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ISSN: 2056-9890

Tetra­methyl­ammonium borohydride from powder data

aFaculty of Chemistry, University of Warsaw, Pasteura 1, 02093 Warsaw, Poland, and bICM, University of Warsaw, Pawińskiego 5a, 02106 Warsaw, Poland
*Correspondence e-mail: tjaron@chem.uw.edu.pl

(Received 15 June 2011; accepted 20 July 2011; online 30 July 2011)

In the crystal structure of the title compound, C4H12N+·BH4, the tetra­methyl­ammonium cations are situated on special positions with site symmetry [\overline{4}]m2. The borohydride anions are situated on special positions with 4mm site symmetry and show rotational disorder around the fourfold axis.

Related literature

For details of the synthesis, see: Banus et al. (1952[Banus, M. D., Bragdon, R. W. & Gibb, T. R. P. Jr (1952). J. Am. Chem. Soc. 74, 2346-2348.]); King et al. (1956[King, A. J., Kanda, F. A., Russel, V. A. & Katz, W. (1956). J. Am. Chem. Soc. 78, 4176.]). For previous studies of the title compound, see: Harmon et al. (1974[Harmon, K. M., Gennick, I. & Madeira, S. L. (1974). J. Phys. Chem. 78, 2585-2591.]); Eckert et al. (2004[Eckert, J., Sewell, T. D., Kress, J. D., Kober, E. M., Wang, L. L. & Olah, G. (2004). J. Phys. Chem. A, 108, 11369-11374.]). The isostructural compounds (CH3)4NClO4 and (CH3)4NBF4 were reported by McCullough (1964[McCullough, J. D. (1964). Acta Cryst. 17, 1067-1070.]) and Giuseppetti et al. (1992[Giuseppetti, G., Mazzi, F., Tadini, C., Ferloni, P. & Torre, S. (1992). Z. Kristallogr. 202, 81-88.]), respectively. For applications of the title compound, see: Evans et al. (1988[Evans, D. A., Chapman, K. T. & Carreira, M. (1988). J. Am. Chem. Soc. 110, 3560-3578.]).

[Scheme 1]

Experimental

Crystal data
  • C4H12N+·BH4

  • Mr = 88.99

  • Tetragonal, P 4/n m m

  • a = 7.9133 (2) Å

  • c = 5.65696 (17) Å

  • V = 354.24 (2) Å3

  • Z = 2

  • Cu Kα radiation, λ = 1.54051, 1.54433 Å

  • μ = 0.33 mm−1

  • T = 298 K

  • cylinder, 18 × 1 mm

Data collection
  • Bruker D8 Discover diffractometer

  • Specimen mounting: quartz capillary

  • Data collection mode: transmission

  • Scan method: continuous

  • 2θmin = 8°, 2θmax = 121°, 2θstep = 0.012°

Refinement
  • Rp = 0.014

  • Rwp = 0.020

  • Rexp = 0.007

  • RBragg = 0.053

  • χ2 = 7.673

  • 9220 data points

  • 56 parameters

  • 14 restraints

  • H atoms treated by a mixture of independent and constrained refinement

Data collection: DIFFRACplus (Bruker, 2006[Bruker (2006). DIFFRACplus. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: X-CELL (Neumann, 2003[Neumann, M. A. (2003). J. Appl. Cryst. 36, 356-365.]) and JANA2006 (Petricek et al., 2006[Petricek, V., Dusek, M. & Palatinus, L. (2006). JANA2006. Institute of Physics, Praha, Czech Republic.]); data reduction: DIFFRACplus; program(s) used to solve structure: JANA2006; program(s) used to refine structure: JANA2006; molecular graphics: CrystalMaker (Palmer, 2005[Palmer, D. (2005). CrystalMaker. CrystalMaker Software Ltd, Oxfordshire, England.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

Tetramethylammonium borohydride (I) and its derivatives have been used as selective reductors in organic chemistry (Evans et al., 1988) or as a source of hydrogen-rich BH4- anions for inorganic synthesis.

The structure of compound (I) has not been reported before; only the unit-cell parameters (a = 7.29 Å, c = 5.696 Å), the tentative space group (P4/n) (King et al., 1956) and several interatomic distances (Eckert et al., 2004) have been given. The structure presented here is isomorphous to the ambient temperature structures of (CH3)4NBF4 (Giuseppetti et al., 1992) and (CH3)4NClO4 (McCullough, 1964) and is composed of distinct (CH3)4N+ cations and BH4- anions.

The central atoms of the ions are separated by d(N1, B1) = 4.537 (4) Å, which compares well with the shortest N—B distances seen for fluoroborate (4.79 Å, s.u. not given in the paper) and N—Cl distances in perchlorate (4.86 Å, s.u. not given in the paper). Methyl groups in (I) are ordered (in contrast to (CH3)4NClO4, where the hydrogen positions are disordered) and arranged in a staggered conformation like in (CH3)4NBF4. This is explained by an increasing separation of cations as measured by d(N—N') distance of 5.5955 (2), 5.82 (s.u. not given in the paper), and 5.90 (s.u. not given in the paper) for (I), (CH3)4NBF4, and (CH3)4NClO4, respectively. The borohydride anions are centred at 2c (4 mm) site with B1 and H3 atoms at the fourfold symmetry axis, while H4 and H5 are used for the representation of disorder (four BH4- tetrahedra sharing vertex of H3 can be constructed). The B—H infrared absorption bands (δH—B—H = 1072 cm-1, νB—H = 2225 cm-1 and 2288 cm-1) are very broad, up to ca 800 cm-1 for stretching bands (!), which confirms H disorder of the BH4- anions in compound (I) (Harmon et al., 1974). In such arrangement the closest distances between hydrogen atoms of (CH3)4N+ and BH4- are: d(H1—H3) = 2.39 (2) Å, d(H2—H4) = 2.47 (3) Å and d(H2—H5)= 2.49 (3) Å, thus above the maximum range of a typical dihydrogen bond length of 2.2 Å.

Related literature top

For details of the synthesis, see: Banus et al. (1952); King et al. (1956). For previous studies of the title compound, see: Harmon et al. (1974); Eckert et al. (2004). The isostructural compounds (CH3)4NClO4 and (CH3)4NBF4 were reported by McCullough (1964) and Giuseppetti et al. (1992), respectively. For applications of the title compound, see: Evans et al. (1988).

Experimental top

Compound (I) commercially available from Sigma-Aldrich (> 95%) has been used for powder XRD measurements without additional purification. The FTIR spectrum of compound (I) in KBr pellet has been recorded using Bruker Vertex 80v vacuum spectrometer.

Refinement top

The powder diffraction pattern of (I) was indexed with X-Cell (Neumann, 2003) in a tetragonal system of extinction class P4/nmm. The initial model of the structure of compound (I) was constructed according to the symmetry considerations, with all heavy atoms at special positions: N1 at 2 b (4m2), C1 at 8i (m), and B1 at 2c (4 mm). H1 and H2 (hydrogen atoms of the methyl groups) were placed at sites 8i (m), and 16k (1), respectively. An alternative structure with disordered methyl groups led to a worse Rietveld fit. Location of the hydrogen atoms of BH4- group was more problematic, as the tetragonal axis is incompatible with the symmetry alements of tetrahedron. The model containing four overlaping BH4- tetrahedra has been used for the Rietveld refinement performed using Jana2006 (Petricek et al. 2006). The following restraints have been aplied for the refinement: d(C1—H1), d(C1—H2) = 1.00 s.u. = 0.005 [Å], d(B1—H3) = 1.12, s.u. = 0.005 [Å], d(B1—H4), d(B1—H5) = 1.12, s.u. = 0.01 [Å]; a(Hi—C1—Hj), a(Hi—C1—N1) = 109.47, s.u.=0.01 [°], and a(H3—B1—H4), a(H3—B1—H5), a(H4—B1—H5) = 109.47, s.u.=0.01 [°]. The atomic displacement parameters (ADP) of hydrogen atoms were restricted according to the riding model to UisoH1 = UisoH2 = 1.2UisoC1 and UisoH3 = UisoH4 = UisoH5 = 1.5UisoB1.

Computing details top

Data collection: DIFFRACplus (Bruker, 2006); cell refinement: X-CELL (Neumann, 2003) and JANA2006 (Petricek et al., 2006); data reduction: DIFFRACplus (Bruker, 2006); program(s) used to solve structure: PLEASE SUPPLY; program(s) used to refine structure: JANA2006 (Petricek et al., 2006); molecular graphics: CrystalMaker (Palmer, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. A content of the unit cell of (I) viewed along axis c and showing the atomic labelling and 50% probabilty displacement ellipsoids [symmetry codes: (i) -x + 1,-y + 1,-z + 1; (ii) -x + 1/2,-y + 3/2,z; (iii) x + 1/2,y - 1/2,-z + 1; (iv) -y + 1,x + 1/2,-z + 1; (v) y,-x + 1/2,z; (vi) y - 1/2,-x + 1,-z + 1; (vii) -y + 3/2,x,z]. The H atoms are shown as spheres of arbitrary radius. Only one orientation of disordered BH4 anions is shown for clarity.
[Figure 2] Fig. 2. The results of Rietveld refinement. Measured data are given as asterisks, the calculated profile as a solid line, and the difference profile as a solid line below. Vertical markers above the difference profile indicate the calculated Bragg reflection positions. The insert shows high-angle part magnified ca 18 times.
tetramethylammonium borohydride top
Crystal data top
C4H12N+·BH4F(000) = 104
Mr = 88.99Dx = 0.834 Mg m3
Dm = 0.813 Mg m3
Dm measured by helium pycnometry (Banus et al., 1952)
Tetragonal, P4/nmmCu Kα radiation, λ = 1.54051, 1.54433 Å
Hall symbol: -P 4a 2aµ = 0.33 mm1
a = 7.9133 (2) ÅT = 298 K
c = 5.65696 (17) Åwhite
V = 354.24 (2) Å3cylinder, 18 × 1 mm
Z = 2Specimen preparation: Prepared at 298 K
Data collection top
Bruker D8 Discover
diffractometer
Data collection mode: transmission
None monochromatorScan method: continuous
Specimen mounting: quartz capillary2θmin = 8°, 2θmax = 120.999°, 2θstep = 0.012°
Refinement top
Rp = 0.01414 restraints
Rwp = 0.0202 constraints
Rexp = 0.007All H-atom parameters refined
RBragg = 0.053Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0016I2]
χ2 = 7.673(Δ/σ)max = 0.009
9220 data pointsBackground function: 25 Legendre polynoms
Profile function: Pseudo-VoigtPreferred orientation correction: none
56 parameters
Crystal data top
C4H12N+·BH4Z = 2
Mr = 88.99Cu Kα radiation, λ = 1.54051, 1.54433 Å
Tetragonal, P4/nmmµ = 0.33 mm1
a = 7.9133 (2) ÅT = 298 K
c = 5.65696 (17) Åcylinder, 18 × 1 mm
V = 354.24 (2) Å3
Data collection top
Bruker D8 Discover
diffractometer
Scan method: continuous
Specimen mounting: quartz capillary2θmin = 8°, 2θmax = 120.999°, 2θstep = 0.012°
Data collection mode: transmission
Refinement top
Rp = 0.0149220 data points
Rwp = 0.02056 parameters
Rexp = 0.00714 restraints
RBragg = 0.053All H-atom parameters refined
χ2 = 7.673
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
H40.315 (2)0.363 (4)0.957 (3)0.14971 (4)*0.25
H20.1457 (17)0.5963 (4)0.2429 (17)0.10060 (2)*
B10.250.250.8925 (14)0.084 (5)
H30.250.250.702 (4)0.14971 (4)*
C10.250.5959 (3)0.3460 (5)0.065 (2)
H10.250.492 (2)0.4477 (19)0.10060 (2)*
H50.250.119 (5)0.957 (3)0.14971 (4)*0.25
N10.250.750.50.045 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
B10.100 (7)0.100 (7)0.053 (9)000
C10.084 (4)0.036 (3)0.075 (4)000.013 (3)
N10.045 (4)0.045 (4)0.045 (7)000
Geometric parameters (Å, º) top
B1—H31.08 (2)C1—H11.004 (15)
B1—H41.10 (3)C1—H21.010 (12)
B1—H51.10 (4)C1—N11.498 (3)
H1—C1—H2109.5 (5)H4—B1—H4ii109.5 (16)
H2—C1—N1109.5 (4)H4—B1—H5iii109.5 (12)
H2—C1—H2i109.5 (9)C1—N1—C1iv108.91 (14)
H3—B1—H5109.5 (12)C1—N1—C1v109.75 (7)
H4—B1—H3109.5 (10)
Symmetry codes: (i) x+1/2, y, z; (ii) x, y+1/2, z; (iii) y, x+1/2, z; (iv) x+1/2, y+3/2, z; (v) y1/2, x+1/2, z+1.

Experimental details

Crystal data
Chemical formulaC4H12N+·BH4
Mr88.99
Crystal system, space groupTetragonal, P4/nmm
Temperature (K)298
a, c (Å)7.9133 (2), 5.65696 (17)
V3)354.24 (2)
Z2
Radiation typeCu Kα, λ = 1.54051, 1.54433 Å
µ (mm1)0.33
Specimen shape, size (mm)Cylinder, 18 × 1
Data collection
DiffractometerBruker D8 Discover
diffractometer
Specimen mountingQuartz capillary
Data collection modeTransmission
Scan methodContinuous
2θ values (°)2θmin = 8 2θmax = 120.999 2θstep = 0.012
Refinement
R factors and goodness of fitRp = 0.014, Rwp = 0.020, Rexp = 0.007, RBragg = 0.053, χ2 = 7.673
No. of data points9220
No. of parameters56
No. of restraints14
H-atom treatmentAll H-atom parameters refined

Computer programs: DIFFRACplus (Bruker, 2006), X-CELL (Neumann, 2003) and JANA2006 (Petricek et al., 2006), PLEASE SUPPLY, JANA2006 (Petricek et al., 2006), CrystalMaker (Palmer, 2005), publCIF (Westrip, 2010).

 

Acknowledgements

Przemysław Malinowski MSc and Dominik Kurzydłowski MSc are acknowledged for discussions about JANA2006, and Armand Budzianowski PhD for help with CIF preparation and discussions.

References

First citationBanus, M. D., Bragdon, R. W. & Gibb, T. R. P. Jr (1952). J. Am. Chem. Soc. 74, 2346–2348.  CrossRef CAS Web of Science Google Scholar
First citationBruker (2006). DIFFRACplus. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationEckert, J., Sewell, T. D., Kress, J. D., Kober, E. M., Wang, L. L. & Olah, G. (2004). J. Phys. Chem. A, 108, 11369–11374.  Web of Science CrossRef CAS Google Scholar
First citationEvans, D. A., Chapman, K. T. & Carreira, M. (1988). J. Am. Chem. Soc. 110, 3560–3578.  CrossRef CAS Web of Science Google Scholar
First citationGiuseppetti, G., Mazzi, F., Tadini, C., Ferloni, P. & Torre, S. (1992). Z. Kristallogr. 202, 81–88.  CrossRef CAS Web of Science Google Scholar
First citationHarmon, K. M., Gennick, I. & Madeira, S. L. (1974). J. Phys. Chem. 78, 2585–2591.  CrossRef CAS Web of Science Google Scholar
First citationKing, A. J., Kanda, F. A., Russel, V. A. & Katz, W. (1956). J. Am. Chem. Soc. 78, 4176.  CrossRef Web of Science Google Scholar
First citationMcCullough, J. D. (1964). Acta Cryst. 17, 1067–1070.  CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
First citationNeumann, M. A. (2003). J. Appl. Cryst. 36, 356–365.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationPalmer, D. (2005). CrystalMaker. CrystalMaker Software Ltd, Oxfordshire, England.  Google Scholar
First citationPetricek, V., Dusek, M. & Palatinus, L. (2006). JANA2006. Institute of Physics, Praha, Czech Republic.  Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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ISSN: 2056-9890
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