Structures of potassium, sodium and lithium bis(oxalato)borate salts from powder diffraction data

The crystal structures of the alkali-metal bis(oxalato)borate salts A[B(C₂O₄)₂] (A = K, Na, Li) have been determined ab initio using powder diffraction data obtained from a laboratory diffractometer. The K compound crystallizes in the orthorhombic space group Cmcm and its structure has been solved by direct methods applied to the integrated intensities from full pattern decomposition. The Na compound is isostructural with the K salt, while the crystal structure of the highly hydroscopic Li compound differs from the other two. It has an orthorhombic lattice, space group Pnma, and its structure was solved by the global optimization method using a parallel tempering approach. In the K and Na structures the metal ions and complex borate ions form chains with m2m symmetry. Metal-oxygen bonding between the chains links them into a layer and then a framework with square tunnels. The coordination number of both K and Na is eight. The Li compound also contains chains that have .m. symmetry and are bound together into a three-dimensional framework. The coordination polyhedron of the Li atom is a square pyramid with Li lying in its base. This square pyramidal coordination leads to its high reactivity with moisture to give Li[B(C₂O₄)₂]H₂O with lithium in six coordination.

Computing details

For all compounds, data collection: DMSNT (1999). Program(s) used to solve structure: WinCSD (Akselrud et al., 1993), SHELXS (Sheldrick, 1990) for KBOB; Initial model taken from KBOB for NABOB; FOX (Favre-Nicolin & Cerny, 2002) for LiBOB. For all compounds, program(s) used to refine structure: GSAS (Larson & Von Dreele, 2000); molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: EXPGUI (Toby, 2001).

(KBOB) Potasium bis(oxalato)borate

Crystal data

C4BKO8	F(000) = 448
Mr = 225.96	Dx = 2.018 Mg m^−3
Orthorhombic, Cmcm	CuKα1, CuKα2 radiation, λ = 1.540562, 1.544390 Å
Hall symbol: -C 2c 2	T = 295 K
a = 8.26990 (11) Å	Particle morphology: plate-like
b = 11.0102 (3) Å	white
c = 8.16917 (11) Å	cylinder, 25 × 25 mm
V = 743.83 (2) Å^3	Specimen preparation: Prepared at 295 K and ambient kPa
Z = 4

Data collection

Scintag XDS2000 powder diffractometer	Data collection mode: reflection
Radiation source: sealed X-ray tube	Scan method: step
Specimen mounting: packed powder pellet	2θmin = 10.02°, 2θmax = 79.48°, 2θstep = 0.02°

Refinement

Refinement on Yobs	59 parameters
Least-squares matrix: full	8 restraints
Rp = 0.072	8 constraints
Rwp = 0.097	w = 1/Yobs(i)
Rexp = 0.040	(Δ/σ)max = 0.03
R(F^2) = 0.0702	Background function: GSAS Background function number 1 with 15 terms - Shifted Chebyshev function of 1st kind.
3474 data points	Preferred orientation correction: Spherical Harmonic ODF - Spherical harmonic order = 4. Prefered orientation correction range: Min = 0.79251, Max = 1.46111
Profile function: CW Profile function number 3 with 19 terms. Pseudovoigt profile coefficients as parameterized in P. Thompson, D.E. Cox & J.B. Hastings (1987). J. Appl. Cryst.,20,79-83. Asymmetry correction of L.W. Finger, D.E. Cox & A. P. Jephcoat (1994). J. Appl. Cryst.,27,892-900. Peak tails are ignored where the intensity is below 0.0010 times the peak.

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

	x	y	z	Uiso*/Ueq
K	0.0	0.9304 (3)	0.75	0.0381 (8)*
B1	0.0	0.4268 (8)	0.75	0.027 (4)*
C1	0.0	0.2322 (4)	0.6557 (3)	0.029 (3)*
O1	0.0	0.1443 (4)	0.5706 (5)	0.029 (1)*
O2	0.0	0.3481 (3)	0.6050 (4)	0.029 (2)*
C2	0.0914 (3)	0.6254 (4)	0.75	0.023 (3)*
O3	0.1399 (4)	0.5105 (4)	0.75	0.034 (2)*
O4	0.1741 (5)	0.7148 (4)	0.75	0.037 (2)*

Geometric parameters (Å, º)

K—O1^i	2.774 (5)	B1—O2^viii	1.467 (5)
K—O1^ii	2.774 (5)	B1—O3	1.480 (5)
K—O1^iii	2.745 (4)	B1—O3^v	1.480 (5)
K—O1^iv	2.745 (4)	C1—C1^viii	1.541 (5)
K—O4	2.777 (5)	C1—O1	1.192 (5)
K—O4^v	2.777 (5)	C1—O2	1.341 (5)
K—O3^vi	3.106 (4)	C2—C2^v	1.512 (5)
K—O3^vii	3.106 (4)	C2—O3	1.327 (5)
B1—O2	1.467 (5)	C2—O4	1.199 (5)
O1^i—K—O1^iii	139.33 (14)	O3^vi—K—O4^v	75.26 (10)
O1^i—K—O1^iv	75.53 (13)	O3^vii—K—O4	75.26 (10)
O1^i—K—O1^ii	63.80 (17)	O3^vii—K—O4^v	137.75 (14)
O1^i—K—O3^vi	76.04 (7)	O4—K—O4^v	62.48 (19)
O1^i—K—O3^vii	76.04 (7)	O2—B1—O2^viii	107.6 (6)
O1^i—K—O4	136.54 (7)	O2—B1—O3	111.59 (11)
O1^i—K—O4^v	136.54 (7)	O2—B1—O3^v	111.59 (11)
O1^iii—K—O1^iv	145.1 (2)	O2^viii—B1—O3	111.59 (11)
O1^iii—K—O1^ii	75.53 (13)	O2^viii—B1—O3^v	111.59 (11)
O1^iii—K—O3^vi	94.88 (3)	O3—B1—O3^v	102.9 (6)
O1^iii—K—O3^vii	94.88 (3)	C1^viii—C1—O1	125.7 (3)
O1^iii—K—O4	75.16 (9)	C1^viii—C1—O2	108.0 (2)
O1^iii—K—O4^v	75.16 (9)	O1—C1—O2	126.3 (4)
O1^iv—K—O1^ii	139.33 (14)	K^ix—O1—K^x	104.47 (13)
O1^iv—K—O3^vi	94.88 (3)	K^ix—O1—C1	112.4 (3)
O1^iv—K—O3^vii	94.88 (3)	K^x—O1—C1	143.1 (4)
O1^iv—K—O4	75.16 (9)	B1—O2—C1	108.2 (4)
O1^iv—K—O4^v	75.16 (9)	C2^v—C2—O3	107.6 (2)
O1^ii—K—O3^vi	76.04 (7)	C2^v—C2—O4	124.8 (3)
O1^ii—K—O3^vii	76.04 (7)	O3—C2—O4	127.6 (4)
O1^ii—K—O4	136.54 (7)	K^xi—O3—B1	124.9 (3)
O1^ii—K—O4^v	136.54 (7)	K^xi—O3—C2	124.1 (3)
O3^vi—K—O3^vii	146.99 (16)	B1—O3—C2	110.9 (4)
O3^vi—K—O4	137.75 (14)	K—O4—C2	114.0 (3)

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

(NABOB) Sodium bis(oxalato)borate

Crystal data

C4BNaO8	F(000) = 416
Mr = 209.85	Dx = 2.121 Mg m^−3
Orthorhombic, Cmcm	CuKα1, CuKα2 radiation, λ = 1.540562, 1.544390 Å
Hall symbol: -C 2c 2	T = 295 K
a = 8.12756 (8) Å	Particle morphology: plate-like
b = 10.3399 (2) Å	white
c = 7.82108 (10) Å	cylinder, 25 × 25 mm
V = 657.27 (2) Å^3	Specimen preparation: Prepared at 295 K and ambient kPa
Z = 4

Data collection

Scintag XDS2000 powder diffractometer	Data collection mode: reflection
Radiation source: sealed X-ray tube	Scan method: step
Specimen mounting: packed powder pellet	2θmin = 10.02°, 2θmax = 80.98°, 2θstep = 0.02°

Refinement

Refinement on Yobs	48 parameters
Least-squares matrix: full	8 restraints
Rp = 0.069	8 constraints
Rwp = 0.100	w = 1/Yobs(i)
Rexp = 0.031	(Δ/σ)max = 0.06
R(F^2) = 0.0478	Background function: GSAS Background function number 1 with 12 terms - Shifted Chebyshev function of 1st kind
3549 data points	Preferred orientation correction: Spherical Harmonic ODF - Spherical harmonic order = 4. Prefered orientation correction range: Min = 0.72757, Max = 1.27870
Profile function: CW Profile function number 3 with 19 terms Pseudovoigt profile coefficients as parameterized in P. Thompson, D.E. Cox & J.B. Hastings (1987). J. Appl. Cryst.,20,79-83. Asymmetry correction of L.W. Finger, D.E. Cox & A. P. Jephcoat (1994). J. Appl. Cryst.,27,892-900. Peak tails are ignored where the intensity is below 0.0020 times the peak

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

	x	y	z	Uiso*/Ueq
Na	0.0	0.9318 (3)	0.75	0.0461 (9)*
B1	0.0	0.4273 (6)	0.75	0.025 (3)*
C1	0.0	0.2220 (3)	0.6516 (3)	0.0202 (16)*
O1	0.0	0.1269 (2)	0.5642 (3)	0.0272 (11)*
O2	0.0	0.3440 (2)	0.5993 (3)	0.0204 (10)*
C2	0.0949 (3)	0.6388 (3)	0.75	0.0259 (18)*
O3	0.1440 (3)	0.5173 (2)	0.75	0.0247 (11)*
O4	0.1756 (3)	0.7345 (2)	0.75	0.0291 (10)*

Geometric parameters (Å, º)

Na—Na^i	4.1572 (19)	B1—O2	1.460 (4)
Na—Na^ii	4.1572 (19)	B1—O2^x	1.460 (4)
Na—O1^iii	2.486 (3)	B1—O3	1.495 (4)
Na—O1^iv	2.532 (3)	B1—O3^ix	1.495 (4)
Na—O1^v	2.532 (3)	C1—C1^x	1.539 (5)
Na—O1^vi	2.486 (3)	C1—O1	1.198 (4)
Na—O3^vii	3.025 (2)	C1—O2	1.326 (4)
Na—O3^viii	3.025 (2)	C2—C2^ix	1.542 (5)
Na—O4	2.490 (3)	C2—O3	1.319 (4)
Na—O4^ix	2.490 (3)	C2—O4	1.187 (4)
O1^iii—Na—O1^iv	139.63 (12)	O3^vii—Na—O4^ix	72.02 (7)
O1^iii—Na—O1^v	68.11 (9)	O3^viii—Na—O4	72.02 (7)
O1^iii—Na—O1^vi	71.52 (14)	O3^viii—Na—O4^ix	141.96 (11)
O1^iii—Na—O3^vii	76.28 (6)	O4—Na—O4^ix	69.94 (13)
O1^iii—Na—O3^viii	76.28 (6)	O2—B1—O2^x	107.7 (4)
O1^iii—Na—O4	131.68 (5)	O2—B1—O3	111.54 (7)
O1^iii—Na—O4^ix	131.68 (5)	O2—B1—O3^ix	111.54 (7)
O1^iv—Na—O1^v	152.26 (16)	O2^x—B1—O3	111.54 (7)
O1^iv—Na—O1^vi	68.11 (9)	O2^x—B1—O3^ix	111.54 (7)
O1^iv—Na—O3^vii	94.017 (19)	O3—B1—O3^ix	103.0 (4)
O1^iv—Na—O3^viii	94.017 (19)	C1^x—C1—O1	124.80 (18)
O1^iv—Na—O4	78.67 (7)	C1^x—C1—O2	108.00 (16)
O1^iv—Na—O4^ix	78.67 (7)	O1—C1—O2	127.2 (3)
O1^v—Na—O1^vi	139.63 (12)	Na^xi—O1—Na^xii	111.89 (9)
O1^v—Na—O3^vii	94.017 (19)	Na^xi—O1—C1	109.4 (2)
O1^v—Na—O3^viii	94.017 (19)	Na^xii—O1—C1	138.7 (2)
O1^v—Na—O4	78.67 (7)	B1—O2—C1	108.2 (3)
O1^v—Na—O4^ix	78.67 (7)	C2^ix—C2—O3	107.63 (14)
O1^vi—Na—O3^vii	76.28 (6)	C2^ix—C2—O4	123.56 (17)
O1^vi—Na—O3^viii	76.28 (6)	O3—C2—O4	128.8 (3)
O1^vi—Na—O4	131.68 (5)	Na^xiii—O3—B1	124.5 (2)
O1^vi—Na—O4^ix	131.68 (5)	Na^xiii—O3—C2	124.62 (17)
O3^vii—Na—O3^viii	146.02 (13)	B1—O3—C2	110.9 (3)
O3^vii—Na—O4	141.96 (11)	Na—O4—C2	111.5 (2)

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

(LiBOB) Lithium bis(oxalato)borate

Crystal data

C4BLiO8	F(000) = 448
Mr = 193.79	Dx = 2.021 Mg m^−3
Orthorhombic, Pnma	CuKα1, CuKα2 radiation, λ = 1.540562, 1.544390 Å
Hall symbol: -P 2ac 2n	T = 295 K
a = 6.3635 (4) Å	Particle morphology: plate-like
b = 7.5998 (3) Å	white
c = 13.1715 (9) Å	flat_sheet, 25 × 25 mm
V = 636.99 (6) Å^3	Specimen preparation: Prepared at 295 K and ambient kPa
Z = 4

Data collection

Scintag XDS2000 powder diffractometer	Data collection mode: reflection
Radiation source: sealed X-ray tube	Scan method: step
Specimen mounting: packed powder pellet	2θmin = 10.0°, 2θmax = 59.98°, 2θstep = 0.02°

Refinement

Refinement on Yobs	47 parameters
Least-squares matrix: full	11 restraints
Rp = 0.094	8 constraints
Rwp = 0.118	w = 1/Yobs(i)
Rexp = 0.051	(Δ/σ)max = 0.04
R(F^2) = 0.0343	Background function: GSAS Background function number 1 with 9 terms - Shifted Chebyshev function of 1st kind
2500 data points	Preferred orientation correction: Spherical Harmonic ODF - Spherical harmonic order = 4. Prefered orientation correction range: Min= 0.89704, Max= 1.06720
Profile function: CW Profile function number 3 with 19 terms. Pseudovoigt profile coefficients as parameterized in P. Thompson, D.E. Cox & J.B. Hastings (1987). J. Appl. Cryst.,20,79-83. Asymmetry correction of L.W. Finger, D.E. Cox & A. P. Jephcoat (1994). J. Appl. Cryst.,27,892-900. Peak tails are ignored where the intensity is below 0.0050 times the peak

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

	x	y	z	Uiso*/Ueq
Li	0.534 (5)	0.25	0.325 (3)	0.0278 (17)*
B	0.089 (2)	0.25	0.5403 (11)	0.0278 (17)*
O1	0.2012 (11)	0.0991 (8)	0.5845 (7)	0.0278 (17)*
C1	0.3549 (18)	0.1484 (3)	0.6462 (9)	0.0278 (17)*
O2	0.4795 (10)	0.0535 (7)	0.6881 (6)	0.0278 (17)*
O3	0.117 (2)	0.25	0.4292 (10)	0.0278 (17)*
C2	−0.080 (2)	0.25	0.3910 (10)	0.0278 (17)*
O4	−0.1373 (16)	0.25	0.3045 (9)	0.0278 (17)*
O5	−0.135 (2)	0.25	0.5681 (8)	0.0278 (17)*
C3	−0.2364 (17)	0.25	0.4805 (11)	0.0278 (17)*
O6	−0.4247 (15)	0.25	0.4705 (7)	0.0278 (17)*

Geometric parameters (Å, º)

Li—Li^i	3.74 (4)	B—O5	1.474 (6)
Li—Li^ii	3.74 (4)	C1—O1	1.326 (4)
Li—O6^iii	1.94 (3)	C1—C1^vi	1.544 (5)
Li—O4^ii	2.02 (3)	C1—O2	1.206 (4)
Li—O4^iii	2.11 (3)	C2—O3	1.324 (5)
Li—O2^iv	2.315 (6)	C2—O4	1.196 (5)
Li—O2^v	2.315 (6)	C2—C3	1.543 (5)
B—O1	1.470 (6)	C3—C2	1.543 (5)
B—O1^vi	1.470 (6)	C3—O5	1.321 (5)
B—O3	1.471 (6)	C3—O6	1.205 (5)
O2^iv—Li—O2^v	170.5 (16)	O1—C1—O2	126.6 (4)
O2^iv—Li—O4^iii	91.6 (8)	C1^vi—C1—O2	126.7 (3)
O2^iv—Li—O4^ii	85.3 (8)	Li^iv—O2—C1	122.5 (8)
O2^iv—Li—O6^iii	94.5 (9)	B—O3—C2	106.6 (12)
O2^v—Li—O4^iii	91.6 (8)	O3—C2—O4	130.2 (17)
O2^v—Li—O4^ii	85.3 (8)	O3—C2—C3	107.8 (12)
O2^v—Li—O6^iii	94.5 (9)	O4—C2—C3	122.0 (16)
O4^iii—Li—O4^ii	115.3 (15)	Li^vii—O4—Li^i	129.9 (11)
O4^iii—Li—O6^iii	89.5 (12)	Li^vii—O4—C2	100.5 (13)
O4^ii—Li—O6^iii	155.2 (18)	Li^i—O4—C2	129.6 (13)
O1—B—O1^vi	102.6 (8)	B—O5—C3	104.8 (9)
O1—B—O3	110.2 (9)	Li^vii—C3—C2	75.7 (12)
O1—B—O5	111.8 (9)	Li^vii—C3—O5	173.7 (13)
O1^vi—B—O3	110.2 (9)	Li^vii—C3—O6	48.3 (9)
O1^vi—B—O5	111.8 (9)	C2—C3—O5	110.7 (11)
O3—B—O5	110.1 (9)	C2—C3—O6	123.9 (14)
B—O1—C1	112.3 (7)	O5—C3—O6	125.4 (16)
O1—C1—C1^vi	106.4 (3)	Li^vii—O6—C3	104.1 (13)

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