inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Potassium penta­borate

aDepartment of Power Engineering, Xian Aeronautical College, Xian 710077, People's Republic of China
*Correspondence e-mail: 62010375@163.com

(Received 24 August 2011; accepted 21 October 2011; online 29 October 2011)

The title compound, K[B5O7(OH)2], was obtained from a hydro­thermal reaction. The structure is composed of one K+ cation and a polyborate 1[B5O7(OH)2] anion, which consists of two six-membered rings linked by a common BO4 tetra­hedron. The [B5O7(OH)2] units are linked together through two exocyclic O atoms to neighbouring units, forming a helical chain structure extending parallel to [010]. Adjacent chains are further connected into a three-dimensional structure by K—O bonds and weak O—H⋯O hydrogen-bond inter­actions.

Related literature

For the nonlinear optical properties of alkali metal borates, see: Mori et al. (1995[Mori, Y., Kuroda, I., Nakajima, S., Sasaki, T. & Nakai, S. (1995). Jpn J. Appl. Phys. 34, 296-298.]). For syntheses and crystal structures in the K2O–B2O3–H2O system, see: Marezio (1969[Marezio, M. (1969). Acta Cryst. B25, 1787-1795.]); Salentine (1987[Salentine, C. G. (1987). Inorg. Chem. 26, 128-132.]); Wang et al. (2006[Wang, G. M., Sun, Y. Q., Zheng, S. T. & Yang, G. Y. (2006). Z. Anorg. Allg. Chem. 632, 1586-1590.]); Zhang et al. (2005[Zhang, H. X., Zhang, J., Zheng, S. T. & Yang, G. Y. (2005). Cryst. Growth Des. 5, 157-161.]).

[Scheme 1]

Experimental

Crystal data
  • K[B5O7(OH)2]

  • Mr = 239.17

  • Monoclinic, P 21 /c

  • a = 7.6690 (3) Å

  • b = 9.0445 (3) Å

  • c = 12.2304 (4) Å

  • β = 119.132 (2)°

  • V = 741.01 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.74 mm−1

  • T = 100 K

  • 0.14 × 0.09 × 0.07 mm

Data collection
  • Bruker APEXII diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2008a[Sheldrick, G. M. (2008a). SADABS. University of Göttingen, Germany.]) Tmin = 0.878, Tmax = 0.910

  • 13002 measured reflections

  • 1452 independent reflections

  • 1343 reflections with I > 2σ(I)

  • Rint = 0.027

Refinement
  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.072

  • S = 1.00

  • 1452 reflections

  • 136 parameters

  • H-atom parameters constrained

  • Δρmax = 0.77 e Å−3

  • Δρmin = −0.87 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O10—H10A⋯O6i 0.84 2.36 3.179 (2) 164
O12—H12A⋯O11ii 0.84 2.30 3.0346 (19) 147
O12—H12A⋯O4ii 0.84 2.50 3.170 (2) 138
Symmetry codes: (i) [x-1, -y-{\script{1\over 2}}, z-{\script{1\over 2}}]; (ii) -x, -y, -z.

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b[Sheldrick, G. M. (2008b). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b[Sheldrick, G. M. (2008b). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008b[Sheldrick, G. M. (2008b). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Boron can form a large variety of compounds due to the variability of the coordination environment about B. In the past several decades, much interest has focused on studies of alkali metals borates because some of these compounds show interesting physical properties, such as nonlinear optical behavior for CsLiB6O10 (Mori et al., 1995). So far, several phases had been obtained in the K2O–B2O3–H2O system (Marezio, 1969; Salentine, 1987; Zhang et al., 2005; Wang et al., 2006). In this paper, we describe the synthesis and the crystal structure of a new potassium borate, K[B5O7(OH)2].

It features one K+ cation and a 1[B5O7(OH)2]- polyborate anion (Fig.1), which is closely related to the reported compound of K[B5O7(OH)2].H2O (Zhang et al., 2005).

The 1[B5O7(OH)2]- ion consists of two six-membered rings linked by a common B atom. Each six-membered ring consists of one BO3 triangle, one BO2(OH) triangle and a common BO4 tetrahedron. The [B5O7(OH)2]- units are linked via two exocyclic O atoms (O8 and O8A) to neighboring units, forming a 1-D helical chainlike structure (Fig. 2). Adjacent chains are further connected into a 3-D structure by K—O bonds and O—H···O hydrogen bonds interactions, as shown in Fig.3.

Related literature top

For the nonlinear optical properties of alkali metal borates, see: Mori et al. (1995). For syntheses and crystal structures in the K2O–B2O3–H2O system, see: Marezio (1969); Salentine (1987); Wang et al. (2006); Zhang et al. (2005).

Experimental top

All reagents used in the synthesis were analytic grade and were used without further purification. A mixture of GaO(OH) (0.06 g), H3BO3(0.47 g), KNO3 (0.15 g) and distilled water (0.1 ml) was sealed in a Teflon-lined bomb and heated at 483 K for 3 d and then cooled to room temperature. The resulting colorless crystals were washed with hot deionized water and dried in a vacuum dryer to a constant mass at room temperature.

Refinement top

H atoms bonded to O10 and O12 atoms were positioned geometrically, and were refined riding with O—H = 0.84 Å and Uiso(H) = 1.5Ueq(O).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: SHELXTL (Sheldrick, 2008b); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) -x, -1/2 + y, -1/2 - z.
[Figure 2] Fig. 2. The one-dimensional chain structure constructed by [B5O7(OH)2]- units. B, O and H atoms are shown as green, red and yellow, respectively.
[Figure 3] Fig. 3. Packing view along the c axis of title compound, showing three-dimensional structure constructed by O—H···O hydrogen bonds, where all potassium cations are omitted for clarity. B, O and H atoms are shown as green, red and yellow, respectively. H bonds are drawn as dashed lines.
Potassium pentaborate top
Crystal data top
K[B5O7(OH)2]F(000) = 472
Mr = 239.17Dx = 2.144 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6851 reflections
a = 7.6690 (3) Åθ = 3.0–30.5°
b = 9.0445 (3) ŵ = 0.74 mm1
c = 12.2304 (4) ÅT = 100 K
β = 119.132 (2)°Rod, colourless
V = 741.01 (5) Å30.14 × 0.09 × 0.07 mm
Z = 4
Data collection top
Bruker APEXII
diffractometer
1452 independent reflections
Radiation source: fine-focus sealed tube1343 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
Detector resolution: 83.33 pixels mm-1θmax = 26.0°, θmin = 3.0°
ϕ and ω scansh = 98
Absorption correction: multi-scan
(SADABS; Sheldrick, 2008a)
k = 1111
Tmin = 0.878, Tmax = 0.910l = 1515
13002 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.072H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.026P)2 + 1.7263P]
where P = (Fo2 + 2Fc2)/3
1452 reflections(Δ/σ)max < 0.001
136 parametersΔρmax = 0.77 e Å3
0 restraintsΔρmin = 0.87 e Å3
Crystal data top
K[B5O7(OH)2]V = 741.01 (5) Å3
Mr = 239.17Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.6690 (3) ŵ = 0.74 mm1
b = 9.0445 (3) ÅT = 100 K
c = 12.2304 (4) Å0.14 × 0.09 × 0.07 mm
β = 119.132 (2)°
Data collection top
Bruker APEXII
diffractometer
1452 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2008a)
1343 reflections with I > 2σ(I)
Tmin = 0.878, Tmax = 0.910Rint = 0.027
13002 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0300 restraints
wR(F2) = 0.072H-atom parameters constrained
S = 1.00Δρmax = 0.77 e Å3
1452 reflectionsΔρmin = 0.87 e Å3
136 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
O40.2494 (2)0.13046 (15)0.14778 (13)0.0093 (3)
O50.0757 (2)0.32468 (15)0.19460 (13)0.0095 (3)
O60.0327 (2)0.25360 (15)0.01760 (12)0.0096 (3)
O70.4011 (2)0.14669 (15)0.50951 (12)0.0097 (3)
O80.1858 (2)0.45303 (15)0.01975 (13)0.0091 (3)
O90.4141 (2)0.26660 (15)0.33902 (12)0.0095 (3)
O100.6325 (2)0.33377 (16)0.55281 (13)0.0111 (3)
H10A0.73600.32230.54650.017*
O110.1489 (2)0.08947 (15)0.30142 (13)0.0101 (3)
O120.1416 (2)0.06260 (16)0.05911 (13)0.0108 (3)
H12A0.02860.03800.11720.016*
B10.0458 (3)0.3419 (2)0.0712 (2)0.0088 (4)
B20.1192 (3)0.1489 (2)0.0252 (2)0.0094 (4)
B30.4815 (3)0.2516 (2)0.4635 (2)0.0095 (4)
B40.2217 (3)0.2019 (2)0.2457 (2)0.0093 (4)
B50.2421 (3)0.5629 (2)0.0753 (2)0.0091 (4)
K10.34799 (7)0.07665 (5)0.26481 (4)0.01448 (14)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O40.0097 (7)0.0089 (7)0.0088 (7)0.0014 (5)0.0040 (6)0.0006 (5)
O50.0104 (7)0.0097 (7)0.0085 (7)0.0015 (5)0.0047 (6)0.0002 (5)
O60.0104 (7)0.0098 (7)0.0080 (7)0.0016 (5)0.0041 (6)0.0002 (5)
O70.0109 (7)0.0097 (7)0.0080 (6)0.0017 (6)0.0040 (6)0.0001 (5)
O80.0102 (7)0.0092 (7)0.0077 (6)0.0014 (5)0.0043 (6)0.0001 (5)
O90.0093 (7)0.0100 (7)0.0089 (7)0.0010 (5)0.0041 (6)0.0008 (5)
O100.0096 (7)0.0126 (7)0.0112 (7)0.0027 (6)0.0051 (6)0.0009 (6)
O110.0092 (7)0.0112 (7)0.0085 (7)0.0021 (5)0.0032 (6)0.0009 (5)
O120.0098 (7)0.0115 (7)0.0095 (7)0.0018 (5)0.0035 (6)0.0015 (5)
B10.0095 (10)0.0070 (10)0.0105 (10)0.0015 (8)0.0052 (9)0.0004 (8)
B20.0101 (10)0.0073 (10)0.0124 (11)0.0014 (8)0.0067 (9)0.0003 (8)
B30.0097 (10)0.0074 (10)0.0118 (11)0.0016 (8)0.0054 (9)0.0003 (8)
B40.0098 (10)0.0083 (10)0.0092 (10)0.0000 (8)0.0043 (9)0.0005 (8)
B50.0100 (10)0.0082 (10)0.0111 (10)0.0005 (8)0.0067 (9)0.0000 (8)
K10.0143 (2)0.0188 (3)0.0091 (2)0.00475 (18)0.00474 (18)0.00124 (17)
Geometric parameters (Å, º) top
O4—B21.347 (3)O9—B31.356 (3)
O4—B41.464 (3)O9—B41.477 (3)
O5—B11.342 (3)O10—B31.362 (3)
O5—B41.482 (3)O10—H10A0.8400
O6—B11.391 (3)O11—B5i1.339 (3)
O6—B21.391 (3)O11—B41.477 (3)
O7—B5i1.381 (3)O12—B21.369 (3)
O7—B31.391 (3)O12—H12A0.8400
O8—B11.379 (3)B5—O11ii1.339 (3)
O8—B51.386 (3)B5—O7ii1.381 (3)
B2—O4—B4122.10 (16)O12—B2—O6119.56 (18)
B1—O5—B4121.96 (16)O9—B3—O10123.79 (19)
B1—O6—B2117.54 (16)O9—B3—O7121.38 (18)
B5i—O7—B3118.31 (16)O10—B3—O7114.82 (17)
B1—O8—B5131.13 (17)O4—B4—O11108.14 (16)
B3—O9—B4121.29 (16)O4—B4—O9108.59 (16)
B3—O10—H10A109.4O11—B4—O9112.07 (16)
B5i—O11—B4121.94 (16)O4—B4—O5111.51 (16)
B2—O12—H12A109.4O11—B4—O5109.41 (16)
O5—B1—O8123.92 (19)O9—B4—O5107.14 (16)
O5—B1—O6122.50 (18)O11ii—B5—O7ii122.64 (18)
O8—B1—O6113.46 (17)O11ii—B5—O8123.92 (19)
O4—B2—O12118.11 (18)O7ii—B5—O8113.41 (18)
O4—B2—O6122.32 (18)
B4—O5—B1—O8178.99 (18)B2—O4—B4—O11103.7 (2)
B4—O5—B1—O65.3 (3)B2—O4—B4—O9134.42 (18)
B5—O8—B1—O53.4 (3)B2—O4—B4—O516.6 (3)
B5—O8—B1—O6179.45 (18)B5i—O11—B4—O4125.34 (19)
B2—O6—B1—O53.0 (3)B5i—O11—B4—O95.7 (3)
B2—O6—B1—O8173.13 (17)B5i—O11—B4—O5113.01 (19)
B4—O4—B2—O12171.24 (17)B3—O9—B4—O4135.83 (18)
B4—O4—B2—O610.0 (3)B3—O9—B4—O1116.4 (3)
B1—O6—B2—O40.7 (3)B3—O9—B4—O5103.6 (2)
B1—O6—B2—O12178.03 (17)B1—O5—B4—O414.3 (3)
B4—O9—B3—O10165.13 (18)B1—O5—B4—O11105.3 (2)
B4—O9—B3—O716.1 (3)B1—O5—B4—O9132.97 (18)
B5i—O7—B3—O93.6 (3)B1—O8—B5—O11ii6.9 (3)
B5i—O7—B3—O10177.49 (17)B1—O8—B5—O7ii175.04 (18)
Symmetry codes: (i) x, y+1/2, z1/2; (ii) x, y1/2, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O10—H10A···O6iii0.842.363.179 (2)164
O12—H12A···O11iv0.842.303.0346 (19)147
O12—H12A···O4iv0.842.503.170 (2)138
Symmetry codes: (iii) x1, y1/2, z1/2; (iv) x, y, z.

Experimental details

Crystal data
Chemical formulaK[B5O7(OH)2]
Mr239.17
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)7.6690 (3), 9.0445 (3), 12.2304 (4)
β (°) 119.132 (2)
V3)741.01 (5)
Z4
Radiation typeMo Kα
µ (mm1)0.74
Crystal size (mm)0.14 × 0.09 × 0.07
Data collection
DiffractometerBruker APEXII
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2008a)
Tmin, Tmax0.878, 0.910
No. of measured, independent and
observed [I > 2σ(I)] reflections
13002, 1452, 1343
Rint0.027
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.072, 1.00
No. of reflections1452
No. of parameters136
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.77, 0.87

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008b), SHELXL97 (Sheldrick, 2008b), SHELXTL (Sheldrick, 2008b).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O10—H10A···O6i0.842.363.179 (2)164
O12—H12A···O11ii0.842.303.0346 (19)147
O12—H12A···O4ii0.842.503.170 (2)138
Symmetry codes: (i) x1, y1/2, z1/2; (ii) x, y, z.
 

Acknowledgements

The author thanks the National Natural Science Foundation of China (grant No. 20871078) for supporting this study.

References

First citationBruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationMarezio, M. (1969). Acta Cryst. B25, 1787–1795.  CrossRef CAS IUCr Journals Web of Science Google Scholar
First citationMori, Y., Kuroda, I., Nakajima, S., Sasaki, T. & Nakai, S. (1995). Jpn J. Appl. Phys. 34, 296–298.  CrossRef Web of Science Google Scholar
First citationSalentine, C. G. (1987). Inorg. Chem. 26, 128–132.  CrossRef CAS Web of Science Google Scholar
First citationSheldrick, G. M. (2008a). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008b). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWang, G. M., Sun, Y. Q., Zheng, S. T. & Yang, G. Y. (2006). Z. Anorg. Allg. Chem. 632, 1586–1590.  Web of Science CrossRef CAS Google Scholar
First citationZhang, H. X., Zhang, J., Zheng, S. T. & Yang, G. Y. (2005). Cryst. Growth Des. 5, 157–161.  Web of Science CSD CrossRef CAS Google Scholar

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