supplementary materials


ng5334 scheme

Acta Cryst. (2013). E69, m424    [ doi:10.1107/S1600536813017108 ]

Di-[mu]-bromido-bis[(diethyl ether-[kappa]O)(2,4,6-trimethylphenyl)magnesium]: the mesityl Grignard reagent

Ö. Seven, M. Bolte and H.-W. Lerner

Abstract top

The crystal structure of the title compound, [Mg2Br2(C9H11)2(C4H10O)2], features a centrosymmetric two-centre magnesium complex with half a molecule in the asymmetric unit. The Mg atom is in a considerably distorted Br2CO coordination. Bond lengths and angles are comparable with already published values. The crystal packing is stabilized by C-H...[pi] interactions linking the complexes into sheets parallel to (0-11).

Comment top

Besides organo lithium compounds Grignard reagents RMgX are among the most widely used metal organic reagents in synthesis (Figure 1). It is therefore not surprising that much effort has been devoted to structural elucidation both in the solid state and in solution, since knowing the structure of highly reactive reagents is of essential importance, when it comes to understanding the principles governing the high reactivity. When the structural characteristics of Grignard reagents are understood, tuning of their reactivity becomes possible. It was reported (Sakamoto et al., 2001; Blasberg et al., 2012) that there is an equilibrium between the Grignard compounds RMgX on the one hand and diorganylmagnesium B and the MgX2 adducts C on the other hand (Figure 2). This finding can be regarded as an extension of the Schlenk equilibrium. However, in same cases magnesate complexes of type D and E were isolated from Grignard solution.

The mesityl Grignard reagent MgBrMes established itself as a practical and easily accessible nucleophile. As a unique building block, MgBrMes has been used in various reactions in the last a few decades. The commercial use is justified on the one hand by the C2 symmetry and on the other hand by the increased steric bulk at the 2,6-positions of the mesityl unit. Compared to phenyl Grignard reagent, the three methyl groups of MgBrMes increase the solubility of the product yielding from a reaction with an electrophile. Furthermore, the three methyl groups of the mesityl ring facilitate analytical investigations of obtained products: for instance, in a 1H NMR spectrum, the integral ratio between the methyl groups of the mesityl unit and the proton of the electrophile gives a well defined product.

Therefore the structural elucidation of MgBrMes is of great interest. We obtained X-ray quality crystals of [MgBrMes(OEt2)]2 by gas diffusion of toluene in the filtered diethyl ether reaction solution of MgBrMes and ortho-C6H4(BH2(pyridine))2. As shown in Figure 3, the Grignard compound MgBrMes was thereby synthesized by a textbook procedure.

In contrast to the structure of mesityl lithium (LiMes) which crystallizes as an infinite zigzag-chain of [LiMes]2 dimers along the crystallographic c axis (Hübner et al., 2010) the crystal structure of [MgBrMes(OEt2)]2 reveals discrete dimers of the type A2 in the solid state and no magnesates of type C, D, and E were crystallized.

The structural parameters of the mesityl anion in [MgBrMes(OEt2)]2 are comparable with those found in the corresponding homoleptic compounds [LiMes]2 (Hübner et al., 2010) and [MMes2] (M = Mg, Zn, Cd, Hg; Waggoner & Power, 1992; Cole et al., 2003; Hayashi et al., 2011).

The title compound features a centrosymmetric two-centre magnesium complex (Figure 4). There is just half a molecule in the asymmetric unit. Each Mg centre is four-coordinated by two bridging bromo atoms, one oxygen atom of a diethyl ether molecule and a carbon atom of a mesityl ligand. The coordination sphere of the Mg centres is a distorted tetrahedron (Table 1). The two Mg—Br bonds show essentially the same length. The bond angles at Mg range from 91.72 (2)° for Br—Mg—Br to 126.30 (6)° for C—Mg—Br. Whereas the innercyclic Br—Mg—Br angle is significantly smaller than the ideal tetrahedral value, the two C—Mg—Br angles are substantially widened. The bond angle at Br is 88.28 (2)°. The dihedral angle between the four-membered Mg2Br2 ring and the aromatic ring is 40.39 (4)°. It is remarkable to note that none of the ether methyl groups adopts an antiperiplanar conformation with respect to the Mg centre (Table 1). The torsion angle C4—C3—O1—Mg1 adopts a gauche conformation and the torsion angle C2—C3—O1—Mg1 adopts a partially eclipsed conformation.

A search in the Cambridge Crystallographic Database yielded only two structures with a four-coordinated Mg centre bonded to two bromo atoms, an oxygen atom and an aromatic carbon atom, which are bis((µ2-bromo)-(dibutyl ether)-anthracen-9-yl-magnesium) (CSD refcode TATNAD; Bock et al., 1996) and bis((µ2-bromo)-(2,6-dimesitylphenyl)-(tetrahydrofuran)-magnesium) (CSD refcode RUGNEM; Ellison & Power, 1996). Thus, average bond distances for a four-coordinated Mg atom to a three-coordinated O atom, a four-coordinated Mg atom to an aromatic C atom, and a four-coordinated Mg atom to a two-coordinated Br atom were retrieved from three different searches in the CSD (Table 2). These values agree well with those of the title compound and the two already retrieved structures having a four-coordinated Mg centre bonded to two bromo atoms, an oxygen atom and an aromatic carbon atom.

The crystal packing of the title compound (Figure 5) shows that the molecules are connected by C—H···π interactions. One is between a methylene group at C3 and the centroid (cog) of a mesityl ring of a neighbouring molecule (C3—H3B 0.990 Å, H3B···cogi 2.833 Å, C3—H3B···cogi 158.9°; symmetry operator (i) x - 1, y, z). The other one connects a methyl group at C18 and the centroid of a mesityl ring of a another molecule (C18—H18B 0.980 Å, H18B···cogii 3.047 Å, C3—H3B···cogii 122.1°; symmetry operator (ii) -x + 2, -y, -z). These interactions connect the complexes to sheets parallel to the (0 1 1) plane (Figure 6).

Related literature top

For literature on other Grignard reagents, see: Blasberg et al. (2012); Bock et al. (1996); Cole et al. (2003); Ellison & Power (1996); Hübner et al. (2010); Hayashi et al. (2011); Sakamoto et al. (2001); Waggoner & Power (1992).

Experimental top

MgBrMes: In a two-necked flask equipped with a reflux condenser and a dropping funnel, Mg turnings (1.0 g, 41.1 mmol) were heated with a heat gun under vacuum for 15 min. After the flask had cooled to room temperature again, diethyl ether (50 ml) was added. A solution of 2-bromomesitylene (5.0 ml, 6.5 g, 32.7 mmol) in diethyl ether (10 ml) was added dropwise over 1 h to the vigorously stirred reaction mixture. After the addition was complete, the yellowish brown reaction mixture was heated at reflux temperature for 8 h and allowed to cool to room temperature again. The mixture was filtered, and the concentration of the filtrate was determined by titration (0.38 M). Single crystals of [MgBrMes(OEt2)]2 were obtained by the following procedure: In a two-necked flask equipped with a reflux condenser and a dropping funnel, the pyridine adduct with ditopic borane ortho-C6H4(BH2(pyridine))2 (1.1 g, 4.2 mmol) was suspended in 20 ml diethyl ether. The mesityl Grignard reagent (0.38 M in diethyl ether, 22 ml, 8.4 mmol) was added dropwise over 3 h to the yellowish suspension. After the addition was complete, the reddish suspension was heated 1 h at reflux temperature and finally the formed precipitate was removed by filtration. Gas diffusion of toluene into the filtrate gave colorless crystals of [MgBrMes(OEt2)]2.

Refinement top

All H atoms were located in difference Fourier maps. Nevertheless, they were geometrically positioned and refined using a riding model with aromatic C—H = 0.95 Å, methyl C—H = 0.98 Å, secondary C—H = 0.99 Å, and with Uiso(H) = 1.5Ueq(C) for methyl H or 1.2Ueq(C) for secondary and aromatic H. The methyl groups of the mesityl rings were allowed to rotate but not to tip.

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: SHELXL2012 (Sheldrick, 2012); molecular graphics: XP (Sheldrick, 2008); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. Structures of Magnesium Organyles in Donor Solvents (R = alkyl, aryl; X = halogen; Do = donor).
[Figure 2] Fig. 2. Grignard Compounds (RMgX) in Donor Solvents.
[Figure 3] Fig. 3. Synthesis of [MgBrMes(OEt2)]2.
[Figure 4] Fig. 4. A perspective view of (I) showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Only the symmetry independent atoms have been labelled. Symmetry equivalent atoms were generated applying the symmetry operator -x + 1, -y + 1, -z + 1.
[Figure 5] Fig. 5. Crystal packing of (I) showing the C—H···cog interactions as dashed lines.
[Figure 6] Fig. 6. Crystal packing of (I) with view along the a axis showing the sheets of molecules.
Di-µ-bromido-bis[(diethyl ether-κO)(2,4,6-trimethylphenyl)magnesium] top
Crystal data top
[Mg2Br2(C9H11)2(C4H10O)2]Z = 1
Mr = 595.03F(000) = 308
Triclinic, P1Dx = 1.303 Mg m3
a = 7.8516 (6) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.8285 (6) ÅCell parameters from 29361 reflections
c = 12.1356 (8) Åθ = 3.4–30.1°
α = 87.285 (6)°µ = 2.73 mm1
β = 82.516 (6)°T = 173 K
γ = 65.396 (5)°Plate, colourless
V = 758.30 (10) Å30.23 × 0.19 × 0.13 mm
Data collection top
Stoe IPDS II two-circle
diffractometer
3839 reflections with I > 2σ(I)
Radiation source: Genix 3D IµS microfocus X-ray sourceRint = 0.048
ω scansθmax = 29.7°, θmin = 3.2°
Absorption correction: multi-scan
(X-AREA; Stoe & Cie, 2001)
h = 1010
Tmin = 0.572, Tmax = 0.718k = 1212
18010 measured reflectionsl = 1614
4227 independent reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.096 w = 1/[σ2(Fo2) + (0.0555P)2 + 0.1885P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
4227 reflectionsΔρmax = 0.70 e Å3
148 parametersΔρmin = 0.55 e Å3
Crystal data top
[Mg2Br2(C9H11)2(C4H10O)2]γ = 65.396 (5)°
Mr = 595.03V = 758.30 (10) Å3
Triclinic, P1Z = 1
a = 7.8516 (6) ÅMo Kα radiation
b = 8.8285 (6) ŵ = 2.73 mm1
c = 12.1356 (8) ÅT = 173 K
α = 87.285 (6)°0.23 × 0.19 × 0.13 mm
β = 82.516 (6)°
Data collection top
Stoe IPDS II two-circle
diffractometer
4227 independent reflections
Absorption correction: multi-scan
(X-AREA; Stoe & Cie, 2001)
3839 reflections with I > 2σ(I)
Tmin = 0.572, Tmax = 0.718Rint = 0.048
18010 measured reflectionsθmax = 29.7°
Refinement top
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.096Δρmax = 0.70 e Å3
S = 1.06Δρmin = 0.55 e Å3
4227 reflectionsAbsolute structure: ?
148 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.47162 (3)0.70177 (2)0.43643 (2)0.04331 (8)
Mg10.56669 (9)0.40755 (8)0.36418 (5)0.03510 (14)
O10.3353 (2)0.4088 (2)0.30685 (13)0.0454 (3)
C10.1452 (4)0.4898 (4)0.3613 (2)0.0646 (7)
H1A0.14590.54770.42900.077*
H1B0.09660.40470.38440.077*
C20.0172 (5)0.6124 (4)0.2880 (3)0.0745 (8)
H2A0.11020.66460.32810.112*
H2B0.01390.55530.22150.112*
H2C0.06340.69810.26600.112*
C30.3630 (4)0.2712 (3)0.2340 (2)0.0549 (6)
H3A0.45370.26760.16820.066*
H3B0.24160.29020.20770.066*
C40.4358 (4)0.1090 (4)0.2927 (3)0.0650 (7)
H4A0.45290.01920.24200.097*
H4B0.34520.11180.35720.097*
H4C0.55710.08910.31770.097*
C110.8009 (3)0.2966 (3)0.24069 (16)0.0376 (4)
C120.8019 (3)0.3733 (3)0.13610 (18)0.0435 (4)
C130.9428 (4)0.2965 (4)0.04831 (19)0.0517 (5)
H130.94010.35270.02060.062*
C141.0863 (3)0.1401 (3)0.0595 (2)0.0509 (5)
C151.0878 (3)0.0633 (3)0.1619 (2)0.0479 (5)
H151.18450.04410.17160.057*
C160.9509 (3)0.1396 (3)0.25080 (18)0.0404 (4)
C170.6470 (4)0.5430 (3)0.1164 (2)0.0579 (6)
H17A0.67570.58280.04250.087*
H17B0.63910.62190.17310.087*
H17C0.52600.53390.12070.087*
C181.2346 (4)0.0568 (5)0.0371 (3)0.0665 (8)
H18A1.31520.11710.05340.100*
H18B1.17290.05800.10250.100*
H18C1.31180.05860.01780.100*
C190.9662 (4)0.0501 (3)0.3609 (2)0.0531 (5)
H19A0.85880.02000.37880.080*
H19B0.96560.12330.41930.080*
H19C1.08400.05120.35600.080*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.05753 (14)0.03546 (11)0.03474 (11)0.01729 (8)0.00527 (8)0.00114 (7)
Mg10.0392 (3)0.0381 (3)0.0299 (3)0.0168 (3)0.0070 (2)0.0023 (2)
O10.0436 (7)0.0608 (9)0.0388 (7)0.0271 (7)0.0068 (6)0.0099 (6)
C10.0522 (14)0.096 (2)0.0501 (14)0.0355 (14)0.0017 (11)0.0116 (14)
C20.0584 (16)0.0700 (18)0.096 (3)0.0244 (14)0.0198 (16)0.0042 (17)
C30.0679 (15)0.0638 (14)0.0474 (12)0.0386 (12)0.0135 (11)0.0086 (10)
C40.0670 (16)0.0671 (16)0.0712 (18)0.0358 (14)0.0158 (14)0.0015 (14)
C110.0418 (9)0.0448 (9)0.0318 (9)0.0230 (8)0.0050 (7)0.0035 (7)
C120.0525 (11)0.0531 (11)0.0341 (9)0.0302 (9)0.0079 (8)0.0011 (8)
C130.0634 (14)0.0732 (15)0.0318 (9)0.0425 (12)0.0006 (9)0.0049 (9)
C140.0490 (12)0.0728 (15)0.0440 (12)0.0389 (11)0.0046 (9)0.0200 (10)
C150.0406 (10)0.0548 (12)0.0515 (12)0.0225 (9)0.0015 (9)0.0166 (10)
C160.0396 (9)0.0466 (10)0.0389 (10)0.0208 (8)0.0056 (8)0.0051 (8)
C170.0731 (16)0.0603 (14)0.0420 (12)0.0291 (12)0.0121 (11)0.0120 (10)
C180.0574 (14)0.098 (2)0.0557 (15)0.0463 (15)0.0119 (12)0.0291 (14)
C190.0505 (12)0.0512 (12)0.0490 (13)0.0127 (10)0.0075 (10)0.0047 (10)
Geometric parameters (Å, º) top
Br1—Mg12.5503 (7)C11—C121.411 (3)
Br1—Mg1i2.5900 (7)C12—C131.399 (3)
Mg1—O12.0243 (16)C12—C171.518 (4)
Mg1—C112.123 (2)C13—C141.386 (4)
Mg1—Br1i2.5900 (7)C13—H130.9500
O1—C11.440 (3)C14—C151.385 (4)
O1—C31.462 (3)C14—C181.511 (3)
C1—C21.486 (5)C15—C161.392 (3)
C1—H1A0.9900C15—H150.9500
C1—H1B0.9900C16—C191.513 (3)
C2—H2A0.9800C17—H17A0.9800
C2—H2B0.9800C17—H17B0.9800
C2—H2C0.9800C17—H17C0.9800
C3—C41.488 (4)C18—H18A0.9800
C3—H3A0.9900C18—H18B0.9800
C3—H3B0.9900C18—H18C0.9800
C4—H4A0.9800C19—H19A0.9800
C4—H4B0.9800C19—H19B0.9800
C4—H4C0.9800C19—H19C0.9800
C11—C161.409 (3)
Mg1—Br1—Mg1i88.28 (2)H4B—C4—H4C109.5
O1—Mg1—C11108.18 (7)C16—C11—C12115.81 (19)
O1—Mg1—Br1105.96 (5)C16—C11—Mg1124.39 (15)
C11—Mg1—Br1121.22 (6)C12—C11—Mg1119.46 (16)
O1—Mg1—Br1i100.23 (5)C13—C12—C11121.6 (2)
C11—Mg1—Br1i126.30 (6)C13—C12—C17118.3 (2)
Br1—Mg1—Br1i91.72 (2)C11—C12—C17120.1 (2)
O1—Mg1—Mg1i108.92 (5)C14—C13—C12121.5 (2)
C11—Mg1—Mg1i142.89 (6)C14—C13—H13119.3
Br1—Mg1—Mg1i46.315 (16)C12—C13—H13119.3
Br1i—Mg1—Mg1i45.403 (16)C15—C14—C13117.6 (2)
C1—O1—C3113.41 (19)C15—C14—C18121.5 (3)
C1—O1—Mg1124.89 (15)C13—C14—C18120.8 (3)
C3—O1—Mg1117.26 (15)C14—C15—C16121.6 (2)
O1—C1—C2112.1 (3)C14—C15—H15119.2
O1—C1—H1A109.2C16—C15—H15119.2
C2—C1—H1A109.2C15—C16—C11121.9 (2)
O1—C1—H1B109.2C15—C16—C19118.4 (2)
C2—C1—H1B109.2C11—C16—C19119.79 (19)
H1A—C1—H1B107.9C12—C17—H17A109.5
C1—C2—H2A109.5C12—C17—H17B109.5
C1—C2—H2B109.5H17A—C17—H17B109.5
H2A—C2—H2B109.5C12—C17—H17C109.5
C1—C2—H2C109.5H17A—C17—H17C109.5
H2A—C2—H2C109.5H17B—C17—H17C109.5
H2B—C2—H2C109.5C14—C18—H18A109.5
O1—C3—C4111.2 (2)C14—C18—H18B109.5
O1—C3—H3A109.4H18A—C18—H18B109.5
C4—C3—H3A109.4C14—C18—H18C109.5
O1—C3—H3B109.4H18A—C18—H18C109.5
C4—C3—H3B109.4H18B—C18—H18C109.5
H3A—C3—H3B108.0C16—C19—H19A109.5
C3—C4—H4A109.5C16—C19—H19B109.5
C3—C4—H4B109.5H19A—C19—H19B109.5
H4A—C4—H4B109.5C16—C19—H19C109.5
C3—C4—H4C109.5H19A—C19—H19C109.5
H4A—C4—H4C109.5H19B—C19—H19C109.5
C3—O1—C1—C281.3 (3)C12—C13—C14—C151.3 (3)
Mg1—O1—C1—C2123.2 (2)C12—C13—C14—C18178.4 (2)
C1—O1—C3—C494.6 (3)C13—C14—C15—C160.2 (3)
Mg1—O1—C3—C462.9 (3)C18—C14—C15—C16179.8 (2)
C16—C11—C12—C130.5 (3)C14—C15—C16—C111.8 (3)
Mg1—C11—C12—C13173.11 (16)C14—C15—C16—C19178.0 (2)
C16—C11—C12—C17179.8 (2)C12—C11—C16—C151.9 (3)
Mg1—C11—C12—C176.6 (3)Mg1—C11—C16—C15171.33 (15)
C11—C12—C13—C141.1 (3)C12—C11—C16—C19177.86 (19)
C17—C12—C13—C14178.6 (2)Mg1—C11—C16—C198.9 (3)
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C1–C6 phenyl ring.
D—H···AD—HH···AD—H···A
C3—H3B···Cg1ii0.992.83159
C18—H18B···Cg1iii0.983.05122
Symmetry codes: (ii) x1, y, z; (iii) x+2, y, z.

Experimental details

Crystal data
Chemical formula[Mg2Br2(C9H11)2(C4H10O)2]
Mr595.03
Crystal system, space groupTriclinic, P1
Temperature (K)173
a, b, c (Å)7.8516 (6), 8.8285 (6), 12.1356 (8)
α, β, γ (°)87.285 (6), 82.516 (6), 65.396 (5)
V3)758.30 (10)
Z1
Radiation typeMo Kα
µ (mm1)2.73
Crystal size (mm)0.23 × 0.19 × 0.13
Data collection
DiffractometerStoe IPDS II two-circle
diffractometer
Absorption correctionMulti-scan
(X-AREA; Stoe & Cie, 2001)
Tmin, Tmax0.572, 0.718
No. of measured, independent and
observed [I > 2σ(I)] reflections
18010, 4227, 3839
Rint0.048
(sin θ/λ)max1)0.696
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.096, 1.06
No. of reflections4227
No. of parameters148
No. of restraints0
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.70, 0.55

Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 (Sheldrick, 2008), SHELXL2012 (Sheldrick, 2012), XP (Sheldrick, 2008), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Selected geometric parameters (Å, º) top
Br1—Mg12.5503 (7)Mg1—O12.0243 (16)
Br1—Mg1i2.5900 (7)Mg1—C112.123 (2)
O1—Mg1—C11108.18 (7)O1—Mg1—Br1i100.23 (5)
O1—Mg1—Br1105.96 (5)C11—Mg1—Br1i126.30 (6)
C11—Mg1—Br1121.22 (6)
Mg1—O1—C1—C2123.2 (2)Mg1—O1—C3—C462.9 (3)
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C1–C6 phenyl ring.
D—H···AD—HH···AD—H···A
C3—H3B···Cg1ii0.9902.833158.9
C18—H18B···Cg1iii0.9803.047122.1
Symmetry codes: (ii) x1, y, z; (iii) x+2, y, z.
Bond distances (Å) involving the Mg centre top
Mg—OMg—CMg—BrMg—Br
Title compound2.0243 (16)2.123 (2)2.5503 (7)2.5900 (7)
RUGNEM2.0112.1312.5582.580
TATNAD2.0242.1302.5722.582
CSD2.02 (6)2.17 (5)2.57 (8)
Bond distances (Å) involving the Mg centre top
Mg—OMg—CMg—BrMg—Br
Title compound2.0243 (16)2.123 (2)2.5503 (7)2.5900 (7)
RUGNEM2.0112.1312.5582.580
TATNAD2.0242.1302.5722.582
CSD2.02 (6)2.17 (5)2.57 (8)
references
References top

Blasberg, F., Bolte, M., Wagner, M. & Lerner, H.-W. (2012). Organometallics, 31, 1001–1005.

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