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) A Ê , b = 9.054(6) A Ê , c = 10.260(7) A Ê , a = 124.27(5)°, b = 90.23(5)°, c = 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 b'-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 b'-Mn 3 (PO 4 ) 2 [P2 1 /c, Z = 12, a = 8.948(2) A Ê , b = 10.050(2) A Ê , c = 24.084(2) A Ê , b = 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.