Synthesis and crystal structure of NaCsB5O8(OH)·H2O

Zou, M.-J.; Zhou, X.-L.; Cheng, J.-W.; Wen, Y.-H.

doi:10.1107/S2056989026006018

research communications

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ISSN: 2056-9890

Volume 82| Part 7| July 2026| Pages 821-824

https://doi.org/10.1107/S2056989026006018

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Synthesis and crystal structure of NaCsB₅O₈(OH)·H₂O

Mei-Jun Zou,^a Xiao-Liang Zhou,^a Jian-Wen Cheng ^a and Yi-Hang Wen ^a ^*

^aKey Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, People's Republic of China
^*Correspondence e-mail: [email protected]

Edited by M. Weil, Vienna University of Technology, Austria (Received 16 April 2026; accepted 8 June 2026; online 12 June 2026)

The solvothermal reaction of H₃BO₃, Cs₂CO₃, NaBO₂·4H₂O, formic acid and ethanol led to a new mixed alkali metal borate, NaCsB₅O₈(OH)·H₂O, sodium caesium pentaborate hydroxide monohydrate. Its crystal structure contains pentaborate [B₅O₁₀(OH)]^6– building units, and displays a layered structure containing nine-membered rings. The layers extend parallel to the ab plane and are stacked along the c axis. Na⁺ and Cs⁺ cations are situated between the layers and bond to oxygen atoms with coordination numbers of 7 and 10, respectively. The water molecule likewise occupies the interlayer space and is hydrogen-bonded to the layers, both as a donor and an acceptor.

Keywords: alkali metal borates; pentaborate anion; solvothermal synthesis; hydrogen bond; crystal structure.

CCDC reference: 2545474

1. Chemical context

Crystalline borates have been well recognized as promising ultraviolet and deep-ultraviolet nonlinear optical and birefringent materials (Zhang et al., 2026 ; Li et al., 2023a ,b ; Lu et al., 2024 ; Ou et al., 2025 ; Zou et al., 2026 ). Borates exhibit a remarkably rich structural chemistry originating from the various coordination modes of boron to oxygen atoms: BO₃ triangles and BO₄ tetrahedra that can be interconnected via corner-sharing oxygen atoms to construct a variety of polyborate anions (Lin & Yang, 2011 ; Huang et al., 2019 ; Chen et al., 2024b ). To date, more than 3900 borate compounds have been documented in the literature (Mutailipu et al., 2021 ).

Pentaborates constitute a family of structurally rich borates, whose fundamental building units typically comprise two B₃O₃ rings that are nearly orthogonal to each other. The linkage modes between BO₄ tetrahedra and BO₃ triangles give rise to a series of pentaborate anions, including [B₅O₁₀]^5–, [B₅O₁₁]^7–, [B₅O₁₂]^9–, and [B₅O₁₄]^13–. Hydroxyl-functionalized pentaborate anions are also well-documented, such as [B₅O₁₀(OH)]^6–, [B₅O₈(OH)₂]^3–, [B₅O₉(OH)₃]^6– and [B₅O₆(OH)₄]⁻ (Wei et al., 2014 ; Ding et al., 2018 ). Moreover, extended crystalline frameworks of borates can be formed through condensation reactions accompanied by the elimination of water molecules (Li et al., 2024 ; Shi et al., 2019 ; Zhao et al., 2022 ,2024 ; Chen et al., 2024a ; Wang et al., 2025 ; Chen & Yang, 2024 ).

In this work, we present the solvothermal synthesis and single-crystal X-ray structure analysis of a novel mixed alkali-metal pentaborate, NaCsB₅O₈(OH)·H₂O, (I).

2. Structural commentary

The asymmetric unit of (I) consists of one formula unit. The pentaborate [B₅O₁₀(OH)]^6– building unit (Fig. 1) is constructed by the linkage of two BO₃ triangles (B4, B5), two BO₄ tetrahedra (B2, B3), and one BO₂(OH) group (B1), with the B—O bond lengths falling in the range of 1.340 (8) to 1.502 (8) Å (Table 1). Furthermore, each [B₅O₁₀(OH)]^6– unit links to four identical units, giving rise to a layered _∞²[B₅O₈(OH)]^2– anion extending parallel to the ab plane featuring nine-membered rings (Fig. 2). The layers stack along the c axis in an …ABAB… alternating fashion. The Na⁺ cations, Cs⁺ cations, and crystal water molecules reside in the interlayer space. The Na⁺ cation is seven-coordinated in a highly distorted pentagonal–bipyramidal coordination environment, while the Cs⁺ cation is ten-coordinated in a distorted pentagonal-prismatic coordination environment (Pinsky & Avnir, 1998 ), as shown in Fig. 3. The Na—O bond lengths range from 2.290 (5) to 2.654 (5) Å and the Cs—O bond lengths from 3.054 (4) to 3.604 (4) Å (Table 1).

Table 1
Selected bond lengths (Å)

Cs—O1ⁱ	3.110 (5)	B1—O1^viii	1.382 (9)
Cs—O2	3.054 (4)	B1—O2	1.363 (8)
Cs—O2ⁱⁱ	3.604 (4)	B1—O3	1.353 (9)
Cs—O3ⁱⁱ	3.406 (5)	B2—O3	1.502 (8)
Cs—O3ⁱⁱⁱ	3.335 (4)	B2—O4	1.474 (8)
Cs—O4ⁱⁱⁱ	3.324 (4)	B2—O5	1.429 (8)
Cs—O6ⁱⁱ	3.313 (4)	B2—O7^ix	1.493 (8)
Cs—O7^iv	3.356 (4)	B3—O2	1.478 (8)
Cs—O9	3.111 (4)	B3—O5	1.433 (8)
Cs—O10	3.407 (11)	B3—O6	1.493 (8)
Na—O4^v	2.652 (5)	B3—O9	1.480 (8)
Na—O5^vi	2.431 (5)	B4—O6	1.358 (8)
Na—O5	2.290 (5)	B4—O7	1.340 (8)
Na—O6^vi	2.457 (5)	B4—O8	1.408 (9)
Na—O7^vii	2.567 (5)	B5—O4ⁱⁱⁱ	1.340 (9)
Na—O8^iv	2.563 (5)	B5—O8	1.399 (8)
Na—O9	2.654 (5)	B5—O9	1.366 (8)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z]$ ; (ii) ; (iii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iv) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (v) ; (vi) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (vii) ; (viii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ix) $[-x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

Figure 1
The [B₅O₁₀(OH)]^6– building unit in (I) with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (iii) −x + $[{1\over 2}]$ , y + $[{1\over 2}]$ , z; (viii) −x + 1, y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ; (ix) −x − $[{1\over 2}]$ , y − $[{1\over 2}]$ , z.]

Figure 2
Formation of anionic layers extending parallel to the ab plane.

Figure 3
The coordination polyhedra around Na⁺ and Cs⁺ cations.

A view of the crystal structure is given in Fig. 4. The extended structure is consolidated by hydrogen-bonding interactions between the hydroxy group (O1) and the water molecule (O10), and between the water molecule and the anionic framework (Table 2).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O10	0.91	1.90	2.683 (9)	143
O10—H10A⋯O3ⁱⁱⁱ	0.87	2.35	3.173 (13)	157
O10—H10B⋯O2ⁱⁱ	0.87	1.95	2.796 (9)	165
Symmetry codes: (ii) ; (iii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ .

Figure 4
The crystal structure of (I) in a view along the a axis. Hydrogen-bonding interactions are shown as dashed lines; bonds to the cations are not shown for clarity.

3. Database survey

A search of the Inorganic Crystal Structure Database (ICSD, version 5.6.0, updated January 2026; Zagorac et al., 2019 ) for alkali metal compounds with the [B₅O₈(OH)]^2– anion returned seven hits: NaKB₅O₈(OH)·H₂O (triclinic, P $[\overline{1}]$ ; Li et al., 2024), LiRbB₅O₈(OH)·H₂O (monoclinic, P2₁/n: Shi et al., 2019), K₂B₅O₈(OH)·2H₂O (orthorhombic, Pna2₁; Shi et al., 2019), Rb₂B₅O₈(OH) (orthorhombic, Pca2₁; Qiu et al., 2021 ), LiCsB₅O₈(OH)·H₂O (monoclinic, P2₁/c; Chen et al., 2017 ), LiKB₅O₈(OH)·1.5H₂O (orthorhombic, C222₁; Li & Yang, 2019 ), and Na₂B₅O₈(OH)·2H₂O (orthorhombic, Pna2₁; Corazza et al., 1975 , Wang et al., 2009 ). Compared with compound (I), the seven compounds adopt a similar layered structure and share the same [B₅O₁₀(OH)]^6– building unit, but they contain different alkali metal ions and possess different space groups, making (I) unique.

4. Synthesis and crystallization

A mixture of H₃BO₃ (0.3710 g, 6 mmol), Cs₂CO₃ (0.3258 g, 1 mmol), NaBO₂·4H₂O (0.1378 g, 1 mmol), formic acid (0.25 ml) and ethanol (4 ml) was sealed in a 30 ml Teflon-lined autoclave at 453 K for 6 d and then cooled to room temperature. Colorless crystals of (I) were obtained by filtration, washed with distilled water, and dried in air.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms bonded to O atoms were positioned geometrically and refined using a riding model [O_hydroxyl—H = 0.91 Å and O_water—H = 0.87 Å, U_iso(H) = 1.5 U_eq(O)]. O10 of the water molecule exhibits relatively large displacement parameters, suggesting the presence of potential positional disorder. In the current structure refinement, O10 was modeled as a single site.

Table 3
Experimental details

Crystal data
Chemical formula	NaCsB₅O₈(OH)·H₂O
M_r	372.97
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	152
a, b, c (Å)	6.5803 (3), 11.2304 (6), 24.3738 (12)
V (Å³)	1801.21 (15)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	4.20
Crystal size (mm)	0.18 × 0.18 × 0.16

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.49, 0.51
No. of measured, independent and observed [I > 2σ(I)] reflections	21866, 1643, 1228
R_int	0.125
(sin θ/λ)_max (Å⁻¹)	0.602

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.091, 1.02
No. of reflections	1643
No. of parameters	154
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.14, −1.24
Computer programs: APEX2 and SAINT (Bruker, 2014 ), SIR2004 (Burla et al., 2007 ), SHELXL (Sheldrick, 2015 ), OLEX2 (Dolomanov et al., 2009 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2545474

Crystal structure: contains datablocks I, 1. DOI: https://doi.org/10.1107/S2056989026006018/wm5800sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989026006018/wm5800Isup2.hkl

checkCIF report

Computing details top

Sodium caesium pentaborate hydroxide monohydrate top

Crystal data top

NaCsB₅O₈(OH)·H₂O	D_x = 2.751 Mg m⁻³
M_r = 372.97	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 3085 reflections
a = 6.5803 (3) Å	θ = 3.3–24.8°
b = 11.2304 (6) Å	µ = 4.20 mm⁻¹
c = 24.3738 (12) Å	T = 152 K
V = 1801.21 (15) Å³	Block, colorless
Z = 8	0.18 × 0.18 × 0.16 mm
F(000) = 1392

Data collection top

Bruker APEXII CCD diffractometer	1228 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.125
ω scans	θ_max = 25.3°, θ_min = 3.3°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −7→7
T_min = 0.49, T_max = 0.51	k = −13→13
21866 measured reflections	l = −29→29
1643 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.041	H-atom parameters constrained
wR(F²) = 0.091	w = 1/[σ²(F_o²) + (0.0194P)² + 20.4113P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max = 0.001
1643 reflections	Δρ_max = 1.14 e Å⁻³
154 parameters	Δρ_min = −1.24 e Å⁻³
0 restraints

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cs	0.54972 (7)	0.30565 (5)	0.66570 (2)	0.03814 (19)
Na	0.2006 (4)	0.1934 (2)	0.48463 (11)	0.0257 (6)
B1	0.0294 (12)	0.1797 (6)	0.6701 (3)	0.0197 (16)
B2	−0.1027 (11)	0.1034 (6)	0.5815 (3)	0.0141 (16)
B3	0.0647 (11)	0.3085 (6)	0.5883 (3)	0.0129 (14)
B4	−0.0397 (12)	0.5207 (6)	0.5698 (3)	0.0157 (15)
B5	0.3167 (11)	0.4635 (6)	0.5607 (3)	0.0150 (16)
O1	0.9171 (9)	0.6659 (5)	0.7755 (2)	0.0392 (15)
H1	0.942046	0.588286	0.767268	0.059*
O2	0.0920 (7)	0.2845 (4)	0.64744 (18)	0.0181 (10)
O3	−0.0829 (7)	0.0978 (4)	0.64290 (18)	0.0203 (11)
O4	−0.0143 (6)	−0.0079 (4)	0.56023 (18)	0.0165 (10)
O5	−0.0124 (6)	0.2079 (4)	0.55865 (16)	0.0123 (9)
O6	−0.0868 (6)	0.4071 (4)	0.58409 (19)	0.0163 (10)
O7	−0.1763 (6)	0.6090 (4)	0.56782 (18)	0.0158 (10)
O8	0.1635 (7)	0.5496 (4)	0.5576 (2)	0.0213 (11)
O9	0.2635 (7)	0.3464 (4)	0.56586 (18)	0.0158 (10)
O10	0.946 (2)	0.4776 (7)	0.7082 (3)	0.132 (5)
H10A	0.875861	0.521456	0.685701	0.198*
H10B	1.007984	0.426560	0.687130	0.198*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cs	0.0248 (3)	0.0548 (4)	0.0349 (3)	0.0060 (3)	−0.0028 (2)	0.0119 (3)
Na	0.0267 (15)	0.0213 (14)	0.0289 (15)	0.0020 (13)	0.0117 (12)	0.0023 (13)
B1	0.029 (4)	0.008 (3)	0.022 (4)	0.002 (3)	−0.002 (4)	−0.002 (3)
B2	0.019 (4)	0.009 (3)	0.015 (4)	0.001 (3)	−0.001 (3)	−0.001 (3)
B3	0.013 (3)	0.008 (3)	0.017 (3)	0.001 (3)	0.005 (3)	−0.003 (3)
B4	0.017 (4)	0.012 (4)	0.018 (4)	0.002 (3)	0.003 (3)	−0.005 (3)
B5	0.019 (4)	0.012 (4)	0.014 (4)	0.002 (3)	0.001 (3)	0.001 (3)
O1	0.065 (4)	0.033 (3)	0.019 (3)	0.015 (3)	−0.017 (3)	−0.004 (2)
O2	0.021 (2)	0.013 (2)	0.020 (2)	−0.0034 (19)	−0.0026 (19)	0.0007 (19)
O3	0.026 (3)	0.015 (2)	0.021 (2)	−0.007 (2)	0.000 (2)	0.003 (2)
O4	0.013 (2)	0.011 (2)	0.026 (2)	0.0023 (18)	−0.002 (2)	−0.0011 (19)
O5	0.013 (2)	0.010 (2)	0.014 (2)	−0.0036 (18)	−0.0017 (17)	−0.0006 (18)
O6	0.010 (2)	0.010 (2)	0.029 (3)	0.0003 (18)	0.0034 (19)	0.003 (2)
O7	0.010 (2)	0.008 (2)	0.029 (3)	−0.0007 (18)	−0.001 (2)	−0.0024 (19)
O8	0.013 (2)	0.009 (2)	0.042 (3)	0.0019 (19)	0.002 (2)	0.005 (2)
O9	0.013 (2)	0.010 (2)	0.024 (2)	−0.0016 (18)	−0.002 (2)	0.0010 (19)
O10	0.268 (15)	0.052 (5)	0.075 (6)	−0.006 (7)	0.057 (8)	−0.033 (5)

Geometric parameters (Å, º) top

Cs—B1ⁱ	3.461 (8)	Na—O7^viii	2.567 (5)
Cs—B5	3.470 (7)	Na—O8^iv	2.563 (5)
Cs—O1ⁱⁱ	3.110 (5)	Na—O9	2.654 (5)
Cs—O2	3.054 (4)	B1—O1^ix	1.382 (9)
Cs—O2ⁱ	3.604 (4)	B1—O2	1.363 (8)
Cs—O3ⁱ	3.406 (5)	B1—O3	1.353 (9)
Cs—O3ⁱⁱⁱ	3.335 (4)	B2—O3	1.502 (8)
Cs—O4ⁱⁱⁱ	3.324 (4)	B2—O4	1.474 (8)
Cs—O6ⁱ	3.313 (4)	B2—O5	1.429 (8)
Cs—O7^iv	3.356 (4)	B2—O7^x	1.493 (8)
Cs—O9	3.111 (4)	B3—O2	1.478 (8)
Cs—O10	3.407 (11)	B3—O5	1.433 (8)
Cs—H10A	3.2737	B3—O6	1.493 (8)
Cs—H10B	3.3482	B3—O9	1.480 (8)
Na—Na^v	3.606 (2)	B4—O6	1.358 (8)
Na—Na^vi	3.606 (2)	B4—O7	1.340 (8)
Na—B2^v	3.080 (8)	B4—O8	1.408 (9)
Na—B3	2.975 (7)	B5—O4ⁱⁱⁱ	1.340 (9)
Na—B3^v	2.983 (8)	B5—O8	1.399 (8)
Na—O4^vii	2.652 (5)	B5—O9	1.366 (8)
Na—O5^v	2.431 (5)	O1—H1	0.9089
Na—O5	2.290 (5)	O10—H10A	0.8700
Na—O6^v	2.457 (5)	O10—H10B	0.8700

O1ⁱⁱ—Cs—O2ⁱ	90.19 (13)	O5—B2—O3	112.8 (5)
O1ⁱⁱ—Cs—O3ⁱⁱⁱ	129.45 (12)	O5—B2—O4	113.3 (5)
O1ⁱⁱ—Cs—O3ⁱ	75.20 (13)	O5—B2—O7^x	106.4 (5)
O1ⁱⁱ—Cs—O4ⁱⁱⁱ	171.26 (12)	O7^x—B2—O3	108.0 (5)
O1ⁱⁱ—Cs—O6ⁱ	129.75 (14)	O2—B3—O6	106.4 (5)
O1ⁱⁱ—Cs—O7^iv	105.19 (12)	O2—B3—O9	107.8 (5)
O1ⁱⁱ—Cs—O9	142.17 (14)	O5—B3—O2	113.0 (5)
O1ⁱⁱ—Cs—O10	88.33 (19)	O5—B3—O6	108.3 (5)
O2—Cs—O1ⁱⁱ	98.94 (14)	O5—B3—O9	110.7 (5)
O2—Cs—O2ⁱ	162.45 (15)	O9—B3—O6	110.6 (5)
O2—Cs—O3ⁱⁱⁱ	96.71 (11)	O6—B4—O8	119.2 (6)
O2—Cs—O3ⁱ	128.53 (11)	O7—B4—O6	123.4 (6)
O2—Cs—O4ⁱⁱⁱ	82.37 (11)	O7—B4—O8	117.4 (6)
O2—Cs—O6ⁱ	130.64 (11)	O4ⁱⁱⁱ—B5—O8	122.2 (6)
O2—Cs—O7^iv	95.17 (11)	O4ⁱⁱⁱ—B5—O9	118.7 (6)
O2—Cs—O9	45.61 (12)	O9—B5—O8	119.1 (6)
O2—Cs—O10	147.53 (19)	B1^xi—O1—Cs^xii	138.7 (4)
O3ⁱ—Cs—O2ⁱ	39.82 (10)	B1^xi—O1—Cs^xi	78.1 (4)
O3ⁱⁱⁱ—Cs—O2ⁱ	88.83 (11)	B1^xi—O1—H1	105.9
O3ⁱⁱⁱ—Cs—O3ⁱ	126.91 (7)	Cs—O2—Cs^xiii	162.45 (15)
O3ⁱⁱⁱ—Cs—O7^iv	120.85 (11)	B1—O2—Cs^xiii	73.0 (4)
O3ⁱ—Cs—O10	83.94 (19)	B1—O2—Cs	107.8 (4)
O3ⁱⁱⁱ—Cs—O10	56.14 (19)	B1—O2—B3	121.0 (5)
O4ⁱⁱⁱ—Cs—O2ⁱ	90.89 (10)	B3—O2—Cs	104.4 (3)
O4ⁱⁱⁱ—Cs—O3ⁱ	110.81 (11)	B3—O2—Cs^xiii	89.3 (3)
O4ⁱⁱⁱ—Cs—O3ⁱⁱⁱ	41.92 (11)	Cs^iv—O3—Cs^xiii	133.91 (14)
O4ⁱⁱⁱ—Cs—O7^iv	83.23 (11)	B1—O3—Cs^xiii	80.9 (4)
O4ⁱⁱⁱ—Cs—O10	86.08 (18)	B1—O3—Cs^iv	123.5 (4)
O6ⁱ—Cs—O2ⁱ	39.98 (10)	B1—O3—B2	120.4 (5)
O6ⁱ—Cs—O3ⁱⁱⁱ	60.94 (11)	B2—O3—Cs^xiii	94.1 (3)
O6ⁱ—Cs—O3ⁱ	68.00 (10)	B2—O3—Cs^iv	102.3 (3)
O6ⁱ—Cs—O4ⁱⁱⁱ	50.92 (10)	Na^vii—O4—Cs^iv	77.98 (12)
O6ⁱ—Cs—O7^iv	67.69 (10)	B2—O4—Cs^iv	103.5 (3)
O6ⁱ—Cs—O10	55.57 (16)	B2—O4—Na^vii	129.0 (4)
O7^iv—Cs—O2ⁱ	67.85 (10)	B5^iv—O4—Cs^iv	84.8 (4)
O7^iv—Cs—O3ⁱ	42.00 (11)	B5^iv—O4—Na^vii	105.3 (4)
O7^iv—Cs—O10	113.51 (17)	B5^iv—O4—B2	125.7 (5)
O9—Cs—O2ⁱ	120.84 (11)	Na—O5—Na^vi	99.56 (15)
O9—Cs—O3ⁱⁱⁱ	76.38 (11)	B2—O5—Na	120.2 (4)
O9—Cs—O3ⁱ	113.76 (11)	B2—O5—Na^vi	102.8 (4)
O9—Cs—O4ⁱⁱⁱ	42.26 (11)	B2—O5—B3	126.7 (5)
O9—Cs—O6ⁱ	85.23 (11)	B3—O5—Na	103.7 (4)
O9—Cs—O7^iv	72.01 (11)	B3—O5—Na^vi	97.7 (4)
O9—Cs—O10	128.16 (18)	Na^vi—O6—Cs^xiii	80.81 (13)
O4^vii—Na—O9	152.63 (17)	B3—O6—Cs^xiii	100.7 (3)
O5—Na—O4^vii	95.63 (17)	B3—O6—Na^vi	94.9 (3)
O5^v—Na—O4^vii	122.56 (17)	B4—O6—Cs^xiii	129.9 (4)
O5—Na—O5^v	141.70 (14)	B4—O6—Na^vi	112.7 (4)
O5—Na—O6^v	156.68 (19)	B4—O6—B3	124.2 (5)
O5^v—Na—O6^v	58.07 (15)	Na^viii—O7—Csⁱⁱⁱ	78.48 (12)
O5—Na—O7^viii	107.02 (17)	B2^xiv—O7—Csⁱⁱⁱ	96.3 (3)
O5^v—Na—O7^viii	55.78 (14)	B2^xiv—O7—Na^viii	95.0 (3)
O5^v—Na—O8^iv	108.50 (17)	B4—O7—Csⁱⁱⁱ	107.2 (4)
O5—Na—O8^iv	73.26 (16)	B4—O7—Na^viii	134.4 (4)
O5—Na—O9	57.44 (15)	B4—O7—B2^xiv	127.9 (5)
O5^v—Na—O9	84.67 (16)	B4—O8—Naⁱⁱⁱ	128.6 (4)
O6^v—Na—O4^vii	67.76 (15)	B5—O8—Naⁱⁱⁱ	102.8 (4)
O6^v—Na—O7^viii	95.33 (16)	B5—O8—B4	120.9 (5)
O6^v—Na—O8^iv	89.14 (17)	Na—O9—Cs	125.63 (16)
O6^v—Na—O9	135.81 (18)	B3—O9—Cs	101.8 (3)
O7^viii—Na—O4^vii	116.43 (17)	B3—O9—Na	87.2 (3)
O7^viii—Na—O9	79.70 (15)	B5—O9—Cs	93.3 (4)
O8^iv—Na—O4^vii	87.28 (16)	B5—O9—Na	126.5 (4)
O8^iv—Na—O7^viii	155.80 (18)	B5—O9—B3	122.5 (5)
O8^iv—Na—O9	80.57 (16)	Cs—O10—Cs^xv	95.6 (2)
O2—B1—O1^ix	114.1 (6)	Cs^xv—O10—H10A	156.6
O3—B1—O1^ix	122.2 (6)	Cs—O10—H10A	73.9
O3—B1—O2	123.6 (6)	Cs—O10—H10B	78.8
O4—B2—O3	106.3 (5)	Cs^xv—O10—H10B	93.4
O4—B2—O7^x	109.9 (5)	H10A—O10—H10B	104.5

Symmetry codes: (i) x+1, y, z; (ii) −x+3/2, y−1/2, z; (iii) −x+1/2, y+1/2, z; (iv) −x+1/2, y−1/2, z; (v) x+1/2, −y+1/2, −z+1; (vi) x−1/2, −y+1/2, −z+1; (vii) −x, −y, −z+1; (viii) −x, −y+1, −z+1; (ix) −x+1, y−1/2, −z+3/2; (x) −x−1/2, y−1/2, z; (xi) −x+1, y+1/2, −z+3/2; (xii) −x+3/2, y+1/2, z; (xiii) x−1, y, z; (xiv) −x−1/2, y+1/2, z; (xv) x+1/2, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O10	0.91	1.90	2.683 (9)	143
O10—H10A···O3ⁱⁱⁱ	0.87	2.35	3.173 (13)	157
O10—H10B···O2ⁱ	0.87	1.95	2.796 (9)	165

Symmetry codes: (i) x+1, y, z; (iii) −x+1/2, y+1/2, z.

Funding information

This work was supported by the National Natural Science Foundation of China (No. 21975224).

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