Potassium bis­(2-methyl­lactato)borate hemihydrate

Gokila, G.; Thiruvalluvar, A.A.; Ramachandra Raja, C.

doi:10.1107/S2414314619002025

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 4| Part 2| February 2019| x190202

https://doi.org/10.1107/S2414314619002025

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Potassium bis(2-methyllactato)borate hemihydrate

Govindharajan Gokila,^a Aravazhi Amalan Thiruvalluvar ^b ^* and Chidambaram Ramachandra Raja ^a

^aDepartment of Physics, Government Arts College (Autonomous), Kumbakonam 612 002, Tamilnadu, India, and ^bPrincipal, Kunthavai Naacchiyaar Government Arts College for Women (Autonomous), Thanjavur 613 007, Tamilnadu, India
^*Correspondence e-mail: thiruvalluvar.a@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 28 January 2019; accepted 5 February 2019; online 8 February 2019)

The asymmetric unit of the title organic–inorganic hybrid salt poly[aquabis[μ₃-bis(2-methyllactato)borato]dipotassium], [K(C₈H₁₂BO₆)(H₂O)_0.5]_n, consists of one bis(2-methyllactato)borate anion, one potassium cation and one water molecule that shows half occupancy due to disorder around a twofold rotation axis. The potassium cation is pseudo-octahedrally coordinated by five O atoms of four symmetry-related bis(2-methyllactato)borate ligands and by the half-occupied water molecule. O—H⋯O hydrogen bonds between the water molecule and one of the borate O atoms of the bis(2-methyllactato)borate ligand are present in the crystal structure.

Keywords: crystal structure; inorganic-organic hybrid material; borate.

CCDC reference: 1895641

Structure description

Lithium-based salts are used in the development of lithium-ion batteries. Allen et al. (2012 ) have reported the structure of lithium bis(2-methyllactato)borate monohydrate. In our investigations we have replaced lithium by another alkali cation, i.e. rubidium (Gokila et al., 2019 ). In this context, we report here the growth and structural analysis of potassium bis(2-methyllactato)borate hemihydrate, prepared by the slow evaporation method. Whereas the lithium and rubidium salts crystallize in the space group Pbca with Z = 8 and P2₁/n with Z = 4, respectively, the potassium title salt crystallizes in the space group C2/c with Z = 8.

The asymmetric unit of the title compound consists of one bis(2-methyllactato)borate anion, a potassium cation and a water molecule (half occupancy) disordered about a twofold rotation axis (Fig. 1). The B—O distances (Table 1) are similar to that of the Rb analogue (Gokila et al., 2019). The five-membered ring O2/C5/C6/O3/B1 adopts an envelope form on the O3 atom [puckering parameters Q₂ = 0.177 (3) Å, φ₂ = 106.7 (10)°] whereas the five-membered ring O4/C1/C2/O5/B1 is essentially planar (r.m.s. deviation from the least-squares plane = 0.0196 Å). The dihedral angle between the above two five-membered ring planes is 89.36 (17)°. The potassium cation is pseudo-octahedrally coordinated by five O atoms from four bis(2-methyllactato)borate ligands (three monodentate, one chelating) and the half-occupied water molecule (Table 1). This arrangement leads to the formation of layers parallel to (001). In the crystal structure, these layers are linked by hydrogen bonds involving the water molecule and the O3 borate O atom (Fig. 2, Table 2).

Table 1
Selected bond lengths (Å)

K1—O6	2.612 (2)	K1—O1ⁱⁱⁱ	3.101 (2)
K1—O5ⁱ	2.6686 (19)	O2—B1	1.514 (4)
K1—O1ⁱⁱ	2.674 (2)	O3—B1	1.425 (4)
K1—O2ⁱⁱⁱ	2.8460 (19)	O4—B1	1.498 (3)
K1—O7	2.851 (6)	O5—B1	1.427 (4)
Symmetry codes: (i) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (ii) x, y+1, z; (iii) $[-x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H1⋯O3^iv	0.83 (5)	2.49 (9)	2.870 (6)	109 (7)
O7—H2⋯O3ⁱ	0.83 (5)	2.14 (6)	2.865 (7)	146 (6)
Symmetry codes: (i) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iv) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 1
A view of the asymmetric unit of the title compound showing the atom numbering with displacement ellipsoids drawn at the 25% probability level.

Figure 2
Packing diagram of the title compound viewed along the b axis. Dashed lines indicate O—H⋯O hydrogen bonds.

As noted above, individual features in the crystal structure of rubidium bis(2-methyllactato)borate monohydrate (Gokila et al., 2019) are very similar to those of the title compound, with the rubidium cation in a likewise pseudo-octahedral coordination sphere defined by five O atoms from four bis(2-methyllactato)borate ligands and by a fully occupied water molecule.

Synthesis and crystallization

The title compound was synthesized by reacting 2-methyllactic acid, boric acid and potassium carbonate (molar ratio 4:2:1) in double-distilled water. Slow evaporation of the solvent yielded good quality crystals in a period of about 50 days.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The occupancy of the O atom of the water molecule (O7) was refined freely and converged with a value close to 0.5. For the final refinement it was constrained to 0.5.

Table 3
Experimental details

Crystal data
Chemical formula	[K(C₈H₁₂BO₆)(H₂O)_0.5]
M_r	263.09
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	12.3919 (7), 10.7917 (6), 19.9794 (12)
β (°)	103.138 (2)
V (Å³)	2601.9 (3)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	0.42
Crystal size (mm)	0.15 × 0.15 × 0.10

Data collection
Diffractometer	Bruker Kappa APEX3 CMOS
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.689, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	32254, 2474, 1904
R_int	0.063
(sin θ/λ)_max (Å⁻¹)	0.611

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.119, 1.16
No. of reflections	2474
No. of parameters	164
No. of restraints	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.26, −0.25
Computer programs: APEX3 and SAINT (Bruker, 2016 ), SHELXT2014 (Sheldrick, 2015a ), SHELXL2018 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ), PLATON (Spek, 2009 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1895641

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314619002025/wm4100sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314619002025/wm4100Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314619002025/wm4100Isup3.cdx

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2018/3 (Sheldrick, 2015b), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Poly[aquabis[µ₃-bis(2-methyllactato)borato]dipotassium] [K(C₈H₁₂BO₆)(H₂O)_0.5] top

Crystal data top

[K(C₈H₁₂BO₆)(H₂O)_0.5]	F(000) = 1096
M_r = 263.09	D_x = 1.343 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.3919 (7) Å	Cell parameters from 9798 reflections
b = 10.7917 (6) Å	θ = 3.0–25.6°
c = 19.9794 (12) Å	µ = 0.42 mm⁻¹
β = 103.138 (2)°	T = 296 K
V = 2601.9 (3) Å³	Block, colourless
Z = 8	0.15 × 0.15 × 0.10 mm

Data collection top

Bruker Kappa APEX3 CMOS diffractometer	2474 independent reflections
Radiation source: fine-focus sealed tube	1904 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.063
ω and φ scan	θ_max = 25.7°, θ_min = 3.4°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −15→15
T_min = 0.689, T_max = 0.745	k = −13→13
32254 measured reflections	l = −24→24

Refinement top

Refinement on F²	3 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.049	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.119	w = 1/[σ²(F_o²) + (0.0384P)² + 3.8042P] where P = (F_o² + 2F_c²)/3
S = 1.16	(Δ/σ)_max < 0.001
2474 reflections	Δρ_max = 0.26 e Å⁻³
164 parameters	Δρ_min = −0.25 e Å⁻³

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.

Refinement. H atoms of the water molecule were discernable from difference Fourier maps and were refined with a distance constraint of d(O—H) = 0.85 (2) Å and U_iso(H) = 1.2U_eq(O).

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
K1	0.15628 (5)	1.09153 (6)	0.42734 (4)	0.0506 (2)
C1	0.2944 (2)	0.7909 (3)	0.39898 (15)	0.0472 (7)
C2	0.4166 (2)	0.7875 (3)	0.43384 (15)	0.0487 (7)
C3	0.4309 (3)	0.8111 (4)	0.51015 (18)	0.0821 (12)
H3A	0.392100	0.748541	0.529535	0.123*
H3B	0.401517	0.891143	0.517026	0.123*
H3C	0.508280	0.808381	0.532212	0.123*
C4	0.4813 (3)	0.8766 (3)	0.3993 (2)	0.0771 (11)
H4A	0.557938	0.875484	0.423076	0.116*
H4B	0.452259	0.958795	0.400604	0.116*
H4C	0.474846	0.851963	0.352400	0.116*
C5	0.3054 (2)	0.3895 (3)	0.40145 (15)	0.0480 (7)
C6	0.3190 (3)	0.4065 (3)	0.32830 (15)	0.0528 (7)
C7	0.2039 (3)	0.4120 (4)	0.28002 (19)	0.0860 (12)
H7A	0.210978	0.433095	0.234536	0.129*
H7B	0.160035	0.473708	0.296120	0.129*
H7C	0.168503	0.332713	0.279131	0.129*
C8	0.3929 (4)	0.3084 (3)	0.3078 (2)	0.0838 (12)
H8A	0.465638	0.313788	0.337303	0.126*
H8B	0.397454	0.321471	0.261032	0.126*
H8C	0.362369	0.227842	0.312210	0.126*
O1	0.27906 (19)	0.2950 (2)	0.42639 (12)	0.0672 (6)
O2	0.32499 (16)	0.49337 (17)	0.43563 (9)	0.0484 (5)
O3	0.37049 (17)	0.52461 (17)	0.33094 (10)	0.0528 (5)
O4	0.26098 (15)	0.68262 (17)	0.37398 (10)	0.0485 (5)
O5	0.44883 (15)	0.66399 (17)	0.42278 (11)	0.0524 (5)
O6	0.23570 (19)	0.8815 (2)	0.39470 (13)	0.0689 (6)
B1	0.3552 (3)	0.5923 (3)	0.38934 (17)	0.0426 (7)
O7	0.0564 (5)	1.1217 (5)	0.2850 (3)	0.0830 (16)	0.5
H1	0.116 (3)	1.085 (6)	0.287 (5)	0.100*	0.5
H2	0.003 (4)	1.075 (5)	0.284 (4)	0.100*	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
K1	0.0514 (4)	0.0405 (3)	0.0654 (4)	0.0067 (3)	0.0246 (3)	−0.0010 (3)
C1	0.0494 (16)	0.0434 (16)	0.0519 (17)	0.0089 (13)	0.0180 (13)	0.0010 (13)
C2	0.0488 (16)	0.0394 (14)	0.0575 (18)	0.0062 (13)	0.0112 (13)	−0.0071 (13)
C3	0.089 (3)	0.087 (3)	0.064 (2)	0.012 (2)	0.004 (2)	−0.023 (2)
C4	0.060 (2)	0.059 (2)	0.114 (3)	−0.0066 (17)	0.022 (2)	0.005 (2)
C5	0.0484 (16)	0.0454 (16)	0.0549 (17)	−0.0027 (13)	0.0219 (13)	0.0039 (14)
C6	0.070 (2)	0.0454 (16)	0.0492 (17)	−0.0095 (15)	0.0264 (15)	−0.0073 (14)
C7	0.096 (3)	0.102 (3)	0.057 (2)	−0.028 (2)	0.011 (2)	−0.006 (2)
C8	0.124 (3)	0.055 (2)	0.091 (3)	−0.002 (2)	0.063 (3)	−0.0203 (19)
O1	0.0784 (16)	0.0540 (13)	0.0759 (15)	−0.0148 (12)	0.0314 (12)	0.0125 (11)
O2	0.0640 (12)	0.0447 (11)	0.0418 (10)	0.0017 (9)	0.0231 (9)	0.0006 (9)
O3	0.0756 (14)	0.0422 (11)	0.0522 (12)	−0.0075 (10)	0.0384 (11)	−0.0040 (9)
O4	0.0395 (10)	0.0466 (11)	0.0583 (12)	0.0044 (9)	0.0089 (9)	−0.0035 (9)
O5	0.0405 (11)	0.0397 (10)	0.0752 (14)	0.0069 (8)	0.0092 (9)	−0.0081 (10)
O6	0.0674 (14)	0.0531 (13)	0.0881 (17)	0.0248 (11)	0.0218 (12)	−0.0003 (12)
B1	0.0435 (16)	0.0383 (15)	0.0492 (18)	0.0034 (14)	0.0177 (14)	0.0007 (14)
O7	0.112 (4)	0.074 (3)	0.082 (3)	−0.023 (3)	0.061 (3)	−0.024 (3)

Geometric parameters (Å, º) top

K1—O6	2.612 (2)	C4—H4C	0.9600
K1—O5ⁱ	2.6686 (19)	C5—O1	1.212 (3)
K1—O1ⁱⁱ	2.674 (2)	C5—O2	1.307 (3)
K1—O2ⁱⁱⁱ	2.8460 (19)	C5—C6	1.520 (4)
K1—O7	2.851 (6)	C6—O3	1.421 (3)
K1—O1ⁱⁱⁱ	3.101 (2)	C6—C8	1.515 (4)
K1—C5ⁱⁱⁱ	3.351 (3)	C6—C7	1.530 (5)
K1—K1^iv	4.7390 (13)	C7—H7A	0.9600
K1—H1	2.74 (9)	C7—H7B	0.9600
K1—H2	3.05 (7)	C7—H7C	0.9600
C1—O6	1.210 (3)	C8—H8A	0.9600
C1—O4	1.301 (3)	C8—H8B	0.9600
C1—C2	1.517 (4)	C8—H8C	0.9600
C2—O5	1.423 (3)	O2—B1	1.514 (4)
C2—C4	1.515 (4)	O3—B1	1.425 (4)
C2—C3	1.516 (4)	O4—B1	1.498 (3)
C3—H3A	0.9600	O5—B1	1.427 (4)
C3—H3B	0.9600	O7—O7^v	1.738 (13)
C3—H3C	0.9600	O7—H1	0.83 (2)
C4—H4A	0.9600	O7—H2	0.83 (2)
C4—H4B	0.9600

O6—K1—O5ⁱ	131.34 (7)	O1—C5—O2	122.9 (3)
O6—K1—O1ⁱⁱ	117.60 (8)	O1—C5—C6	126.6 (3)
O5ⁱ—K1—O1ⁱⁱ	107.73 (7)	O2—C5—C6	110.5 (2)
O6—K1—O2ⁱⁱⁱ	90.45 (7)	O1—C5—K1ⁱⁱⁱ	67.72 (17)
O5ⁱ—K1—O2ⁱⁱⁱ	89.68 (6)	O2—C5—K1ⁱⁱⁱ	56.47 (13)
O1ⁱⁱ—K1—O2ⁱⁱⁱ	110.43 (7)	C6—C5—K1ⁱⁱⁱ	162.42 (19)
O6—K1—O7	87.30 (12)	O3—C6—C8	110.0 (3)
O5ⁱ—K1—O7	74.69 (12)	O3—C6—C5	102.7 (2)
O1ⁱⁱ—K1—O7	91.02 (11)	C8—C6—C5	112.4 (3)
O2ⁱⁱⁱ—K1—O7	156.71 (12)	O3—C6—C7	109.6 (3)
O6—K1—O1ⁱⁱⁱ	123.14 (7)	C8—C6—C7	113.0 (3)
O5ⁱ—K1—O1ⁱⁱⁱ	87.54 (6)	C5—C6—C7	108.7 (3)
O1ⁱⁱ—K1—O1ⁱⁱⁱ	69.93 (7)	C6—C7—H7A	109.5
O2ⁱⁱⁱ—K1—O1ⁱⁱⁱ	43.41 (6)	C6—C7—H7B	109.5
O7—K1—O1ⁱⁱⁱ	148.82 (11)	H7A—C7—H7B	109.5
O6—K1—C5ⁱⁱⁱ	109.51 (7)	C6—C7—H7C	109.5
O5ⁱ—K1—C5ⁱⁱⁱ	85.92 (7)	H7A—C7—H7C	109.5
O1ⁱⁱ—K1—C5ⁱⁱⁱ	90.47 (7)	H7B—C7—H7C	109.5
O2ⁱⁱⁱ—K1—C5ⁱⁱⁱ	22.50 (6)	C6—C8—H8A	109.5
O7—K1—C5ⁱⁱⁱ	160.05 (12)	C6—C8—H8B	109.5
O1ⁱⁱⁱ—K1—C5ⁱⁱⁱ	21.20 (6)	H8A—C8—H8B	109.5
O6—K1—K1^iv	128.25 (6)	C6—C8—H8C	109.5
O5ⁱ—K1—K1^iv	98.26 (5)	H8A—C8—H8C	109.5
O1ⁱⁱ—K1—K1^iv	37.93 (5)	H8B—C8—H8C	109.5
O2ⁱⁱⁱ—K1—K1^iv	73.83 (4)	C5—O1—K1^vi	154.3 (2)
O7—K1—K1^iv	124.74 (10)	C5—O1—K1ⁱⁱⁱ	91.08 (19)
O1ⁱⁱⁱ—K1—K1^iv	32.00 (4)	K1^vi—O1—K1ⁱⁱⁱ	110.07 (7)
C5ⁱⁱⁱ—K1—K1^iv	52.73 (5)	C5—O2—B1	109.2 (2)
O6—C1—O4	124.4 (3)	C5—O2—K1ⁱⁱⁱ	101.03 (16)
O6—C1—C2	125.0 (3)	B1—O2—K1ⁱⁱⁱ	146.83 (16)
O4—C1—C2	110.6 (2)	C6—O3—B1	110.4 (2)
O5—C2—C4	109.1 (2)	C1—O4—B1	109.9 (2)
O5—C2—C3	109.9 (3)	C2—O5—B1	110.7 (2)
C4—C2—C3	113.5 (3)	C2—O5—K1^vii	124.83 (16)
O5—C2—C1	103.7 (2)	B1—O5—K1^vii	122.08 (15)
C4—C2—C1	110.6 (3)	C1—O6—K1	159.7 (2)
C3—C2—C1	109.5 (3)	O3—B1—O5	114.6 (2)
C2—C3—H3A	109.5	O3—B1—O4	114.1 (2)
C2—C3—H3B	109.5	O5—B1—O4	104.8 (2)
H3A—C3—H3B	109.5	O3—B1—O2	103.6 (2)
C2—C3—H3C	109.5	O5—B1—O2	112.6 (2)
H3A—C3—H3C	109.5	O4—B1—O2	107.1 (2)
H3B—C3—H3C	109.5	O7^v—O7—K1	152.9 (4)
C2—C4—H4A	109.5	O7^v—O7—H1	125 (6)
C2—C4—H4B	109.5	K1—O7—H1	74 (7)
H4A—C4—H4B	109.5	O7^v—O7—H2	60 (6)
C2—C4—H4C	109.5	K1—O7—H2	96 (6)
H4A—C4—H4C	109.5	H1—O7—H2	114 (4)
H4B—C4—H4C	109.5

O6—C1—C2—O5	−177.6 (3)	O6—C1—O4—B1	−179.5 (3)
O4—C1—C2—O5	2.3 (3)	C2—C1—O4—B1	0.7 (3)
O6—C1—C2—C4	−60.7 (4)	C4—C2—O5—B1	−122.4 (3)
O4—C1—C2—C4	119.1 (3)	C3—C2—O5—B1	112.6 (3)
O6—C1—C2—C3	65.1 (4)	C1—C2—O5—B1	−4.4 (3)
O4—C1—C2—C3	−115.0 (3)	C4—C2—O5—K1^vii	40.3 (3)
O1—C5—C6—O3	−169.1 (3)	C3—C2—O5—K1^vii	−84.7 (3)
O2—C5—C6—O3	11.7 (3)	C1—C2—O5—K1^vii	158.28 (16)
K1ⁱⁱⁱ—C5—C6—O3	−27.9 (8)	O4—C1—O6—K1	147.2 (5)
O1—C5—C6—C8	−51.0 (4)	C2—C1—O6—K1	−33.0 (8)
O2—C5—C6—C8	129.9 (3)	C6—O3—B1—O5	141.7 (3)
K1ⁱⁱⁱ—C5—C6—C8	90.2 (7)	C6—O3—B1—O4	−97.4 (3)
O1—C5—C6—C7	74.9 (4)	C6—O3—B1—O2	18.6 (3)
O2—C5—C6—C7	−104.3 (3)	C2—O5—B1—O3	130.7 (3)
K1ⁱⁱⁱ—C5—C6—C7	−143.9 (6)	K1^vii—O5—B1—O3	−32.6 (3)
O2—C5—O1—K1^vi	133.4 (4)	C2—O5—B1—O4	4.8 (3)
C6—C5—O1—K1^vi	−45.7 (6)	K1^vii—O5—B1—O4	−158.41 (15)
K1ⁱⁱⁱ—C5—O1—K1^vi	146.1 (5)	C2—O5—B1—O2	−111.2 (3)
O2—C5—O1—K1ⁱⁱⁱ	−12.7 (3)	K1^vii—O5—B1—O2	85.5 (2)
C6—C5—O1—K1ⁱⁱⁱ	168.2 (3)	C1—O4—B1—O3	−129.5 (2)
O1—C5—O2—B1	−179.8 (3)	C1—O4—B1—O5	−3.3 (3)
C6—C5—O2—B1	−0.6 (3)	C1—O4—B1—O2	116.4 (2)
K1ⁱⁱⁱ—C5—O2—B1	166.1 (2)	C5—O2—B1—O3	−10.8 (3)
O1—C5—O2—K1ⁱⁱⁱ	14.1 (3)	K1ⁱⁱⁱ—O2—B1—O3	143.6 (2)
C6—C5—O2—K1ⁱⁱⁱ	−166.6 (2)	C5—O2—B1—O5	−135.1 (2)
C8—C6—O3—B1	−138.6 (3)	K1ⁱⁱⁱ—O2—B1—O5	19.3 (4)
C5—C6—O3—B1	−18.8 (3)	C5—O2—B1—O4	110.2 (2)
C7—C6—O3—B1	96.6 (3)	K1ⁱⁱⁱ—O2—B1—O4	−95.4 (3)

Symmetry codes: (i) x−1/2, y+1/2, z; (ii) x, y+1, z; (iii) −x+1/2, −y+3/2, −z+1; (iv) −x+1/2, −y+5/2, −z+1; (v) −x, y, −z+1/2; (vi) x, y−1, z; (vii) x+1/2, y−1/2, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H1···O3^viii	0.83 (5)	2.49 (9)	2.870 (6)	109 (7)
O7—H2···O3ⁱ	0.83 (5)	2.14 (6)	2.865 (7)	146 (6)

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

Acknowledgements

The authors thank the Sophisticated Analytical Instrument Facility (SAIF), Indian Institute of Technology Madras (IITM), Chennai 600 036, Tamilnadu, India, for the single-crystal X-ray diffraction data.

References

Allen, J. L., Paillard, E., Boyle, P. D. & Henderson, W. A. (2012). Acta Cryst. E68, m749. CrossRef IUCr Journals Google Scholar
Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Gokila, G., Thiruvalluvar, A. A. & Ramachandra Raja, C. (2019). IUCrData, 4, x190039. Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar

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