- Email: [email protected]
The new silver borate Ag3B5O9
Author's Accepted Manuscript
The new silver borate Ag3B5O9 Gerhard Sohr, Viktoria Falkowski, Hubert Huppertz
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PII: DOI: Reference:
S0022-4596(14)00519-2 http://dx.doi.org/10.1016/j.jssc.2014.12.002 YJSSC18722
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Journal of Solid State Chemistry
Received date: 21 October 2014 Revised date: 28 November 2014 Accepted date: 3 December 2014 Cite this article as: Gerhard Sohr, Viktoria Falkowski, Hubert Huppertz, The new silver borate Ag3B5O9, Journal of Solid State Chemistry, http://dx.doi.org/ 10.1016/j.jssc.2014.12.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
The New Silver Borate Ag3B5O9 Gerhard Sohr,[a] Viktoria Falkowski,[a] and Hubert Huppertz*[a]
[a]
Gerhard Sohr, Viktoria Falkowski, Prof. Dr. H. Huppertz (Email: [email protected]), Institut für Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 80-82, A-6020 Innsbruck (Österreich)
Abstract Single crystals of Ag3B5O9 were obtained via high-pressure synthesis at 3 GPa and 600 °C, using a Walker-type multianvil high-pressure device. Ag3B5O9 crystalizes with a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, V = 0.7025(2) nm3, and Z = 4 in the noncentrosymmetric space group P212121 (No. 19). The orthorhombic structure was refined from 3740 independent reflections with R1 = 0.0496 and wR2 = 0.587 (all data). It is built up from infinite corner-sharing chains of BO4 tetrahedra along the a axis, which are interconnected by BO3 groups to form a network. In the structure, three crystallographically independent sites are occupied with Ag+ cations exhibiting argentophillic interactions. The synthetic conditions as well as the results of the single crystal structure analysis are presented. Keywords: borates • silver • high-pressure chemistry • argentophillic interaction • structure elucidation
Introduction During our research in the field of high-pressure alkali metal borates, we noticed that HP-RbB3O5 is isotypic to HP-KB3O5,[1] according to the similar ionic radii of the alkali metal cations differing by 7 pm (K: 173 pm, Rb: 180 pm).[2] Consequently, pseudo alkali metal borates with comparable ionic radii can form isotypic structures or substitution variants, as can be seen in the compounds HP-(NH4)B3O5 or HPTlB3O5.[3] Even the significantly larger cesium ion (195 pm)[2] fits into this structure type, if it is occupying not more than one half of the M+ positions, as was
2 demonstrated in the compound HP-Cs1-x(H3O)xB3O5 (x = 0.5-0.7).[4] Another structure type present in lighter high-pressure alkali metal borates is found in the sodium tetraborate HP-Na2B4O7.[5] With the knowledge that the radius of the pseudo alkali metal ion silver (142 pm) differs by just 10 pm from the value of the sodium ion (132 pm),[2] we started investigations in the system Ag-B-O. Under ambient-pressure conditions seven ternary borate phases are known in this system: the metaborate AgBO2,[6] the orthoborates Ag3BO3-I[7] and Ag3BO3-II,[8] two forms of Ag2B8O13,[9] as well as Ag2B4O7 and AgB9O14.[10] Within these ambient-pressure phases, there are examples for silver borates being isotypic to sodium borates like β-Ag2B8O13 to β-Na2B8O13.[9b] However, there are also examples for phases possessing a different structure. For example, AgBO2 crystallizes in a different structure than NaBO2 or KBO2. In literature, this difference is used to underline a structure influencing factor of Ag+ ions that, for example, is also observed in the system Ag-Si-O.[6] This ascinating structure influencing factor is caused by the fully occupied 4d orbitals of the Ag+ ions (electronic configuration: [Kr]4d10). Homoatomic d10-d10 interactions lead to shortened distances between the Ag+ cations in the range between 253.35(5) pm (Ag-Ag single bond) and 344 pm (van der Waals radius). These argentophillic interactions lead to substructures of the silver cations of different complexity, ranging from simple dimers up to complex networks.[11] The question arises, how the system Ag-B-O behaves under high-pressure conditions. Is there a silver borate isotypic to HP-Na2B4O7 or does the structural chemistry differ due to argentophillic interactions? Interestingly, no high-pressure silver borates were known until we started our investigations in this system. With the compound AgB3O5, we recently synthesized the first high-pressure silver borate with an interesting, non-centrosymmetric structure.[12] Non-centrosymmetric borates are highly interesting materials due to their industrial application as non-linear optical materials, e.g. β-BaB2O4 (BBO).[13] In this work, the second high-pressure silver borate possessing the composition Ag3B5O9 will be presented. Synthetic conditions as well as the crystal structure of the new compound will be described.
3
Results and Discussion Crystal structure: The silver borate Ag3B5O9 crystalizes with four formula units (Z = 4) in the orthorhombic space group P212121 (No. 19). The dimensions of the unit cell are a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, and V = 0.7025(2) nm3 (see Table 1). Figure 1 displays the unit cell down the a axis. The fundamental building block is presented in Figure 2 together with the atom labeling (for atomic coordinates and displacement parameters see Tables 2 and 3). BO4 tetrahedra and BO3 groups are linked by common oxygen atoms to form a noncentrosymmetric B-O network structure. Three crystallographically independent BO4 tetrahedra are present in the structure. They exhibit B–O bond lengths between 145.0(6)-149.9(6) pm (av. 147.2 pm), 144.7(6)-149.7(6) pm (av. 147.5 pm), and 145.5(6)-149.1(6) pm (av. 147.5 pm) for the tetrahedra around B1, B3, and B4, respectively (see Table 4). The O–B–O bond angles in these tetrahedra are distributed from 106.0(3) to 112.2(4)°, 105.1(3) to 112.1(4)°, and 105.9(4) to 112.4(4)° (see Table 5). The mean O–B–O bond angle in the tetrahedra around B1 and B3 is 109.5°, while the tetrahedron around B4 exhibits a value of 109.4°. The B–O bond lengths within the two independent BO3 groups range from 137.0(7) to 140.3(6) pm (av. 138.3 pm) and from 136.1(6) to 138.0(6) pm (av. 137.2 pm) with O–B–O bond angles from 115.1(4) to 121.6(4)° (av. 119.2°) and 117.8(4) to 121.4(4)° (av. 120.0°) for B2O3 and B5O3, respectively. These values are within the range of the values found in literature for BO4
tetrahedra
(137.3-169.9
pm,
av. 147.6(3.5) pm
and
95.7-119.4°,
av. 109.4(2.8)°)[14] and for BO3 groups (135.1-140.3 pm, av. 137.0 pm and 109-129°, av. 120.0°).[15] The BO4 tetrahedra are linked by common oxygen atoms to form chains along the a axis (see Figure 1, bottom). In each chain, corners of two neighboring BO4 tetrahedra (B3O4 to B4O4 and B4O4 to B1O4) are additionally connected by BO3 groups (B5O3 and B2O3, respectively), yielding two crystallographically different “dreier” rings.[16] The remaining corner of the BO3 groups connect to the remaining corner of BO4 tetrahedra in the neighbored chains (see Figure 3), resulting in a network of BO3 and BO4 groups. Within this network, channels are formed along [101] and [100] which incorporate the Ag1 and Ag2 sites, respectively. The Ag3 site is stacked with the B5O3 groups along the a axis. As shown in Figure 4, the silver
4 ions are surrounded by five (Ag1, Ag3) and four (Ag2) oxygen atoms with distances from 217.2(4) to 270.3(4) pm (av. 248.5 pm), 226.5(3) to 254.1(3) pm (av. 242.5 pm), and from 234.6(3) to 304.5(4) pm (av. 255.5 pm)), for Ag1, Ag2, and Ag3, respectively. According to the ECoN values (Effective Coordination Numbers),[17] the coordination numbers of the silver ions in Ag3B5O9 (CN = 4, 5) are within the range of coordination numbers found in other phases of the system Ag-B-O (CN = 2[7]-8[12]). The value for the shortest (Ag-Omin) as well as for the longest (Ag-Omax) Ag–O bond length within the coordination spheres of the siver ions is comparable to other silver borates. (Ag-Omin = 211.1(2)[8] to 237.2(4)[12] pm, Ag-Omax = 212.5(7)[7] to 304.6(6)[12] pm). The average Ag-O distances for Ag1, Ag2, and Ag3 are 248.5, 242.5, and 255.5 pm, respectively. Other phases show average values in the same region (212.5[7] to 278.1[6] pm). Compared to the recently discovered high-pressure phase AgB3O5, the surrounding of the silver ions in Ag3B5O9 resembles the ambientpressure phases rather than AgB3O5. Solely the Ag-Omin and Ag-Omax value of the ion Ag3 (234.6(3) and 304.5(4) pm) are comparable to the values in AgB3O5 (237.2(4) and 304.6(6) pm).[12] The shortest distances between the silver ions are 286.56(7) (Ag1··Ag3),
294.89(8)
(Ag1··Ag2),
301.47(9)
(Ag2··Ag3),
(Ag1··Ag2) compared to 295.4(2) and 306.2(1) pm in AgBO2
and [6]
324.73(8) pm
and Ag3BO3-II[8],
respectively. The first distance is even shorter than the distance found in metallic silver (289 pm). These short distances clearly indicate the presence of argentophillic interactions, which also explain the color of the crystals.[11] A representation of the resulting silver substructure is displayed in Figure 5. With the bond-length / bondstrength- (ΣV)[18] and the CHARDI- (Charge distribution in solids, ΣQ)[19] concepts, the bond-valence sums for Ag3B5O9 were calculated. The formal ionic charge of each atom fits to the expected values within the limits of the concepts (see Table 6). The MAPLE-value (Madelung Part of Lattice Energy)[17] of Ag3B5O9 was calculated to compare it to the stoichiometric sum of the binary oxides B2O3-II[20] and Ag2O.[21] The calculation for Ag3B5O9 led to a value of 59515 kJ/mol, while from the stoichiometric sum of the binary compounds (2.5 × B2O3-II (54846 kJ/mol) + 1.5 × Ag2O (4513 kJ/mol)) a value of 59359 kJ/mol was derived. As expected by the additive potential of the MAPLE values, both are in good agreement (deviation: 0.26 %).
5
Conclusion In this work, we reported about the high-pressure synthesis and crystal structure of the second high-pressure silver borate Ag3B5O9. Single crystals of this compound were found during high-pressure investigations in the system Ag-B-O. The compound crystalizes in the orthorhombic, noncentrosymmetric space group P212121 (No. 19) with the parameters a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, V = 0.7025(2) nm3, and Z = 4. This new structure type is built up from BO3 and BO4 groups connected by common oxygen atoms. The BO4 tetrahedra form infinite chains along the a axis. They are interconnected by the BO3 groups to form a B-O network incorporating the four- and five-fold coordinated silver ions. It was not possible to obtain vibrational spectroscopy data due to the light sensitivity of the compound, which also thwarts investigations of possible non-linear optical properties. The compound is the second high-pressure silver borate so far. However, further results indicate the presence of additional phases.
Experimental section Synthesis Single crystals of Ag3B5O9 were obtained as a sidephase from a reaction mixture of 0.3156 g Ag2O (0.0014 mol, 99+ %, Alfa Aesar, Karlsruhe, Germany) and 0.1873 g B2O3 (0.003427 mol, 99.9+ %, Strem Chemicals, Kehl, Germany). The chemicals were finely ground together under argon atmosphere and transferred into a gold capsule (0.025 mm foil, 99.99 %, Sigma-Aldrich, Steinheim, Germany). The capsule was inserted into a crucible made from hexagonal boron nitride (HeBoSint® P100, Henze BNP GmbH, Kempten, Germany), and built into an 18/11 assembly. It was compressed to 3 GPa within one and a half hour by a high-pressure device consisting of a hydraulic 1000 t press (mavo press LPR 1000-400/50, Max Voggenreiter GmbH, Mainleus, Germany) and a Walker-type module (also Max Voggenreiter GmbH) with eight tungsten carbide cubes (HA-7%Co, Hawedia, Marklkofen, Germany). The mixture was heated from ambient temperature to 600 °C in 5 min and after further 5 min the temperature was lowered to 250 °C within 15 min.
6 The reaction was quenched and the decompression needed four hours. Details on the high-pressure device and its preparation are described in the references.[22] After separation of the product from the assembly materials, transparent crystals with different coloring (pale pink, yellow, green/yellow, brown/red yellow/orange) were isolated. The pale pink transparent crystals were found to be Ag3B5O9. The exposition to light was avoided wherever possible since some silver compounds, especially Ag2O, are sensitive to light. The powder diffraction pattern of the product revealed a very poor signal to noise ratio due to the mainly amorphous character of the sample. Reduced silver as well as B2O3 could be identified as the main phases. Crystal Structure Analyses The single crystal data set of Ag3B5O9 was collected at ambient-temperature on a Kappa CCD single crystal diffractometer (Bruker AXS-Nonius, Karlsruhe, Germany) with graphite-monochromatized MoKα radiation (λ = 71.073 pm). The intensity data was corrected from absorption based on equivalent and redundant intensities (SCALEPACK[23]). The systematic extinctions indicated the space group P212121 (No. 19). The structure was solved with direct methods using SHELXS-2013.[24] The fullmatrix least-squares refinement on F2 was performed with SHELXL-2013.[25] A check with the Addsym routine of PLATON[26] indicated no additional symmetry. All atoms were refined anisotropically, resulting in R1 and wR2 values over all data of 0.0496 and 0.0587, respectively. The relevant details of the data collections and evaluations are listed in Table 1. The positional parameters, anisotropic displacement parameters, interatomic distances, and angles are listed in Tables 2-5. Additional details of the crystal structure investigations may be obtained from Fachinformationszentrum Karlsruhe, 76344
Eggenstein-Leopoldshafen,
[email protected],
Germany
(fax:
+49-7247-808-666;
e-mail:
http://www.fiz-
karlsruhe.de/request_for_deposited_data.html) on quoting the deposition number CSD-428143.
7 Acknowledgements The authors are grateful to Dr. Gunter Heymann for the collection of the single crystal data set. This work was financially supported by the Austrian Science Fund (FWF): ZFP 232120.
8 Table 1. Crystal data and structure refinement of Ag3B5O9 (standard deviations in parentheses). Empirical formula
Ag3B5O9
Molar mass, g·mol-1
521.66
Crystal system
orthorhombic
Space group
P212121 (No. 19)
Single crystal diffractometer
Enraf-Nonius Kappa CCD
Radiation
MoKα (λ = 71.073 pm) (graded multilayer X-ray optics)
Single crystal data a, pm
674.7(2)
b, pm
943.5(2)
c, pm V, nm
1103.5(2) 3
0.7025(2)
Formula units per cell Calculated density, g·cm Crystal size, mm
Z=4 -3
4.932
3
0.037 x 0.035 x 0.020
Temperature, K
293(2)
Absorption coefficient, mm-1
8.316
F(000)
952
θ range, °
2.84 - 37.72
Range in hkl
-11 ≥ h ≥ 11, -13 ≥ k ≥ 16, -18 ≥ l ≥ 18
Total no. of reflections
10856 (Rint = 0.0560)
Independent reflections
3740 (Rσ = 0.0579)
Reflections with I ≥ 2σ(I)
3150
Data / parameters
3740 / 154
Absorption correction
multi-scan (Scalepack[23])
Goodness-of-fit on Fi2
1.052
Flack-Parameter
-0.05(3)
Final R indices [I ≥ 2σ(I)]
R1 = 0.0367 wR2 = 0.0557
Final R indices (all data)
R1 = 0.0496 wR2 = 0.0587
Largest diff. peak and hole, e·Å
-3
1.341 / -1.633
9 Table 2. Atomic coordinates and equivalent isotropic displacement parameters Ueq (Å2) of Ag3B5O9. Ueq is defined as one third of the trace of the orthogonalized Uij tensor (standard deviations in parentheses). The Wyckoff-position of all sites is 4a. Atom
x
y
z
Ueq
Ag1
0.18484(7)
0.22978(4)
0.72958(4)
0.02012(9)
Ag2
0.43543(7)
0.19198(5)
0.51304(4)
0.0231(2)
Ag3
0.97096(7)
0.10349(6)
0.92623(5)
0.0348(2)
O1
0.0595(5)
0.0327(3)
0.6597(3)
0.0093(6)
O2
0.3293(5)
0.1071(4)
0.9877(3)
0.0133(6)
O3
0.5435(5)
0.3482(3)
0.6886(3)
0.0112(6)
O4
0.2651(5)
0.4385(4)
0.7966(3)
0.0106(6)
O5
0.2657(5)
0.3257(3)
0.3779(3)
0.0099(6)
O6
0.6622(5)
0.0230(4)
0.9958(3)
0.0114(6)
O7
0.5138(5)
0.0966(4)
0.8082(3)
0.0121(6)
O8
0.8233(5)
0.2924(4)
0.8133(3)
0.0134(6)
O9
0.5947(5)
0.4807(3)
0.8747(3)
0.0089(6)
B1
0.4735(8)
0.4647(5)
0.7671(4)
0.0087(8)
B2
0.7025(9)
0.2638(6)
0.7160(5)
0.017(2)
B3
0.1489(7)
0.5280(6)
0.8760(5)
0.0088(9)
B4
0.2038(8)
0.9266(6)
0.6173(4)
0.0097(8)
B5
0.5025(8)
0.0744(6)
0.9311(5)
0.0101(9)
10 Table 3. Anisotropic displacement parameters (Å2) of Ag3B5O9 (standard deviations in parentheses). Atom
U11
U22
U33
U12
U13
U23
Ag1
0.0185(2)
0.0141(2)
0.0278(2)
-0.0062(2)
0.0051(2)
-0.0097(2)
Ag2
0.0326(2)
0.0186(2)
0.0182(2)
0.0015(2)
-0.0089(2)
0.0048(2)
Ag3
0.0164(2)
0.0518(3)
0.0361(2)
0.0043(2)
0.0004(2)
0.0308(2)
O1
0.006(2)
0.010(2)
0.011(2)
0.000(2)
-0.000(2)
-0.003(2)
O2
0.012(2)
0.018(2)
0.010(2)
0.005(2)
0.002(2)
0.004(2)
O3
0.013(2)
0.011(2)
0.010(2)
0.003(2)
-0.001(2)
-0.004(2)
O4
0.007(2)
0.011(2)
0.014(2)
-0.001(2)
0.002(2)
-0.002(2)
O5
0.013(2)
0.007(2)
0.010(2)
-0.001(2)
-0.002(2)
0.000(2)
O6
0.011(2)
0.014(2)
0.009(2)
0.000(2)
-0.001(2)
0.002(2)
O7
0.019(2)
0.009(2)
0.008(2)
0.004(2)
-0.002(2)
-0.001(2)
O8
0.011(2)
0.012(2)
0.017(2)
0.003(2)
-0.006(2)
-0.005(2)
O9
0.008(2)
0.011(2)
0.008(2)
0.001(2)
-0.001(2)
-0.002(2)
B1
0.009(2)
0.010(2)
0.008(2)
-0.000(2)
0.002(2)
-0.001(2)
B2
0.014(2)
0.018(2)
0.018(2)
0.006(2)
-0.005(2)
-0.011(2)
B3
0.008(2)
0.010(2)
0.008(2)
-0.001(2)
-0.001(2)
-0.000(2)
B4
0.009(2)
0.013(2)
0.007(2)
0.002(2)
0.001(2)
-0.001(2)
B5
0.013(2)
0.009(2)
0.008(2)
0.000(2)
-0.002(2)
0.002(2)
11 Table 4. Interatomic distances (pm) in Ag3B5O9 (standard deviations in parentheses). Ag1-O4
217.2(4)
Ag2-O5
226.5(3)
Ag3-O6
234.6(3)
Ag1-O1
218.3(3)
Ag2-O9
235.6(3)
Ag3-O8
239.2(3)
Ag1-O8
267.4(4)
Ag2-O5
253.8(3)
Ag3-O9
248.0(3)
Ag1-O7
269.4(3)
Ag2-O3
254.1(3)
Ag3-O2
251.2(4)
Ag1-O3
270.3(4)
av. Ag2-O
242.5
Ag3-O2
304.5(4)
av. Ag1-O
248.5
av. Ag3-O
255.5
B1-O9
145.0(6)
B2-O3
137.0(7)
B3-O4
144.7(6)
B1-O4
146.5(6)
B2-O8
137.5(6)
B3-O1
146.1(6)
B1-O3
147.7(6)
B2-O5
140.3(6)
B3-O5
149.6(6)
B1-O7
149.9(6)
av. B2-O
138.3
B3-O6
149.7(6)
av. B1-O
147.2
av. B3-O
147.5
B4-O9
145.5(6)
B5-O2
136.1(6)
B4-O1
147.3(6)
B5-O7
137.4(6)
B4-O2
148.2(6)
B5-O6
138.0(6)
B4-O8
149.1(6)
av. B5-O
137.2
av. B4-O
147.5
12 Table 5. Interatomic angles (deg) in Ag3B5O9 (standard deviations in parentheses). O3-B1-O7
106.0(3)
O3-B2-O5
115.1(4)
O5-B3-O6
105.1(3)
O4-B1-O3
108.2(4)
O8-B2-O5
121.0(5)
O1-B3-O6
108.8(4)
O4-B1-O7
108.6(4)
O3-B2-O8
121.6(4)
O4-B3-O5
109.8(4)
O9-B1-O7
109.6(4)
av. O-B2-O
119.2
O1-B3-O5
110.3(4)
O9-B1-O4
112.1(4)
O4-B3-O6
110.6(4)
O9-B1-O3
112.2(4)
O4-B3-O1
112.1(4)
av. O-B1-O
109.5
av. O-B3-O
109.5
O9-B4-O2
105.9(4)
O2-B5-O7
117.8(4)
O2-B4-O8
107.1(4)
O2-B5-O6
120.8(4)
O1-B4-O8
109.5(4)
O7-B5-O6
121.4(4)
O1-B4-O2
110.6(4)
av. O-B5-O
120.0
O9-B4-O1
111.1(4)
O9-B4-O8
112.4(4)
av. O-B4-O
109.4
13 Table 6. Charge distribution in Ag3B5O9, calculated with the bond-length / bondstrength concept (ΣV)[18] and the CHARDI-concept (ΣQ)[19]. Ag1
Ag2
Ag3
B1
B2
B3
B4
B5
ΣV
+1.01
+0.79
+0.78
+3.04
+2.91
+3.02
+3.02
+3.00
ΣQ
+1.00
+0.95
+0.99
+3.04
+2.91
+2.97
+2.94
+3.20
O1
O2
O3
O4
O5
O6
O7
O8
O9
ΣV
-1.90
-1.95
-1.98
-1.96
-2.06
-1.92
-1.79
-2.01
-1.99
ΣQ
-1.98
-1.99
-2.00
-2.05
-2.13
-1.95
-1.70
-2.06
-2.14
14 Figure Captions Figure 1.
Top: Unit cell of Ag3B5O9 down the a axis exhibiting corner-sharing BO4 tetrahedra as well as BO3 groups. Bottom: chains of BO4 tetrahedra and BO3 groups running along the a axis. Spheres: 90 % probability ellipsoids of the atoms (color: see legend). Blue polyhedra: corner-sharing BO4 tetrahedra; yellow tetrahedra and green bonds: fundamental building block.
Figure 2.
Fundamental building block of Ag3B5O9 together with the labeling of the atoms. The block is linked via O3 and O9 to form the chain presented in Figure 1.
Figure 3.
Linkage between the chains running along a via BO3 groups forming sheets in the ab plane.
Figure 4.
Coordination spheres of the silver ions in the crystal structure of Ag3B5O9.
Figure 5.
Unit cell of Ag3B5O9 (background) together with the silver substructure (green lines).
15 Figures
Figure 1. Top: Unit cell of Ag3B5O9 exhibiting corner-sharing BO4 tetrahedra as well as BO3 groups. Bottom: chains of BO4 tetrahedra and BO3 groups running along the a axis. Spheres: 90 % probability ellipsoids of the atoms (color: see legend). Blue polyhedra: corner-sharing BO4 tetrahedra; yellow tetrahedra and green bonds: fundamental building block.
16
Figure 2. Fundamental building block of Ag3B5O9 together with the labeling of the atoms. The block is linked via O3 and O9 to form the chain presented in Figure 1.
17
Figure 3. Linkage between the chains running along a via BO3 groups forming sheets in the ab plane.
18
Figure 4. Coordination spheres of the silver ions in the crystal structure of Ag3B5O9.
19
Figure 5. Unit cell of Ag3B5O9 (background) together with the silver substructure (green lines).
20 References [1]
[2] [3]
[4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]
[17]
[18] [19]
[20] [21] [22]
[23] [24] [25]
a) G. Sohr, S. C. Neumair, H. Huppertz, Z. Naturforsch. 2012, 67b, 1197-1204; b) S. C. Neumair, S. Vanicek, R. Kaindl, D. M. Többens, C. Martineau, F. Taulelle, J. Senker, H. Huppertz, Eur. J. Inorg. Chem. 2011, 4147-4152. M. O'Keeffe, Struct. Bonding 1989, 71, 161-190. a) G. Sohr, D. Wilhelm, D. Vitzthum, M. K. Schmitt, H. Huppertz, Z. Anorg. Allg. Chem. 2014, 640, 2753-2758; b) G. Sohr, L. Perfler, H. Huppertz, Z. Naturforsch. 2014, 69b, in press. G. Sohr, S. C. Neumair, G. Heymann, K. Wurst, J. Schmedt auf der Günne, H. Huppertz, Chem. Eur. J. 2014, 20, 4316-4323. S. C. Neumair, G. Sohr, S. Vanicek, K. Wurst, R. Kaindl, H. Huppertz, Z. Anorg. Allg. Chem. 2012, 638, 81-87. G. Brachtel, M. Jansen, Z. Anorg. Allg. Chem. 1981, 478, 13-19. M. Jansen, W. Scheld, Z. Anorg. Allg. Chem. 1981, 477, 85-89. M. Jansen, G. Brachtel, Z. Anorg. Allg. Chem. 1982, 489, 42-46. a) J. Krogh-Moe, Acta Cryst. 1965, 18, 77-81; b) N. Penin, M. Touboul, G. Nowogrocki, Solid State Sci. 2003, 5, 559-564. J. Kocher, N. Sadeghi, C. R. Séances Acad. Sci., Sér. C 1967, 264, 1481-1484. a) M. Jansen, Angewandte Chemie 1987, 99, 1136-1149; b) H. Schmidbaur, A. Schier, Angewandte Chemie 2014, DOI: 10.1002/ange.201405936. G. Sohr, V. Falkowski, M. Schauperl, K. Liedl, H. Huppertz, Eur. J. Inorg. Chem. 2014, in press. P. Becker, Adv. Mater. 1998, 10, 979-992. E. Zobetz, Z. Kristallogr. 1990, 191, 45-57. E. Zobetz, Z. Kristallogr. 1982, 160, 81-92. a) The term “dreier” ring was initially coined by F. Liebau in his book Structural Chemistry of Silicates (Springer-Verlag, Berlin, 1985). It is derived from the German word “drei”, which means three. However, a “dreier” ring is not a three membered ring, but a six-membered ring comprising three tetrahedral centers (B). Similar terms exist for rings made up of two, four, five, and six tetrahedral centers, namely “zweier”, "vierer", "fünfer", and "sechser" rings, respectively; b) F. Liebau, Structural Chemistry of Silicates, Springer-Verlag, Berlin, 1985. a) R. Hoppe, Angew. Chem. Int. Ed. 1966, 5, 95-106; b) R. Hoppe, Angew. Chem. Int. Ed. 1970, 9, 25-34; c) R. Hübenthal, MAPLE, PROGRAM FOR THE CALCULATION OF MAPLE VALUES, University of Gießen, Gießen (Germany), 1993. a) N. E. Brese, M. O'Keeffe, Acta Cryst. B 1991, 47, 192-197; b) I. D. Brown, D. Altermatt, Acta Cryst. B 1985, 41, 244-247. a) R. Hoppe, Z. Kristallogr. - Cryst. Mater. 1979, 150, 23-52; b) R. Hoppe, S. Voigt, H. Glaum, J. Kissel, H. P. Müller, K. Bernet, J. Less-Common Met. 1989, 156, 105122. C. T. Prewitt, R. D. Shannon, Acta Cryst. B 1968, 24, 869-874. A. Werner, H. D. Hochheimer, Phys. Rev. B: Condens. Matter Mater. Phys. 1982, 25, 5929-5934. a) H. Huppertz, Z. Kristallogr. 2004, 219, 330-338; b) D. Walker, M. A. Carpenter, C. M. Hitch, Am. Mineral. 1990, 75, 1020-1028; c) D. Walker, Am. Mineral. 1991, 76, 1092-1100; d) D. C. Rubie, Phase Transitions 1999, 68, 431-451. Z. Otwinowski, W. Minor, Methods Enzymol. 1997, 276, 307-326. G. M. Sheldrick, SHELXS - CRYSTAL STRUCTURE SOLUTION, 2013/1, University of Göttingen, Göttingen (Germany), 2013. G. M. Sheldrick, SHELXL - CRYSTAL STRUCTURE REFINEMENT - MULTI-CPU VERSION, 2013/4, University of Göttingen, Göttingen (Germany), 2013.
21 [26]
A. L. Spek, Acta Cryst. D 2009, 65, 148-155.
22 A noncentrosymmetric borate Ag3B5O9 is accessible via high-pressure synthesis Ag3B5O9 is the second high-pressure silver borate Ag+⋅⋅⋅Ag+ distances in clearly indicate the presence of argentophillic interactions
*Graphical Abstract (TOC Figure)
*Graphical Abstract Legend (TOC Figure)
1
Table of contents entry Non-centrosymmetric silver borate: During investigations in the system Ag-B-O, a new noncentrosymmetric silver borate Ag3B5O9 was discovered. The new structure type is built up from corner-sharing BO3 and BO4 groups, forming a network. Argentophillic interactions are clearly indicated by the Ag+×××Ag+ distances present in the structure.
The new silver borate Ag3B5O9 Gerhard Sohr, Viktoria Falkowski, Hubert Huppertz
www.elsevier.com/locate/jssc
PII: DOI: Reference:
S0022-4596(14)00519-2 http://dx.doi.org/10.1016/j.jssc.2014.12.002 YJSSC18722
To appear in:
Journal of Solid State Chemistry
Received date: 21 October 2014 Revised date: 28 November 2014 Accepted date: 3 December 2014 Cite this article as: Gerhard Sohr, Viktoria Falkowski, Hubert Huppertz, The new silver borate Ag3B5O9, Journal of Solid State Chemistry, http://dx.doi.org/ 10.1016/j.jssc.2014.12.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
The New Silver Borate Ag3B5O9 Gerhard Sohr,[a] Viktoria Falkowski,[a] and Hubert Huppertz*[a]
[a]
Gerhard Sohr, Viktoria Falkowski, Prof. Dr. H. Huppertz (Email: [email protected]), Institut für Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 80-82, A-6020 Innsbruck (Österreich)
Abstract Single crystals of Ag3B5O9 were obtained via high-pressure synthesis at 3 GPa and 600 °C, using a Walker-type multianvil high-pressure device. Ag3B5O9 crystalizes with a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, V = 0.7025(2) nm3, and Z = 4 in the noncentrosymmetric space group P212121 (No. 19). The orthorhombic structure was refined from 3740 independent reflections with R1 = 0.0496 and wR2 = 0.587 (all data). It is built up from infinite corner-sharing chains of BO4 tetrahedra along the a axis, which are interconnected by BO3 groups to form a network. In the structure, three crystallographically independent sites are occupied with Ag+ cations exhibiting argentophillic interactions. The synthetic conditions as well as the results of the single crystal structure analysis are presented. Keywords: borates • silver • high-pressure chemistry • argentophillic interaction • structure elucidation
Introduction During our research in the field of high-pressure alkali metal borates, we noticed that HP-RbB3O5 is isotypic to HP-KB3O5,[1] according to the similar ionic radii of the alkali metal cations differing by 7 pm (K: 173 pm, Rb: 180 pm).[2] Consequently, pseudo alkali metal borates with comparable ionic radii can form isotypic structures or substitution variants, as can be seen in the compounds HP-(NH4)B3O5 or HPTlB3O5.[3] Even the significantly larger cesium ion (195 pm)[2] fits into this structure type, if it is occupying not more than one half of the M+ positions, as was
2 demonstrated in the compound HP-Cs1-x(H3O)xB3O5 (x = 0.5-0.7).[4] Another structure type present in lighter high-pressure alkali metal borates is found in the sodium tetraborate HP-Na2B4O7.[5] With the knowledge that the radius of the pseudo alkali metal ion silver (142 pm) differs by just 10 pm from the value of the sodium ion (132 pm),[2] we started investigations in the system Ag-B-O. Under ambient-pressure conditions seven ternary borate phases are known in this system: the metaborate AgBO2,[6] the orthoborates Ag3BO3-I[7] and Ag3BO3-II,[8] two forms of Ag2B8O13,[9] as well as Ag2B4O7 and AgB9O14.[10] Within these ambient-pressure phases, there are examples for silver borates being isotypic to sodium borates like β-Ag2B8O13 to β-Na2B8O13.[9b] However, there are also examples for phases possessing a different structure. For example, AgBO2 crystallizes in a different structure than NaBO2 or KBO2. In literature, this difference is used to underline a structure influencing factor of Ag+ ions that, for example, is also observed in the system Ag-Si-O.[6] This ascinating structure influencing factor is caused by the fully occupied 4d orbitals of the Ag+ ions (electronic configuration: [Kr]4d10). Homoatomic d10-d10 interactions lead to shortened distances between the Ag+ cations in the range between 253.35(5) pm (Ag-Ag single bond) and 344 pm (van der Waals radius). These argentophillic interactions lead to substructures of the silver cations of different complexity, ranging from simple dimers up to complex networks.[11] The question arises, how the system Ag-B-O behaves under high-pressure conditions. Is there a silver borate isotypic to HP-Na2B4O7 or does the structural chemistry differ due to argentophillic interactions? Interestingly, no high-pressure silver borates were known until we started our investigations in this system. With the compound AgB3O5, we recently synthesized the first high-pressure silver borate with an interesting, non-centrosymmetric structure.[12] Non-centrosymmetric borates are highly interesting materials due to their industrial application as non-linear optical materials, e.g. β-BaB2O4 (BBO).[13] In this work, the second high-pressure silver borate possessing the composition Ag3B5O9 will be presented. Synthetic conditions as well as the crystal structure of the new compound will be described.
3
Results and Discussion Crystal structure: The silver borate Ag3B5O9 crystalizes with four formula units (Z = 4) in the orthorhombic space group P212121 (No. 19). The dimensions of the unit cell are a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, and V = 0.7025(2) nm3 (see Table 1). Figure 1 displays the unit cell down the a axis. The fundamental building block is presented in Figure 2 together with the atom labeling (for atomic coordinates and displacement parameters see Tables 2 and 3). BO4 tetrahedra and BO3 groups are linked by common oxygen atoms to form a noncentrosymmetric B-O network structure. Three crystallographically independent BO4 tetrahedra are present in the structure. They exhibit B–O bond lengths between 145.0(6)-149.9(6) pm (av. 147.2 pm), 144.7(6)-149.7(6) pm (av. 147.5 pm), and 145.5(6)-149.1(6) pm (av. 147.5 pm) for the tetrahedra around B1, B3, and B4, respectively (see Table 4). The O–B–O bond angles in these tetrahedra are distributed from 106.0(3) to 112.2(4)°, 105.1(3) to 112.1(4)°, and 105.9(4) to 112.4(4)° (see Table 5). The mean O–B–O bond angle in the tetrahedra around B1 and B3 is 109.5°, while the tetrahedron around B4 exhibits a value of 109.4°. The B–O bond lengths within the two independent BO3 groups range from 137.0(7) to 140.3(6) pm (av. 138.3 pm) and from 136.1(6) to 138.0(6) pm (av. 137.2 pm) with O–B–O bond angles from 115.1(4) to 121.6(4)° (av. 119.2°) and 117.8(4) to 121.4(4)° (av. 120.0°) for B2O3 and B5O3, respectively. These values are within the range of the values found in literature for BO4
tetrahedra
(137.3-169.9
pm,
av. 147.6(3.5) pm
and
95.7-119.4°,
av. 109.4(2.8)°)[14] and for BO3 groups (135.1-140.3 pm, av. 137.0 pm and 109-129°, av. 120.0°).[15] The BO4 tetrahedra are linked by common oxygen atoms to form chains along the a axis (see Figure 1, bottom). In each chain, corners of two neighboring BO4 tetrahedra (B3O4 to B4O4 and B4O4 to B1O4) are additionally connected by BO3 groups (B5O3 and B2O3, respectively), yielding two crystallographically different “dreier” rings.[16] The remaining corner of the BO3 groups connect to the remaining corner of BO4 tetrahedra in the neighbored chains (see Figure 3), resulting in a network of BO3 and BO4 groups. Within this network, channels are formed along [101] and [100] which incorporate the Ag1 and Ag2 sites, respectively. The Ag3 site is stacked with the B5O3 groups along the a axis. As shown in Figure 4, the silver
4 ions are surrounded by five (Ag1, Ag3) and four (Ag2) oxygen atoms with distances from 217.2(4) to 270.3(4) pm (av. 248.5 pm), 226.5(3) to 254.1(3) pm (av. 242.5 pm), and from 234.6(3) to 304.5(4) pm (av. 255.5 pm)), for Ag1, Ag2, and Ag3, respectively. According to the ECoN values (Effective Coordination Numbers),[17] the coordination numbers of the silver ions in Ag3B5O9 (CN = 4, 5) are within the range of coordination numbers found in other phases of the system Ag-B-O (CN = 2[7]-8[12]). The value for the shortest (Ag-Omin) as well as for the longest (Ag-Omax) Ag–O bond length within the coordination spheres of the siver ions is comparable to other silver borates. (Ag-Omin = 211.1(2)[8] to 237.2(4)[12] pm, Ag-Omax = 212.5(7)[7] to 304.6(6)[12] pm). The average Ag-O distances for Ag1, Ag2, and Ag3 are 248.5, 242.5, and 255.5 pm, respectively. Other phases show average values in the same region (212.5[7] to 278.1[6] pm). Compared to the recently discovered high-pressure phase AgB3O5, the surrounding of the silver ions in Ag3B5O9 resembles the ambientpressure phases rather than AgB3O5. Solely the Ag-Omin and Ag-Omax value of the ion Ag3 (234.6(3) and 304.5(4) pm) are comparable to the values in AgB3O5 (237.2(4) and 304.6(6) pm).[12] The shortest distances between the silver ions are 286.56(7) (Ag1··Ag3),
294.89(8)
(Ag1··Ag2),
301.47(9)
(Ag2··Ag3),
(Ag1··Ag2) compared to 295.4(2) and 306.2(1) pm in AgBO2
and [6]
324.73(8) pm
and Ag3BO3-II[8],
respectively. The first distance is even shorter than the distance found in metallic silver (289 pm). These short distances clearly indicate the presence of argentophillic interactions, which also explain the color of the crystals.[11] A representation of the resulting silver substructure is displayed in Figure 5. With the bond-length / bondstrength- (ΣV)[18] and the CHARDI- (Charge distribution in solids, ΣQ)[19] concepts, the bond-valence sums for Ag3B5O9 were calculated. The formal ionic charge of each atom fits to the expected values within the limits of the concepts (see Table 6). The MAPLE-value (Madelung Part of Lattice Energy)[17] of Ag3B5O9 was calculated to compare it to the stoichiometric sum of the binary oxides B2O3-II[20] and Ag2O.[21] The calculation for Ag3B5O9 led to a value of 59515 kJ/mol, while from the stoichiometric sum of the binary compounds (2.5 × B2O3-II (54846 kJ/mol) + 1.5 × Ag2O (4513 kJ/mol)) a value of 59359 kJ/mol was derived. As expected by the additive potential of the MAPLE values, both are in good agreement (deviation: 0.26 %).
5
Conclusion In this work, we reported about the high-pressure synthesis and crystal structure of the second high-pressure silver borate Ag3B5O9. Single crystals of this compound were found during high-pressure investigations in the system Ag-B-O. The compound crystalizes in the orthorhombic, noncentrosymmetric space group P212121 (No. 19) with the parameters a = 674.7(2), b = 943.5(2), c = 1103.5(2) pm, V = 0.7025(2) nm3, and Z = 4. This new structure type is built up from BO3 and BO4 groups connected by common oxygen atoms. The BO4 tetrahedra form infinite chains along the a axis. They are interconnected by the BO3 groups to form a B-O network incorporating the four- and five-fold coordinated silver ions. It was not possible to obtain vibrational spectroscopy data due to the light sensitivity of the compound, which also thwarts investigations of possible non-linear optical properties. The compound is the second high-pressure silver borate so far. However, further results indicate the presence of additional phases.
Experimental section Synthesis Single crystals of Ag3B5O9 were obtained as a sidephase from a reaction mixture of 0.3156 g Ag2O (0.0014 mol, 99+ %, Alfa Aesar, Karlsruhe, Germany) and 0.1873 g B2O3 (0.003427 mol, 99.9+ %, Strem Chemicals, Kehl, Germany). The chemicals were finely ground together under argon atmosphere and transferred into a gold capsule (0.025 mm foil, 99.99 %, Sigma-Aldrich, Steinheim, Germany). The capsule was inserted into a crucible made from hexagonal boron nitride (HeBoSint® P100, Henze BNP GmbH, Kempten, Germany), and built into an 18/11 assembly. It was compressed to 3 GPa within one and a half hour by a high-pressure device consisting of a hydraulic 1000 t press (mavo press LPR 1000-400/50, Max Voggenreiter GmbH, Mainleus, Germany) and a Walker-type module (also Max Voggenreiter GmbH) with eight tungsten carbide cubes (HA-7%Co, Hawedia, Marklkofen, Germany). The mixture was heated from ambient temperature to 600 °C in 5 min and after further 5 min the temperature was lowered to 250 °C within 15 min.
6 The reaction was quenched and the decompression needed four hours. Details on the high-pressure device and its preparation are described in the references.[22] After separation of the product from the assembly materials, transparent crystals with different coloring (pale pink, yellow, green/yellow, brown/red yellow/orange) were isolated. The pale pink transparent crystals were found to be Ag3B5O9. The exposition to light was avoided wherever possible since some silver compounds, especially Ag2O, are sensitive to light. The powder diffraction pattern of the product revealed a very poor signal to noise ratio due to the mainly amorphous character of the sample. Reduced silver as well as B2O3 could be identified as the main phases. Crystal Structure Analyses The single crystal data set of Ag3B5O9 was collected at ambient-temperature on a Kappa CCD single crystal diffractometer (Bruker AXS-Nonius, Karlsruhe, Germany) with graphite-monochromatized MoKα radiation (λ = 71.073 pm). The intensity data was corrected from absorption based on equivalent and redundant intensities (SCALEPACK[23]). The systematic extinctions indicated the space group P212121 (No. 19). The structure was solved with direct methods using SHELXS-2013.[24] The fullmatrix least-squares refinement on F2 was performed with SHELXL-2013.[25] A check with the Addsym routine of PLATON[26] indicated no additional symmetry. All atoms were refined anisotropically, resulting in R1 and wR2 values over all data of 0.0496 and 0.0587, respectively. The relevant details of the data collections and evaluations are listed in Table 1. The positional parameters, anisotropic displacement parameters, interatomic distances, and angles are listed in Tables 2-5. Additional details of the crystal structure investigations may be obtained from Fachinformationszentrum Karlsruhe, 76344
Eggenstein-Leopoldshafen,
[email protected],
Germany
(fax:
+49-7247-808-666;
e-mail:
http://www.fiz-
karlsruhe.de/request_for_deposited_data.html) on quoting the deposition number CSD-428143.
7 Acknowledgements The authors are grateful to Dr. Gunter Heymann for the collection of the single crystal data set. This work was financially supported by the Austrian Science Fund (FWF): ZFP 232120.
8 Table 1. Crystal data and structure refinement of Ag3B5O9 (standard deviations in parentheses). Empirical formula
Ag3B5O9
Molar mass, g·mol-1
521.66
Crystal system
orthorhombic
Space group
P212121 (No. 19)
Single crystal diffractometer
Enraf-Nonius Kappa CCD
Radiation
MoKα (λ = 71.073 pm) (graded multilayer X-ray optics)
Single crystal data a, pm
674.7(2)
b, pm
943.5(2)
c, pm V, nm
1103.5(2) 3
0.7025(2)
Formula units per cell Calculated density, g·cm Crystal size, mm
Z=4 -3
4.932
3
0.037 x 0.035 x 0.020
Temperature, K
293(2)
Absorption coefficient, mm-1
8.316
F(000)
952
θ range, °
2.84 - 37.72
Range in hkl
-11 ≥ h ≥ 11, -13 ≥ k ≥ 16, -18 ≥ l ≥ 18
Total no. of reflections
10856 (Rint = 0.0560)
Independent reflections
3740 (Rσ = 0.0579)
Reflections with I ≥ 2σ(I)
3150
Data / parameters
3740 / 154
Absorption correction
multi-scan (Scalepack[23])
Goodness-of-fit on Fi2
1.052
Flack-Parameter
-0.05(3)
Final R indices [I ≥ 2σ(I)]
R1 = 0.0367 wR2 = 0.0557
Final R indices (all data)
R1 = 0.0496 wR2 = 0.0587
Largest diff. peak and hole, e·Å
-3
1.341 / -1.633
9 Table 2. Atomic coordinates and equivalent isotropic displacement parameters Ueq (Å2) of Ag3B5O9. Ueq is defined as one third of the trace of the orthogonalized Uij tensor (standard deviations in parentheses). The Wyckoff-position of all sites is 4a. Atom
x
y
z
Ueq
Ag1
0.18484(7)
0.22978(4)
0.72958(4)
0.02012(9)
Ag2
0.43543(7)
0.19198(5)
0.51304(4)
0.0231(2)
Ag3
0.97096(7)
0.10349(6)
0.92623(5)
0.0348(2)
O1
0.0595(5)
0.0327(3)
0.6597(3)
0.0093(6)
O2
0.3293(5)
0.1071(4)
0.9877(3)
0.0133(6)
O3
0.5435(5)
0.3482(3)
0.6886(3)
0.0112(6)
O4
0.2651(5)
0.4385(4)
0.7966(3)
0.0106(6)
O5
0.2657(5)
0.3257(3)
0.3779(3)
0.0099(6)
O6
0.6622(5)
0.0230(4)
0.9958(3)
0.0114(6)
O7
0.5138(5)
0.0966(4)
0.8082(3)
0.0121(6)
O8
0.8233(5)
0.2924(4)
0.8133(3)
0.0134(6)
O9
0.5947(5)
0.4807(3)
0.8747(3)
0.0089(6)
B1
0.4735(8)
0.4647(5)
0.7671(4)
0.0087(8)
B2
0.7025(9)
0.2638(6)
0.7160(5)
0.017(2)
B3
0.1489(7)
0.5280(6)
0.8760(5)
0.0088(9)
B4
0.2038(8)
0.9266(6)
0.6173(4)
0.0097(8)
B5
0.5025(8)
0.0744(6)
0.9311(5)
0.0101(9)
10 Table 3. Anisotropic displacement parameters (Å2) of Ag3B5O9 (standard deviations in parentheses). Atom
U11
U22
U33
U12
U13
U23
Ag1
0.0185(2)
0.0141(2)
0.0278(2)
-0.0062(2)
0.0051(2)
-0.0097(2)
Ag2
0.0326(2)
0.0186(2)
0.0182(2)
0.0015(2)
-0.0089(2)
0.0048(2)
Ag3
0.0164(2)
0.0518(3)
0.0361(2)
0.0043(2)
0.0004(2)
0.0308(2)
O1
0.006(2)
0.010(2)
0.011(2)
0.000(2)
-0.000(2)
-0.003(2)
O2
0.012(2)
0.018(2)
0.010(2)
0.005(2)
0.002(2)
0.004(2)
O3
0.013(2)
0.011(2)
0.010(2)
0.003(2)
-0.001(2)
-0.004(2)
O4
0.007(2)
0.011(2)
0.014(2)
-0.001(2)
0.002(2)
-0.002(2)
O5
0.013(2)
0.007(2)
0.010(2)
-0.001(2)
-0.002(2)
0.000(2)
O6
0.011(2)
0.014(2)
0.009(2)
0.000(2)
-0.001(2)
0.002(2)
O7
0.019(2)
0.009(2)
0.008(2)
0.004(2)
-0.002(2)
-0.001(2)
O8
0.011(2)
0.012(2)
0.017(2)
0.003(2)
-0.006(2)
-0.005(2)
O9
0.008(2)
0.011(2)
0.008(2)
0.001(2)
-0.001(2)
-0.002(2)
B1
0.009(2)
0.010(2)
0.008(2)
-0.000(2)
0.002(2)
-0.001(2)
B2
0.014(2)
0.018(2)
0.018(2)
0.006(2)
-0.005(2)
-0.011(2)
B3
0.008(2)
0.010(2)
0.008(2)
-0.001(2)
-0.001(2)
-0.000(2)
B4
0.009(2)
0.013(2)
0.007(2)
0.002(2)
0.001(2)
-0.001(2)
B5
0.013(2)
0.009(2)
0.008(2)
0.000(2)
-0.002(2)
0.002(2)
11 Table 4. Interatomic distances (pm) in Ag3B5O9 (standard deviations in parentheses). Ag1-O4
217.2(4)
Ag2-O5
226.5(3)
Ag3-O6
234.6(3)
Ag1-O1
218.3(3)
Ag2-O9
235.6(3)
Ag3-O8
239.2(3)
Ag1-O8
267.4(4)
Ag2-O5
253.8(3)
Ag3-O9
248.0(3)
Ag1-O7
269.4(3)
Ag2-O3
254.1(3)
Ag3-O2
251.2(4)
Ag1-O3
270.3(4)
av. Ag2-O
242.5
Ag3-O2
304.5(4)
av. Ag1-O
248.5
av. Ag3-O
255.5
B1-O9
145.0(6)
B2-O3
137.0(7)
B3-O4
144.7(6)
B1-O4
146.5(6)
B2-O8
137.5(6)
B3-O1
146.1(6)
B1-O3
147.7(6)
B2-O5
140.3(6)
B3-O5
149.6(6)
B1-O7
149.9(6)
av. B2-O
138.3
B3-O6
149.7(6)
av. B1-O
147.2
av. B3-O
147.5
B4-O9
145.5(6)
B5-O2
136.1(6)
B4-O1
147.3(6)
B5-O7
137.4(6)
B4-O2
148.2(6)
B5-O6
138.0(6)
B4-O8
149.1(6)
av. B5-O
137.2
av. B4-O
147.5
12 Table 5. Interatomic angles (deg) in Ag3B5O9 (standard deviations in parentheses). O3-B1-O7
106.0(3)
O3-B2-O5
115.1(4)
O5-B3-O6
105.1(3)
O4-B1-O3
108.2(4)
O8-B2-O5
121.0(5)
O1-B3-O6
108.8(4)
O4-B1-O7
108.6(4)
O3-B2-O8
121.6(4)
O4-B3-O5
109.8(4)
O9-B1-O7
109.6(4)
av. O-B2-O
119.2
O1-B3-O5
110.3(4)
O9-B1-O4
112.1(4)
O4-B3-O6
110.6(4)
O9-B1-O3
112.2(4)
O4-B3-O1
112.1(4)
av. O-B1-O
109.5
av. O-B3-O
109.5
O9-B4-O2
105.9(4)
O2-B5-O7
117.8(4)
O2-B4-O8
107.1(4)
O2-B5-O6
120.8(4)
O1-B4-O8
109.5(4)
O7-B5-O6
121.4(4)
O1-B4-O2
110.6(4)
av. O-B5-O
120.0
O9-B4-O1
111.1(4)
O9-B4-O8
112.4(4)
av. O-B4-O
109.4
13 Table 6. Charge distribution in Ag3B5O9, calculated with the bond-length / bondstrength concept (ΣV)[18] and the CHARDI-concept (ΣQ)[19]. Ag1
Ag2
Ag3
B1
B2
B3
B4
B5
ΣV
+1.01
+0.79
+0.78
+3.04
+2.91
+3.02
+3.02
+3.00
ΣQ
+1.00
+0.95
+0.99
+3.04
+2.91
+2.97
+2.94
+3.20
O1
O2
O3
O4
O5
O6
O7
O8
O9
ΣV
-1.90
-1.95
-1.98
-1.96
-2.06
-1.92
-1.79
-2.01
-1.99
ΣQ
-1.98
-1.99
-2.00
-2.05
-2.13
-1.95
-1.70
-2.06
-2.14
14 Figure Captions Figure 1.
Top: Unit cell of Ag3B5O9 down the a axis exhibiting corner-sharing BO4 tetrahedra as well as BO3 groups. Bottom: chains of BO4 tetrahedra and BO3 groups running along the a axis. Spheres: 90 % probability ellipsoids of the atoms (color: see legend). Blue polyhedra: corner-sharing BO4 tetrahedra; yellow tetrahedra and green bonds: fundamental building block.
Figure 2.
Fundamental building block of Ag3B5O9 together with the labeling of the atoms. The block is linked via O3 and O9 to form the chain presented in Figure 1.
Figure 3.
Linkage between the chains running along a via BO3 groups forming sheets in the ab plane.
Figure 4.
Coordination spheres of the silver ions in the crystal structure of Ag3B5O9.
Figure 5.
Unit cell of Ag3B5O9 (background) together with the silver substructure (green lines).
15 Figures
Figure 1. Top: Unit cell of Ag3B5O9 exhibiting corner-sharing BO4 tetrahedra as well as BO3 groups. Bottom: chains of BO4 tetrahedra and BO3 groups running along the a axis. Spheres: 90 % probability ellipsoids of the atoms (color: see legend). Blue polyhedra: corner-sharing BO4 tetrahedra; yellow tetrahedra and green bonds: fundamental building block.
16
Figure 2. Fundamental building block of Ag3B5O9 together with the labeling of the atoms. The block is linked via O3 and O9 to form the chain presented in Figure 1.
17
Figure 3. Linkage between the chains running along a via BO3 groups forming sheets in the ab plane.
18
Figure 4. Coordination spheres of the silver ions in the crystal structure of Ag3B5O9.
19
Figure 5. Unit cell of Ag3B5O9 (background) together with the silver substructure (green lines).
20 References [1]
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22 A noncentrosymmetric borate Ag3B5O9 is accessible via high-pressure synthesis Ag3B5O9 is the second high-pressure silver borate Ag+⋅⋅⋅Ag+ distances in clearly indicate the presence of argentophillic interactions
*Graphical Abstract (TOC Figure)
*Graphical Abstract Legend (TOC Figure)
1
Table of contents entry Non-centrosymmetric silver borate: During investigations in the system Ag-B-O, a new noncentrosymmetric silver borate Ag3B5O9 was discovered. The new structure type is built up from corner-sharing BO3 and BO4 groups, forming a network. Argentophillic interactions are clearly indicated by the Ag+×××Ag+ distances present in the structure.