- Email: [email protected]
Syntheses and crystal structures of the new compounds BaFe2(SeO3)4, AgFe(SeO3)2 and RbFe(SeO4)(SeO3)
Journal of Alloys and Compounds 308 (2000) 71–76
L
www.elsevier.com / locate / jallcom
Syntheses and crystal structures of the new compounds BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ) Gerald Giester* ¨ Mineralogie und Kristallographie, Geozentrum, Universitat ¨ Wien, Althanstrasse 14, A-1090 Vienna, Austria Institut f ur Received 6 March 2000; accepted 16 March 2000
Abstract Single crystals of the new compounds BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ), have been synthesized at lowhydrothermal conditions. Their structures were determined from CCD X-ray diffraction data: BaFe 2 (SeO 3 ) 4 : space group P2 /n, ˚ b 596.31(1)8, V5557.0(2) A ˚ 3 , Z52, R 1 5 0.020. AgFe(SeO 3 ) 2 : space group Pna21 , a510.098(2), b55.238(1) c510.595(2) A, 3 ] ˚ ˚ a513.975(3), b55.249(1) c57.609(2) A, V5558.2(2) A , Z54, R 1 50.020. RbFe(SeO 4 )(SeO 3 ): space group R3m, a55.339(1), 3 ˚ V51040.2(3) A ˚ , Z56, R 1 5 0.034. 2000 Elsevier Science S.A. All rights reserved. c541.206(8) A, Keywords: BaFe 2 (SeO 3 ) 4 ; AgFe(SeO 3 ) 2 ; RbFe(SeO 4 )(SeO 3 ); Crystal structure
1. Introduction In the course of experiments to investigate selenites of first row transition metal elements, BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ) were also obtained. These compounds belong to a large group of Fe 31 bearing selenites, studied in detail within the last few years [1–3 and references cited therein]. The crystal structure of BaFe 2 (SeO 3 ) 4 is related to those of the previously described selenites KFe 2 (SeO 2 OH)(SeO 3 ) 3 and SrCo 2 (SeO 2 OH) 2 (SeO 3 ) 2 [4]. In the text, these compounds will be abbreviated as BAFE, AGFE, RBFE, KFE and SRCO.
2. Experimental
2.1. Preparation Synthesis of the title compounds was done by a lowhydrothermal technique successfully used at our institute to grow single crystals of a large suite of selenites: the starting materials are filled in PTFE vessels of 3–50 cm 3 capacity, adding water in filling rates ranging from 10–90
*E-mail address: [email protected] (G. Giester).
(vol.%). The vessels are inserted in steel autoclaves, heated to temperatures up to 500 K, kept constant for a few hours to weeks, and then slowly cooled to room temperature. The mother liquid is removed from the final products, and water, diluted methanol or acetone are added. The crystals are treated for a few minutes in an ultrasonic cleaner, separated and dried at 330 K. Details of the syntheses of BAFE, AGFE and RBFE are given in Table 1.
2.2. X-ray diffraction studies The single crystal experiments were performed with a Nonius KappaCCD diffractometer at room temperature. Information on crystal data, procedures of measurements and refinements are compiled in Table 1. Programs used are DENZO-SMN [5], SHELXS97 [6] and SHELXL97 [7]. Refined structure parameters as well as interatomic distances and bond angles are listed in Tables 2 and 3, respectively.
3. Results and discussion The crystal structure of BAFE (see Fig. 1) is closely related to those of KFE and SRCO [4]. Interpolyhedral connectivity is the same — BAFE too can be derived from the hypothetic structure model [4] of SrFe 2 (SeO 3 ) 4 in space group P2 /m (Fig. 2). Differences are characterized
0925-8388 / 00 / $ – see front matter 2000 Elsevier Science S.A. All rights reserved. PII: S0925-8388( 00 )00848-3
72
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Table 1 Crystal data and details of the intensity measurements and structure refinements for BAFE, AGFE and RBFE BAFE
AGFE
RBFE
Temperature (K) / heating period Colour of crystals Coprecipitates
BaCO 3 , SeO 2 , FeC 2 O 4 ?2H 2 O 490 / 1 week Yellow BaSeO 3
Ag 2 CO 3 , SeO 2 , FeC 2 O 4 ?2H 2 O 500 / 1 week Yellow Fe 2 O(SeO 3 ) 2 , Fe 2 (SeO 3 ) 3 ?H 2 O FeH(SeO 3 ) 2
Rb 2 CO 3 , SeO 3 , FeC 2 O 4 ?2H 2 O 490 / 2 weeks Green-yellow None
Crystal data Space group ˚ a (A) ˚ b (A) ˚ c (A) b (8) ˚ 3) V (A Z rcalc (g cm 23 ) m (MoKa) (cm 21 )
P2 /n 10.098(2) 5.238(1) 10.595(2) 96.31(1) 557.0(2) 2 4.51 192
Pna21 13.975(3) 5.249(1) 7.609(2) 558.2(2) 4 4.97 191
1040.2(3) 6 3.94 196
60 1629 1583 91 0.0083(5) 0.020 0.053
60 1522 1491 93 0.0029(3) 0.020 0.048
60 465 460 30 0.0020(3) 0.034 0.091
0.025, 0.25
0.017, 1.6
0.01, 26.0
20.9 / 1.8
20.9 / 1.2
22.2 / 0.8
Synthesis Starting materials
Data collection and refinement 2umax (8) Unique data set data with Fo . 4s (Fo ) Variables Extinction coefficient R 1 [for Fo . 4s (Fo )] wR 2 [for all F 2o ] R 1 5 S uuFo u 2 uFc uu / S uFo u wR 2 5 [Sw(F 2o 2 F 2c )2 / SwF 4o ] 1 / 2 w 5 1 / [s 2 (F 2o ) 1 (a 3 P)2 1 b 3 P] P 5 h[max of (0 or F 2o )] 1 2F 2c j / 3 ˚ 23 ) Drmin / max (eA
a, b 5
by the loss of a part of the symmetry elements occurring in the model structure type. The compensation of charges within the group is realized by the ratio of (SeO 2 OH)- and (SeO 3 ) anions. Consequently, BAFE should be capable to adopt the SrFe 2 (SeO 3 ) 4 type, but in the real BAFE structure this concept is only partly fulfilled. The barium atoms (symmetry 2) are 10-coordinated ˚ similar (Ba–O bond lengths are in the range 2.75–3.25 A), to the potassium atoms in KFE. The crystal structure of AgFe(SeO 3 ) 2 differs from the structure type of the compounds KFe(SeO 3 ) 2 [9] and NaFe(SeO 3 ) 2 [10], which both are isotypic, by the way of linking the selenite groups and FeO 6 octahedra. Remarkably, AGFE [with doubled formula Ag 2 Fe 2 (SeO 3 ) 4 ] shows some relationships with the compounds of the SrFe 2 (SeO 3 ) 4 type. The charge compensation is done by additional silver atoms (see Fig. 3a and b), causing a reorientation of part of the selenite groups. The silver atoms have a distorted octahedral coordination (Ag–O5 ˚ the three nearest 2.41, 2.43, 2.51, 2.60, 2.72, 2.79 A), oxygen atoms are in almost planar coordination (bond
] R3 m 5.339(1) 41.206(8)
˚ angle sum O–Ag–O5359.68, aplanarity 0.088(3) A). ˚ apart. Further oxygen atoms are as far as 3.6 A RbFe(SeO 4 )(SeO 3 ) belongs to a quite new structure type among compounds of ferric iron which contain selenite groups. Up to now, only a few examples of 22 22 selenites are known to have both (SeO 3 ) and (SeO 4 ) anions. Representatives are Pb 2 Cu 2 (OH) 4 (SeO 3 )(SeO 4 ) [11], Li 2 Cu 3 (SeO 3 ) 2 (SeO 4 ) 2 [12], Fe(SeO 2 OH)(SeO 4 )? H2O [13], Er(SeO 3 )(SeO 4 ) 0.5 ?H 2 O [14], and La(SeO 2 OH)(SeO 4 )?2H 2 O [15]. Within the framework structure of RbFe(SeO 4 )(SeO 3 ) sheets parallel to (001) can be emphasized, which are built up by FeO 6 octahedra, linked via the SeO 3 and SeO 4 groups; they are intercalated by the Rb ions (Fig. 4). The ˚ (123) respectively 3.16 and Rb–O bondlengths are 3.21 A ˚ (each 63). Bond angles of the SeO 4 groups are 3.17 A ˚ nearly ideal, the mean Se–O distance is 1.62 A. The kFe–Ol distances of all three investigated com˚ pounds well correspond with the value of 2.013(11) A derived from 50 individual Fe 31 O 6 polyhedra known up to now in selenites.
Table 2 Atomic coordinates and displacement parameters Ueqv with e.s.d. values in parentheses for BAFE, AGFE and RBFE y
z
Ueqv
U11
U22
U33
U23
1/4 0 0 20.02358(3) 0.15797(3) 0.04837(19) 0.32243(19) 0.12175(17) 0.15662(17) 0.06847(17) 0.05553(17)
0.93809(5) 0 1/2 0.49387(5) 0.00647(5) 0.5779(4) 0.0509(4) 0.1881(4) 0.7109(4) 0.6947(4) 0.2124(4)
1/4 1/2 0 0.31726(2) 20.09641(2) 0.18486(16) 20.09930(19) 0.02980(16) 20.03137(19) 0.41760(16) 0.35199(16)
0.01299(9) 0.00913(12) 0.00942(12) 0.00973(8) 0.00998(9) 0.0157(4) 0.0146(4) 0.0135(3) 0.0192(4) 0.0121(3) 0.0128(3)
0.01083(12) 0.0103(3) 0.0104(2) 0.00946(14) 0.00837(14) 0.0223(10) 0.0086(8) 0.0154(8) 0.0134(8) 0.0126(7) 0.0174(8)
0.01560(13) 0.0078(2) 0.0079(2) 0.00886(14) 0.01080(15) 0.0164(10) 0.0182(9) 0.0124(9) 0.0091(9) 0.0100(8) 0.0087(8)
0.01276(12) 0.0097(3) 0.0100(3) 0.01070(15) 0.01060(15) 0.0083(8) 0.0170(9) 0.0127(8) 0.0360(11) 0.0136(8) 0.0132(8)
0 20.00054(16) 20.00044(16) 20.00095(8) 20.00053(8) 0.0008(7) 0.0044(8) 20.0018(7) 0.0043(8) 20.0054(7) 0.0013(7)
0.00233(8) 0.0028(2) 0.0011(2) 0.00040(11) 0.00026(11) 0.0013(7) 0.0019(7) 0.0009(6) 0.0068(8) 0.0007(6) 0.0062(6)
0 0.00013(16) 20.00073(16) 0.00027(8) 0.00025(8) 20.0025(7) 20.0011(7) 0.0027(7) 20.0010(7) 20.0002(7) 0.0015(7)
Ag Fe Se1 Se2 O1 O2 O3 O4 O5 O6
0.37890(3) 0.12599(5) 0.47319(3) 0.27694(3) 0.5876(3) 0.4879(2) 0.4627(2) 0.2616(2) 0.2865(2) 0.1630(3)
0.13675(8) 0.29117(11) 0.30206(8) 0.27260(7) 0.2431(7) 0.5767(6) 0.0891(6) 20.0022(5) 0.4870(6) 0.3314(7)
0.68389(8) 0.69510(13) 0.01300(6) 0.37401(6) 20.0499(5) 0.1279(5) 0.1799(6) 0.2625(5) 0.2053(5) 0.4387(5)
0.02441(11) 0.01168(13) 0.01105(10) 0.01087(10) 0.0157(7) 0.0160(8) 0.0152(6) 0.0146(7) 0.0142(6) 0.0160(7)
0.01268(16) 0.0107(3) 0.0109(2) 0.0103(2) 0.0115(16) 0.0125(15) 0.0153(14) 0.0137(16) 0.0169(14) 0.0151(17)
0.0351(2) 0.0111(3) 0.01104(17) 0.01133(18) 0.0215(17) 0.0137(16) 0.0130(14) 0.0077(14) 0.0114(14) 0.0213(17)
0.0255(2) 0.0133(3) 0.0112(2) 0.0110(2) 0.0140(19) 0.022(2) 0.0174(16) 0.022(2) 0.0143(18) 0.0118(17)
0.0061(2) 0.0004(3) 20.00067(17) 0.00034(18) 0.0000(12) 20.0041(14) 0.0019(15) 20.0022(13) 0.0035(12) 0.0004(13)
20.00149(16) 0.0002(2) 0.0003(2) 20.00026(19) 20.0001(14) 0.0011(13) 0.0007(16) 0.0009(13) 0.0006(14) 0.0033(14)
20.00419(16) 20.0001(2) 20.00053(15) 0.00097(14) 0.0040(12) 0.0009(12) 20.0026(11) 0.0004(11) 20.0014(11) 0.0039(13)
0 0 0 0 0 0 0.1592(5) 0.3278(13)
0 1/2 0.09880(3) 0.22851(2) 0.61347(2) 0.65254(19) 0.20872(10) 0.60040(13)
0.0235(4) 0.0252(4) 0.0131(4) 0.0133(3) 0.0118(3) 0.030(2) 0.0302(12) 0.0507(19)
0.0276(6) 0.0282(6) 0.0110(5) 0.0135(4) 0.0122(4) 0.038(3) 0.051(3) 0.077(4)
0.0276(6) 0.0282(6) 0.0110(5) 0.0135(4) 0.0122(4) 0.038(3) 0.051(3) 0.018(3)
0.0153(6) 0.0192(7) 0.0171(7) 0.0130(4) 0.0110(4) 0.012(3) 0.0170(18) 0.038(3)
0 0 0 0 0 0 0.0001(8) 0.013(2)
0 0 0 0 0 0 20.0001(8) 0.0067(12)
Rb1 Rb2 Fe Se1 Se2 O1 O2 O3
0 0 0 0 0 0 20.1592(5) 0.1639(7)
U13
U12
0.0138(3) 0.0141(3) 0.0055(2) 0.00673(18) 0.00608(18) 0.0191(17) 0.046(3) 0.0090(14)
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
x Ba Fe1 Fe2 Se1 Se2 O1 O2 O3 O4 O5 O6
73
74
Table 3 ˚ and angles (8) in BAFE, AGFE and RBFE Selected interatomic distances (A) BAFE
AGFE 23 23 23 23 23
2.749(2) 2.806(2) 2.859(2) 2.976(2) 3.252(2) 2.928
Fe1–O5 Fe1–O2 Fe1–O6 kFe1–Ol
23 23 23
1.982(2) 1.995(2) 2.051(2) 2.009
Fe2–O4 Fe2–O1 Fe2–O3 kFe2–Ol
23 23 23
1.987(2) 2.008(2) 2.048(2) 2.014
RBFE
Ag–O2 Ag–O5 Ag–O3 Ag–O6 Ag–O1 Ag–O4 kAg–Ol
2.431(3) 2.447(3) 2.511(3) 2.583(4) 2.713(4) 2.794(3) 2.580
Fe–O4 Fe–O3 Fe–O5 Fe–O2 Fe–O1 Fe–O6 kFe–Ol
1.977(3) 1.999(3) 2.013(3) 2.015(3) 2.021(4) 2.030(4) 2.009
Se1–O5 Se1–O6 Se1–O1 kSe1–Ol
1.698(2) 1.698(2) 1.707(2) 1.701
Se1–O1 Se1–O3 Se1–O2 kSe1–Ol
1.697(4) 1.698(4) 1.698(3) 1.698
O5–Se1–O6 O5–Se1–O1 O6–Se1–O1 kO–Se1–Ol
100.96(9) 95.83(9) 99.74(9) 98.84
O1–Se1–O3 O1–Se1–O2 O3–Se1–O2 kO–Se1–Ol
99.90(16) 100.73(17) 100.61(18) 100.41
Se2–O2 Se2–O4 Se2–O3 kSe2–Ol
1.681(2) 1.695(2) 1.713(2) 1.696
Se2–O4 Se2–O6 Se2–O5 kSe2–Ol
1.687(3) 1.695(3) 1.712(4) 1.698
O2–Se2–O4 O2–Se2–O3 O4–Se2–O3 kO–Se2–Ol
100.72(9) 103.50(9) 100.24(9) 101.49
O4–Se2–O6 O4–Se2–O5 O6–Se2–O5 kO–Se2–Ol
100.50(18) 101.24(18) 99.86(16) 100.53
Rb1–O3 Rb1–O1 kRb1–Ol
63 63
3.157(6) 3.171(2) 3.164
Rb2–O2
123
3.209(2)
Fe–O2 Fe–O3 kFe–Ol
33 33
1.945(5) 2.076(6) 2.011
Se1–O2
33
1.698(5)
O2–Se1–O2
33
98.85(19)
Se2–O1 Se2–O3 kSe2–Ol
33
1.610(8) 1.624(6) 1.621
O1–Se2–O3 O3–Se2–O3 kO–Se2–Ol
33 33
109.4(2) 109.6(2) 109.5
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Ba–O6 Ba–O1 Ba–O3 Ba–O5 Ba–O4 kBa–Ol
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Fig. 1. Crystal structure of BAFE in a projection parallel to [010]. The drawings are done with the program
75
ATOMS
[8].
Fig. 2. Cell relations and symmetry operators for (a) hypothetic SrFe 2 (SeO 3 ) 4 , (b) BAFE, (c) KFE and (d) SRCO.
76
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Fig. 3. Crystal structure of AGFE in projections parallel to (a) [010] and (b) [001].
References [1] G. Giester, Z. Anorg. Allg. Chem. 622 (1996) 1788–1792. [2] G. Giester, Acta Chem. Scand. A51 (1997) 501–503. [3] G. Giester, A. Beran, G.J. Redhammer, J. Sol. St. Chem. 131 (1997) 54–63. [4] G. Giester, M. Wildner, J. Alloys Compd. 239 (1996) 99–102. [5] Denzo SMN, Nonius, Delft, 1998. [6] G.M. Sheldrick, SHELXS-97, a program for the solution of crystal ¨ structures, University Gottingen, Germany, 1997. [7] G.M. Sheldrick, SHELXL-97, a program for crystal structure refine¨ ment, University Gottingen, Germany, 1997. [8] E. Dowty, ATOMS for Windows 5.0, a computer program for displaying atomic structures, Kingsport, TN, 1999.
Fig. 4. Atomic arrangement in RBFE.
[9] [10] [11] [12] [13] [14]
G. Giester, Z. Krist. 207 (1993) 1–7. G. Giester, M. Wildner, J. Alloys Compd. 239 (1996) 99–102. H. Effenberger, Min. Petrol. 36 (1987) 3–12. G. Giester, Mh. Chem. 120 (1989) 661–666. G. Giester, Mh. Chem. 123 (1992) 957–963. R.E. Morris, A.P. Wilkinson, A.K. Cheetham, Inorg. Chem. 31 (1992) 4774–4777. [15] W.T.A. Harrison, Z. Zhang, Eur. J. Solid State Inorg. Chem. 34 (1997) 599–606.
L
www.elsevier.com / locate / jallcom
Syntheses and crystal structures of the new compounds BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ) Gerald Giester* ¨ Mineralogie und Kristallographie, Geozentrum, Universitat ¨ Wien, Althanstrasse 14, A-1090 Vienna, Austria Institut f ur Received 6 March 2000; accepted 16 March 2000
Abstract Single crystals of the new compounds BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ), have been synthesized at lowhydrothermal conditions. Their structures were determined from CCD X-ray diffraction data: BaFe 2 (SeO 3 ) 4 : space group P2 /n, ˚ b 596.31(1)8, V5557.0(2) A ˚ 3 , Z52, R 1 5 0.020. AgFe(SeO 3 ) 2 : space group Pna21 , a510.098(2), b55.238(1) c510.595(2) A, 3 ] ˚ ˚ a513.975(3), b55.249(1) c57.609(2) A, V5558.2(2) A , Z54, R 1 50.020. RbFe(SeO 4 )(SeO 3 ): space group R3m, a55.339(1), 3 ˚ V51040.2(3) A ˚ , Z56, R 1 5 0.034. 2000 Elsevier Science S.A. All rights reserved. c541.206(8) A, Keywords: BaFe 2 (SeO 3 ) 4 ; AgFe(SeO 3 ) 2 ; RbFe(SeO 4 )(SeO 3 ); Crystal structure
1. Introduction In the course of experiments to investigate selenites of first row transition metal elements, BaFe 2 (SeO 3 ) 4 , AgFe(SeO 3 ) 2 and RbFe(SeO 4 )(SeO 3 ) were also obtained. These compounds belong to a large group of Fe 31 bearing selenites, studied in detail within the last few years [1–3 and references cited therein]. The crystal structure of BaFe 2 (SeO 3 ) 4 is related to those of the previously described selenites KFe 2 (SeO 2 OH)(SeO 3 ) 3 and SrCo 2 (SeO 2 OH) 2 (SeO 3 ) 2 [4]. In the text, these compounds will be abbreviated as BAFE, AGFE, RBFE, KFE and SRCO.
2. Experimental
2.1. Preparation Synthesis of the title compounds was done by a lowhydrothermal technique successfully used at our institute to grow single crystals of a large suite of selenites: the starting materials are filled in PTFE vessels of 3–50 cm 3 capacity, adding water in filling rates ranging from 10–90
*E-mail address: [email protected] (G. Giester).
(vol.%). The vessels are inserted in steel autoclaves, heated to temperatures up to 500 K, kept constant for a few hours to weeks, and then slowly cooled to room temperature. The mother liquid is removed from the final products, and water, diluted methanol or acetone are added. The crystals are treated for a few minutes in an ultrasonic cleaner, separated and dried at 330 K. Details of the syntheses of BAFE, AGFE and RBFE are given in Table 1.
2.2. X-ray diffraction studies The single crystal experiments were performed with a Nonius KappaCCD diffractometer at room temperature. Information on crystal data, procedures of measurements and refinements are compiled in Table 1. Programs used are DENZO-SMN [5], SHELXS97 [6] and SHELXL97 [7]. Refined structure parameters as well as interatomic distances and bond angles are listed in Tables 2 and 3, respectively.
3. Results and discussion The crystal structure of BAFE (see Fig. 1) is closely related to those of KFE and SRCO [4]. Interpolyhedral connectivity is the same — BAFE too can be derived from the hypothetic structure model [4] of SrFe 2 (SeO 3 ) 4 in space group P2 /m (Fig. 2). Differences are characterized
0925-8388 / 00 / $ – see front matter 2000 Elsevier Science S.A. All rights reserved. PII: S0925-8388( 00 )00848-3
72
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Table 1 Crystal data and details of the intensity measurements and structure refinements for BAFE, AGFE and RBFE BAFE
AGFE
RBFE
Temperature (K) / heating period Colour of crystals Coprecipitates
BaCO 3 , SeO 2 , FeC 2 O 4 ?2H 2 O 490 / 1 week Yellow BaSeO 3
Ag 2 CO 3 , SeO 2 , FeC 2 O 4 ?2H 2 O 500 / 1 week Yellow Fe 2 O(SeO 3 ) 2 , Fe 2 (SeO 3 ) 3 ?H 2 O FeH(SeO 3 ) 2
Rb 2 CO 3 , SeO 3 , FeC 2 O 4 ?2H 2 O 490 / 2 weeks Green-yellow None
Crystal data Space group ˚ a (A) ˚ b (A) ˚ c (A) b (8) ˚ 3) V (A Z rcalc (g cm 23 ) m (MoKa) (cm 21 )
P2 /n 10.098(2) 5.238(1) 10.595(2) 96.31(1) 557.0(2) 2 4.51 192
Pna21 13.975(3) 5.249(1) 7.609(2) 558.2(2) 4 4.97 191
1040.2(3) 6 3.94 196
60 1629 1583 91 0.0083(5) 0.020 0.053
60 1522 1491 93 0.0029(3) 0.020 0.048
60 465 460 30 0.0020(3) 0.034 0.091
0.025, 0.25
0.017, 1.6
0.01, 26.0
20.9 / 1.8
20.9 / 1.2
22.2 / 0.8
Synthesis Starting materials
Data collection and refinement 2umax (8) Unique data set data with Fo . 4s (Fo ) Variables Extinction coefficient R 1 [for Fo . 4s (Fo )] wR 2 [for all F 2o ] R 1 5 S uuFo u 2 uFc uu / S uFo u wR 2 5 [Sw(F 2o 2 F 2c )2 / SwF 4o ] 1 / 2 w 5 1 / [s 2 (F 2o ) 1 (a 3 P)2 1 b 3 P] P 5 h[max of (0 or F 2o )] 1 2F 2c j / 3 ˚ 23 ) Drmin / max (eA
a, b 5
by the loss of a part of the symmetry elements occurring in the model structure type. The compensation of charges within the group is realized by the ratio of (SeO 2 OH)- and (SeO 3 ) anions. Consequently, BAFE should be capable to adopt the SrFe 2 (SeO 3 ) 4 type, but in the real BAFE structure this concept is only partly fulfilled. The barium atoms (symmetry 2) are 10-coordinated ˚ similar (Ba–O bond lengths are in the range 2.75–3.25 A), to the potassium atoms in KFE. The crystal structure of AgFe(SeO 3 ) 2 differs from the structure type of the compounds KFe(SeO 3 ) 2 [9] and NaFe(SeO 3 ) 2 [10], which both are isotypic, by the way of linking the selenite groups and FeO 6 octahedra. Remarkably, AGFE [with doubled formula Ag 2 Fe 2 (SeO 3 ) 4 ] shows some relationships with the compounds of the SrFe 2 (SeO 3 ) 4 type. The charge compensation is done by additional silver atoms (see Fig. 3a and b), causing a reorientation of part of the selenite groups. The silver atoms have a distorted octahedral coordination (Ag–O5 ˚ the three nearest 2.41, 2.43, 2.51, 2.60, 2.72, 2.79 A), oxygen atoms are in almost planar coordination (bond
] R3 m 5.339(1) 41.206(8)
˚ angle sum O–Ag–O5359.68, aplanarity 0.088(3) A). ˚ apart. Further oxygen atoms are as far as 3.6 A RbFe(SeO 4 )(SeO 3 ) belongs to a quite new structure type among compounds of ferric iron which contain selenite groups. Up to now, only a few examples of 22 22 selenites are known to have both (SeO 3 ) and (SeO 4 ) anions. Representatives are Pb 2 Cu 2 (OH) 4 (SeO 3 )(SeO 4 ) [11], Li 2 Cu 3 (SeO 3 ) 2 (SeO 4 ) 2 [12], Fe(SeO 2 OH)(SeO 4 )? H2O [13], Er(SeO 3 )(SeO 4 ) 0.5 ?H 2 O [14], and La(SeO 2 OH)(SeO 4 )?2H 2 O [15]. Within the framework structure of RbFe(SeO 4 )(SeO 3 ) sheets parallel to (001) can be emphasized, which are built up by FeO 6 octahedra, linked via the SeO 3 and SeO 4 groups; they are intercalated by the Rb ions (Fig. 4). The ˚ (123) respectively 3.16 and Rb–O bondlengths are 3.21 A ˚ (each 63). Bond angles of the SeO 4 groups are 3.17 A ˚ nearly ideal, the mean Se–O distance is 1.62 A. The kFe–Ol distances of all three investigated com˚ pounds well correspond with the value of 2.013(11) A derived from 50 individual Fe 31 O 6 polyhedra known up to now in selenites.
Table 2 Atomic coordinates and displacement parameters Ueqv with e.s.d. values in parentheses for BAFE, AGFE and RBFE y
z
Ueqv
U11
U22
U33
U23
1/4 0 0 20.02358(3) 0.15797(3) 0.04837(19) 0.32243(19) 0.12175(17) 0.15662(17) 0.06847(17) 0.05553(17)
0.93809(5) 0 1/2 0.49387(5) 0.00647(5) 0.5779(4) 0.0509(4) 0.1881(4) 0.7109(4) 0.6947(4) 0.2124(4)
1/4 1/2 0 0.31726(2) 20.09641(2) 0.18486(16) 20.09930(19) 0.02980(16) 20.03137(19) 0.41760(16) 0.35199(16)
0.01299(9) 0.00913(12) 0.00942(12) 0.00973(8) 0.00998(9) 0.0157(4) 0.0146(4) 0.0135(3) 0.0192(4) 0.0121(3) 0.0128(3)
0.01083(12) 0.0103(3) 0.0104(2) 0.00946(14) 0.00837(14) 0.0223(10) 0.0086(8) 0.0154(8) 0.0134(8) 0.0126(7) 0.0174(8)
0.01560(13) 0.0078(2) 0.0079(2) 0.00886(14) 0.01080(15) 0.0164(10) 0.0182(9) 0.0124(9) 0.0091(9) 0.0100(8) 0.0087(8)
0.01276(12) 0.0097(3) 0.0100(3) 0.01070(15) 0.01060(15) 0.0083(8) 0.0170(9) 0.0127(8) 0.0360(11) 0.0136(8) 0.0132(8)
0 20.00054(16) 20.00044(16) 20.00095(8) 20.00053(8) 0.0008(7) 0.0044(8) 20.0018(7) 0.0043(8) 20.0054(7) 0.0013(7)
0.00233(8) 0.0028(2) 0.0011(2) 0.00040(11) 0.00026(11) 0.0013(7) 0.0019(7) 0.0009(6) 0.0068(8) 0.0007(6) 0.0062(6)
0 0.00013(16) 20.00073(16) 0.00027(8) 0.00025(8) 20.0025(7) 20.0011(7) 0.0027(7) 20.0010(7) 20.0002(7) 0.0015(7)
Ag Fe Se1 Se2 O1 O2 O3 O4 O5 O6
0.37890(3) 0.12599(5) 0.47319(3) 0.27694(3) 0.5876(3) 0.4879(2) 0.4627(2) 0.2616(2) 0.2865(2) 0.1630(3)
0.13675(8) 0.29117(11) 0.30206(8) 0.27260(7) 0.2431(7) 0.5767(6) 0.0891(6) 20.0022(5) 0.4870(6) 0.3314(7)
0.68389(8) 0.69510(13) 0.01300(6) 0.37401(6) 20.0499(5) 0.1279(5) 0.1799(6) 0.2625(5) 0.2053(5) 0.4387(5)
0.02441(11) 0.01168(13) 0.01105(10) 0.01087(10) 0.0157(7) 0.0160(8) 0.0152(6) 0.0146(7) 0.0142(6) 0.0160(7)
0.01268(16) 0.0107(3) 0.0109(2) 0.0103(2) 0.0115(16) 0.0125(15) 0.0153(14) 0.0137(16) 0.0169(14) 0.0151(17)
0.0351(2) 0.0111(3) 0.01104(17) 0.01133(18) 0.0215(17) 0.0137(16) 0.0130(14) 0.0077(14) 0.0114(14) 0.0213(17)
0.0255(2) 0.0133(3) 0.0112(2) 0.0110(2) 0.0140(19) 0.022(2) 0.0174(16) 0.022(2) 0.0143(18) 0.0118(17)
0.0061(2) 0.0004(3) 20.00067(17) 0.00034(18) 0.0000(12) 20.0041(14) 0.0019(15) 20.0022(13) 0.0035(12) 0.0004(13)
20.00149(16) 0.0002(2) 0.0003(2) 20.00026(19) 20.0001(14) 0.0011(13) 0.0007(16) 0.0009(13) 0.0006(14) 0.0033(14)
20.00419(16) 20.0001(2) 20.00053(15) 0.00097(14) 0.0040(12) 0.0009(12) 20.0026(11) 0.0004(11) 20.0014(11) 0.0039(13)
0 0 0 0 0 0 0.1592(5) 0.3278(13)
0 1/2 0.09880(3) 0.22851(2) 0.61347(2) 0.65254(19) 0.20872(10) 0.60040(13)
0.0235(4) 0.0252(4) 0.0131(4) 0.0133(3) 0.0118(3) 0.030(2) 0.0302(12) 0.0507(19)
0.0276(6) 0.0282(6) 0.0110(5) 0.0135(4) 0.0122(4) 0.038(3) 0.051(3) 0.077(4)
0.0276(6) 0.0282(6) 0.0110(5) 0.0135(4) 0.0122(4) 0.038(3) 0.051(3) 0.018(3)
0.0153(6) 0.0192(7) 0.0171(7) 0.0130(4) 0.0110(4) 0.012(3) 0.0170(18) 0.038(3)
0 0 0 0 0 0 0.0001(8) 0.013(2)
0 0 0 0 0 0 20.0001(8) 0.0067(12)
Rb1 Rb2 Fe Se1 Se2 O1 O2 O3
0 0 0 0 0 0 20.1592(5) 0.1639(7)
U13
U12
0.0138(3) 0.0141(3) 0.0055(2) 0.00673(18) 0.00608(18) 0.0191(17) 0.046(3) 0.0090(14)
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
x Ba Fe1 Fe2 Se1 Se2 O1 O2 O3 O4 O5 O6
73
74
Table 3 ˚ and angles (8) in BAFE, AGFE and RBFE Selected interatomic distances (A) BAFE
AGFE 23 23 23 23 23
2.749(2) 2.806(2) 2.859(2) 2.976(2) 3.252(2) 2.928
Fe1–O5 Fe1–O2 Fe1–O6 kFe1–Ol
23 23 23
1.982(2) 1.995(2) 2.051(2) 2.009
Fe2–O4 Fe2–O1 Fe2–O3 kFe2–Ol
23 23 23
1.987(2) 2.008(2) 2.048(2) 2.014
RBFE
Ag–O2 Ag–O5 Ag–O3 Ag–O6 Ag–O1 Ag–O4 kAg–Ol
2.431(3) 2.447(3) 2.511(3) 2.583(4) 2.713(4) 2.794(3) 2.580
Fe–O4 Fe–O3 Fe–O5 Fe–O2 Fe–O1 Fe–O6 kFe–Ol
1.977(3) 1.999(3) 2.013(3) 2.015(3) 2.021(4) 2.030(4) 2.009
Se1–O5 Se1–O6 Se1–O1 kSe1–Ol
1.698(2) 1.698(2) 1.707(2) 1.701
Se1–O1 Se1–O3 Se1–O2 kSe1–Ol
1.697(4) 1.698(4) 1.698(3) 1.698
O5–Se1–O6 O5–Se1–O1 O6–Se1–O1 kO–Se1–Ol
100.96(9) 95.83(9) 99.74(9) 98.84
O1–Se1–O3 O1–Se1–O2 O3–Se1–O2 kO–Se1–Ol
99.90(16) 100.73(17) 100.61(18) 100.41
Se2–O2 Se2–O4 Se2–O3 kSe2–Ol
1.681(2) 1.695(2) 1.713(2) 1.696
Se2–O4 Se2–O6 Se2–O5 kSe2–Ol
1.687(3) 1.695(3) 1.712(4) 1.698
O2–Se2–O4 O2–Se2–O3 O4–Se2–O3 kO–Se2–Ol
100.72(9) 103.50(9) 100.24(9) 101.49
O4–Se2–O6 O4–Se2–O5 O6–Se2–O5 kO–Se2–Ol
100.50(18) 101.24(18) 99.86(16) 100.53
Rb1–O3 Rb1–O1 kRb1–Ol
63 63
3.157(6) 3.171(2) 3.164
Rb2–O2
123
3.209(2)
Fe–O2 Fe–O3 kFe–Ol
33 33
1.945(5) 2.076(6) 2.011
Se1–O2
33
1.698(5)
O2–Se1–O2
33
98.85(19)
Se2–O1 Se2–O3 kSe2–Ol
33
1.610(8) 1.624(6) 1.621
O1–Se2–O3 O3–Se2–O3 kO–Se2–Ol
33 33
109.4(2) 109.6(2) 109.5
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Ba–O6 Ba–O1 Ba–O3 Ba–O5 Ba–O4 kBa–Ol
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Fig. 1. Crystal structure of BAFE in a projection parallel to [010]. The drawings are done with the program
75
ATOMS
[8].
Fig. 2. Cell relations and symmetry operators for (a) hypothetic SrFe 2 (SeO 3 ) 4 , (b) BAFE, (c) KFE and (d) SRCO.
76
G. Giester / Journal of Alloys and Compounds 308 (2000) 71 – 76
Fig. 3. Crystal structure of AGFE in projections parallel to (a) [010] and (b) [001].
References [1] G. Giester, Z. Anorg. Allg. Chem. 622 (1996) 1788–1792. [2] G. Giester, Acta Chem. Scand. A51 (1997) 501–503. [3] G. Giester, A. Beran, G.J. Redhammer, J. Sol. St. Chem. 131 (1997) 54–63. [4] G. Giester, M. Wildner, J. Alloys Compd. 239 (1996) 99–102. [5] Denzo SMN, Nonius, Delft, 1998. [6] G.M. Sheldrick, SHELXS-97, a program for the solution of crystal ¨ structures, University Gottingen, Germany, 1997. [7] G.M. Sheldrick, SHELXL-97, a program for crystal structure refine¨ ment, University Gottingen, Germany, 1997. [8] E. Dowty, ATOMS for Windows 5.0, a computer program for displaying atomic structures, Kingsport, TN, 1999.
Fig. 4. Atomic arrangement in RBFE.
[9] [10] [11] [12] [13] [14]
G. Giester, Z. Krist. 207 (1993) 1–7. G. Giester, M. Wildner, J. Alloys Compd. 239 (1996) 99–102. H. Effenberger, Min. Petrol. 36 (1987) 3–12. G. Giester, Mh. Chem. 120 (1989) 661–666. G. Giester, Mh. Chem. 123 (1992) 957–963. R.E. Morris, A.P. Wilkinson, A.K. Cheetham, Inorg. Chem. 31 (1992) 4774–4777. [15] W.T.A. Harrison, Z. Zhang, Eur. J. Solid State Inorg. Chem. 34 (1997) 599–606.