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Acta Crystallogr Sect E Struct Rep Online. 2009 August 1; 65(Pt 8): m888.
Published online 2009 July 8. doi:  10.1107/S1600536809024702
PMCID: PMC2977434

Dibromidotris(dimethyl­amine)magnesium(II)

Abstract

The Mg centre in the title compound, [MgBr2(C2H7N)3], is penta­coordinated in a trigonal-bipyramidal mode with the two Br atoms in axial positions and the N atoms of the dimethyl­amine ligands in equatorial positions. The MgII centre is located on a crystallographic twofold rotation axis. The crystal structure is stabilized by N—H(...)Br hydrogen bonds. The N atom and H atoms of one dimethylamine ligand are disordered over two equally occupied positions.

Related literature

The solid-state structures of Mg–Br compounds feature coordination numbers of the Mg center from four as in [MgBr(SitBu3)(THF)]2 (Lerner et al., 2003 [triangle]) to six as in [MgBr2(THF)4] (Lorbach et al., 2007 [triangle]).

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Object name is e-65-0m888-scheme1.jpg

Experimental

Crystal data

  • [MgBr2(C2H7N)3]
  • M r = 319.39
  • Hexagonal, An external file that holds a picture, illustration, etc.
Object name is e-65-0m888-efi1.jpg
  • a = 9.0951 (7) Å
  • c = 14.4544 (12) Å
  • V = 1035.49 (14) Å3
  • Z = 3
  • Mo Kα radiation
  • μ = 5.88 mm−1
  • T = 173 K
  • 0.25 × 0.25 × 0.23 mm

Data collection

  • Stoe IPDSII two-circle diffractometer
  • Absorption correction: multi-scan (MULABS; Spek, 2003 [triangle]; Blessing, 1995 [triangle]) T min = 0.321, T max = 0.345 (expected range = 0.241–0.258)
  • 5279 measured reflections
  • 1285 independent reflections
  • 1223 reflections with I > 2σ(I)
  • R int = 0.037

Refinement

  • R[F 2 > 2σ(F 2)] = 0.022
  • wR(F 2) = 0.049
  • S = 0.96
  • 1285 reflections
  • 61 parameters
  • H-atom parameters constrained
  • Δρmax = 0.25 e Å−3
  • Δρmin = −0.34 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 517 Friedel pairs
  • Flack parameter: −0.012 (17)

Data collection: X-AREA (Stoe & Cie, 2001 [triangle]); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809024702/at2830sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809024702/at2830Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

The solid-state structures of Mg—Br compounds feature coordination numbers of the Mg center from four as in [MgBr(SitBu3)(THF)]2 (Lerner et al., 2003) to six as in [MgBr2(THF)4] (Lorbach et al., 2007). Most of the Mg—Br compounds possess an octahedral coordination sphere which surrounds the Mg cation whereas only a few compounds are found in the Cambridge Structural Database with four- and five-coordinated Mg centers. We report here the X-ray crystal structure analysis of [MgBr2(NHMe2)3], the adduct of MgBr2 with three dimethylamine molecules, which was obtained as a by-product from the reaction of C6F5MgBr with BrB(NMe2) in Et2O.

Experimental

At 273 K, BrB(NMe2) (3.5 g, 19.6 mmol) was added to a solution of C6F5MgBr in Et2O which was obtained from C6F5Br (4,6 g, 18.6 mmol) and Mg (0.5 g, 21.0 mmol) in 25 ml Et2O. After distillation of C6F5B(NMe2) (yield 73%) colourless crystals of the title compound were obtained as distillation residue.

Refinement

H atoms were geometrically positioned and refined using a riding model with fixed individual displacement parameters [Uiso(H) = 1.2 Ueq(N) or Uiso(H) = 1.5 Ueq(C)] and with N—H = 0.93Å and C—H = 0.98 Å. The N atom and H atoms of one dimethylamine ligand are disordered over two equally occupied positions.

Figures

Fig. 1.
Perspective view of the title compound with the atom numbering scheme; displacement ellipsoids are at the 50% probability level; H atoms are drawn as small spheres of arbitrary radii. Only one of the two disordered moieties is shown.

Crystal data

[MgBr2(C2H7N)3]Dx = 1.537 Mg m3
Mr = 319.39Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P3221Cell parameters from 5127 reflections
Hall symbol: P 32 2"θ = 3.8–25.6°
a = 9.0951 (7) ŵ = 5.88 mm1
c = 14.4544 (12) ÅT = 173 K
V = 1035.49 (14) Å3Block, colourless
Z = 30.25 × 0.25 × 0.23 mm
F(000) = 480

Data collection

Stoe IPDSII two-circle diffractometer1285 independent reflections
Radiation source: fine-focus sealed tube1223 reflections with I > 2σ(I)
graphiteRint = 0.037
ω scansθmax = 25.6°, θmin = 3.8°
Absorption correction: multi-scan (MULABS; Spek, 2003; Blessing, 1995)h = −11→8
Tmin = 0.321, Tmax = 0.345k = −7→11
5279 measured reflectionsl = −17→17

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.022w = 1/[σ2(Fo2) + (0.0277P)2 + 0.2606P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.049(Δ/σ)max = 0.001
S = 0.96Δρmax = 0.25 e Å3
1285 reflectionsΔρmin = −0.33 e Å3
61 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0106 (8)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 517 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: −0.012 (17)

Special details

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)

xyzUiso*/UeqOcc. (<1)
Br10.39287 (4)0.37977 (4)0.318621 (17)0.03405 (12)
Mg10.41479 (13)0.41479 (13)0.50000.0231 (3)
N10.4463 (3)0.1927 (3)0.50042 (15)0.0301 (5)
H10.48870.18970.44230.036*
C10.5661 (5)0.1872 (5)0.5683 (2)0.0441 (9)
H1A0.67680.29100.56300.066*
H1B0.57890.08830.55560.066*
H1C0.52170.17870.63100.066*
C20.2791 (5)0.0368 (4)0.5070 (3)0.0474 (9)
H2A0.20120.04190.46200.071*
H2B0.23340.02700.56950.071*
H2C0.2916−0.06210.49390.071*
N20.6685 (6)0.6265 (6)0.5188 (3)0.0293 (12)0.50
H20.71830.58960.56230.035*0.50
C30.6750 (5)0.7809 (4)0.5616 (2)0.0444 (8)
H3A0.79330.87160.56840.067*0.50
H3B0.62060.75080.62260.067*0.50
H3C0.61430.82010.52180.067*0.50
H3D0.77150.89200.54570.067*0.50
H3E0.57850.79400.58030.067*0.50
H3F0.70630.73090.61250.067*0.50

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br10.0453 (2)0.04152 (19)0.02015 (14)0.02533 (16)0.00289 (12)−0.00057 (12)
Mg10.0233 (5)0.0233 (5)0.0200 (5)0.0096 (6)0.0012 (2)−0.0012 (2)
N10.0368 (15)0.0336 (14)0.0232 (12)0.0199 (12)0.0007 (12)−0.0026 (11)
C10.055 (2)0.057 (2)0.0385 (17)0.041 (2)−0.0087 (17)−0.0075 (17)
C20.048 (2)0.0276 (17)0.057 (2)0.0121 (16)0.0043 (18)−0.0044 (15)
N20.027 (2)0.027 (3)0.028 (3)0.010 (2)−0.0027 (19)0.005 (2)
C30.054 (2)0.0249 (16)0.0425 (18)0.0111 (16)−0.0098 (17)−0.0037 (14)

Geometric parameters (Å, °)

Br1—Mg12.6365 (4)C2—H2B0.9800
Mg1—N22.159 (5)C2—H2C0.9800
Mg1—N2i2.159 (5)N2—N2i0.856 (9)
Mg1—N12.177 (3)N2—C3i1.463 (6)
Mg1—N1i2.177 (3)N2—C31.508 (6)
Mg1—Br1i2.6365 (4)N2—H20.9300
N1—C21.475 (4)C3—N2i1.463 (6)
N1—C11.486 (4)C3—H3A0.9800
N1—H10.9300C3—H3B0.9800
C1—H1A0.9800C3—H3C0.9800
C1—H1B0.9800C3—H3D0.9788
C1—H1C0.9800C3—H3E0.9803
C2—H2A0.9800C3—H3F0.9780
N2—Mg1—N2i22.9 (2)C3i—N2—C3110.5 (4)
N2—Mg1—N1104.45 (16)N2i—N2—Mg178.57 (12)
N2i—Mg1—N1122.07 (17)C3i—N2—Mg1116.3 (3)
N2—Mg1—N1i122.07 (17)C3—N2—Mg1114.1 (3)
N2i—Mg1—N1i104.45 (16)N2i—N2—H2175.2
N1—Mg1—N1i133.08 (16)C3i—N2—H2104.6
N2—Mg1—Br1i88.69 (13)C3—N2—H2105.1
N2i—Mg1—Br1i102.44 (14)Mg1—N2—H2105.0
N1—Mg1—Br1i89.66 (6)N2i—C3—H3A119.2
N1i—Mg1—Br1i85.86 (6)N2—C3—H3A109.9
N2—Mg1—Br1102.44 (14)N2i—C3—H3B125.9
N2i—Mg1—Br188.69 (13)N2—C3—H3B109.2
N1—Mg1—Br185.86 (6)H3A—C3—H3B109.5
N1i—Mg1—Br189.66 (6)N2i—C3—H3C76.1
Br1i—Mg1—Br1168.72 (5)N2—C3—H3C109.3
C2—N1—C1110.2 (3)H3A—C3—H3C109.5
C2—N1—Mg1110.0 (2)H3B—C3—H3C109.5
C1—N1—Mg1118.2 (2)N2i—C3—H3D109.6
C2—N1—H1105.9N2—C3—H3D117.5
C1—N1—H1105.9H3B—C3—H3D124.5
Mg1—N1—H1105.9H3C—C3—H3D82.1
N1—C1—H1A109.5N2i—C3—H3E109.2
N1—C1—H1B109.5N2—C3—H3E127.2
H1A—C1—H1B109.5H3A—C3—H3E122.9
N1—C1—H1C109.5H3B—C3—H3E55.2
H1A—C1—H1C109.5H3C—C3—H3E54.3
H1B—C1—H1C109.5H3D—C3—H3E109.5
N1—C2—H2A109.5N2i—C3—H3F109.2
N1—C2—H2B109.5N2—C3—H3F76.2
H2A—C2—H2B109.5H3A—C3—H3F82.1
N1—C2—H2C109.5H3B—C3—H3F54.4
H2A—C2—H2C109.5H3C—C3—H3F163.4
H2B—C2—H2C109.5H3D—C3—H3F109.7
N2i—N2—C3i76.2 (6)H3E—C3—H3F109.6
N2i—N2—C370.4 (6)
N2—Mg1—N1—C2168.6 (2)Br1—Mg1—N2—N2i54.3 (8)
N2i—Mg1—N1—C2−175.4 (2)N2i—Mg1—N2—C3i−68.2 (7)
N1i—Mg1—N1—C2−3.95 (19)N1—Mg1—N2—C3i75.0 (3)
Br1i—Mg1—N1—C280.0 (2)N1i—Mg1—N2—C3i−111.4 (3)
Br1—Mg1—N1—C2−89.6 (2)Br1i—Mg1—N2—C3i164.3 (3)
N2—Mg1—N1—C140.9 (3)Br1—Mg1—N2—C3i−13.9 (4)
N2i—Mg1—N1—C156.8 (3)N2i—Mg1—N2—C362.2 (7)
N1i—Mg1—N1—C1−131.7 (2)N1—Mg1—N2—C3−154.6 (3)
Br1i—Mg1—N1—C1−47.7 (2)N1i—Mg1—N2—C319.0 (4)
Br1—Mg1—N1—C1142.7 (2)Br1i—Mg1—N2—C3−65.3 (3)
N1—Mg1—N2—N2i143.2 (7)Br1—Mg1—N2—C3116.5 (3)
N1i—Mg1—N2—N2i−43.2 (8)C3i—N2—C3—N2i66.2 (5)
Br1i—Mg1—N2—N2i−127.5 (7)Mg1—N2—C3—N2i−67.0 (4)

Symmetry codes: (i) y, x, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1···Br1ii0.932.903.638 (2)137
N2—H2···Br1iii0.932.703.554 (5)153

Symmetry codes: (ii) −x+1, −x+y, −z+2/3; (iii) −x+y+1, −x+1, z+1/3.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2830).

References

  • Blessing, R. H. (1995). Acta Cryst. A51, 33–38. [PubMed]
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Lerner, H.-W., Scholz, S., Bolte, M., Wiberg, N., Nöth, H. & Krossing, I. (2003). Eur. J. Inorg. Chem. pp. 666–670.
  • Lorbach, A., Lerner, H.-W. & Bolte, M. (2007). Acta Cryst. C63, m174–m176. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.
  • Stoe & Cie (2001). X-AREA Stoe & Cie, Darmstadt, Germany.

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