Redetermination of the borax structure from laboratory X-ray data at 145 K.

THE TITLE COMPOUND, SODIUM TETRABORATE DECAHYDRATE (MINERAL NAME: borax), Na(2)[B(4)O(5)(OH)(4)]·8H(2)O, has been studied previously using X-ray [Morimoto (1956). Miner. J.2, 1-18] and neutron [Levy & Lisensky (1978). Acta Cryst. B34, 3502-3510] diffraction data. The structure contains tetra-borate anions [B(4)O(5)(OH)(4)](2-) with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H(2)O)(6)] octa-hedra that form zigzag chains [Na(H(2)O)(4/2)(H(2)O)(2/1)]. The O-H bond distances obtained from the present redetermination at 145 K are shorter than those in the neutron study by an average of 0.127 (19) Å.

Related literature

For previous studies of the borax structure, see: Morimoto (1956 ▶); Levy & Lisenky (1978 ▶). For other structures listed in the Cambridge Structural Database (Allen, 2002 ▶) that contain the [B4O5(OH)4]2− anion, see: Wang et al. (2004 ▶); Pan et al. (2007 ▶). For related structures, see: Yi et al. (2005 ▶). For comparative studies of hydrogen bonds obtained from X-ray and neutron data, see: Allen (1986 ▶); Smrčok et al. (2006 ▶).

Experimental

Crystal data

Na2[B4O5(OH)4]·8H2O

M = 381.38

Monoclinic,

a = 11.8843 (5) Å

b = 10.6026 (4) Å

c = 12.2111 (5) Å

β = 106.790 (2)°

V = 1473.06 (10) Å3

Z = 4

Mo Kα radiation

μ = 0.22 mm−1

T = 145 (2) K

0.65 × 0.36 × 0.26 mm

Data collection

Bruker–Nonius APEX2 CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T min = 0.813, T max = 0.94

8429 measured reflections

2275 independent reflections

2137 reflections with I > 2σ(I)

R int = 0.018

Refinement

R[F 2 > 2σ(F 2)] = 0.025

wR(F 2) = 0.076

S = 1.08

2275 reflections

147 parameters

All H-atom parameters refined

Δρmax = 0.37 e Å−3

Δρmin = −0.22 e Å−3

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808010441/wm2174sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808010441/wm2174Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Na2[B4O5(OH)4]·8H2O	F000 = 792
Mr = 381.38	Dx = 1.720 Mg m−3
Monoclinic, C2/c	Mo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 6688 reflections
a = 11.8843 (5) Å	θ = 2.6–31.9º
b = 10.6026 (4) Å	µ = 0.22 mm−1
c = 12.2111 (5) Å	T = 145 (2) K
β = 106.790 (2)º	Prism, colourless
V = 1473.06 (10) Å3	0.65 × 0.36 × 0.26 mm
Z = 4

Bruker–Nonius APEX2 CCD area-detector diffractometer	2275 independent reflections
Radiation source: fine-focus sealed tube	2137 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.018
Detector resolution: 8.192 pixels mm-1	θmax = 33.2º
T = 145(2) K	θmin = 2.6º
φ and ω scans	h = −17→16
Absorption correction: multi-scan(SADABS; Bruker, 2006)	k = −15→15
Tmin = 0.813, Tmax = 0.94	l = −16→17
8429 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.025	All H-atom parameters refined
wR(F2) = 0.076	w = 1/[σ2(Fo2) + (0.0482P)2 + 0.3901P] where P = (Fo2 + 2Fc2)/3
S = 1.08	(Δ/σ)max = 0.001
2275 reflections	Δρmax = 0.37 e Å−3
147 parameters	Δρmin = −0.22 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

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.

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.

	x	y	z	Uiso*/Ueq
Na1	0.0000	0.0000	0.0000	0.01676 (10)
Na2	0.0000	0.84795 (4)	0.2500	0.01796 (11)
B1	0.08552 (6)	0.34499 (6)	0.21553 (5)	0.01044 (13)
B2	0.09847 (6)	0.45643 (6)	0.39269 (6)	0.01154 (13)
O1	0.0000	0.26659 (6)	0.2500	0.01094 (13)
O2	0.15546 (4)	0.41927 (4)	0.31574 (4)	0.01276 (11)
O3	0.01964 (4)	0.43573 (4)	0.12445 (4)	0.01339 (11)
O4	0.16140 (4)	0.27014 (5)	0.16772 (4)	0.01570 (11)
O5	0.16369 (4)	0.51522 (5)	0.49130 (4)	0.01815 (12)
O6	0.12357 (5)	0.84607 (5)	0.44846 (5)	0.01851 (12)
O7	0.12296 (5)	0.00117 (5)	0.19548 (5)	0.01799 (12)
O8	0.11919 (5)	0.16556 (5)	0.46252 (5)	0.02067 (12)
O9	0.11746 (5)	0.70654 (6)	0.17227 (5)	0.02187 (12)
H4	0.7717 (12)	0.2622 (11)	0.2876 (12)	0.032 (3)*
H5	0.1187 (13)	0.4667 (13)	0.0305 (12)	0.040 (3)*
H6A	0.3089 (13)	0.3828 (14)	0.0413 (12)	0.042 (4)*
H6B	0.8662 (14)	0.2018 (16)	0.4941 (13)	0.051 (4)*
H7A	0.3098 (13)	0.4817 (11)	0.3051 (12)	0.030 (3)*
H7B	0.1304 (12)	0.0776 (14)	0.2014 (12)	0.039 (3)*
H8A	0.9099 (12)	0.1906 (13)	0.1075 (11)	0.036 (3)*
H8B	0.8131 (12)	0.1365 (12)	0.0352 (11)	0.034 (3)*
H9A	0.4018 (13)	0.1300 (15)	0.3385 (12)	0.046 (4)*
H9B	0.6140 (15)	0.2331 (15)	0.1058 (14)	0.053 (4)*

	U11	U22	U33	U12	U13	U23
Na1	0.0165 (2)	0.01812 (19)	0.0158 (2)	0.00057 (13)	0.00485 (15)	0.00047 (13)
Na2	0.0179 (2)	0.0201 (2)	0.0176 (2)	0.000	0.00773 (16)	0.000
B1	0.0100 (3)	0.0121 (3)	0.0096 (3)	0.0012 (2)	0.0035 (2)	−0.00028 (19)
B2	0.0108 (3)	0.0133 (3)	0.0111 (3)	−0.0014 (2)	0.0040 (2)	−0.0014 (2)
O1	0.0117 (3)	0.0104 (3)	0.0111 (3)	0.000	0.0037 (2)	0.000
O2	0.0103 (2)	0.0168 (2)	0.0122 (2)	−0.00223 (15)	0.00493 (16)	−0.00376 (15)
O3	0.0103 (2)	0.0180 (2)	0.0130 (2)	0.00309 (15)	0.00519 (16)	0.00559 (15)
O4	0.0119 (2)	0.0209 (2)	0.0142 (2)	0.00489 (17)	0.00365 (17)	−0.00434 (16)
O5	0.0132 (2)	0.0275 (3)	0.0150 (2)	−0.00595 (18)	0.00593 (19)	−0.00949 (18)
O6	0.0146 (2)	0.0219 (2)	0.0186 (2)	−0.00109 (18)	0.00414 (19)	0.00229 (18)
O7	0.0151 (3)	0.0160 (2)	0.0232 (3)	0.00012 (17)	0.0061 (2)	0.00003 (17)
O8	0.0185 (3)	0.0242 (3)	0.0184 (3)	0.00116 (19)	0.0039 (2)	0.00608 (19)
O9	0.0217 (3)	0.0196 (2)	0.0229 (3)	−0.00047 (19)	0.0041 (2)	−0.00352 (19)

Na1—O8i	2.3815 (6)	Na2—O6ii	2.4441 (6)
Na1—O8ii	2.3815 (6)	Na2—O6	2.4441 (6)
Na1—O6iii	2.3979 (5)	B1—O4	1.4451 (8)
Na1—O6iv	2.3979 (5)	B1—O1	1.4657 (7)
Na1—O7v	2.4121 (6)	B1—O2	1.4902 (8)
Na1—O7	2.4121 (6)	B1—O3	1.5075 (8)
Na2—O7vi	2.4041 (6)	B2—O2	1.3655 (8)
Na2—O7vii	2.4041 (6)	B2—O3ii	1.3757 (8)
Na2—O9	2.4214 (6)	B2—O5	1.3784 (8)
Na2—O9ii	2.4214 (6)
O8i—Na1—O8ii	180.00 (2)	O9—Na2—O6ii	81.696 (19)
O8i—Na1—O6iii	90.45 (2)	O9ii—Na2—O6ii	97.72 (2)
O8ii—Na1—O6iii	89.55 (2)	O7vi—Na2—O6	88.29 (2)
O8i—Na1—O6iv	89.55 (2)	O7vii—Na2—O6	92.34 (2)
O8ii—Na1—O6iv	90.45 (2)	O9—Na2—O6	97.72 (2)
O6iii—Na1—O6iv	180.00 (3)	O9ii—Na2—O6	81.70 (2)
O8i—Na1—O7v	91.717 (19)	O6ii—Na2—O6	179.07 (3)
O8ii—Na1—O7v	88.283 (19)	O4—B1—O1	111.72 (5)
O6iii—Na1—O7v	89.177 (19)	O4—B1—O2	110.91 (5)
O6iv—Na1—O7v	90.823 (19)	O1—B1—O2	109.42 (4)
O8i—Na1—O7	88.283 (19)	O4—B1—O3	107.71 (5)
O8ii—Na1—O7	91.717 (19)	O1—B1—O3	108.56 (5)
O6iii—Na1—O7	90.823 (19)	O2—B1—O3	108.43 (5)
O6iv—Na1—O7	89.177 (19)	O2—B2—O3ii	122.44 (6)
O7v—Na1—O7	180.000 (16)	O2—B2—O5	117.78 (6)
O7vi—Na2—O7vii	94.98 (3)	O3ii—B2—O5	119.78 (6)
O7vi—Na2—O9	172.90 (2)	B1ii—O1—B1	110.90 (6)
O7vii—Na2—O9	81.05 (2)	B2—O2—B1	116.59 (5)
O7vi—Na2—O9ii	81.05 (2)	B2ii—O3—B1	120.25 (5)
O7vii—Na2—O9ii	172.90 (2)	Na1vi—O6—Na2	90.952 (19)
O9—Na2—O9ii	103.49 (3)	Na2viii—O7—Na1	91.581 (19)
O7vi—Na2—O6ii	92.34 (2)	Na2viii—O7—H7B	134.8 (10)
O7vii—Na2—O6ii	88.29 (2)	Na1—O7—H7B	96.4 (10)
O4—B1—O1—B1ii	−172.74 (6)	O7vi—Na2—O6—Na1vi	−0.355 (19)
O2—B1—O1—B1ii	64.05 (4)	O7vii—Na2—O6—Na1vi	94.56 (2)
O3—B1—O1—B1ii	−54.12 (3)	O9—Na2—O6—Na1vi	175.84 (2)
O3ii—B2—O2—B1	−4.91 (9)	O9ii—Na2—O6—Na1vi	−81.56 (2)
O5—B2—O2—B1	174.23 (5)	O6ii—Na2—O6—Na1vi	−132.911 (15)
O4—B1—O2—B2	−156.88 (5)	O8i—Na1—O7—Na2viii	−89.93 (2)
O1—B1—O2—B2	−33.19 (7)	O8ii—Na1—O7—Na2viii	90.07 (2)
O3—B1—O2—B2	85.06 (6)	O6iii—Na1—O7—Na2viii	179.640 (19)
O4—B1—O3—B2ii	136.95 (6)	O6iv—Na1—O7—Na2viii	−0.360 (19)
O1—B1—O3—B2ii	15.82 (7)	O7v—Na1—O7—Na2viii	−122 (44)
O2—B1—O3—B2ii	−102.97 (6)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5ix···O3ix	0.836 (15)	1.895 (15)	2.7300 (7)	176.3 (15)
O4x—H4···O9xi	0.828 (14)	2.049 (14)	2.8658 (8)	168.4 (12)
O6—H6Axii···O5xiii	0.868 (16)	1.978 (16)	2.8323 (8)	167.9 (14)
O6xiv—H6B···O4x	0.846 (16)	2.040 (15)	2.8624 (8)	163.9 (16)
O7xii—H7A···O2	0.827 (16)	1.989 (16)	2.8135 (8)	174.1 (12)
O7—H7B···O4	0.816 (15)	2.135 (15)	2.9233 (8)	162.3 (14)
O8x—H8A···O1xv	0.866 (13)	1.936 (13)	2.7865 (6)	167.0 (14)
O8x—H8B···O5xvi	0.855 (15)	2.341 (14)	3.1320 (8)	154.2 (12)
O9—H9Axii···O3	0.843 (16)	2.253 (16)	3.0894 (8)	171.7 (15)
O9—H9Bxvii···O8iii	0.849 (17)	2.069 (16)	2.9034 (8)	167.4 (15)

Table 1

Selected bond lengths (Å)

Na1—O8i	2.3815 (6)
Na1—O6ii	2.3979 (5)
Na1—O7	2.4121 (6)
Na2—O7iii	2.4041 (6)
Na2—O9	2.4214 (6)
Na2—O6	2.4441 (6)
B1—O4	1.4451 (8)
B1—O1	1.4657 (7)
B1—O2	1.4902 (8)
B1—O3	1.5075 (8)
B2—O2	1.3655 (8)
B2—O3i	1.3757 (8)
B2—O5	1.3784 (8)

Symmetry codes: (i) ; (ii) ; (iii) .

Table 2

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5iv⋯O3iv	0.836 (15)	1.895 (15)	2.7300 (7)	176.3 (15)
O4v—H4⋯O9vi	0.828 (14)	2.049 (14)	2.8658 (8)	168.4 (12)
O6—H6Avii⋯O5viii	0.868 (16)	1.978 (16)	2.8323 (8)	167.9 (14)
O6ix—H6B⋯O4v	0.846 (16)	2.040 (15)	2.8624 (8)	163.9 (16)
O7vii—H7A⋯O2	0.827 (16)	1.989 (16)	2.8135 (8)	174.1 (12)
O7—H7B⋯O4	0.816 (15)	2.135 (15)	2.9233 (8)	162.3 (14)
O8v—H8A⋯O1x	0.866 (13)	1.936 (13)	2.7865 (6)	167.0 (14)
O8v—H8B⋯O5xi	0.855 (15)	2.341 (14)	3.1320 (8)	154.2 (12)
O9—H9Avii⋯O3	0.843 (16)	2.253 (16)	3.0894 (8)	171.7 (15)
O9—H9Bxii⋯O8xiii	0.849 (17)	2.069 (16)	2.9034 (8)	167.4 (15)

Symmetry codes: (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) ; (x) ; (xi) ; (xii) ; (xiii) .