metal-organic compounds
Di-μ-bromido-bis[benzyl(diethyl ether)magnesium]
aUniversity of Illinois at Urbana-Champaign, School of Chemical Sciences, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
*Correspondence e-mail: girolami@scs.illinois.edu
The title benzyl Grignard reagent, [Mg2Br2(C7H7)2(C4H10O)2], was obtained by reaction of benzyl bromide with magnesium in diethyl ether, followed by crystallization from toluene. The comprises one half-molecule, the structural dimeric unit being generated by inversion symmetry with an Mg⋯Mg distance of 3.469 (2) Å. The Mg(II) atom exhibits a distorted tetrahedral coordination geometry. The crystal packing is defined by van der Waals interactions only.
Related literature
For the structures of some other diethyl ether adducts of ); Guggenberger & Rundle (1968); Engelhardt et al. (1988); Antolini et al. (2003); Avent et al. (2004). For the structures of some tetrahydrofuran and diisopropyl ether adducts of see: Maurice (1969); Spek et al. (1974); Krieck et al. (2009).
see: Stucky & Rundle (1964Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2010); cell SAINT (Bruker, 2005); data reduction: SAINT and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: XCIF (Bruker, 2005).
Supporting information
https://doi.org/10.1107/S1600536812025445/kp2423sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812025445/kp2423Isup2.hkl
A 250 mL round bottom flask was charged with Mg turnings (2.6 g, 107 mmol) and diethyl ether (90 mL). To the stirred suspension was added benzyl bromide (10 mL, 84 mmol) dropwise by means of an addition funnel over 30 min. After the slight exotherm had subsided, the solution was brought to reflux for two h. The solution was filtered and the filtrate was stored at 253 K. Titration with 0.13 M HCl showed the solution to have a concentration of 0.93 M.
An
of the benzyl magnesium bromide solution (11.5 mL, 10.7 mmol) was taken to dryness under reduced pressure at 263 K and the residue was extracted with 1:1 benzene/toluene (50 mL). The clear yellow extract was concentrated to ca 20 mL and stored at 253 K overnight affording large colourless crystals.A structural dimeric model of (I) is [Mg(µ-Br)(CH2Ph)(OEt2)]2 whereas an
comprises a half of the molecule. All non-H atoms were located from the difference map and refined anisotropically. H atom treatment: methyl H atom positions, R–CH3, were optimised by rotation about R–C bonds with idealised C–H, R–H and H–H distances; the remaining H atoms were included as riding idealised contributors. Methyl H atom U's were assigned as 1.5 times Ueq of the remaining H atom U's were assigned as 1.2 times carrier Ueq.Similar dimeric structures have been reported for the bromo
[Mg(µ-Br){CH(SiMe2Ph)(SiMe3)}(OEt2)]2 (Antolini, et al., 2003), [Mg(µ-Br){CH(SiMe3)2}(OEt2)]2 (Avent, et al., 2004), and [Mg(µ-Br)Et(O-i-Pr2)]2 (Spek, et al., 1974). In all three of these molecules, the magnesium centres each bear one ether ligand, and two Mg–Br–Mg bridges join the metal centres. Most bromo with two ether molecule per Mg centre are monomeric; examples include MgBrPh(OEt2)2 (Stucky & Rundle, 1964), MgBrEt(OEt2)2 (Guggenberger & Rundle, 1968), MgBr(CPh3)(OEt2)2 (Engelhardt et al., 1988) and MgBr(2,4,6-C6H2Ph3)(thf)2 (Krieck et al., 2009). Finally, there are some monomeric bromo in which the magnesium centre bears three ether ligands and very small organic groups, such as in MgBrMe(thf)3 (Maurice, 1969).For the structures of some other diethyl ether adducts of
see: Stucky & Rundle (1964); Guggenberger & Rundle (1968); Engelhardt et al. (1988); Antolini et al. (2003); Avent et al. (2004). For the structures of some tetrahydrofuran and diisopropyl ether adducts of see: Maurice (1969); Spek et al. (1974); Krieck et al. (2009).Data collection: APEX2 (Bruker, 2010); cell
SAINT (Bruker, 2005); data reduction: SAINT and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: XCIF (Bruker, 2005).[Mg2Br2(C7H7)2(C4H10O)2] | F(000) = 552 |
Mr = 538.93 | Dx = 1.363 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5006 reflections |
a = 8.0657 (4) Å | θ = 2.3–23.5° |
b = 12.4288 (6) Å | µ = 3.15 mm−1 |
c = 13.1840 (6) Å | T = 193 K |
β = 96.370 (3)° | Prism, colourless |
V = 1313.50 (11) Å3 | 0.38 × 0.27 × 0.23 mm |
Z = 2 |
Bruker Platform APEXII CCD diffractometer | 2396 independent reflections |
Radiation source: normal-focus sealed tube | 1808 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.078 |
profile data from φ and ω scans | θmax = 25.3°, θmin = 2.3° |
Absorption correction: integration (SADABS; Bruker, 2007) | h = −9→9 |
Tmin = 0.440, Tmax = 0.635 | k = −14→14 |
22801 measured reflections | l = −15→15 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.073 | H-atom parameters not refined |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0305P)2 + 0.0177P] where P = (Fo2 + 2Fc2)/3 |
2396 reflections | (Δ/σ)max = 0.001 |
129 parameters | Δρmax = 0.42 e Å−3 |
0 restraints | Δρmin = −0.36 e Å−3 |
[Mg2Br2(C7H7)2(C4H10O)2] | V = 1313.50 (11) Å3 |
Mr = 538.93 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.0657 (4) Å | µ = 3.15 mm−1 |
b = 12.4288 (6) Å | T = 193 K |
c = 13.1840 (6) Å | 0.38 × 0.27 × 0.23 mm |
β = 96.370 (3)° |
Bruker Platform APEXII CCD diffractometer | 2396 independent reflections |
Absorption correction: integration (SADABS; Bruker, 2007) | 1808 reflections with I > 2σ(I) |
Tmin = 0.440, Tmax = 0.635 | Rint = 0.078 |
22801 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.073 | H-atom parameters not refined |
S = 1.04 | Δρmax = 0.42 e Å−3 |
2396 reflections | Δρmin = −0.36 e Å−3 |
129 parameters |
Experimental. One distinct cell was identified using APEX2 (Bruker, 2010). Ten frame series were integrated and filtered for statistical outliers using SAINT (Bruker, 2005) then corrected for absorption by integration using SHELXTL/XPREP V2005/2 (Bruker, 2005) before using SADABS (Bruker, 2005) to sort, merge, and scale the combined data. No decay correction was applied. |
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. The structure was phased by direct methods (Sheldrick, 2008). The systematic conditions suggested the unambiguous space group. The space group choice was confirmed by successful convergence of the full-matrix least-squares refinement on F2. The highest peaks in the final difference Fourier map were in the vicinity of atom Br1; the final map had no other significant features. A final analysis of variance between observed and calculated structure factors showed little dependence on amplitude or resolution. |
x | y | z | Uiso*/Ueq | ||
Mg1 | 1.18152 (11) | 0.47556 (7) | 0.08013 (7) | 0.0396 (2) | |
Br1 | 0.89572 (3) | 0.55206 (2) | 0.11052 (2) | 0.05037 (13) | |
O1 | 1.1776 (2) | 0.32859 (13) | 0.14171 (14) | 0.0459 (5) | |
C1 | 1.3770 (3) | 0.6793 (2) | 0.0998 (2) | 0.0396 (7) | |
C2 | 1.4242 (4) | 0.7119 (2) | 0.0058 (2) | 0.0521 (8) | |
H2 | 1.4702 | 0.6604 | −0.0364 | 0.063* | |
C3 | 1.4058 (4) | 0.8173 (3) | −0.0276 (3) | 0.0655 (10) | |
H3 | 1.4394 | 0.8370 | −0.0919 | 0.079* | |
C4 | 1.3403 (4) | 0.8927 (3) | 0.0310 (3) | 0.0712 (10) | |
H4 | 1.3288 | 0.9651 | 0.0080 | 0.085* | |
C5 | 1.2908 (4) | 0.8638 (2) | 0.1233 (3) | 0.0624 (9) | |
H5 | 1.2448 | 0.9164 | 0.1644 | 0.075* | |
C6 | 1.3072 (3) | 0.7593 (2) | 0.1567 (2) | 0.0488 (7) | |
H6 | 1.2702 | 0.7407 | 0.2203 | 0.059* | |
C7 | 1.3934 (3) | 0.56671 (19) | 0.1365 (2) | 0.0468 (7) | |
H7A | 1.4057 | 0.5658 | 0.2120 | 0.056* | |
H7B | 1.4947 | 0.5340 | 0.1134 | 0.056* | |
C8 | 1.0390 (4) | 0.2534 (2) | 0.1235 (2) | 0.0545 (8) | |
H8A | 0.9597 | 0.2804 | 0.0665 | 0.065* | |
H8B | 0.9794 | 0.2499 | 0.1852 | 0.065* | |
C9 | 1.0940 (4) | 0.1444 (2) | 0.0986 (2) | 0.0708 (10) | |
H9A | 0.9964 | 0.0977 | 0.0838 | 0.106* | |
H9B | 1.1665 | 0.1153 | 0.1567 | 0.106* | |
H9C | 1.1557 | 0.1477 | 0.0387 | 0.106* | |
C10 | 1.2862 (4) | 0.3105 (2) | 0.2361 (2) | 0.0547 (8) | |
H10A | 1.3958 | 0.3446 | 0.2307 | 0.066* | |
H10B | 1.3047 | 0.2322 | 0.2457 | 0.066* | |
C11 | 1.2145 (4) | 0.3549 (3) | 0.3267 (2) | 0.0777 (10) | |
H11A | 1.2928 | 0.3431 | 0.3880 | 0.117* | |
H11B | 1.1088 | 0.3187 | 0.3345 | 0.117* | |
H11C | 1.1948 | 0.4323 | 0.3173 | 0.117* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Mg1 | 0.0341 (5) | 0.0340 (5) | 0.0493 (6) | 0.0000 (4) | −0.0015 (4) | 0.0023 (4) |
Br1 | 0.0424 (2) | 0.0587 (2) | 0.0502 (2) | 0.00999 (14) | 0.00602 (14) | −0.00680 (14) |
O1 | 0.0356 (11) | 0.0375 (10) | 0.0617 (12) | −0.0040 (8) | −0.0073 (9) | 0.0111 (9) |
C1 | 0.0255 (16) | 0.0405 (16) | 0.0514 (18) | −0.0041 (12) | −0.0023 (13) | −0.0063 (13) |
C2 | 0.0464 (19) | 0.0541 (19) | 0.056 (2) | −0.0063 (15) | 0.0071 (16) | −0.0068 (15) |
C3 | 0.059 (2) | 0.069 (2) | 0.069 (2) | −0.0160 (18) | 0.0071 (19) | 0.0179 (18) |
C4 | 0.059 (2) | 0.042 (2) | 0.109 (3) | −0.0042 (17) | −0.005 (2) | 0.015 (2) |
C5 | 0.050 (2) | 0.0429 (19) | 0.093 (3) | 0.0043 (16) | 0.0063 (19) | −0.0131 (18) |
C6 | 0.0376 (18) | 0.0501 (18) | 0.0593 (19) | −0.0034 (14) | 0.0081 (15) | −0.0048 (14) |
C7 | 0.0356 (17) | 0.0392 (16) | 0.064 (2) | −0.0012 (13) | −0.0001 (14) | 0.0002 (13) |
C8 | 0.0441 (18) | 0.0441 (17) | 0.074 (2) | −0.0092 (15) | 0.0004 (16) | 0.0044 (15) |
C9 | 0.093 (3) | 0.0498 (19) | 0.068 (2) | −0.0076 (19) | 0.001 (2) | −0.0049 (16) |
C10 | 0.0472 (19) | 0.0471 (18) | 0.065 (2) | 0.0049 (14) | −0.0134 (17) | 0.0164 (15) |
C11 | 0.087 (3) | 0.085 (3) | 0.060 (2) | 0.004 (2) | 0.002 (2) | 0.0078 (19) |
Mg1—O1 | 2.0006 (18) | C5—C6 | 1.373 (4) |
Mg1—C7 | 2.115 (3) | C5—H5 | 0.9500 |
Mg1—Br1i | 2.5448 (9) | C6—H6 | 0.9500 |
Mg1—Br1 | 2.5659 (9) | C7—H7A | 0.9900 |
Mg1—Mg1i | 3.4690 (17) | C7—H7B | 0.9900 |
Br1—Mg1i | 2.5448 (9) | C8—C9 | 1.474 (4) |
O1—C8 | 1.456 (3) | C8—H8A | 0.9900 |
O1—C10 | 1.458 (3) | C8—H8B | 0.9900 |
C1—C2 | 1.396 (4) | C9—H9A | 0.9800 |
C1—C6 | 1.401 (3) | C9—H9B | 0.9800 |
C1—C7 | 1.482 (3) | C9—H9C | 0.9800 |
C2—C3 | 1.385 (4) | C10—C11 | 1.490 (4) |
C2—H2 | 0.9500 | C10—H10A | 0.9900 |
C3—C4 | 1.358 (4) | C10—H10B | 0.9900 |
C3—H3 | 0.9500 | C11—H11A | 0.9800 |
C4—C5 | 1.371 (4) | C11—H11B | 0.9800 |
C4—H4 | 0.9500 | C11—H11C | 0.9800 |
O1—Mg1—C7 | 113.26 (9) | C1—C6—H6 | 119.0 |
O1—Mg1—Br1i | 105.34 (6) | C1—C7—Mg1 | 110.56 (17) |
C7—Mg1—Br1i | 121.26 (9) | C1—C7—H7A | 109.5 |
O1—Mg1—Br1 | 102.71 (6) | Mg1—C7—H7A | 109.5 |
C7—Mg1—Br1 | 116.84 (8) | C1—C7—H7B | 109.5 |
Br1i—Mg1—Br1 | 94.50 (3) | Mg1—C7—H7B | 109.5 |
O1—Mg1—Mg1i | 110.90 (6) | H7A—C7—H7B | 108.1 |
C7—Mg1—Mg1i | 135.62 (8) | O1—C8—C9 | 112.5 (3) |
Br1i—Mg1—Mg1i | 47.51 (2) | O1—C8—H8A | 109.1 |
Br1—Mg1—Mg1i | 47.00 (2) | C9—C8—H8A | 109.1 |
Mg1i—Br1—Mg1 | 85.50 (3) | O1—C8—H8B | 109.1 |
C8—O1—C10 | 114.8 (2) | C9—C8—H8B | 109.1 |
C8—O1—Mg1 | 124.43 (16) | H8A—C8—H8B | 107.8 |
C10—O1—Mg1 | 116.89 (15) | C8—C9—H9A | 109.5 |
C2—C1—C6 | 115.8 (3) | C8—C9—H9B | 109.5 |
C2—C1—C7 | 122.7 (3) | H9A—C9—H9B | 109.5 |
C6—C1—C7 | 121.5 (3) | C8—C9—H9C | 109.5 |
C3—C2—C1 | 121.7 (3) | H9A—C9—H9C | 109.5 |
C3—C2—H2 | 119.1 | H9B—C9—H9C | 109.5 |
C1—C2—H2 | 119.1 | O1—C10—C11 | 112.2 (2) |
C4—C3—C2 | 120.5 (3) | O1—C10—H10A | 109.2 |
C4—C3—H3 | 119.7 | C11—C10—H10A | 109.2 |
C2—C3—H3 | 119.7 | O1—C10—H10B | 109.2 |
C3—C4—C5 | 119.6 (3) | C11—C10—H10B | 109.2 |
C3—C4—H4 | 120.2 | H10A—C10—H10B | 107.9 |
C5—C4—H4 | 120.2 | C10—C11—H11A | 109.5 |
C4—C5—C6 | 120.3 (3) | C10—C11—H11B | 109.5 |
C4—C5—H5 | 119.8 | H11A—C11—H11B | 109.5 |
C6—C5—H5 | 119.8 | C10—C11—H11C | 109.5 |
C5—C6—C1 | 122.0 (3) | H11A—C11—H11C | 109.5 |
C5—C6—H6 | 119.0 | H11B—C11—H11C | 109.5 |
Symmetry code: (i) −x+2, −y+1, −z. |
Experimental details
Crystal data | |
Chemical formula | [Mg2Br2(C7H7)2(C4H10O)2] |
Mr | 538.93 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 193 |
a, b, c (Å) | 8.0657 (4), 12.4288 (6), 13.1840 (6) |
β (°) | 96.370 (3) |
V (Å3) | 1313.50 (11) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.15 |
Crystal size (mm) | 0.38 × 0.27 × 0.23 |
Data collection | |
Diffractometer | Bruker Platform APEXII CCD |
Absorption correction | Integration (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.440, 0.635 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 22801, 2396, 1808 |
Rint | 0.078 |
(sin θ/λ)max (Å−1) | 0.602 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.073, 1.04 |
No. of reflections | 2396 |
No. of parameters | 129 |
H-atom treatment | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.42, −0.36 |
Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2005), SAINT and XPREP (Bruker, 2005), SHELXTL (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), XCIF (Bruker, 2005).
Mg1—O1 | 2.0006 (18) | Mg1—Br1i | 2.5448 (9) |
Mg1—C7 | 2.115 (3) | Mg1—Br1 | 2.5659 (9) |
Symmetry code: (i) −x+2, −y+1, −z. |
Acknowledgements
This work was supported financially by the National Science Foundation (CHE-1112360). X-ray data were collected in the Materials Chemistry Laboratory at the University of Illinois (supported in part by grants NSF CHE 95–03145 and NSF CHE 03–43032 from the National Science Foundation).
References
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Similar dimeric structures have been reported for the bromo Grignard reagents [Mg(µ-Br){CH(SiMe2Ph)(SiMe3)}(OEt2)]2 (Antolini, et al., 2003), [Mg(µ-Br){CH(SiMe3)2}(OEt2)]2 (Avent, et al., 2004), and [Mg(µ-Br)Et(O-i-Pr2)]2 (Spek, et al., 1974). In all three of these molecules, the magnesium centres each bear one ether ligand, and two Mg–Br–Mg bridges join the metal centres. Most bromo Grignard reagents with two ether molecule per Mg centre are monomeric; examples include MgBrPh(OEt2)2 (Stucky & Rundle, 1964), MgBrEt(OEt2)2 (Guggenberger & Rundle, 1968), MgBr(CPh3)(OEt2)2 (Engelhardt et al., 1988) and MgBr(2,4,6-C6H2Ph3)(thf)2 (Krieck et al., 2009). Finally, there are some monomeric bromo Grignard reagents in which the magnesium centre bears three ether ligands and very small organic groups, such as in MgBrMe(thf)3 (Maurice, 1969).