 /c, Z = 12, a = 8.948(2) Å, b = 10.050(2) Å, c = 24.084(2) Å, β = 120.50°, 2953 independent reflections, R1 = 0.0314, wR2 = 0.095] contains 9 independent Mn 2+ . The reinvestigation of the crystal structure led to distinctly better agreement factors and significantly reduced standard deviations for the interatomic distances.