Two potassium gadolinium(III) ortho-thiophosphates(V): K3Gd3[PS4]4 and K9Gd[PS4]4

Abstract K 3 Gd 3 [PS 4 ] 4 and K 9 Gd[PS 4 ] 4 form by the reaction of gadolinium, red phosphorus and sulfur with appropriate portions of K 2 S at 950 °C for 14 days in evacuated torch-sealed silica ampoules. Both structures contain isolated [PS 4 ] 3− tetrahedra ( d (P–S) = 201–208 pm) and eightfold coordinated Gd 3+ cations ( d (Gd–S) = 278–307 pm). K 3 Gd 3 [PS 4 ] 4 which is isotypic with K 3 Ho 3 [PS 4 ] 4 crystallizes monoclinically in the space group C 2/ c ( a  = 1601.87(9) pm, b  = 1162.48(6) pm, c  = 1452.39(8) pm, β  = 90.773(5)°; Z  = 4). The structure is built up of a three-dimensional network of edge-sharing {Gd[PS 4 ] 4 } 9− polyhedra with the K + cations located in channels along [1 1 0]. K 9 Gd[PS 4 ] 4 which is pseudo-isotypic with K 9 Ce[PS 4 ] 4 crystallizes also monoclinically but in the space group C 2 ( a  = 2021.93(12) pm, b  = 979.35(6) pm, c  = 1747.08(11) pm, β  = 115.661(5)°; Z  = 4) as inversion-twinned crystals. In the crystal structure, one-dimensional chains of edge-sharing [GdS 8 ] 12− polyhedra can be found which are separated by the potassium cations. Thereby three of the four Gd 3+ positions (two times 2 a , two times 2 b ) are partially inhabited by K + cations in amounts of about 87, 79 and 23%, so that statistically even isolated {Gd[PS 4 ] 4 } 9− units must occur.