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

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ISSN: 2056-9890

Poly[diaceto­nitrile­[μ3-di­fluoro­(oxalato)borato]sodium]

aIonic Liquids and Electrolytes for Energy Technologies (ILEET) Laboratory, Department of Chemical and Biomolecular Engineering, North Carolina State University, 911 Partners Way, Raleigh, NC 27695, USA, and bX-ray Structural Facility, Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
*Correspondence e-mail: wesley_henderson@ncsu.edu

(Received 19 April 2011; accepted 21 April 2011; online 7 May 2011)

The title compound, [Na(C2BF2O4)(CH3CN)2]n, forms infinite two-dimensional layers running parallel to (010). The layers lie across crystallographic mirror planes at y = 1/4 and 3/4. The Na, B and two F atoms reside on these mirror planes. The Na+ cations are six-coordinate. Two equatorial coordination positions are occupied by acetonitrile mol­ecules. The other two equatorial coordination sites are occupied by the chelating O atoms from the difluoro­(oxalato)borate anion (DFOB). The axial coordination sites are occupied by two F atoms from two different DFOB anions.

Related literature

For the electrochemical properties of the DFOB anion, see: Zhang (2007[Zhang, S. S. (2007). J. Power Sources, 163, 713-718.]); Chen et al. (2007[Chen, Z., Liu, J. & Amine, K. (2007). Electrochem. Solid State Lett. 10, A45-A47.]); Fu et al. (2010[Fu, M., Huang, K., Liu, S., Liu, J. & Li, Y. (2010). J. Power Sources, 195, 862-866.]). For ionic liquids based on the DFOB anion, see: Schreiner et al. (2009[Schreiner, C., Amereller, M. & Gores, H. J. (2009). Chem. Eur. J. 15, 2270-2272.]). For the benefits of ionic liquid additives in Li+ ion batteries, see: Kim et al. (2010[Kim, J.-K., Matic, A., Ahn, J.-H. & Jacobsson, P. (2010). J. Power Sources, 195, 7639-7643.]); Schreiner et al. (2009[Schreiner, C., Amereller, M. & Gores, H. J. (2009). Chem. Eur. J. 15, 2270-2272.]); Sugimoto et al. (2009[Sugimoto, T., Atsumi, Y., Kikuta, M., Ishiko, E., Kono, M. & Ishikawa, M. (2009). J. Power Sources, 189, 802-805.]); Moosbauer et al. (2010[Moosbauer, D., Zugmann, S., Amereller, M. & Gores, H. J. (2010). J. Chem. Eng. Data, 55, 1794-1798.]).

[Scheme 1]

Experimental

Crystal data
  • [Na(C2BF2O4)(C2H3N)2]

  • Mr = 241.93

  • Orthorhombic, P n m a

  • a = 11.6932 (3) Å

  • b = 14.1254 (3) Å

  • c = 6.5130 (1) Å

  • V = 1075.76 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.17 mm−1

  • T = 110 K

  • 0.38 × 0.37 × 0.23 mm

Data collection
  • Bruker–Nonius Kappa-axis X8 APEXII diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.938, Tmax = 0.961

  • 33523 measured reflections

  • 3243 independent reflections

  • 2599 reflections with I > 2σ(I)

  • Rint = 0.032

Refinement
  • R[F2 > 2σ(F2)] = 0.037

  • wR(F2) = 0.112

  • S = 1.09

  • 3243 reflections

  • 81 parameters

  • H-atom parameters constrained

  • Δρmax = 0.47 e Å−3

  • Δρmin = −0.33 e Å−3

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: cif2tables.py (Boyle, 2008[Boyle, P. D. (2008). http://www.xray.ncsu.edu/PyCIFUtils/ .]).

Supporting information


Comment top

Ionic liquids (ILs) have attracted much attention recently, especially room-temperature ionic liquids (RTILs), due to their many favorable properties including large liquid range, high conductivity, low vapor pressure, tailorable hydrophobicity and high thermal stability. Recently, a new class of ILs based upon the DFOB- anion has been reported (Schreiner et al., 2009). These ILs may contribute extensively to the solid-electrolyte interface (SEI) formation in Li-ion batteries (Zhang, 2007; Chen et al., 2007; Fu et al., 2010), especially when used as an additive (Kim et al., 2010; Sugimoto et al., 2009; Moosbauer et al., 2010). The synthesis of ILs based on the DFOB- anion has thus far been a multi-step process involving the synthesis of tetrafluoroborate BF4--based ILs, which are then reacted to displace two F atoms with an oxalate moiety to form DFOB- anions. The title compound, sodium difluoro(oxalato)borate (NaDFOB), can be used as an alternative reagent for the synthesis of DFOB--based ILs by reacting it directly with bromide salts with organic cations producing the DFOB--based ILs and NaBr. Therefore, the title compound may become an important reagent for use in the synthesis of ILs for Li-ion battery electrolytes.

The Na+ cation in the title structure, which resides on a crystallographic mirror plane, is coordinated by two carbonyl O atoms from a single DFOB- anion, two F atoms from two distinct DFOB- anions and two N atoms from two acetonitrile molecules (Fig. 1). The pseudo-octahedral structure is packed in the crystal structure such that Z = 4 (Fig. 2), forming two dimensional layers in which acetonitrile molecules form the exterior of the layer (Fig. 3). The shortest C···C contact between the acetonitrile exteriors of the layers is 3.675 Å.

Related literature top

For electrochemical properties of the DFOB- anion, see: Zhang (2007); Chen et al. (2007); Fu et al. (2010). For ionic liquids based on the DFOB- anion, see: Schreiner et al. (2009). For the benefits of ionic liquid additives in Li+ ion batteries, see: Kim et al. (2010); Schreiner et al. (2009); Sugimoto et al. (2009); Moosbauer et al. (2010).

Experimental top

NaDFOB was synthesized by the direct reaction of excess boron trifluoride diethyl etherate (BF3-ether) with sodium oxalate, both used as-received from Sigma-Aldrich. The resulting salt was extracted with anhydrous acetonitrile (Sigma-Aldrich) by dissolving the NaDFOB and filtering off the NaF solid byproduct. NaDFOB was allowed to slow crystallize at -20°C forming colorless crystals suitable for X-ray analysis.

Refinement top

The structure was solved by direct methods using the XS program. All non-hydrogen atoms were obtained from the initial solution. The hydrogen atoms were introduced at idealized positions and were allowed to ride on the parent carbon atom. The CH3 orientation and the C—H distance were allowed to vary during the refinement. The structural model was fit to the data using full matrix least-squares based on F2. The calculated structure factors included corrections for anomalous dispersion from the usual tabulation. The structure was refined using the XL program from SHELXTL, graphic plots were produced using the ORTEP-3 crystallographic program suite.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SADABS [SAINT?] (Bruker, 2009); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: cif2tables.py (Boyle, 2008).

Figures top
[Figure 1] Fig. 1. Asymmetric unit of (AN)2:NaDFOB reflected across its mirror plane with naming/numbering scheme. Thermal ellipsoids are at 50% probability (Na-purple, O-red, F-green, B-tan, C-grey, N-blue).
[Figure 2] Fig. 2. Ion and solvent coordination in (AN)2:NaDFOB. Thermal ellipsoids are at 50% probability (Na-purple, O-red, F-green, B-tan, C-grey, N-blue).
[Figure 3] Fig. 3. Packing diagram of (AN)2:NaDFOB. Thermal ellipsoids are at 50% probability (Na-purple, O-red, F-green, B-tan, C-grey, N-blue).
Poly[diacetonitrile[µ3-difluoro(oxalato)borato]sodium] top
Crystal data top
[Na(C2BF2O4)(C2H3N)2]F(000) = 488
Mr = 241.93Dx = 1.494 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 9940 reflections
a = 11.6932 (3) Åθ = 3.4–38.5°
b = 14.1254 (3) ŵ = 0.17 mm1
c = 6.5130 (1) ÅT = 110 K
V = 1075.76 (4) Å3Prism, colorless
Z = 40.38 × 0.37 × 0.23 mm
Data collection top
Bruker–Nonius Kappa-axis X8 APEXII
diffractometer
3243 independent reflections
Radiation source: fine-focus sealed tube2599 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.032
ω and ϕ scansθmax = 39.4°, θmin = 3.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 2020
Tmin = 0.938, Tmax = 0.961k = 2522
33523 measured reflectionsl = 1111
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)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.112H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0573P)2 + 0.1343P]
where P = (Fo2 + 2Fc2)/3
3243 reflections(Δ/σ)max = 0.001
81 parametersΔρmax = 0.47 e Å3
0 restraintsΔρmin = 0.33 e Å3
Crystal data top
[Na(C2BF2O4)(C2H3N)2]V = 1075.76 (4) Å3
Mr = 241.93Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 11.6932 (3) ŵ = 0.17 mm1
b = 14.1254 (3) ÅT = 110 K
c = 6.5130 (1) Å0.38 × 0.37 × 0.23 mm
Data collection top
Bruker–Nonius Kappa-axis X8 APEXII
diffractometer
3243 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
2599 reflections with I > 2σ(I)
Tmin = 0.938, Tmax = 0.961Rint = 0.032
33523 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.112H-atom parameters constrained
S = 1.09Δρmax = 0.47 e Å3
3243 reflectionsΔρmin = 0.33 e Å3
81 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
Na10.53868 (3)0.25000.20509 (6)0.01770 (9)
O10.44700 (5)0.14747 (4)0.05163 (8)0.02226 (11)
O20.34387 (5)0.16659 (4)0.34157 (8)0.02147 (11)
C10.40112 (5)0.19563 (4)0.18020 (9)0.01607 (11)
B10.30460 (9)0.25000.46233 (16)0.01987 (18)
F10.35481 (6)0.25000.65402 (9)0.02390 (13)
F20.18741 (6)0.25000.47948 (11)0.0361 (2)
N10.60143 (7)0.12710 (6)0.43675 (12)0.03178 (16)
C20.62179 (6)0.07466 (5)0.56558 (11)0.02313 (13)
C30.64674 (7)0.00803 (5)0.72867 (13)0.02731 (15)
H3A0.6132 (7)0.0290 (3)0.8509 (11)0.041*
H3B0.7260 (7)0.0035 (4)0.7461 (9)0.041*
H3C0.6171 (7)0.0515 (5)0.6943 (7)0.041*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Na10.01740 (17)0.02188 (18)0.01382 (16)0.0000.00027 (12)0.000
O10.0307 (3)0.0182 (2)0.0179 (2)0.00205 (17)0.00250 (18)0.00271 (15)
O20.0256 (2)0.0215 (2)0.0174 (2)0.00691 (17)0.00341 (17)0.00137 (16)
C10.0167 (2)0.0164 (2)0.0151 (2)0.00148 (17)0.00062 (18)0.00046 (17)
B10.0140 (4)0.0303 (5)0.0153 (4)0.0000.0009 (3)0.000
F10.0217 (3)0.0354 (3)0.0146 (2)0.0000.0017 (2)0.000
F20.0139 (3)0.0714 (6)0.0230 (3)0.0000.0036 (2)0.000
N10.0300 (3)0.0352 (3)0.0301 (3)0.0053 (3)0.0019 (3)0.0104 (3)
C20.0211 (3)0.0235 (3)0.0247 (3)0.0018 (2)0.0018 (2)0.0026 (2)
C30.0334 (4)0.0199 (3)0.0287 (3)0.0007 (2)0.0077 (3)0.0053 (2)
Geometric parameters (Å, º) top
Na1—N12.4143 (8)C1—C1i1.5360 (12)
Na1—N1i2.4143 (8)B1—F21.3748 (12)
Na1—F2ii2.2768 (8)B1—F11.3797 (12)
Na1—F1iii2.3377 (7)B1—O2i1.4892 (8)
Na1—O12.4582 (6)F1—Na1iv2.3377 (7)
Na1—O1i2.4582 (6)F2—Na1v2.2768 (8)
Na1—C13.0780 (7)N1—C21.1443 (10)
Na1—C1i3.0780 (7)C2—C31.4489 (10)
O1—C11.2049 (8)C3—H3A0.9359
O2—C11.3119 (8)C3—H3B0.9359
O2—B11.4892 (8)C3—H3C0.9359
F2ii—Na1—F1iii162.92 (3)O1i—Na1—C1i21.651 (16)
F2ii—Na1—N1i99.86 (3)C1—Na1—C1i28.90 (2)
F1iii—Na1—N1i91.96 (2)C1—O1—Na1109.52 (4)
F2ii—Na1—N199.86 (3)C1—O2—B1109.46 (5)
F1iii—Na1—N191.96 (2)O1—C1—O2127.40 (6)
N1i—Na1—N191.96 (4)O1—C1—C1i124.38 (4)
F2ii—Na1—O183.93 (2)O2—C1—C1i108.22 (4)
F1iii—Na1—O182.29 (2)O1—C1—Na148.83 (3)
N1i—Na1—O1168.90 (3)O2—C1—Na1176.22 (4)
N1—Na1—O197.70 (2)C1i—C1—Na175.551 (11)
F2ii—Na1—O1i83.93 (2)F2—B1—F1110.52 (8)
F1iii—Na1—O1i82.29 (2)F2—B1—O2i110.50 (5)
N1i—Na1—O1i97.70 (2)F1—B1—O2i110.29 (5)
N1—Na1—O1i168.90 (3)F2—B1—O2110.50 (5)
O1—Na1—O1i72.20 (3)F1—B1—O2110.29 (5)
F2ii—Na1—C182.71 (2)O2i—B1—O2104.59 (7)
F1iii—Na1—C180.76 (2)B1—F1—Na1iv138.30 (6)
N1i—Na1—C1147.97 (2)B1—F2—Na1v144.47 (6)
N1—Na1—C1119.27 (2)C2—N1—Na1170.74 (7)
O1—Na1—C121.651 (16)N1—C2—C3179.60 (9)
O1i—Na1—C150.549 (18)C2—C3—H3A109.5
F2ii—Na1—C1i82.71 (2)C2—C3—H3B109.5
F1iii—Na1—C1i80.76 (2)H3A—C3—H3B109.5
N1i—Na1—C1i119.27 (2)C2—C3—H3C109.5
N1—Na1—C1i147.97 (2)H3A—C3—H3C109.5
O1—Na1—C1i50.549 (18)H3B—C3—H3C109.5
F2ii—Na1—O1—C185.53 (5)F2ii—Na1—C1—C1i88.110 (6)
F1iii—Na1—O1—C184.36 (5)F1iii—Na1—C1—C1i87.597 (6)
N1i—Na1—O1—C125.08 (17)N1i—Na1—C1—C1i8.83 (5)
N1—Na1—O1—C1175.30 (5)N1—Na1—C1—C1i174.65 (3)
O1i—Na1—O1—C10.02 (5)O1—Na1—C1—C1i179.98 (5)
C1i—Na1—O1—C10.01 (3)O1i—Na1—C1—C1i0.01 (2)
Na1—O1—C1—O2179.80 (5)C1—O2—B1—F2121.16 (7)
Na1—O1—C1—C1i0.02 (5)C1—O2—B1—F1116.34 (6)
B1—O2—C1—O1178.41 (7)C1—O2—B1—O2i2.23 (9)
B1—O2—C1—C1i1.44 (6)F2—B1—F1—Na1iv180.0
B1—O2—C1—Na1176.1 (7)O2i—B1—F1—Na1iv57.51 (5)
F2ii—Na1—C1—O191.91 (5)O2—B1—F1—Na1iv57.51 (5)
F1iii—Na1—C1—O192.38 (5)F1—B1—F2—Na1v0.0
N1i—Na1—C1—O1171.15 (6)O2i—B1—F2—Na1v122.36 (5)
N1—Na1—C1—O15.34 (6)O2—B1—F2—Na1v122.36 (5)
O1i—Na1—C1—O1179.97 (7)F2ii—Na1—N1—C2156.5 (5)
C1i—Na1—C1—O1179.98 (5)F1iii—Na1—N1—C235.9 (5)
F2ii—Na1—C1—O289.5 (7)N1i—Na1—N1—C256.1 (5)
F1iii—Na1—C1—O294.8 (7)O1—Na1—N1—C2118.4 (5)
N1i—Na1—C1—O2173.6 (7)O1i—Na1—N1—C294.4 (5)
N1—Na1—C1—O27.7 (7)C1—Na1—N1—C2116.4 (5)
O1—Na1—C1—O22.4 (7)C1i—Na1—N1—C2111.6 (5)
O1i—Na1—C1—O2177.6 (7)Na1—N1—C2—C366 (14)
C1i—Na1—C1—O2177.6 (7)
Symmetry codes: (i) x, y+1/2, z; (ii) x+1/2, y+1/2, z1/2; (iii) x, y, z+1; (iv) x, y, z1; (v) x1/2, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formula[Na(C2BF2O4)(C2H3N)2]
Mr241.93
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)110
a, b, c (Å)11.6932 (3), 14.1254 (3), 6.5130 (1)
V3)1075.76 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.17
Crystal size (mm)0.38 × 0.37 × 0.23
Data collection
DiffractometerBruker–Nonius Kappa-axis X8 APEXII
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.938, 0.961
No. of measured, independent and
observed [I > 2σ(I)] reflections
33523, 3243, 2599
Rint0.032
(sin θ/λ)max1)0.893
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.112, 1.09
No. of reflections3243
No. of parameters81
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.47, 0.33

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SADABS [SAINT?] (Bruker, 2009), SHELXS (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), cif2tables.py (Boyle, 2008).

 

Acknowledgements

This work was funded by the US DOE BATT Program (contract No. DE-AC02-05-CH11231). JLA thanks the SMART Scholarship Program and the American Society for Engineering Education (ASEE) for the award of a SMART Graduate Research Fellowship.

References

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First citationZhang, S. S. (2007). J. Power Sources, 163, 713–718.  CrossRef CAS Google Scholar

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