The low-temperature structure of diethyl ether magnesium oxybromide

Vitze, H.; Lerner, H.-W.; Bolte, M.

doi:10.1107/S1600536811043820

metal-organic compounds

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Volume 67| Part 11| November 2011| Page m1614

doi:10.1107/S1600536811043820

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The low-temperature structure of diethyl ether magnesium oxybromide

Hannes Vitze,^a Hans-Wolfram Lerner ^a and Michael Bolte ^a ^*

^aInstitut für Anorganische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
^*Correspondence e-mail: bolte@chemie.uni-frankfurt.de

(Received 28 September 2011; accepted 21 October 2011; online 29 October 2011)

The crystal structure of the title compound, hexa-μ₂-bromido-μ₄-oxido-tetrakis[(diethyl ether)magnesium], [Mg₄Br₆O(C₄H₁₀O)₄], determined from data measured at 173 K, differs from the previously known structure of diethyl ether magnesium oxybromide, which was determined from room-temperature data [Stucky & Rundle (1964 ). J. Am. Chem. Soc. 86, 4821–4825]. The title compound crystallizes in the tetragonal space group I $[\overline{4}]$ , whereas the previously known structure crystallizes in a different tetragonal space group, namely P $[\overline{4}]$ 2₁c. Both molecules have crystallographic $[\overline{4}]$ symmetry and show almost identical geometric parameters for the Mg, Br and O atoms. The crystal of the title compound turned out to be a merohedral twin emulating a structure with apparent Laue symmetry 4/mmm, whereas the correct Laue group is just 4/m. The fractional contribution of the minor twin component converged to 0.462 (1).

Related literature

For Mg–Br complexes, see: Lerner (2005 ); Lerner et al. (2003 ); Metzler et al. (1994 ). For a polymorph of the title compound, see: Stucky & Rundle (1964). For the Cambridge Structural Database, see: Allen (2002 ).

Experimental

Crystal data

[Mg₄Br₆O(C₄H₁₀O)₄]
M_r = 889.18
Tetragonal, $[I \overline 4]$
a = 10.4630 (13) Å
c = 15.276 (2) Å
V = 1672.3 (4) Å³
Z = 2
Mo Kα radiation
μ = 7.30 mm⁻¹
T = 173 K
0.25 × 0.22 × 0.18 mm

Data collection

Stoe IPDS II two-circle diffractometer
Absorption correction: multi-scan [MULABS (Spek, 2009 ; Blessing, 1995 )] T_min = 0.169, T_max = 0.269
3746 measured reflections
1479 independent reflections
1455 reflections with I > 2σ(I)
R_int = 0.044

Refinement

R[F² > 2σ(F²)] = 0.026
wR(F²) = 0.067
S = 1.08
1479 reflections
73 parameters
H-atom parameters constrained
Δρ_max = 0.62 e Å⁻³
Δρ_min = −0.56 e Å⁻³
Absolute structure: Flack (1983 ), 689 Friedel pairs
Flack parameter: −0.02 (2)

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

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811043820/bh2385sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811043820/bh2385Isup2.hkl

checkCIF report

Comment top

The solid-state structures of Mg–Br compounds feature coordination numbers of the Mg center from four as in [MgBr(Si^tBu₃)(THF)]₂ (Lerner et al., 2003; Lerner, 2005) to six as in [MgBr₂(THF)₄] (Metzler et al., 1994). 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 (Allen, 2002) with five-coordinated Mg centers as found in the solid-state structure of the title compound. We report here the X-ray crystal structure analysis of [(MgOEt₂)₄Br₆O], which could be isolated from a solution of C₆F₅MgBr in Et₂O.

Data for the crystal structure of the title compound were collected at 173 K. It crystallizes in the tetragonal space group I4 with crystallographic 4 symmetry. The previously known polymorph (Stucky & Rundle, 1964) for which data were collected at room temperature crystallizes in the space group P42₁c and has crystallographic 4 symmetry, too. However, in the latter structure there is severe disorder of the C atoms, whereas in the title compound, no disorder was found. The geometric parameters involving Mg, Br and O atoms agree well in both structures.

Since the structures show striking similarities and were measured at different temperatures, a phase transition between them cannot be excluded.

Related literature top

For Mg–Br complexes, see: Lerner (2005); Lerner et al. (2003); Metzler et al. (1994). For a polymorph of the title compound, see: Stucky & Rundle (1964). For the Cambridge Structural Database, see: Allen (2002).

Experimental top

To a suspension of Mg turnings (0.5 g, 20.2 mmol) in 25 ml Et₂O, 2.3 ml C₆F₅Br is added dropwise. The reaction starts when 0.3 ml of C₆F₅Br have been added. The rest of C₆F₅Br is added dropwise at such a rate that the reaction mixture remains at its boiling point and refluxing is continued for 1 h until the magnesium turnings have dissolved completely. During the storing of this solution for 3 weeks, colorless crystals of the title compound were grown at room temperature.

Computing details top

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

Figures top

Fig. 1. Perspective view of the title compound with displacement ellipsoids at the 50% probability level. H atoms are omitted for clarity. Symmetry operators for generating equivalent atoms: (A): 1 - x, -y z; (B): 1/2 + y, 1/2 - x, 1/2 - z; (C): 1/2 - y, -1/2 + x, 1/2 - z.

hexa-µ₂-bromido-µ₄-oxido-tetrakis[(diethyl ether)magnesium] top

Crystal data top

[Mg₄Br₆O(C₄H₁₀O)₄]	D_x = 1.766 Mg m⁻³
M_r = 889.18	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4	Cell parameters from 3746 reflections
Hall symbol: I -4	θ = 3.8–25.6°
a = 10.4630 (13) Å	µ = 7.30 mm⁻¹
c = 15.276 (2) Å	T = 173 K
V = 1672.3 (4) Å³	Block, colourless
Z = 2	0.25 × 0.22 × 0.18 mm
F(000) = 868

Data collection top

Stoe IPDS II two-circle diffractometer	1479 independent reflections
Radiation source: fine-focus sealed tube	1455 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.044
ω scans	θ_max = 25.3°, θ_min = 3.8°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −12→12
T_min = 0.169, T_max = 0.269	k = −8→12
3746 measured reflections	l = −13→18

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.026	w = 1/[σ²(F_o²) + (0.0427P)² + 0.284P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.067	(Δ/σ)_max < 0.001
S = 1.08	Δρ_max = 0.62 e Å⁻³
1479 reflections	Δρ_min = −0.56 e Å⁻³
73 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0036 (4)
0 constraints	Absolute structure: Flack (1983), with 689 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.02 (2)
Secondary atom site location: difference Fourier map

Crystal data top

[Mg₄Br₆O(C₄H₁₀O)₄]	Z = 2
M_r = 889.18	Mo Kα radiation
Tetragonal, I4	µ = 7.30 mm⁻¹
a = 10.4630 (13) Å	T = 173 K
c = 15.276 (2) Å	0.25 × 0.22 × 0.18 mm
V = 1672.3 (4) Å³

Data collection top

Stoe IPDS II two-circle diffractometer	1479 independent reflections
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	1455 reflections with I > 2σ(I)
T_min = 0.169, T_max = 0.269	R_int = 0.044
3746 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.026	H-atom parameters constrained
wR(F²) = 0.067	Δρ_max = 0.62 e Å⁻³
S = 1.08	Δρ_min = −0.56 e Å⁻³
1479 reflections	Absolute structure: Flack (1983), with 689 Friedel pairs
73 parameters	Absolute structure parameter: −0.02 (2)
0 restraints

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

	x	y	z	U_iso*/U_eq
Mg1	0.40713 (19)	0.12350 (19)	0.32357 (13)	0.0135 (5)
Br1	0.5000	0.0000	0.45892 (4)	0.01815 (19)
Br2	0.19607 (5)	0.04477 (5)	0.24533 (6)	0.02114 (18)
O1	0.5000	0.0000	0.2500	0.0120 (13)
C1	0.2012 (10)	0.4180 (8)	0.3236 (7)	0.044 (2)
H1A	0.1953	0.5113	0.3196	0.065*
H1B	0.1161	0.3823	0.3348	0.065*
H1C	0.2345	0.3836	0.2685	0.065*
C2	0.2906 (8)	0.3818 (7)	0.3982 (6)	0.0286 (17)
H2A	0.3759	0.4195	0.3875	0.034*
H2B	0.2573	0.4174	0.4538	0.034*
O2	0.3026 (5)	0.2433 (5)	0.4064 (3)	0.0210 (10)
C3	0.2032 (8)	0.1864 (7)	0.4613 (5)	0.0289 (16)
H3A	0.1932	0.0953	0.4453	0.035*
H3B	0.1210	0.2299	0.4495	0.035*
C4	0.2326 (9)	0.1958 (10)	0.5579 (5)	0.040 (2)
H4A	0.1629	0.1570	0.5915	0.061*
H4B	0.2413	0.2859	0.5744	0.061*
H4C	0.3126	0.1507	0.5704	0.061*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Mg1	0.0173 (10)	0.0158 (10)	0.0075 (9)	0.0031 (8)	0.0010 (8)	−0.0015 (8)
Br1	0.0265 (7)	0.0226 (6)	0.0054 (3)	0.0057 (6)	0.000	0.000
Br2	0.0149 (3)	0.0285 (3)	0.0200 (3)	0.0026 (2)	−0.0018 (4)	−0.0064 (4)
O1	0.0150 (18)	0.0150 (18)	0.006 (3)	0.000	0.000	0.000
C1	0.056 (5)	0.035 (4)	0.040 (5)	0.020 (4)	−0.001 (5)	0.002 (4)
C2	0.038 (4)	0.015 (3)	0.032 (4)	0.010 (3)	0.004 (3)	−0.008 (3)
O2	0.024 (2)	0.023 (2)	0.015 (2)	0.005 (2)	0.008 (2)	−0.0037 (19)
C3	0.029 (4)	0.027 (4)	0.031 (4)	0.009 (3)	0.013 (3)	0.001 (4)
C4	0.051 (6)	0.056 (6)	0.014 (4)	0.027 (5)	0.009 (3)	−0.004 (4)

Geometric parameters (Å, º) top

Mg1—O1	1.969 (2)	C1—H1A	0.9800
Mg1—O2	2.090 (5)	C1—H1B	0.9800
Mg1—Br2ⁱ	2.597 (2)	C1—H1C	0.9800
Mg1—Br1	2.625 (2)	C2—O2	1.460 (8)
Mg1—Br2	2.643 (2)	C2—H2A	0.9900
Mg1—Mg1ⁱ	3.206 (3)	C2—H2B	0.9900
Mg1—Mg1ⁱⁱ	3.206 (3)	O2—C3	1.463 (9)
Mg1—Mg1ⁱⁱⁱ	3.233 (4)	C3—C4	1.510 (11)
Br1—Mg1ⁱⁱⁱ	2.625 (2)	C3—H3A	0.9900
Br2—Mg1ⁱⁱ	2.597 (2)	C3—H3B	0.9900
O1—Mg1ⁱⁱⁱ	1.9689 (19)	C4—H4A	0.9800
O1—Mg1ⁱ	1.969 (2)	C4—H4B	0.9800
O1—Mg1ⁱⁱ	1.969 (2)	C4—H4C	0.9800
C1—C2	1.523 (12)

O1—Mg1—O2	175.84 (18)	Mg1—O1—Mg1ⁱ	109.01 (6)
O1—Mg1—Br2ⁱ	88.40 (7)	Mg1ⁱⁱⁱ—O1—Mg1ⁱⁱ	109.01 (6)
O2—Mg1—Br2ⁱ	95.71 (15)	Mg1—O1—Mg1ⁱⁱ	109.01 (6)
O1—Mg1—Br1	86.78 (7)	Mg1ⁱ—O1—Mg1ⁱⁱ	110.39 (12)
O2—Mg1—Br1	90.70 (16)	C2—C1—H1A	109.5
Br2ⁱ—Mg1—Br1	118.15 (8)	C2—C1—H1B	109.5
O1—Mg1—Br2	87.12 (7)	H1A—C1—H1B	109.5
O2—Mg1—Br2	91.33 (16)	C2—C1—H1C	109.5
Br2ⁱ—Mg1—Br2	120.44 (8)	H1A—C1—H1C	109.5
Br1—Mg1—Br2	120.81 (8)	H1B—C1—H1C	109.5
O1—Mg1—Mg1ⁱ	35.49 (3)	O2—C2—C1	111.3 (6)
O2—Mg1—Mg1ⁱ	148.63 (17)	O2—C2—H2A	109.4
Br2ⁱ—Mg1—Mg1ⁱ	52.92 (7)	C1—C2—H2A	109.4
Br1—Mg1—Mg1ⁱ	103.98 (7)	O2—C2—H2B	109.4
Br2—Mg1—Mg1ⁱ	103.99 (9)	C1—C2—H2B	109.4
O1—Mg1—Mg1ⁱⁱ	35.49 (3)	H2A—C2—H2B	108.0
O2—Mg1—Mg1ⁱⁱ	142.70 (17)	C2—O2—C3	113.0 (6)
Br2ⁱ—Mg1—Mg1ⁱⁱ	106.54 (9)	C2—O2—Mg1	126.1 (5)
Br1—Mg1—Mg1ⁱⁱ	103.98 (7)	C3—O2—Mg1	118.4 (4)
Br2—Mg1—Mg1ⁱⁱ	51.63 (7)	O2—C3—C4	112.9 (7)
Mg1ⁱ—Mg1—Mg1ⁱⁱ	60.57 (7)	O2—C3—H3A	109.0
O1—Mg1—Mg1ⁱⁱⁱ	34.80 (6)	C4—C3—H3A	109.0
O2—Mg1—Mg1ⁱⁱⁱ	142.56 (16)	O2—C3—H3B	109.0
Br2ⁱ—Mg1—Mg1ⁱⁱⁱ	104.34 (9)	C4—C3—H3B	109.0
Br1—Mg1—Mg1ⁱⁱⁱ	51.98 (4)	H3A—C3—H3B	107.8
Br2—Mg1—Mg1ⁱⁱⁱ	104.66 (9)	C3—C4—H4A	109.5
Mg1ⁱ—Mg1—Mg1ⁱⁱⁱ	59.72 (4)	C3—C4—H4B	109.5
Mg1ⁱⁱ—Mg1—Mg1ⁱⁱⁱ	59.72 (4)	H4A—C4—H4B	109.5
Mg1ⁱⁱⁱ—Br1—Mg1	76.05 (9)	C3—C4—H4C	109.5
Mg1ⁱⁱ—Br2—Mg1	75.45 (9)	H4A—C4—H4C	109.5
Mg1ⁱⁱⁱ—O1—Mg1	110.39 (12)	H4B—C4—H4C	109.5
Mg1ⁱⁱⁱ—O1—Mg1ⁱ	109.01 (6)

O1—Mg1—Br1—Mg1ⁱⁱⁱ	0.0	Br2ⁱ—Mg1—O1—Mg1ⁱⁱ	−121.97 (10)
O2—Mg1—Br1—Mg1ⁱⁱⁱ	176.68 (18)	Br1—Mg1—O1—Mg1ⁱⁱ	119.72 (9)
Br2ⁱ—Mg1—Br1—Mg1ⁱⁱⁱ	−86.46 (9)	Br2—Mg1—O1—Mg1ⁱⁱ	−1.38 (7)
Br2—Mg1—Br1—Mg1ⁱⁱⁱ	84.71 (9)	Mg1ⁱ—Mg1—O1—Mg1ⁱⁱ	−120.57 (8)
Mg1ⁱ—Mg1—Br1—Mg1ⁱⁱⁱ	−31.31 (7)	Mg1ⁱⁱⁱ—Mg1—O1—Mg1ⁱⁱ	119.72 (9)
Mg1ⁱⁱ—Mg1—Br1—Mg1ⁱⁱⁱ	31.31 (7)	C1—C2—O2—C3	−86.8 (8)
O1—Mg1—Br2—Mg1ⁱⁱ	1.02 (5)	C1—C2—O2—Mg1	74.9 (8)
O2—Mg1—Br2—Mg1ⁱⁱ	−175.11 (18)	Br2ⁱ—Mg1—O2—C2	17.5 (6)
Br2ⁱ—Mg1—Br2—Mg1ⁱⁱ	87.47 (9)	Br1—Mg1—O2—C2	135.9 (6)
Br1—Mg1—Br2—Mg1ⁱⁱ	−83.50 (9)	Br2—Mg1—O2—C2	−103.3 (6)
Mg1ⁱ—Mg1—Br2—Mg1ⁱⁱ	32.52 (7)	Mg1ⁱ—Mg1—O2—C2	16.9 (8)
Mg1ⁱⁱⁱ—Mg1—Br2—Mg1ⁱⁱ	−29.32 (7)	Mg1ⁱⁱ—Mg1—O2—C2	−109.6 (6)
Br2ⁱ—Mg1—O1—Mg1ⁱⁱⁱ	118.31 (8)	Mg1ⁱⁱⁱ—Mg1—O2—C2	140.2 (5)
Br1—Mg1—O1—Mg1ⁱⁱⁱ	0.0	Br2ⁱ—Mg1—O2—C3	178.3 (5)
Br2—Mg1—O1—Mg1ⁱⁱⁱ	−121.10 (8)	Br1—Mg1—O2—C3	−63.3 (5)
Mg1ⁱ—Mg1—O1—Mg1ⁱⁱⁱ	119.72 (9)	Br2—Mg1—O2—C3	57.5 (5)
Mg1ⁱⁱ—Mg1—O1—Mg1ⁱⁱⁱ	−119.72 (9)	Mg1ⁱ—Mg1—O2—C3	177.7 (4)
Br2ⁱ—Mg1—O1—Mg1ⁱ	−1.40 (7)	Mg1ⁱⁱ—Mg1—O2—C3	51.2 (6)
Br1—Mg1—O1—Mg1ⁱ	−119.72 (4)	Mg1ⁱⁱⁱ—Mg1—O2—C3	−59.0 (6)
Br2—Mg1—O1—Mg1ⁱ	119.19 (10)	C2—O2—C3—C4	−82.1 (8)
Mg1ⁱⁱ—Mg1—O1—Mg1ⁱ	120.57 (8)	Mg1—O2—C3—C4	114.7 (6)
Mg1ⁱⁱⁱ—Mg1—O1—Mg1ⁱ	−119.72 (9)

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

Experimental details

Crystal data
Chemical formula	[Mg₄Br₆O(C₄H₁₀O)₄]
M_r	889.18
Crystal system, space group	Tetragonal, I4
Temperature (K)	173
a, c (Å)	10.4630 (13), 15.276 (2)
V (Å³)	1672.3 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	7.30
Crystal size (mm)	0.25 × 0.22 × 0.18

Data collection
Diffractometer	Stoe IPDS II two-circle diffractometer
Absorption correction	Multi-scan (MULABS; Spek, 2009; Blessing, 1995)
T_min, T_max	0.169, 0.269
No. of measured, independent and observed [I > 2σ(I)] reflections	3746, 1479, 1455
R_int	0.044
(sin θ/λ)_max (Å⁻¹)	0.601

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.026, 0.067, 1.08
No. of reflections	1479
No. of parameters	73
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.62, −0.56
Absolute structure	Flack (1983), with 689 Friedel pairs
Absolute structure parameter	−0.02 (2)

Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP (Sheldrick, 2008).

References

Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Blessing, R. H. (1995). Acta Cryst. A51, 33–38. CrossRef CAS Web of Science IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Lerner, H.-W. (2005). Coord. Chem. Rev. 249, 781–798. Web of Science CrossRef CAS Google Scholar
Lerner, H.-W., Scholz, S., Bolte, M., Wiberg, N., Nöth, H. & Krossing, I. (2003). Eur. J. Inorg. Chem. pp. 666–670. CSD CrossRef Google Scholar
Metzler, N., Nöth, H., Schmidt, M. & Treitl, A. (1994). Z. Naturforsch. Teil B, 49, 1448–1451. CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stoe & Cie (2001). X-AREA. Stoe & Cie, Darmstadt, Germany. Google Scholar
Stucky, G. & Rundle, R. E. (1964). J. Am. Chem. Soc. 86, 4821–4825. CSD CrossRef CAS Web of Science Google Scholar