The Quaternary Arsenide Oxides Ce Au As O and Pr Au As O

Z. Naturforsch. 2016; 71(12)b: 1245–1252

Timo Bartsch, Rolf-Dieter Hoffmann and Rainer Pöttgen*

The quaternary arsenide oxides Ce9Au5–xAs8O6 and

Pr9Au5–xAs8O6 DOI 10.1515/znb-2016-0160 and Ag+ and this is possible with uranium and especially Received July 19, 2016; accepted July 26, 2016 thorium. Electronic structure calculations [14] show sub- stantial covalent bonding within the [Th O ] and [Cu Pn ] Abstract: The quaternary gold arsenide oxides 2 2 2 2 layers which are held together by ionic interactions. The Ce Au As O and Pr Au As O were synthesized from 9 5−x 8 6 9 5−x 8 6 charge transfers range from 1.94 to 2.08 e−, much smaller the rare earth elements (RE), rare earth oxides, arsenic than expected from a formal charge splitting (Th O )4+ and gold powder at maximum annealing temperatures 2 2 (Cu Pn )4−. of 1173 K. The structures were refined from single crys- 2 2 Polycrystalline and single crystalline UCuPO samples tal X-ray diffractometer data: Pnnm, a = 1321.64(6) pm, show a high Néel temperature of T = 220 K [8–10]. The b = 4073.0(3), c = 423.96(2), wR2 = 0.0842, 3106 F2 values, N spin alignment (AF I type; + − + −) was determined from 160 variables for Ce Au As O and Pnnm, a = 1315.01(4), 9 4.91(4) 8 6 neutron diffraction data. Isotypic NpCuPO [10] was b = 4052.87(8), c = 420.68(1) pm, wR2 = 0.0865, 5313 F2 obtained by reaction of neptunium metal, CuO and phos- values, 160 variables for Pr Au As O . They represent 9 4.75(1) 8 6 phorus. Resistivity measurements indicate long-range a new structure type and show a further extension of magnetic ordering around 90 K which has been confirmed pnictide oxide crystal chemistry. A complex polyanionic by DFT calculations. gold arsenide network [Au As ]15− (with some disorder in 5 8 Besides the ZrCuSiAs-type phases, U Cu P O (formerly the gold substructure) is charge compensated with poly- 2 2 3 reported as a ternary phosphide U Cu P [15–18] with a cationic strands of condensed edge-sharing O@RE and 4 4 7 4/4 half-occupied phosphorus site) and U Cu As O [19] have O@RE tetrahedra ([RE O ] 12+) as well as RE3+ cations in 2 2 3 4/3 4 3 2 been reported. These structures contain similar layers cavities. of condensed OU4/4 and CuPn4/4 tetrahedra. U2Cu2P3O

Keywords: arsenide oxides; crystal structure. orders antiferromagnetically at TN = 146 K [16]. Resistiv- ity measurements on single crystals (grown with iodine as transport agent) show distinctly anisotropic transport 1 Introduction behavior [17]. The rare earth-based phosphide oxides RE3Cu4P4O2 (RE = La–Nd, Sm) [20–23] and arsenide oxides RE Cu As O The crystal chemistry of pnictide (Pn) oxides [1–5] is domi- 3 4 4 2 (RE = La–Pr) [24] also exhibit layers of condensed CuPn nated by compounds with the ZrCuSiAs-type structure. 4/4 tetrahedra, however, they are related by a mirror plane, More than 150 phases with this structure type have been leading to the formation of P and As dumbbells with reported. The most prominent examples are the super- 2 2 single bond character. Incorporation of purely ionic LaOCl conductors LaFeAsO F (x = 0.05–0.12; T = 26 K) [6] and 1−x x C slabs into La Cu P O and La Cu As O was observed for SmFeAsO F (x = 0.1; T = 55 K) [7]. Besides the intensive 3 4 4 2 3 4 4 2 1−x x C La Cu P O Cl (≡ La Cu P O ⋅2LaOCl) [23] and isotypic studies on the iron based phases, such pnictide oxides have 5 4 4 4 2 3 4 4 2 La Cu As O Cl (≡ La Cu As O ⋅2LaOCl) [25], nicely extend- also been reported with manganese, cobalt, zinc or ruthe- 5 4 4 4 2 3 4 4 2 ing the structural chemistry of these pnictide oxides. nium [2]. Comparatively few representatives are known The gold-based pnictide oxides show different with the coinage metals, i.e. UCuPO [8–10], ThCuPO [11], crystal chemistry. Nd Au As O and Sm Au As O [26] ThAgPO [12, 13] and ThCuAsO [11]. For an electron-precise 10 3 8 10 10 3 8 10 are remarkable compounds with Au(I) in almost square- description one needs a tetravalent cation besides Cu+ planar coordination by arsenic dumbbells. These polyanionic layers are stacked and charge-compensated by

polycationic layers of condensed edge-sharing ORE4/4 *Corresponding author: Rainer Pöttgen, Institut für Anorganische tetrahedra. Almost trigonal-planar coordination of Au(I) und Analytische Chemie, Universität Münster, Corrensstrasse 30, by two P3− and one P 4− dumbbell (end-on) occurs in the 48149 Münster, Germany, e-mail: [email protected] 2 = Timo Bartsch and Rolf-Dieter Hoffmann: Institut für Anorganische phosphide oxides RE2AuP2O (RE La–Nd) [27, 28]. Both und Analytische Chemie, Universität Münster, Corrensstrasse 30, the polyanionic and the polycationic substructures are 48149 Münster, Germany one-dimensional and arranged in the motif of a hexagonal

1246 T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 rod packing, an entirely new motif in pnictide oxide struc- was obtained almost phase pure (see Fig. 1). The cerium tural chemistry. compound on the contrary could not be synthesized In continuation of our phase analytical studies of the without rare earth oxide and arsenide impurities. quaternary systems RE-Au-Pn-O we obtained well-shaped Suitable crystals for structure determination were single crystals of Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 from prepared via salt flux synthesis [29]. Polycrystalline

NaCl/KCl salt flux synthesis. The structural chemistry of RE9Au5−xAs8O6 (200–300 mg) and an equimolar NaCl/KCl these arsenide oxides is reported herein. mixture (~1 g) were sealed in evacuated silica ampoules, heated up to 1223 K (72 h, 100 K h−1), slowly cooled down to 773 K (2 K h−1) and finally to room temperature by shutting off the furnace. Slat-shaped single crystals 2 Experimental (especially for the praseodymium compound, see Fig. 2) with metallic luster could be isolated from the reaction 2.1 Synthesis mixture after dissolving the NaCl/KCl flux with deminer- alised water. Starting materials for the syntheses were cerium (Sigma- Aldrich, >99.9%), praseodymium (Sigma-Aldrich, >99.9%), cerium(IV) oxide (ChemPur, >99.99%), praseodymium 2.2 X-ray image plate data and data (III,IV) oxide (ChemPur, >99.9%), gold (Agosi, >99.9%) collections and arsenic granules (Ventron). Filings of cerium and praseodymium were prepared under dried paraffin oil (sodium The polycrystalline RE9Au5−xAs8O6 samples were charac- wire), washed with cyclohexane and stored under argon terized by Guinier powder patterns: Enraf Nonius FR 552 prior to synthesis. Argon was purified with titanium sponge camera, image plate system Fuji film, BAS-1800, CuKα1 (870 K), silica gel and molecular sieves. Gold powder was radiation and α-quartz (a = 491.30, c = 540.46 pm) as an obtained by dissolving gold pieces in aqua regia and sub- internal standard. The orthorhombic lattice parameters 3 sequent precipitation using (NH4)2Fe(SO4)2 · xH2O (VWR, (a = 1321.7(3), b = 4073.5(6), c = 423.9(1) pm, V = 2.2823 nm

>99%). Arsenic was resublimed, stored under argon and for the Ce9Au5−xAs8O6 and a = 1316.1(2), b = 4051.4(6), 3 pulverized prior synthesis. c = 421.1(1) pm, V = 2.2453 nm for the Pr9Au5−xAs8O6 Black, polycrystalline samples were prepared via sample) were deduced from least-squares refinements. mixing filings of the rare earth elements (RE), their Correct indexing was facilitated by intensity calculations oxides, gold powder and powder of arsenic in the molar with LazyPulverix [30]. 63 6 ratios 6:3:5:8 (Ce9Au5As8O6) and /11: /11:5:8 (Pr9Au5As8O6). Well-shaped single crystals of both compounds Amounts of 0.5 g were cold-pressed to pellets, sealed in were glued to thin quartz fibers using bees wax and first evacuated silica ampoules and heated in a resistance tested by Laue photographs on a Buerger camera (white furnace; first up to 873 K (24 h annealing) and finally molybdenum radiation, image plate technique, Fuji- at 1173 K (72 h annealing). Heating rates were 100 K h−1, film, BAS-1800). Intensity data were collected at ambient cooling was done by shutting off the furnace. Except for temperature by use of a Stoe StadiVari diffractometer a small impurity of elemental gold and with regard to the equipped with a Mo micro focus source and a Pilatus limit of detection via XRD, the praseodymium compound detection system. Due to a Gaussian-shaped profile of the

Fig. 1: Experimental (blue) and calculated (red) Guinier powder pattern (CuKα1 radiation) of Pr9Au4−xAs8O6.

T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 1247

3 Results and discussion

3.1 Structure refinements

Analyses of the four data sets revealed primitive orthorhombic lattices and the systematic extinctions were compatible with the centrosymmetric space group Pnnm. The starting atomic parameters were deduced with the Superflip algorithm [31] and the structures were refined 2 with Jana2006 (full-matrix least-squares on Fo ) [32] with anisotropic displacement parameters for the RE, Au and As atoms and isotropic ones for the oxygen atoms. Except for the partially occupied Au3 and Au4 sites, all positions were fully occupied within two standard deviations. The partial occupancies were refined as least-squares variables in the final cycles. The final difference Fourier syntheses were flat. The refined positional parameters, displacement parameters and interatomic distances are

exemplarily listed in Tables 2 and 3 for Pr9Au4.75(1)As8O6. The other compounds show slightly differing partial gold occupancies and these crystallographic data have been deposited. Further details of the crystal structure investiga- tions may be obtained from Fachinformationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany (fax: +49-7247-808-666; e-mail: crysdata@fiz-karlsruhe. de, http://www.fiz-karlsruhe.de/request_for_deposited_ data.html) on quoting the deposition numbers CSD-431599

(Ce9Au4.91As8O6), CSD-431600 (Pr9Au4.75As8O6), CSD-431601

(Pr9Au4.86As8O6), and CSD-431602 (Pr9Au4.87As8O6).

Fig. 2: Single crystals of Pr9Au5−xAs8O6 mounted on quartz fibers.

3.2 Crystal chemistry X-ray source, scaling was applied along with the numeri- cal absorption corrections. Details of the data collections The quaternary arsenide oxides Ce9Au5−xAs8O6 and and the structure refinements are listed in Table 1. Pr9Au5−xAs8O6 show new structural motifs in the crystal chemistry of pnictide oxides. Besides the tetragonal arse-

nides Nd10Au3As8O10 and Sm10Au3As8O10 [26] and polytypic

2.3 EDX data Ca10(FeAs)10(Pt3As8) [33, 34] they are among the structurally most complex phases in this family of materials.

The single crystals measured on the diffractometer were Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 crystallize with their own analyzed semi-quantitatively using a Zeiss EVO MA10 structure type, space group Pnnm, Pearson symbol oP116 29 scanning electron microscope with CeO2, PrF3, Au, InAs and Wyckoff sequence g . and SiO2 as standards. No impurity elements heavier than A projection of the Pr9Au5−xAs8O6 structure along the sodium (detection limit of the instrument) were observed. short unit cell axis is presented in Fig. 3. We start the The experimentally determined RE:Au:As ratios were in crystal chemical discussion with the cationic unit. The close agreement with the compositions obtained from the six crystallographically independent oxygen atoms have structure refinements. The oxygen content could not be distorted tetrahedral praseodymium coordination with a obtained reliably due to the limitation of the instrument’s broad range of O–Pr distances from 225 to 243 pm. These resolution. six OPr4 tetrahedra are condensed via common edges in b

1248 T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6

Table 1: Crystal data and structure refinement results for Ce9Au4.91(4)As8O6 and Pr9Au5−xAs8O6 (x = 0.13–0.25), space group Pnnm, Z = 4.

Compound Ce9Au4.91(4)As8O6 Pr9Au4.75(1)As8O6 Pr9Au4.87(2)As8O6 Pr9Au4.86(1)As8O6 Unit cell dimensions (single crystal data) a, pm 1321.64(6) 1315.45(9) 1315.63(7) 1315.01(4) b, pm 4073.0(3) 4047.9(2) 4049.8(1) 4052.87(8) c, pm 423.96(2) 421.44(2) 421.40(1) 420.68(1) Cell volume V, nm3 2.2821 2.2441 2.2452 2.2420 Molar mass M, g mol−1 2923.6 2899.1 2922.8 2920.8 Calculated density, g cm−3 8.51 8.58 8.65 8.64 Detector distance, mm 110 120 110 90 Absorption coefficient, mm−1 60.5 61.7 62.5 62.4 Integr. param. A/B/EMS 12.0/1.8/0.010 7.0/−4.7/0.019 7.8/−5.8/0.011 7.7/−5.5/0.010 F(000), e 4887 4872 4911 4908 Crystal size, µm3 113 × 8 × 4 85 × 15 × 3 39 × 12 × 7 39 × 12 × 7 Transm. ratio (min /max) 0.10/0.76 0.36/0.83 0.38/0.67 0.50/0.74 θ range, deg 1.6–27.9 1.0–35.6 2.5–29.4 3.1–30.8 Range in hkl ±17, ±53, ±5 ±21, ±66, ±6 ±18, ±55, ±5 ±18, ±57, ±5 Total no. reflections 9886 51017 40029 4812

Independent reflections/Rint 3106/0.1234 5313/0.0827 3358/0.1645 2673/0.0469

Reflections with I > 3 σ(I)/Rσ 895/0.3062 2570/0.0936 970/0.2651 1155/0.1497 Data/ref. parameters 3106/160 5313/160 3358/160 2673/160 Goodness-of-fit on F2 0.59 1.25 0.73 0.81 R1/wR2 for I > 3 σ(I) 0.0276/0.0521 0.0357/0.0711 0.0313/0.0616 0.0325/0.0606 R1/wR2 for all data 0.1270/0.0842 0.0741/0.0865 0.0931/0.0748 0.0893/0.0753 Extinction coefficient 164(7) 500(20) 140(20) 20(20) Largest diff. peak/hole, e Å−3 3.19/−3.26 4.60/−4.18 0.81/−0.92 2.45/−2.45 Refined occupancies of relevant gold sites in % Au3 49(4) 27(1) 37(2) 41(1) Au4 42(3) 48(1) 50(2) 45(1)

direction and the resulting chains are further condensed sites. Half of the arsenic atoms are isolated (no As–As in c direction forming strands. Only the praseodymium bonding) and can be considered as As3− Zintl anions. As1, atoms Pr1–Pr5 and Pr7–Pr9 take part in this polycationic As2, As5 and As8 form As2 dumbbells with As–As distances unit. The Pr6 atoms have no Pr–O contact. They are located of 244–257 pm, similar to Nd10Au3As8O10 (255 pm As–As) within the gold-arsenide network. As a consequence of [26] and the Zintl phase CaAs (256 pm As–As) [38]. These 4− the structurally complex anionic unit we observe a slight are typical single bond distances and we can assume As2 12+ bending of the polycationic [Pr8O6] units, leading to the Zintl anions (isoelectronic with bromine). broader range of O–Pr distances. In tetragonal, ZrCuSiAs The gold substructure of Pr9Au5−xAs8O6 is the com- type α-PrZnPO [35] and PrZnSbO [36] the planar [PrO]+ plicated part of this structure type. Au1, Au2, Au5, and layers contain only one crystallographically independ- Au6 have distorted tetrahedral arsenic coordination (by 3− 4− ent praseodymium and oxygen atoms and all O–Pr dis- As and end-on coordinated As2 ) with Au–As distances tances are equal, i.e. 238 pm in PrZnSbO and 233 pm in ranging from 224 to 289 pm. In Nd10Au3As8O10 [26] with

α-PrZnPO. The gross structural features of Pr9Au5−xAs8O6 square-planar and rectangular coordinated gold atoms are similar to those of the recently reported germanide the Au–As distances show a much smaller range of oxide Ce4Ag3Ge4O0.5 [37], where a chain of trans-edge-shar- 256–259 pm, a consequence of the higher site symmetry. ing OCe4 tetrahedra is embedded within the polyanionic The shorter Au4–As6 distance of 224 pm in Pr9Au5−xAs8O6

[Ag3Ge4] network. is a consequence of the disorder in the gold substructure Now we turn to the structural description of the poly- discussed below. A molecular pendant to these pnictide anionic network. The latter is by far more complex than oxides is the diiodobis(o-phenylenebis(dimethylarsine)) the simple layers of edge-sharing tetrahedra in the ZrCu- gold(III) ion [39–41] with Au–As distances of 243–246 pm SiAs family of compounds [2]. The polyanionic network in almost square-planar coordination. Further exam- + − contains six crystallographically independent gold sites ples are the arsonium salts [(C6H5)3PAu]4As BF4 ⋅3CH2Cl2 + − (Au3 and Au4 show partial occupancy) and eight arsenic and [(C6H5)3PAu]4As BF4 ⋅4CH2Cl2 with average Au–As

T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 1249

2 Table 2: Atomic coordinates and anisotropic/isotropic displacement parameters (pm ) of Pr9Au4.75(1)As8O6, z = 0, U13 = U23 = 0, Ueq is defined as one third of the trace of the orthogonalized Uij tensor. All atoms lie on Wyckoff positions 4g.

Atom x y U11 U22 U33 U12 Ueq Pr1 0.08267(8) 0.09253(2) 195(4) 182(4) 175(5) 4(3) 184(2) Pr2 0.04567(8) 0.19326(2) 212(4) 184(4) 170(5) 10(3) 188(3) Pr3 0.84494(8) 0.00319(2) 204(4) 173(4) 166(5) −2(3) 181(2) Pr4 0.01942(8) 0.28784(2) 212(4) 167(4) 184(5) 10(4) 188(2) Pr5 0.72082(8) 0.25560(2) 216(4) 166(4) 183(5) −2(3) 188(3) Pr6 0.17616(8) 0.37413(2) 246(5) 174(4) 185(5) 2(4) 202(3) Pr7 0.73336(8) 0.34930(2) 210(4) 159(4) 178(5) 1(3) 182(2) Pr8 0.11788(8) 0.46946(2) 193(4) 177(4) 175(5) −4(3) 182(2) Pr9 0.78814(8) 0.44304(2) 201(4) 165(4) 168(5) −9(3) 178(3) Au1 0.52612(7) 0.08196(2) 303(4) 221(3) 300(4) 42(3) 274(2) Au2 0.48128(7) 0.15315(2) 391(4) 228(3) 304(4) 1(3) 308(2) Au3a 0.8319(3) 0.1555(1) 240(20) 450(30) 189(17) −107(18) 293(13) Au4a 0.8716(2) 0.1385(1) 405(15) 580(20) 279(12) −82(14) 420(9) Au5 0.31101(9) 0.30764(3) 382(6) 252(4) 1466(15) 64(4) 700(5) Au6 0.36989(7) 0.42554(2) 295(4) 232(3) 562(6) −31(3) 363(3) As1 0.4375(1) 0.02216(4) 218(9) 190(8) 155(9) 20(7) 188(5) As2 0.3444(1) 0.20034(4) 200(8) 182(7) 198(9) −10(7) 193(5) As3 0.7268(2) 0.07290(4) 240(9) 192(8) 180(9) 1(7) 204(5) As4 0.6643(2) 0.18130(4) 308(10) 179(8) 175(9) −3(7) 221(5) As5 0.4190(2) 0.25679(4) 231(9) 167(7) 216(10) −2(7) 205(5) As6 0.4294(2) 0.36433(6) 349(13) 234(10) 940(20) 5(10) 506(10) As7 0.9445(2) 0.38580(5) 197(9) 223(8) 240(10) 3(7) 220(5) As8 0.5112(1) 0.46847(4) 197(8) 186(8) 190(9) 1(7) 191(5) O1 0.213(1) 0.0530(3) – – – – 180(20) O2 0.154(1) 0.1463(3) – – – – 200(20) O3 0.134(1) 0.2458(3) – – – – 170(20) O4 0.625(1) 0.3037(3) – – – – 230(30) O5 0.667(1) 0.4014(3) – – – – 200(20) O6 0.259(1) 0.5008(3) – – – – 160(20) aThe Au3 and Au4 sites show small defects (Table 1).

distances of 250 and 249 pm [42], respectively. An over- Also refinements in translationengleiche subgroups did view of various gold complexes with heavy group V ele- not resolve the disorder. A possible ordering pattern is ments is given by Laguna [43]. presented in the lower right-hand part of Fig. 3. In such a

Layers of edge-sharing AuAs4 tetrahedra with Au–As model, only one of the two split positions can be occupied distances ranging from 272 to 274 pm occur in PrAuAs2 and the neighboring Au5 and As6 atoms show an ordered [44]. The latter are slightly longer than the sum of the displacement in c direction to allow for reasonable dis- covalent radii for Au + As of 255 pm [45]. tances. In the second domain the adjacent split position Au3 and Au4 correspond to a split position (Fig. 3) is occupied and the Au5 and As6 atoms are displaced in with partial occupancies ranging from 27 to 50% (Table 1), the opposite direction emphasized by dashed red lines in manifesting a small homogeneity range for the two com- the figure. Probably the disordered cages around the Pr6 pounds. Consequently we observe a physically impossibly atoms are too far away to enable long-range ordering. short Au3–Au4 distance of 87 pm. Thus, only one of these Besides the split positions we need to mention the positions can be occupied in an ordered model. The Au5 slightly lower occupancy parameters especially for the and As6 atoms react on this split position with enhanced Au3 sites. The local gold-arsenic substructure around displacement parameters U33. The four data sets were care- the Pr6 atoms is closely related to the ZrCuSiAs and fully checked with respect to superstructure reflections, ThCr2Si2 phases, which often show ordering of defects which might enable gold ordering in a lower-symmetry [2, 46]. This is also similar to CeAu0.985As2 [47] and space group. No additional reflections were observed. CeAu0.838Sb2 [48].

1250 T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6

Table 3: Interatomic distances (pm) in Pr9Au4.75(1)As8O6.

Pr1: 1 O1 235(1) Pr7: 1 O5 228(1) Au5: 1 As5 250.3(2) As5: 1 As2 248.9(3) 1 O2 237(1) 1 O4 234(1) 2 Au3 259.5(3) 1 Au5 250.3(2) 2 O5 239.5(6) 2 O2 235.6(6) 1 As6 277.5(3) 2 Pr4 307.4(2) 1 Au4 334.5(4) 1 As7 314.8(2) 2 As4 289.2(2) 1 O4 331(1) 2 As8 338.0(2) 2 As2 325.8(2) 2 Au4 313.5(3) 2 Pr2 336.3(2) 2 As6 340.0(2) Pr8: 1 O6 225(1) 1 Pr6 322.6(2) 2 Pr5 338.9(2) 2 Au6 357.9(1) 2 As3 307.1(2) 1 O3 342(1) As6: 2 Au4 224.2(2) Pr2: 2 O4 235.2(6) 2 As1 308.6(2) 2 Pr5 352.2(1) 2 Au3 259.4(3) 1 O2 238(1) 2 As1 319.1(2) Au6: 1 As8 254.7(2) 1 Au6 260.0(3) 1 O3 243(1) 2 Au1 319.8(1) 1 As6 260.0(3) 1 Au5 277.5(3) 1 Au4 319.0(4) Pr9: 1 O5 232(1) 2 As3 282.5(2) 1 Pr6 335.6(3) 1 Au3 320.2(5) 2 O1 233.0(5) 1 Pr6 329.2(2) 2 Pr1 340.0(2) 2 As5 336.3(2) 1 O6 236(1) 2 Au4 334.1(3) 1 O5 347(1) 2 As6 349.6(2) 1 As7 310.1(2) 1 O6 338(1) 2 Pr2 349.6(2) Pr3: 2 O6 239.8(6) 2 As1 320.7(2) 2 Pr1 357.9(1) As7: 2 Au2 267.5(1) 1 O1 240(1) Au1: 1 As3 266.7(2) 2 Pr3 358.9(1) 2 Au1 270.0(1) 2 As8 316.1(2) 1 As1 268.9(2) As1: 1 As1 243.5(3) 1 Pr6 308.5(2) 1 As3 322.4(2) 2 As7 270.0(1) 1 Au1 268.9(2) 1 Pr9 310.1(2) 2 As8 324.7(2) 1 Au2 294.4(1) 2 Pr8 308.6(2) 1 Pr7 314.8(2) 2 Au6 358.9(1) 2 Pr8 319.8(1) 2 Pr8 319.1(2) As8: 1 Au6 254.7(2) Pr4: 1 O3 228(1) 2 Pr6 339.1(1) 2 Pr9 320.7(2) 1 As8 257.2(3) 2 As5 307.4(2) Au2: 1 As2 262.7(2) As2: 1 As5 248.9(3) 2 Pr3 316.1(2) 2 As4 310.3(2) 1 As4 266.5(2) 1 Au2 262.7(2) 2 Pr3 324.7(2) 2 As2 315.8(2) 2 As7 267.5(1) 2 Pr4 315.8(2) 1 O6 328(1) 2 Au2 322.5(1) 1 Au1 294.4(1) 2 Pr5 320.4(2) 2 Pr1 338.0(2) Pr5: 1 O4 232(1) 2 Pr4 322.5(1) 2 Pr7 325.8(2) O1: 2 Pr9 233.0(5) 2 O3 239.5(6) 2 Pr6 349.7(1) As3: 1 Au1 266.7(2) 1 Pr1 235(1) 1 As4 310.1(2) Au3: 1 Au4 86.5(6)a 2 Au6 282.5(2) 1 Pr3 240(1) 2 As2 320.4(2) 1 As4 244.0(5)a 2 Pr8 307.1(2) O2: 2 Pr7 235.6(6) 2 As5 338.9(2) 2 As6 259.4(3) 2 Pr6 308.0(2) 1 Pr1 237(1) 2 Au5 352.2(1) 2 Au5 259.5(3) 1 Pr3 322.4(2) 1 Pr2 238(1) Pr6: 2 As3 308.0(2) 2 Pr6 317.4(4) 1 Au4 327.0(4) O3: 1 Pr4 228(1) 2 As4 308.2(2) 1 Pr2 320.2(5) As4: 1 Au3 244.0(5) 2 Pr5 239.5(6) 1 As7 308.5(2) Au4: 1 Au3 86.5(6)a 1 Au2 266.5(2) 1 Pr2 243(1) 2 Au3 317.4(4) 2 As6 224.2(2)a 2 Au5 289.2(2) O4: 1 Pr5 232(1) 1 Au5 322.6(2) 2 Au5 313.5(3) 2 Pr6 308.2(2) 1 Pr7 234(1) 1 Au6 329.2(2) 1 Pr2 319.0(4) 1 Pr5 310.1(2) 2 Pr2 235.2(6) 1 As6 335.6(3) 1 As4 323.2(4) 2 Pr4 310.3(2) O5: 1 Pr7 228(1) 2 Au4 336.3(3) 1 As3 327.0(4) 1 Au4 323.2(4) 1 Pr9 232(1) 2 Au1 339.1(1) 2 Au6 334.1(3) 2 Pr1 239.5(6) 2 Au2 349.7(1) 1 Pr1 334.5(4) O6: 1 Pr8 225(1) 2 Pr6 336.3(3) 1 Pr9 236(1) 2 Pr3 239.8(6)

All distances within the first coordination spheres are listed. Standard deviations are given in parentheses. aDistances affected by the split positions.

A further possibility hindering the correct structure Assuming the ideal composition Pr9Au5As8O6 (neglect- solution might be twinning. Indications for merohe- ing the partial occupancies of Au3 and Au4) we can write dry, partial merohedry or especially pseudo-merohedry up an electron precise formula: (9Pr3+)(5Au+)(4As3−) 4− 2− would be elongated reflections for high diffraction angles (2As2 )(6O ). This formula is only a first approximation. along with the large lattice parameter b, pretending high Besides the vacancies in the Au3 and Au4 substructure, orthorhombic Laue symmetry (mmm) typically for mono- the compound exhibits a variety of Au–Au interactions clinic lattices with β angles close to 90° [49]. However, with Au–Au distances ranging from 260 to 334 pm (the suitable models could not be found up to now. shorter ones are affected by the partial occupancy and do

T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6 1251

Fig. 3: (left) The crystal structure of Pr9Au5−xAs8O6. Praseodymium, gold and arsenic atoms are drawn as gray, black and open circles, 12+ respectively. Polycationic strands of edge-sharing O@Pr4/4 and O@Pr4/3 tetrahedra ([Pr4O3]2 polycation) and the polyanionic gold arse- 15− 3+ nide network [Au5As8] are emphasized. The Pr6 cations ensure full charge compensation. (Right) Building block from the gold arsenide network. Atoms are drawn as ellipsoids representing 90% probability of presence level. The cut-out shows the averaged coordination of the gold sites Au3 and Au4. Atom labels and distances (pm) are given. Red ones are smaller than the sum of the covalent radii. A possible ordering pattern is indicated. For details see text. not occur in the ordered model), comparable to that in fcc References gold (288 pm) [50]. [1] D. Johrendt, R. Pöttgen, Angew. Chem. Int. Ed. 2008, 47, 4782. Acknowledgments: We thank Dipl.-Ing. U. Ch. Rodewald [2] R. Pöttgen, D. Johrendt, Z. Naturforsch. 2008, 63b, 1135. [3] T. C. Ozawa, S. M. Kauzlarich, Sci. Techn. Adv. Mater. 2008, 9, for collecting the single-crystal diffractometer data. 033003. This work was financially supported by the Deutsche [4] D. C. Johnston, Adv. Phys. 2010, 59, 803. Forschungsgemeinschaft through SPP 1458 Hochtempera- [5] D. Johrendt, H. Hosono, R.-D. Hoffmann, R. Pöttgen, Z. Kristal- tursupraleitung in Eisenpniktiden. logr. 2011, 226, 435.

1252 T. Bartsch et al.: The quaternary arsenide oxides Ce9Au5−xAs8O6 and Pr9Au5−xAs8O6

[6] Y. Kamihara, T. Watanabe, M. Hirano, H. Hosono, J. Am. Chem. [27] M. Eul, M. H. Möller, R.-D. Hoffmann, W. Jeitschko, R. Pöttgen, Soc. 2008, 130, 3296. Z. Anorg. Allg. Chem. 2012, 638, 331. [7] Z.-A. Ren, W. Lu, J. Yang, W. Yi, X.-L. Shen, Z.-C. Li, G.-C. Che, [28] T. Bartsch, T. Wiegand, J. Ren, H. Eckert, D. Johrendt, O. X.-L. Dong, L.-L. Sun, F. Zhou, Z.-X. Zhao, Chin. Phys. Lett. Niehaus, M. Eul, R. Pöttgen, Inorg. Chem. 2013, 52, 2094. 2008, 25, 2215. [29] D. E. Bugaris, H.-C. zur Loye, Angew. Chem. Int. Ed. 2012, 51, [8] D. Kaczorowski, J. H. Albering, H. Noël, W. Jeitschko, J. Alloys 3780. Compd. 1994, 216, 117. [30] K. Yvon, W. Jeitschko, E. Parthé, J. Appl. Crystallogr. 1977, 10, 73. [9] H. Sakai, N. Tateiwa, T. D. Matsuda, T. Sugai, E. Yamamoto, Y. [31] L. Palatinus, G. Chapuis, J. Appl. Crystallogr. 2007, 40, 786. Haga, J. Phys. Soc. Jpn. 2010, 79, 074721. [32] V. Petříček, M. Dušek, L. Palatinus, Z. Kristallogr. 2014, 229, [10] D. M. Wells, E. Ringe, D. Kaczorowski, D. Gnida, G. André, R. G. 345. Haire, D. E. Ellis, J. A. Ibers, Inorg. Chem. 2011, 50, 576. [33] T. Stürzer, G. Derondeau, D. Johrendt, Phys. Rev. B 2012, 86, [11] J. H. Albering, W. Jeitschko, Z. Naturforsch. 1996, 51b, 257. 060516. [12] A. T. Nientiedt, B. I. Zimmer, P. Wollesen, W. Jeitschko, Z. [34] T. Stürzer, G. Derondeau, E.-M. Bertschler, D. Johrendt, Solid Kristallogr. 1996, Suppl. 11, 101. State Commun. 2015, 201, 36. [13] W. Jeitschko, B. I. Zimmer, R. Glaum, L. Boonk, U. Ch. [35] H. Lincke, T. Nilges, R. Pöttgen, Z. Anorg. Allg. Chem. 2006, Rodewald, Z. Naturforsch. 2008, 63b, 934. 632, 1804. [14] V. V. Bannikov, I. R. Shein, A. L. Ivanovskii, Comput. Mater. Sci. [36] I. Schellenberg, H. Lincke, W. Hermes, V. Dittrich, R. Glaum, M. 2011, 50, 2736. H. Möller, R. Pöttgen, Z. Naturforsch. 2010, 65b, 1191. [15] H. Noël, Z. Żołnierek, D. Kaczorowski, R. Troć, J. Stępień-Damm, [37] G. Heymann, J. F. Riecken, D. Johrendt, S. Rayaprol, R. Pöttgen, J. Less-Common Met. 1987, 135, 61. H. Huppertz, Dalton Trans. 2013, 42, 15207. [16] D. Kaczorowski, R. Troć, H. Noël, J. Less-Common Met. 1990, [38] A. Iandelli, E. Franceschi, J. Less-Common Met. 1973, 30, 211. 161, 239. [39] V. F. Duckworth, N. C. Stephenson, Inorg. Chem. 1969, 8, 1661. [17] J. Schoenes, D. Kaczorowski, C. Beeli, Z. Phys. B – Condens. [40] C. M. Harris, R. S. Nyholm, J. Chem. Soc. 1957, 63. Matter 1992, 88, 135. [41] V. F. Duckworth, C. M. Harris, N. C. Stephenson, Inorg. Nucl. [18] P. Burlet, R. Troć, D. Kaczorowski, H. Noël, J. Rossat-Mignod, J. Chem. Lett. 1968, 4, 419. Magn. Magn. Mater. 1994, 130, 237. [42] E. Zeller, H. Beruda, A. Kolb, P. Bissinger, J. Riede, H. [19] D. Kaczorowski, M. Potel, H. Noël, J. Solid State Chem. 1994, Schmidbaur, Nature 1991, 352, 141. 112, 228. [43] A. Laguna, Gold Compounds of Phosphorus and the Heavy [20] R. J. Cava, H. W. Zandbergen, J. J. Krajewski, T. Siegrist, H. Y. Group V Elements, in Gold, Progress in Chemistry, Biochemis- Hwang, A. P. Ramirez, B. Batlogg, Mater. Res. Soc. Symp. Proc. try and Technology (Ed.: H. Schmidbaur), John Wiley & Sons, 1997, 453, 305. Chichester, 1999, chapter 12, p. 349. [21] R. J. Cava, H. W. Zandbergen, J. J. Krajewski, T. Siegrist, H. Y. [44] D. Rutzinger, C. Bartsch, M. Doerr, H. Rosner, V. Neu, T. Doert, Hwang, B. Batlogg, J. Solid State Chem. 1997, 129, 250. M. Ruck, J. Solid State Chem. 2010, 183, 510. [22] J. W. Kaiser, W. Jeitschko, Z. Naturforsch. 2002, 57b, 165. [45] J. Emsley, The Elements, Oxford University Press, Oxford, 1999. [23] T. Bartsch, C. Benndorf, H. Eckert, M. Eul, R. Pöttgen, Z. Natur- [46] R. Pöttgen, Z. Anorg. Allg. Chem. 2014, 640, 869. forsch. 2016, 71b, 149. [47] D. Rutzinger, T. Doert, M. Ruck, Acta Crystallogr. B 2009, 65, 519. [24] J. K. Wang, A. Marcinkova, C.-W. Chen, H. He, M. Aronson, E. [48] L. P. Salamakha, E. Bauer, S. I. Mudryi, A. P. Gonçalves, M. Morosan, Phys. Rev. B 2014, 89, 094405. Almeida, H. Noël, J. Alloys Compd. 2009, 419, 184. [25] M. Eul, D. Johrendt, R. Pöttgen, Z. Naturforsch. 2009, 64b, 1353. [49] W. Massa, Kristallstrukturbestimmung, 5th edition, Teubner, [26] T. Bartsch, O. Niehaus, D. Johrendt, Y. Kobayashi, M. Seto, P. M. Wiesbaden, 2007. Abdala, M. Bartsch, H. Zacharias, R.-D. Hoffmann, B. Gerke, U. [50] J. Donohue, The Structures of the Elements, Wiley, New York, Ch. Rodewald, R. Pöttgen, Dalton Trans. 2015, 44, 5854. 1974.