RbBa₂(N₃)₅: a new ternary azide

Rubidium dibarium penta­azide, RbBa₂(N₃)₅, was prepared from an aqueous solution of the binary azides at room temperature. It crystallizes in the monoclinic system (space group P2/n). Two central atoms of azide groups occupy the 2c () and 2b () positions, another azide group lies completely on a twofold axis (2f), while Rb atoms are situated in 2e (2) positions. The crystal structure of RbBa₂(N₃)₅ can be regarded as a distorted AlB₂-type arrangement of the metal atoms, with the azide groups occupying the voids between the cations. This results in coordination numbers of 8 (Rb) and 10 (Ba). The N-N distances are in the range 1.169 (8)-1.190 (5) Å, typical for the azide group.

S1. Comment

The chemistry of metal azides has been developing fast recently, exemplified by syntheses and characterization of new binaries M(N₃)₆ (M = Mo or W) for the d metals (Haiges et al., 2005) and U(N₃)₇³⁻ for the f elements (Crawford et al., 2005) just in the past year.

On the other side, more stable azides of the s metals have been known for a long time. Alkali metal azides, especially NaN₃, are classical sources of pure metals and/or nitrogen. Alkaline earth metal azides have not been used for this purpose as extensively owing to their somewhat more violent thermal decomposition and the greater effort needed to obtain solvent-free azides. Anhydrous barium azide can be relatively easily obtained because of the large cation size; its crystallization (Manno, 1965; Marinkas, 1966) and crystal structure (Choi, 1969; Walitzi & Krischner, 1970) attracted some attention previously because of its potential as a high-energy material. Recently, it was shown that Ba(N₃)₂ can be employed as a valuable precursor, e.g. for the preparation of barium pernitride BaN₂ by controlled thermal decomposition (Vajenine et al., 2001). Moreover, anhydrous barium azide can also be used as a barium and nitrogen source in the syntheses of new intermetallic (Smetana et al., 2006a) and subnitride (Smetana et al., 2006b) phases.

Therefore, the search for new complex azides is important for the development of nitride chemistry. Especially numerous are the mixed azides of alkali and alkaline earth metals. Anhydrous coumpounds with compositions Cs₇Ca₄(N₃)₁₅ (Krischner et al., 1984), CSSR(N₃)₃ (Krischner et al., 1981a), Cs₂Sr(N₃)₄ (Krischner et al., 1981b), and CsBa₂(N₃)₅ (Krischner et al., 1982) have been reported so far. Additionally, a number of hydrated azides have been described: K₂Ca(N₃)₄·4H₂O (Krischner et al., 1980), Rb₂Ca(N₃)₄·4H₂O (Mautner & Krischner, 1988), CsCa(N₃)₃·H₂O (Krischner, Mautner & Kratky, 1983), Cs₅Ca₂(N₃)₉·2H₂O (Saracoglu et al., 1983), Cs₆Ca(N₃)₈·2H₂O (Krischner, Saracoglu et al., 1983), and K_2.24Sr_1.34(N₃)_4.92·6.16H₂O (Walitzi & Krischner, 1978).

In this study we focused on ternary azides of alkali metals with barium. The synthesis of the hitherto only known azide of this kind, CsBa₂(N₃)₅, was reproduced and a new rubidium compound with the same stoichiometry was obtained. Our attempts to prepare ternary azides of barium with potassium or sodium were unsuccessful.

The crystal structures of orthorhombic CsBa₂(N₃)₅ and monoclinic RbBa₂(N₃)₅ are similar. The arrangements of the metal ions in both azides can be regarded as distorted variants of the AlB₂-type structure (Fig. 1); graphite-like sheets of barium ions are separated by alkali metal cations. Azide anions occupy the voids between the cations, whereby a slight difference in their coordination environment leads to a lower crystal symmetry in the case of RbBa₂(N₃)₅.

The coordination polyhedra of rubidium and barium in RbBa₂(N₃)₅ are shown in Fig. 2. The barium cations are surrounded by ten terminal N atoms of azide groups in the form of a trigonal prism with four additional caps. The Ba—N distances range from 2.834 (3) to 3.255 (5) Å, which is comparable to the ranges for ninefold coordinated barium in CsBa₂(N₃)₅ [2.816 (6)–3.087 (6) Å] and Ba(N₃)₂ [2.883 (3)–2.985 (3) Å]. The rubidium coordination can be described as a polyhedron intermediate between a cube and a square antiprism. Here the distances to the terminal N atoms [3.047 (5)–3.251 (4) Å] are only slightly shorter than the closest contacts to the central atoms of the azide groups [3.165 (4)–3.308 (4) Å]. Two additional capping azide groups lie much farther away at 4.352 (5) Å, favoring the thermal motion of the rubidium cations along the a axis. Eightfold coordination of rubidium is also found in RbN₃, with Rb—N distances of 3.099 Å (Choi & Prince, 1976), and in Rb₂Ca(N₃)₄·4H₂O [six Rb—N contacts of 2.967 (7)–3.133 (7) Å with two additional water molecules].

The coordination environments of the four crystallographically inequivalent azide groups in RbBa₂(N₃)₅ are shown in Fig. 3. The arrangement of the metal cations can be described as distorted octahedra of four barium and two trans-rubidium cations. These two rubidium positions lie farther away (cf. the rubidium environment above) in the case of the N6/N5/N7 azide group, resulting in a 4 + 2 coordination. The nearly side-on coordination of the azide group to rubidium is particularly evident for the N9/N8/N10 group. The latter is also the only azide group not restricted to be linear by symmetry, though this anion is almost linear with a bonding angle of 179.6 (5)°. The N—N distances range from 1.169 (8) to 1.190 (5) Å and are thus in a good agreement with the structures of other known azide compounds.

In comparison to CsBa₂(N₃)₅, in which three of four crystallographically inequivalent azide groups are in a fivefold coordination and only one is in a sixfold coordination by metal cations, the average coordination number of the azide groups in RbBa₂(N₃)₅ is slightly higher (six for three azide groups and four for one) owing to the smaller size of Rb⁺ compared with Cs⁺. This minute difference is apparently sufficient to favorize the monoclinic structure for the rubidium compound.

An alternative description of the crystal structure of RbBa₂(N₃)₅ is instructive. If the positions of the central atoms of the azide groups alone are considered (i.e. the centers of mass of the anions), then the ternary azide may be described as a slightly distorted variant of the Ga₃Pt₅ structure (Bhan & Schubert, 1960) with the metal cations in the gallium positions and the azide groups in the platinum sites. The latter intermetallic phase is in turn an ordered 2 × 2 × 1 superstructure of the fcc packing with 16 atoms in the unit cell [Z = 2 as in RbBa₂(N₃)₅]. The observed axis ratio of a:b:c = 1.54:1:2.08 for the azide group illustrates the degree of distortion compared with the expected value of 2:1:2 for the ideal fcc lattice. Interestingly, the crystal structure of CsBa₂(N₃)₅ can also be reduced to the Ga₃Pt₅ structure type.

According to our preliminary results, thermal decomposition of the ternary azides RbBa₂(N₃)₅ and CsBa₂(N₃)₅ leads to BaN₂ accompanied by evaporation of the alkali metal.

S2. Experimental

Barium azide (98.5%, Schuchardt) was recrystallized twice from aqueous solution by adding ethanol. RbN₃ was obtained by mixing aqueous solutions of Ba(N₃)₂ and Rb₂CO₃ (99%, Merck) in a 1:1 molar ratio followed by filtration and recrystallization. Transparent colorless single crystals of RbBa₂(N₃)₅ were obtained by slowly evaporating concentrated aqueous solutions of Ba(N₃)₂ with a sixfold excess of RbN₃.

S3. Refinement

The slight deviation of the β value from 90° was confirmed by powder X-ray diffraction on a single-phase sample, where splitting of relevant reflections, especially for 412 and 412, is evident.

Computing details

Data collection: EXPOSE in IPDS Software (Stoe & Cie, 1998); cell refinement: CELL in IPDS Software; data reduction: INTEGRATE in IPDS Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Crystal Impact, 2005); software used to prepare material for publication: publCIF (Westrip, 2006).

Figures

	Fig. 1. The crystal structure of RbBa2(N3)5 viewed along [010]. [Symmetry codes: (i) −x + 1, −y + 1, −z; (ii) −x, −y + 1, −z.]
	Fig. 2. Tenfold coordination of barium (left) and (8 + 2)-fold coordination of rubidium (right) by N atoms of the azide groups. [Symmetry codes: (iii) x, y + 1, z; (iv) −x, −y + 2, −z; (v) −x + 1/2, y, −z + 1/2; (vi) x + 1/2, −y + 2, z − 1/2; (vii) x, y − 1, z; (viii) −x + 1/2, y − 1, −z + 1/2; other codes as in Fig. 1.]
	Fig. 3. The azide groups in RbBa2(N3)5, each surrounded by four Ba atoms in the horizontal plane and two Ru atoms above and below the plane. [Symmetry codes: (ix) −x + 1, −y + 2, −z; (x) −x + 1/2, y, −z − 1/2; (xi) −x + 1/2, y − 1, −z − 1/2; (xii) x − 1/2, −y + 2, z + 1/2; other codes as in Figs. 1 and 2.]

Rubidium dibarium pentaazide

Crystal data

Ba2N15Rb	F(000) = 508
Mr = 570.30	Dx = 3.310 Mg m^−3
Monoclinic, P2/n	Ag Kα radiation, λ = 0.56086 Å
Hall symbol: -P 2yac	Cell parameters from 8000 reflections
a = 8.6681 (10) Å	θ = 2.7–20.9°
b = 5.6287 (4) Å	µ = 5.91 mm^−1
c = 11.7330 (14) Å	T = 293 K
β = 90.199 (14)°	Potato, colourless
V = 572.45 (10) Å^3	0.16 × 0.07 × 0.05 mm
Z = 2

Data collection

Stoe IPDS-I diffractometer	2812 independent reflections
Radiation source: fine-focus sealed tube	2178 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.075
ϕ scans	θmax = 28.0°, θmin = 2.7°
Absorption correction: numerical [X-RED (Stoe & Cie, 2001) and X-SHAPE (Stoe & Cie, 1999)]	h = −14→14
Tmin = 0.663, Tmax = 0.815	k = −9→9
16393 measured reflections	l = −19→19

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.034	Secondary atom site location: difference Fourier map
wR(F^2) = 0.084	w = 1/[σ^2(Fo^2) + (0.054P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.14	(Δ/σ)max < 0.001
2812 reflections	Δρmax = 1.81 e Å^−3
87 parameters	Δρmin = −1.25 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ba	0.26147 (2)	0.99668 (4)	−0.051000 (17)	0.01396 (6)
Rb	0.2500	0.42675 (13)	0.2500	0.02935 (13)
N1	0.5000	0.5000	0.0000	0.0188 (8)
N2	0.4800 (5)	0.3236 (7)	0.0511 (4)	0.0250 (7)
N3	0.0000	0.5000	0.0000	0.0197 (8)
N4	0.1358 (4)	0.5030 (8)	0.0009 (4)	0.0262 (7)
N5	0.2500	0.5034 (10)	−0.2500	0.0190 (8)
N6	0.2500	0.2957 (10)	−0.2500	0.0255 (11)
N7	0.2500	0.7116 (10)	−0.2500	0.0321 (14)
N8	0.0676 (4)	0.9413 (7)	0.2303 (3)	0.0185 (6)
N9	0.0470 (4)	1.0041 (8)	0.1347 (3)	0.0268 (8)
N10	0.0871 (5)	0.8801 (8)	0.3249 (3)	0.0298 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba	0.01370 (8)	0.01516 (9)	0.01302 (8)	0.00044 (8)	−0.00018 (5)	−0.00053 (7)
Rb	0.0455 (4)	0.0214 (3)	0.0212 (2)	0.000	0.0044 (2)	0.000
N1	0.0140 (16)	0.0160 (19)	0.026 (2)	0.0018 (17)	−0.0006 (14)	−0.0056 (19)
N2	0.0230 (17)	0.0205 (18)	0.0315 (19)	0.0009 (13)	−0.0008 (14)	0.0001 (14)
N3	0.025 (2)	0.0161 (19)	0.0182 (18)	0.0060 (19)	0.0037 (15)	0.0040 (17)
N4	0.0193 (14)	0.032 (2)	0.0270 (17)	0.0012 (15)	0.0021 (12)	0.0031 (15)
N5	0.025 (2)	0.022 (2)	0.0110 (15)	0.000	0.0008 (14)	0.000
N6	0.041 (3)	0.017 (3)	0.019 (2)	0.000	0.003 (2)	0.000
N7	0.064 (4)	0.015 (3)	0.018 (2)	0.000	−0.004 (2)	0.000
N8	0.0163 (13)	0.0203 (15)	0.0188 (13)	0.0004 (11)	0.0003 (11)	−0.0017 (11)
N9	0.0165 (13)	0.040 (2)	0.0240 (15)	0.0005 (15)	−0.0017 (11)	0.0061 (16)
N10	0.034 (2)	0.034 (2)	0.0206 (16)	0.0005 (17)	−0.0023 (14)	0.0020 (15)

Geometric parameters (Å, º)

Ba—N7	2.834 (3)	Rb—N8	3.308 (4)
Ba—N9^i	2.845 (4)	N1—N2	1.173 (4)
Ba—N9	2.869 (4)	N1—N2^ii	1.173 (4)
Ba—N2^ii	2.876 (4)	N1—Rb^ii	3.6762 (5)
Ba—N6^iii	2.880 (3)	N2—Ba^ii	2.876 (4)
Ba—N2^iii	2.897 (4)	N2—Ba^vii	2.897 (4)
Ba—N10^iv	3.027 (4)	N3—N4	1.177 (4)
Ba—N4	3.047 (4)	N3—N4^ix	1.177 (4)
Ba—N4^iii	3.112 (4)	N3—Rb^ix	3.6641 (5)
Ba—N10^v	3.255 (5)	N4—Ba^vii	3.112 (4)
Ba—Rb^iii	4.2831 (6)	N5—N6	1.169 (8)
Ba—Ba^vi	4.3011 (7)	N5—N7	1.172 (8)
Rb—N10^iv	3.047 (5)	N6—Ba^x	2.880 (3)
Rb—N10	3.047 (5)	N6—Ba^vii	2.880 (3)
Rb—N4^iv	3.112 (4)	N7—Ba^xi	2.834 (3)
Rb—N4	3.112 (4)	N8—N10	1.174 (5)
Rb—N2	3.129 (4)	N8—N9	1.190 (5)
Rb—N2^iv	3.129 (4)	N8—Rb^iii	3.165 (4)
Rb—N8^vii	3.165 (4)	N9—Ba^i	2.845 (4)
Rb—N8^viii	3.165 (4)	N9—Rb^iii	3.251 (4)
Rb—N9^vii	3.251 (4)	N10—Ba^iv	3.027 (4)
Rb—N9^viii	3.251 (4)	N10—Ba^xii	3.255 (5)
Rb—N8^iv	3.308 (4)	N10—Rb^iii	3.499 (5)
N7—Ba—N9^i	71.61 (9)	N8^vii—Rb—N8^viii	60.62 (13)
N7—Ba—N9	127.79 (10)	N10^iv—Rb—N9^vii	138.01 (10)
N9^i—Ba—N9	69.60 (13)	N10—Rb—N9^vii	118.82 (11)
N7—Ba—N2^ii	70.74 (10)	N4^iv—Rb—N9^vii	131.43 (11)
N9^i—Ba—N2^ii	136.91 (12)	N4—Rb—N9^vii	62.62 (11)
N9—Ba—N2^ii	121.09 (12)	N2—Rb—N9^vii	84.21 (11)
N7—Ba—N6^iii	70.24 (13)	N2^iv—Rb—N9^vii	80.17 (10)
N9^i—Ba—N6^iii	72.02 (9)	N8^vii—Rb—N9^vii	21.32 (9)
N9—Ba—N6^iii	125.91 (9)	N8^viii—Rb—N9^vii	70.62 (10)
N2^ii—Ba—N6^iii	113.00 (10)	N10^iv—Rb—N9^viii	118.82 (11)
N7—Ba—N2^iii	136.15 (9)	N10—Rb—N9^viii	138.01 (10)
N9^i—Ba—N2^iii	139.11 (12)	N4^iv—Rb—N9^viii	62.62 (11)
N9—Ba—N2^iii	95.81 (12)	N4—Rb—N9^viii	131.43 (11)
N2^ii—Ba—N2^iii	83.67 (12)	N2—Rb—N9^viii	80.17 (10)
N6^iii—Ba—N2^iii	89.12 (11)	N2^iv—Rb—N9^viii	84.21 (11)
N7—Ba—N10^iv	127.80 (12)	N8^vii—Rb—N9^viii	70.62 (10)
N9^i—Ba—N10^iv	134.91 (12)	N8^viii—Rb—N9^viii	21.32 (9)
N9—Ba—N10^iv	67.54 (11)	N9^vii—Rb—N9^viii	85.94 (14)
N2^ii—Ba—N10^iv	61.89 (12)	N10^iv—Rb—N8^iv	20.77 (9)
N6^iii—Ba—N10^iv	148.30 (11)	N10—Rb—N8^iv	57.89 (11)
N2^iii—Ba—N10^iv	59.65 (12)	N4^iv—Rb—N8^iv	70.33 (10)
N7—Ba—N4	68.71 (12)	N4—Rb—N8^iv	95.46 (10)
N9^i—Ba—N4	74.41 (11)	N2—Rb—N8^iv	84.78 (10)
N9—Ba—N4	68.19 (12)	N2^iv—Rb—N8^iv	114.59 (10)
N2^ii—Ba—N4	73.01 (11)	N8^vii—Rb—N8^iv	178.56 (7)
N6^iii—Ba—N4	133.13 (11)	N8^viii—Rb—N8^iv	120.82 (10)
N2^iii—Ba—N4	136.92 (11)	N9^vii—Rb—N8^iv	158.08 (9)
N10^iv—Ba—N4	77.37 (12)	N9^viii—Rb—N8^iv	110.72 (9)
N7—Ba—N4^iii	131.93 (11)	N10^iv—Rb—N8	57.89 (11)
N9^i—Ba—N4^iii	74.92 (12)	N10—Rb—N8	20.77 (9)
N9—Ba—N4^iii	67.03 (12)	N4^iv—Rb—N8	95.46 (10)
N2^ii—Ba—N4^iii	147.92 (11)	N4—Rb—N8	70.33 (10)
N6^iii—Ba—N4^iii	67.19 (11)	N2—Rb—N8	114.59 (10)
N2^iii—Ba—N4^iii	64.30 (11)	N2^iv—Rb—N8	84.78 (10)
N10^iv—Ba—N4^iii	100.25 (12)	N8^vii—Rb—N8	120.82 (10)
N4—Ba—N4^iii	132.09 (13)	N8^viii—Rb—N8	178.56 (7)
N7—Ba—N10^v	77.30 (9)	N9^vii—Rb—N8	110.72 (9)
N9^i—Ba—N10^v	131.40 (11)	N9^viii—Rb—N8	158.08 (9)
N9—Ba—N10^v	154.36 (11)	N8^iv—Rb—N8	57.75 (12)
N2^ii—Ba—N10^v	57.08 (12)	N2—N1—N2^ii	180.0 (4)
N6^iii—Ba—N10^v	62.64 (8)	N2—N1—Rb	53.8 (2)
N2^iii—Ba—N10^v	58.85 (11)	N2^ii—N1—Rb	126.2 (2)
N10^iv—Ba—N10^v	93.67 (11)	N2—N1—Rb^ii	126.2 (2)
N4—Ba—N10^v	126.51 (11)	N2^ii—N1—Rb^ii	53.8 (2)
N4^iii—Ba—N10^v	101.37 (11)	Rb—N1—Rb^ii	180.0
N7—Ba—Rb^iii	176.659 (7)	N1—N2—Ba^ii	114.4 (2)
N9^i—Ba—Rb^iii	105.13 (9)	N1—N2—Ba^vii	115.1 (2)
N9—Ba—Rb^iii	49.36 (9)	Ba^ii—N2—Ba^vii	96.33 (12)
N2^ii—Ba—Rb^iii	112.01 (8)	N1—N2—Rb	108.6 (2)
N6^iii—Ba—Rb^iii	109.72 (9)	Ba^ii—N2—Rb	127.94 (15)
N2^iii—Ba—Rb^iii	46.93 (8)	Ba^vii—N2—Rb	90.52 (11)
N10^iv—Ba—Rb^iii	53.93 (9)	N4—N3—N4^ix	180.0 (4)
N4—Ba—Rb^iii	109.95 (8)	N4—N3—Rb	53.5 (2)
N4^iii—Ba—Rb^iii	46.52 (8)	N4^ix—N3—Rb	126.5 (2)
N10^v—Ba—Rb^iii	105.72 (8)	N4—N3—Rb^ix	126.5 (2)
N7—Ba—Ba^vi	105.37 (2)	N4^ix—N3—Rb^ix	53.5 (2)
N9^i—Ba—Ba^vi	175.95 (8)	Rb—N3—Rb^ix	180.0
N9—Ba—Ba^vi	114.42 (7)	N3—N4—Ba	111.7 (2)
N2^ii—Ba—Ba^vi	42.02 (8)	N3—N4—Ba^vii	109.6 (3)
N6^iii—Ba—Ba^vi	104.54 (2)	Ba—N4—Ba^vii	132.09 (13)
N2^iii—Ba—Ba^vi	41.66 (8)	N3—N4—Rb	108.8 (2)
N10^iv—Ba—Ba^vi	49.05 (9)	Ba—N4—Rb	101.57 (12)
N4—Ba—Ba^vi	107.24 (7)	Ba^vii—N4—Rb	86.97 (10)
N4^iii—Ba—Ba^vi	105.93 (7)	N6—N5—N7	180.0
N10^v—Ba—Ba^vi	44.62 (7)	N5—N6—Ba^x	125.76 (9)
Rb^iii—Ba—Ba^vi	77.919 (12)	N5—N6—Ba^vii	125.76 (9)
N10^iv—Rb—N10	66.27 (17)	Ba^x—N6—Ba^vii	108.47 (18)
N10^iv—Rb—N4^iv	90.53 (11)	N5—N7—Ba	124.47 (10)
N10—Rb—N4^iv	76.10 (11)	N5—N7—Ba^xi	124.47 (10)
N10^iv—Rb—N4	76.10 (11)	Ba—N7—Ba^xi	111.05 (19)
N10—Rb—N4	90.53 (11)	N10—N8—N9	179.6 (5)
N4^iv—Rb—N4	164.15 (16)	N10—N8—Rb^iii	96.6 (3)
N10^iv—Rb—N2	69.10 (11)	N9—N8—Rb^iii	83.4 (3)
N10—Rb—N2	131.88 (11)	N10—N8—Rb	67.0 (3)
N4^iv—Rb—N2	121.65 (10)	N9—N8—Rb	113.3 (3)
N4—Rb—N2	61.74 (10)	Rb^iii—N8—Rb	120.82 (10)
N10^iv—Rb—N2^iv	131.88 (11)	N8—N9—Ba^i	117.6 (3)
N10—Rb—N2^iv	69.10 (11)	N8—N9—Ba	128.1 (3)
N4^iv—Rb—N2^iv	61.74 (10)	Ba^i—N9—Ba	110.40 (13)
N4—Rb—N2^iv	121.65 (10)	N8—N9—Rb^iii	75.3 (3)
N2—Rb—N2^iv	158.61 (16)	Ba^i—N9—Rb^iii	130.66 (15)
N10^iv—Rb—N8^vii	159.03 (10)	Ba—N9—Rb^iii	88.60 (10)
N10—Rb—N8^vii	120.80 (11)	N8—N10—Ba^iv	145.6 (4)
N4^iv—Rb—N8^vii	110.16 (10)	N8—N10—Rb	92.2 (3)
N4—Rb—N8^vii	83.88 (10)	Ba^iv—N10—Rb	103.56 (13)
N2—Rb—N8^vii	96.01 (10)	N8—N10—Ba^xii	103.7 (3)
N2^iv—Rb—N8^vii	64.83 (10)	Ba^iv—N10—Ba^xii	86.33 (11)
N10^iv—Rb—N8^viii	120.80 (11)	Rb—N10—Ba^xii	135.29 (16)
N10—Rb—N8^viii	159.03 (10)	N8—N10—Rb^iii	64.0 (3)
N4^iv—Rb—N8^viii	83.88 (10)	Ba^iv—N10—Rb^iii	81.69 (11)
N4—Rb—N8^viii	110.16 (10)	Rb—N10—Rb^iii	118.44 (14)
N2—Rb—N8^viii	64.83 (10)	Ba^xii—N10—Rb^iii	106.04 (13)
N2^iv—Rb—N8^viii	96.01 (10)

Symmetry codes: (i) −x, −y+2, −z; (ii) −x+1, −y+1, −z; (iii) x, y+1, z; (iv) −x+1/2, y, −z+1/2; (v) x+1/2, −y+2, z−1/2; (vi) −x+1, −y+2, −z; (vii) x, y−1, z; (viii) −x+1/2, y−1, −z+1/2; (ix) −x, −y+1, −z; (x) −x+1/2, y−1, −z−1/2; (xi) −x+1/2, y, −z−1/2; (xii) x−1/2, −y+2, z+1/2.