trans-Dibromidobis(1-ethyl-3-methyl­imidazol-2-yl­idene)palladium(II)

Madsen, S.R.; Lock, N.; Overgaard, J.; Iversen, B.B.

doi:10.1107/S1600536811030480

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 9| September 2011| Page m1205

doi:10.1107/S1600536811030480

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trans-Dibromidobis(1-ethyl-3-methylimidazol-2-ylidene)palladium(II)

Solveig R. Madsen,^a Nina Lock,^a Jacob Overgaard ^a and Bo B. Iversen ^a ^*

^aDepartment of Chemistry & Center for Materials Crystallography, Aarhus University, Aarhus, Denmark
^*Correspondence e-mail: bo@chem.au.dk

(Received 22 July 2011; accepted 28 July 2011; online 6 August 2011)

The title compound, trans-[PdBr₂(C₆H₁₀N₂)₂], was synthesized ionothermally in the ionic liquid solvent 1-ethyl-3-methylimidazolium bromide. In the crystal, the Pd^II atoms are square-planarly coordinated to two Br atoms and two neutral (C₆H₁₀N₂) ligands. The Pd^II atom is located on an inversion centre.

Related literature

The title complex shares many features with a number of known structures, which also contain a Pd^II atom square-planarly coordinated to two bromide ligands in trans-conformation as well as two equivalent organic ligands (Hahn et al., 2004 ; Huynh & Wu, 2009 ). A few of these structures even have the same space group and in some structures the organic ligand is also an imidazolium derivative (Dash et al., 2010 ). The title compound was obtained in a attempt to simplify the synthesis of the cis-complex which was described previously (Madsen et al., 2011 ). For information on the ionothermal synthesis method, see: Welton (1999 ); Babai & Mudring (2006 ); Morris (2009 ).

Experimental

Crystal data

[PdBr₂(C₆H₁₀N₂)₂]
M_r = 486.54
Monoclinic, P 2₁ /n
a = 8.3093 (2) Å
b = 8.6868 (2) Å
c = 12.0788 (3) Å
β = 101.741 (1)°
V = 853.62 (4) Å³
Z = 2
Mo Kα radiation
μ = 5.76 mm⁻¹
T = 296 K
0.15 × 0.15 × 0.1 mm

Data collection

Bruker X8 APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a ) T_min = 0.585, T_max = 0.711
27485 measured reflections
2582 independent reflections
1894 reflections with I > 2σ(I)
R_int = 0.022

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.167
S = 1.63
2582 reflections
88 parameters
H-atom parameters constrained
Δρ_max = 1.84 e Å⁻³
Δρ_min = −1.02 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

C1—Pd1	2.023 (4)
Br1—Pd1	2.4364 (5)

C1—Pd1—C1ⁱ	180
C1—Pd1—Br1	89.14 (12)
C1ⁱ—Pd1—Br1	90.86 (12)
Br1—Pd1—Br1ⁱ	180
Symmetry code: (i) -x+2, -y+2, -z+2.

Data collection: APEX2 (Bruker, 2011 ); cell refinement: SAINT (Bruker, 2011); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811030480/zk2019sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811030480/zk2019Isup2.hkl

checkCIF report

Related literature top

The title complex shares many features with a number of known structures, which also contain a square planar Pd atom coordinated to two bromide ligands in trans-conformation as well as two equivalent organic ligands (Hahn et al., 2004; Huynh & Wu, 2009). A few of these structures even have the same space group and in some structures the organic ligand is also an imidazolium derivative (Dash et al., 2010). The title compound was obtained in a attempt to simplify the synthesis of the cis-complex which was described previously (Madsen et al., 2011). For information on the ionothermal synthesis method, see: Welton (1999); Babai & Mudring (2006); Morris (2009).

Experimental top

The title compound was obtained when palladium(II) acetate and 1-ethyl-3- methylimidazolium bromide were mixed and heated in an autoclave at 100°C for 8 days.

Computing details top

Data collection: APEX2 (Bruker, 2011); cell refinement: SAINT (Bruker, 2011); data reduction: SAINT (Bruker, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

Fig. 1. The molecular structure of trans-[PdBr₂(C₆H₁₀N₂)₂], with atom labels and 50% probability displacement ellipsoids for non-H atoms.

trans-Dibromidobis(1-ethyl-3-methylimidazol-2-ylidene)palladium(II) top

Crystal data top

[PdBr₂(C₆H₁₀N₂)₂]	F(000) = 472
M_r = 486.54	D_x = 1.893 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 9872 reflections
a = 8.3093 (2) Å	θ = 5.5–54.7°
b = 8.6868 (2) Å	µ = 5.76 mm⁻¹
c = 12.0788 (3) Å	T = 296 K
β = 101.741 (1)°	Square, colourless
V = 853.62 (4) Å³	0.15 × 0.15 × 0.1 mm
Z = 2

Data collection top

Bruker X8 APEXII diffractometer	2582 independent reflections
Radiation source: fine-focus sealed tube	1894 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.022
Detector resolution: 12.00 pixels mm^-1	θ_max = 30.5°, θ_min = 2.7°
Narrow slices collected using ϕ and ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	k = −12→12
T_min = 0.585, T_max = 0.711	l = −15→17
27485 measured reflections

Refinement top

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.167	H-atom parameters constrained
S = 1.63	w = 1/[σ²(F_o²) + (0.0705P)²] where P = (F_o² + 2F_c²)/3
2582 reflections	(Δ/σ)_max = 0.008
88 parameters	Δρ_max = 1.84 e Å⁻³
0 restraints	Δρ_min = −1.02 e Å⁻³

Crystal data top

[PdBr₂(C₆H₁₀N₂)₂]	V = 853.62 (4) Å³
M_r = 486.54	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.3093 (2) Å	µ = 5.76 mm⁻¹
b = 8.6868 (2) Å	T = 296 K
c = 12.0788 (3) Å	0.15 × 0.15 × 0.1 mm
β = 101.741 (1)°

Data collection top

Bruker X8 APEXII diffractometer	2582 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	1894 reflections with I > 2σ(I)
T_min = 0.585, T_max = 0.711	R_int = 0.022
27485 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.167	H-atom parameters constrained
S = 1.63	Δρ_max = 1.84 e Å⁻³
2582 reflections	Δρ_min = −1.02 e Å⁻³
88 parameters

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.

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) top

	x	y	z	U_iso*/U_eq
N2	0.8710 (5)	0.9917 (3)	0.7471 (3)	0.0598 (9)
C1	0.9896 (5)	0.9475 (5)	0.8355 (3)	0.0570 (8)
C3	0.9059 (7)	0.9436 (6)	0.6478 (4)	0.0735 (11)
H3	0.8411	0.9594	0.5763	0.088*
C5	1.2461 (7)	0.7839 (10)	0.8505 (6)	0.118 (2)
H5A	1.2269	0.747	0.9225	0.142*
H5B	1.2675	0.6958	0.8062	0.142*
C2	1.0451 (6)	0.8718 (7)	0.6700 (4)	0.0852 (14)
H2	1.1002	0.8294	0.6176	0.102*
C6	1.3777 (13)	0.8815 (14)	0.8675 (10)	0.197 (5)
H6A	1.473	0.8289	0.9084	0.295*
H6B	1.3548	0.9691	0.9104	0.295*
H6C	1.3977	0.9152	0.7959	0.295*
C4	0.7242 (7)	1.0768 (7)	0.7604 (5)	0.0953 (17)
H4A	0.6572	1.0973	0.6873	0.143*
H4B	0.7563	1.1723	0.7986	0.143*
H4C	0.6629	1.0166	0.8041	0.143*
Br1	1.09068 (7)	1.25854 (6)	0.96387 (4)	0.0893 (2)
N1	1.0978 (4)	0.8699 (5)	0.7886 (3)	0.0772 (10)
Pd1	1	1	1	0.0555 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N2	0.075 (2)	0.060 (2)	0.0438 (19)	0.0033 (13)	0.0110 (16)	0.0020 (13)
C1	0.064 (2)	0.063 (2)	0.047 (2)	−0.0089 (17)	0.0168 (16)	−0.0047 (18)
C3	0.104 (4)	0.073 (3)	0.044 (2)	−0.009 (3)	0.016 (2)	−0.002 (2)
C5	0.080 (3)	0.189 (7)	0.088 (4)	0.017 (4)	0.023 (3)	−0.011 (4)
C2	0.100 (4)	0.104 (4)	0.059 (3)	−0.001 (3)	0.033 (3)	−0.006 (3)
C6	0.136 (7)	0.207 (12)	0.231 (13)	−0.009 (9)	0.000 (7)	0.036 (9)
C4	0.104 (4)	0.114 (4)	0.064 (3)	0.052 (4)	0.010 (3)	0.006 (3)
Br1	0.1261 (5)	0.0831 (4)	0.0624 (4)	−0.0312 (3)	0.0278 (3)	−0.0070 (2)
N1	0.0732 (19)	0.108 (3)	0.0529 (19)	0.008 (2)	0.0181 (16)	−0.0060 (19)
Pd1	0.0597 (3)	0.0696 (4)	0.0386 (3)	−0.00208 (16)	0.01357 (18)	−0.00364 (15)

Geometric parameters (Å, º) top

N2—C1	1.353 (6)	C2—N1	1.410 (6)
N2—C3	1.356 (6)	C2—H2	0.93
N2—C4	1.463 (6)	C6—H6A	0.96
C1—N1	1.338 (5)	C6—H6B	0.96
C1—Pd1	2.023 (4)	C6—H6C	0.96
C3—C2	1.293 (7)	C4—H4A	0.96
C3—H3	0.93	C4—H4B	0.96
C5—C6	1.366 (12)	C4—H4C	0.96
C5—N1	1.503 (7)	Br1—Pd1	2.4364 (5)
C5—H5A	0.97	Pd1—C1ⁱ	2.023 (4)
C5—H5B	0.97	Pd1—Br1ⁱ	2.4364 (5)

C1—N2—C3	111.0 (4)	H6A—C6—H6B	109.5
C1—N2—C4	123.1 (4)	C5—C6—H6C	109.5
C3—N2—C4	125.9 (4)	H6A—C6—H6C	109.5
N1—C1—N2	104.7 (3)	H6B—C6—H6C	109.5
N1—C1—Pd1	129.1 (3)	N2—C4—H4A	109.5
N2—C1—Pd1	126.2 (3)	N2—C4—H4B	109.5
C2—C3—N2	107.9 (4)	H4A—C4—H4B	109.5
C2—C3—H3	126	N2—C4—H4C	109.5
N2—C3—H3	126	H4A—C4—H4C	109.5
C6—C5—N1	108.5 (8)	H4B—C4—H4C	109.5
C6—C5—H5A	110	C1—N1—C2	109.1 (4)
N1—C5—H5A	110	C1—N1—C5	126.4 (4)
C6—C5—H5B	110	C2—N1—C5	124.3 (4)
N1—C5—H5B	110	C1—Pd1—C1ⁱ	180.000 (2)
H5A—C5—H5B	108.4	C1—Pd1—Br1	89.14 (12)
C3—C2—N1	107.2 (4)	C1ⁱ—Pd1—Br1	90.86 (12)
C3—C2—H2	126.4	C1—Pd1—Br1ⁱ	90.86 (12)
N1—C2—H2	126.4	C1ⁱ—Pd1—Br1ⁱ	89.14 (12)
C5—C6—H6A	109.5	Br1—Pd1—Br1ⁱ	180
C5—C6—H6B	109.5

C3—N2—C1—N1	−0.5 (5)	Pd1—C1—N1—C5	8.6 (7)
C4—N2—C1—N1	178.1 (4)	C3—C2—N1—C1	−2.4 (6)
C3—N2—C1—Pd1	176.8 (3)	C3—C2—N1—C5	173.7 (5)
C4—N2—C1—Pd1	−4.7 (6)	C6—C5—N1—C1	−91.6 (8)
C1—N2—C3—C2	−1.1 (6)	C6—C5—N1—C2	93.0 (8)
C4—N2—C3—C2	−179.6 (5)	N1—C1—Pd1—Br1	100.3 (4)
N2—C3—C2—N1	2.1 (6)	N2—C1—Pd1—Br1	−76.2 (4)
N2—C1—N1—C2	1.7 (5)	N1—C1—Pd1—Br1ⁱ	−79.7 (4)
Pd1—C1—N1—C2	−175.4 (3)	N2—C1—Pd1—Br1ⁱ	103.8 (4)
N2—C1—N1—C5	−174.3 (5)

Symmetry code: (i) −x+2, −y+2, −z+2.

Experimental details

Crystal data
Chemical formula	[PdBr₂(C₆H₁₀N₂)₂]
M_r	486.54
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	8.3093 (2), 8.6868 (2), 12.0788 (3)
β (°)	101.741 (1)
V (Å³)	853.62 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	5.76
Crystal size (mm)	0.15 × 0.15 × 0.1

Data collection
Diffractometer	Bruker X8 APEXII diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2008a)
T_min, T_max	0.585, 0.711
No. of measured, independent and observed [I > 2σ(I)] reflections	27485, 2582, 1894
R_int	0.022
(sin θ/λ)_max (Å⁻¹)	0.714

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.167, 1.63
No. of reflections	2582
No. of parameters	88
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.84, −1.02

Computer programs: APEX2 (Bruker, 2011), SAINT (Bruker, 2011), SHELXS97 (Sheldrick, 2008b), SHELXL97 (Sheldrick, 2008b), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top

C1—Pd1	2.023 (4)	Br1—Pd1	2.4364 (5)

C1—Pd1—C1ⁱ	180.000 (2)	C1ⁱ—Pd1—Br1	90.86 (12)
C1—Pd1—Br1	89.14 (12)	Br1—Pd1—Br1ⁱ	180

Symmetry code: (i) −x+2, −y+2, −z+2.

Acknowledgements

The authors thank the Center for Materials Crystallography (CMC) for financial support.

References

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