1,3-Bis[(−)-(S)-(1-phenyl­eth­yl)imino­meth­yl]benzene

García, T.; Bernès, S.; Flores-Alamo, M.; Hernández, G.; Gutiérrez, R.

doi:10.1107/S1600536811021556

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 7| July 2011| Pages o1648-o1649

doi:10.1107/S1600536811021556

Open

access

1,3-Bis[(−)-(S)-(1-phenylethyl)iminomethyl]benzene

Tania García,^a Sylvain Bernès,^a ^* Marcos Flores-Alamo,^b Guadalupe Hernández ^c and René Gutiérrez ^c

^aDEP Facultad de Ciencias Químicas, UANL, Guerrero y Progreso S/N, Col. Treviño, 64570 Monterrey, N.L., Mexico, ^bFacultad de Química, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico, and ^cLaboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico
^*Correspondence e-mail: sylvain_bernes@Hotmail.com

(Received 19 May 2011; accepted 3 June 2011; online 11 June 2011)

The title compound, C₂₄H₂₄N₂, is an enantiomerically pure bis-aldimine, which displays twofold crystallographic symmetry, with two C atoms of the central benzene ring lying on the symmetry axis. The imine group is slightly twisted from the benzene core, with a dihedral angle of 12.72 (16)° between the benzene ring and the C=N—C^* plane. The terminal phenyl rings make an angle of 66.44 (4)° and are oriented in opposite directions with respect to the benzene ring. In the crystal, molecules interact weakly through a C—H⋯π interaction involving the phenyl rings, and form chains along the 2₁ screw-axis in the [100] direction.

Related literature

For the structure of the analogous molecule with naphthyl in place of phenyl, see: Espinosa Leija et al. (2009 ). For the structure of the isoformular molecule with a 1,4-disubstituted benzene ring, see: García et al. (2010 ). For the Pd(II) and Pt(II) coordination complexes formed using the title ligand, see: Fossey et al. (2007 ). For background to the synthesis carried out in solvent-free conditions, see: Tanaka & Toda (2000 ); Jeon et al. (2005 ).

Experimental

Crystal data

C₂₄H₂₄N₂
M_r = 340.45
Orthorhombic, P 2₁ 2₁ 2
a = 21.1309 (7) Å
b = 5.6572 (2) Å
c = 8.2290 (3) Å
V = 983.71 (6) Å³
Z = 2
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 130 K
0.33 × 0.26 × 0.14 mm

Data collection

Oxford Diffraction Xcalibur Atlas Gemini diffractometer
Absorption correction: analytical [CrysAlis PRO (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ) based on expressions derived by Clark & Reid (1995 )] T_min = 0.980, T_max = 0.991
6971 measured reflections
1161 independent reflections
1027 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.073
S = 1.06
1161 reflections
154 parameters
Only H-atom coordinates refined
Δρ_max = 0.09 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯Cgⁱ	0.92 (2)	2.97 (2)	3.7265 (18)	140.7 (18)
Symmetry code: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+1]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ); cell refinement: CrysAlis RED (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811021556/lr2012sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811021556/lr2012Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811021556/lr2012Isup3.mol

checkCIF report

Comment top

The title compound was synthesized in an almost quantitative yield, using a one-step solvent-free route. Such procedures are becoming primordial in organic synthetic methods, in order to minimize the quantity of toxic waste and byproducts and to decrease the amount of solvents in the reaction media and/or during the following workups. Indeed, solvent-free reactions or solid-state reactions have been particularly developed these last years. (Jeon et al., 2005; Tanaka & Toda, 2000).

The molecular structure of the title compound is as expected. The imine groups N1═C8 are found in the E configuration, which is known to be more stable than Z. The molecule is placed on a crystallographic twofold axis, passing through benzene atoms C10 and C11 (Fig. 1). Imine groups are not fully conjugated with the benzene core: the dihedral angle between C7—N1═ C8 and benzene mean-planes is 12.72 (16)°. The benzene ring makes an angle of 69.35 (5)° with the phenyl group, and terminal phenyl rings make an angle of 66.44 (4)°. Although the analogous bis-imine bearing a naphthyl group in place of phenyl crystallizes in the same space group, P2₁2₁2, and with identical molecular symmetry, it is stabilized in a different conformation compared to the title molecule. For instance, imine groups are almost perfectly conjugated with the benzene ring (dihedral angle between benzene and C^*—N═C planes less than 0.6°; Espinosa Leija et al., 2009). The title molecule and the naphthyl analogue are also differentiated by the fact that the latter crystallized with lattice solvent, CH₂Cl₂. The title molecule also shows a different conformation to that of the isoformular compound with a central 1,4-disubsituted benzene ring (García et al., 2010): in that case, the molecule crystallizes in P2₁2₁2₁ and is placed in general position (C₁ point group).

The crystal structure (Fig. 2) features chains of molecules placed along the 2₁ screw-axis in the [100] direction, which interact trough rather weak C3—H3···π contacts involving phenyl groups C1···C6. The H3···π separation is 2.97 (2) Å, and the C3—H3···π angle 140.7 (18)°.

Interestingly, (Fossey et al. 2007) reported on the synthesis of chiral bis-aldimine NCN–pincer complexes, where the NCN ligand is derived from the title compound by deprotonation at C10. These authors probed the catalytic activity of Pd(II) and Pt(II) complexes, where the ancillary ligand is an halide ion, Br^- or Cl^-, for Pd and Pt complexes, respectively. The studied reaction, a classical Michael addition between methyl 2-cyanopropanoate and methyl vinyl ketone, showed that addition was not stereocontrolled. This poor selectivity was related to conformational flexibility of the chiral phenylethyl moiety of the ligand. Indeed, that point is confirmed by our structure, since a poor overlay is observed for this part of the molecule, when attempting to fit the title molecule and the main ligand in the complexes. However, differences in point symmetry also deserve to be considered regarding the catalytic activity: the title molecule belongs to C₂ point-group, while complexes prepared by Fossey et al. crystallize in space group P2₁2₁2₁, the whole complexes being placed in general positions. The complexes used for the Michael addition thus actually displayed the non-crystallographic C₂ symmetry.

Related literature top

For the structure of the analogous molecule with naphthyl in place of phenyl, see: Espinosa Leija et al. (2009). For the structure of the isoformular molecule with a 1,4-disubstituted benzene ring, see: García et al. (2010). For the Pd(II) and Pt(II) coordination complexes formed using the title ligand, see: Fossey et al. (2007). For background to the synthesis carried out in solvent-free conditions, see: Tanaka & Toda (2000); Jeon et al. (2005).

Experimental top

Under solvent-free conditions, (S)-(–)-1-phenylethylamine (0.45 g, 3.72 mmol) and benzene-1,3-dicarboxaldehyde (0.25 g, 1.86 mmol) in a 2:1 molar ratio were mixed at room temperature, obtaining a white solid. The crude was recrystallized twice from CH₂Cl₂, affording colorless crystals of the title compound. Yield: 92%; m.p. 80–82 °C. Analysis: [α]²⁵_D = -71.4 (c=1, CHCl₃). FT—IR (KBr): 1645 cm^-1 (C=N). ¹H-NMR (400 MHz, CDCl₃/TMS) δ = 1.58 (d, 6H, CHCH₃), 4.53 (q, 2H, CH), 7.22–8.11 (m, 14H, Ar—CH), 8.36 (s, 2H, HC=N). ¹³C-NMR (100 MHz, CDCl₃/TMS) δ = 24.7 (CCH₃), 69.6 (CHCH₃), 126.5 (Ar), 126.8 (Ar), 128.2 (Ar), 128.3 (Ar), 128.7 (Ar), 130.0 (Ar), 136.6 (Ar), 144.8 (Ar), 158.9 (HC=N). MS—EI: m/z= 340 (M⁺).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006)'; software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The title molecule with displacement ellipsoids for non-H atoms shown at the 60% probability level. Non-labeled atoms are generated by symmetry operation -x, 1 - y, z.
	Fig. 2. A part of the crystal structure of the title compound. The purple molecules are related by the 2₁ symmetry along the a axis, and dashed lines represent C—H···π contacts.

1,3-Bis[(-)-(S)-(1-phenylethyl)iminomethyl]benzene top

Crystal data top

C₂₄H₂₄N₂	D_x = 1.149 Mg m⁻³
M_r = 340.45	Melting point: 353 K
Orthorhombic, P2₁2₁2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2 2ab	Cell parameters from 4133 reflections
a = 21.1309 (7) Å	θ = 3.6–26.0°
b = 5.6572 (2) Å	µ = 0.07 mm⁻¹
c = 8.2290 (3) Å	T = 130 K
V = 983.71 (6) Å³	Prism, colourless
Z = 2	0.33 × 0.26 × 0.14 mm
F(000) = 364

Data collection top

Oxford Diffraction Xcalibur Atlas Gemini diffractometer	1161 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1027 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 10.4685 pixels mm^-1	θ_max = 26.0°, θ_min = 3.7°
ω scans	h = −26→24
Absorption correction: analytical [CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]	k = −6→6
T_min = 0.980, T_max = 0.991	l = −10→9
6971 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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.073	Only H-atom coordinates refined
S = 1.06	w = 1/[σ²(F_o²) + (0.0497P)² + 0.0095P] where P = (F_o² + 2F_c²)/3
1161 reflections	(Δ/σ)_max < 0.001
154 parameters	Δρ_max = 0.09 e Å⁻³
0 restraints	Δρ_min = −0.17 e Å⁻³
0 constraints

Crystal data top

C₂₄H₂₄N₂	V = 983.71 (6) Å³
M_r = 340.45	Z = 2
Orthorhombic, P2₁2₁2	Mo Kα radiation
a = 21.1309 (7) Å	µ = 0.07 mm⁻¹
b = 5.6572 (2) Å	T = 130 K
c = 8.2290 (3) Å	0.33 × 0.26 × 0.14 mm

Data collection top

Oxford Diffraction Xcalibur Atlas Gemini diffractometer	1161 independent reflections
Absorption correction: analytical [CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]	1027 reflections with I > 2σ(I)
T_min = 0.980, T_max = 0.991	R_int = 0.025
6971 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.073	Only H-atom coordinates refined
S = 1.06	Δρ_max = 0.09 e Å⁻³
1161 reflections	Δρ_min = −0.17 e Å⁻³
154 parameters

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

	x	y	z	U_iso*/U_eq
N1	0.08171 (5)	0.8507 (2)	0.09804 (15)	0.0334 (3)
C1	0.18464 (7)	0.9616 (3)	0.20948 (18)	0.0320 (3)
C2	0.19358 (8)	0.7590 (3)	0.3015 (2)	0.0444 (4)
H2	0.1570 (9)	0.669 (3)	0.330 (2)	0.053*
C3	0.25402 (9)	0.6851 (3)	0.3437 (2)	0.0517 (5)
H3	0.2581 (9)	0.549 (4)	0.405 (3)	0.062*
C4	0.30581 (8)	0.8153 (4)	0.2952 (2)	0.0504 (5)
H4	0.3488 (10)	0.765 (4)	0.326 (2)	0.060*
C5	0.29724 (8)	1.0147 (4)	0.2039 (2)	0.0543 (5)
H5	0.3325 (10)	1.099 (4)	0.164 (3)	0.065*
C6	0.23701 (8)	1.0880 (3)	0.1605 (2)	0.0420 (4)
H6	0.2300 (8)	1.226 (4)	0.100 (2)	0.050*
C7	0.11876 (7)	1.0481 (3)	0.16569 (19)	0.0346 (4)
H7	0.1234 (8)	1.176 (3)	0.0885 (19)	0.042*
C8	0.06895 (6)	0.8605 (3)	−0.05179 (18)	0.0320 (4)
H8	0.0837 (7)	0.997 (3)	−0.1224 (19)	0.038*
C9	0.03271 (6)	0.6758 (3)	−0.13695 (17)	0.0313 (3)
C10	0.0000	0.5000	−0.0535 (2)	0.0299 (5)
H10	0.0000	0.5000	0.068 (3)	0.036*
C11	0.0000	0.5000	−0.3906 (3)	0.0441 (6)
H11	0.0000	0.5000	−0.506 (3)	0.053*
C12	0.03173 (7)	0.6752 (3)	−0.30697 (18)	0.0398 (4)
H12	0.0545 (8)	0.797 (3)	−0.363 (2)	0.048*
C13	0.08354 (8)	1.1472 (3)	0.3116 (2)	0.0427 (4)
H13A	0.1078 (8)	1.284 (4)	0.365 (2)	0.051*
H13B	0.0793 (9)	1.021 (4)	0.393 (2)	0.051*
H13C	0.0397 (9)	1.208 (3)	0.279 (2)	0.051*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0258 (6)	0.0373 (7)	0.0370 (7)	−0.0034 (5)	0.0025 (5)	0.0064 (6)
C1	0.0324 (8)	0.0313 (7)	0.0325 (7)	−0.0046 (6)	0.0019 (6)	−0.0027 (7)
C2	0.0393 (9)	0.0360 (8)	0.0580 (11)	−0.0068 (7)	−0.0027 (8)	0.0085 (8)
C3	0.0564 (10)	0.0411 (10)	0.0578 (11)	0.0074 (9)	−0.0127 (9)	0.0024 (9)
C4	0.0371 (9)	0.0653 (12)	0.0489 (10)	0.0111 (9)	−0.0053 (8)	−0.0156 (10)
C5	0.0322 (9)	0.0736 (13)	0.0571 (11)	−0.0111 (9)	0.0038 (8)	0.0015 (11)
C6	0.0361 (9)	0.0460 (10)	0.0440 (9)	−0.0079 (7)	0.0035 (7)	0.0063 (8)
C7	0.0322 (8)	0.0310 (7)	0.0407 (8)	−0.0052 (7)	0.0028 (7)	0.0081 (7)
C8	0.0252 (7)	0.0355 (8)	0.0351 (8)	0.0052 (6)	0.0063 (6)	0.0079 (7)
C9	0.0233 (6)	0.0406 (8)	0.0301 (7)	0.0105 (7)	0.0020 (6)	0.0036 (7)
C10	0.0216 (9)	0.0413 (12)	0.0268 (10)	0.0084 (9)	0.000	0.000
C11	0.0454 (13)	0.0633 (16)	0.0236 (11)	0.0175 (12)	0.000	0.000
C12	0.0347 (8)	0.0520 (10)	0.0326 (8)	0.0119 (8)	0.0048 (7)	0.0090 (8)
C13	0.0360 (8)	0.0424 (9)	0.0496 (10)	−0.0023 (8)	0.0046 (8)	−0.0012 (9)

Geometric parameters (Å, º) top

N1—C8	1.2633 (19)	C7—H7	0.967 (17)
N1—C7	1.4727 (19)	C8—C9	1.473 (2)
C1—C6	1.378 (2)	C8—H8	1.014 (18)
C1—C2	1.387 (2)	C9—C10	1.3920 (17)
C1—C7	1.519 (2)	C9—C12	1.399 (2)
C2—C3	1.388 (2)	C10—C9ⁱ	1.3920 (17)
C2—H2	0.96 (2)	C10—H10	1.00 (2)
C3—C4	1.378 (3)	C11—C12ⁱ	1.380 (2)
C3—H3	0.92 (2)	C11—C12	1.380 (2)
C4—C5	1.367 (3)	C11—H11	0.95 (2)
C4—H4	0.98 (2)	C12—H12	0.959 (19)
C5—C6	1.385 (2)	C13—H13A	1.02 (2)
C5—H5	0.94 (2)	C13—H13B	0.98 (2)
C6—H6	0.94 (2)	C13—H13C	1.023 (18)
C7—C13	1.520 (2)

C8—N1—C7	116.69 (13)	C1—C7—H7	107.7 (10)
C6—C1—C2	118.64 (15)	C13—C7—H7	107.0 (9)
C6—C1—C7	119.96 (14)	N1—C8—C9	122.96 (14)
C2—C1—C7	121.38 (13)	N1—C8—H8	121.8 (9)
C1—C2—C3	120.71 (17)	C9—C8—H8	115.3 (9)
C1—C2—H2	117.7 (12)	C10—C9—C12	118.95 (16)
C3—C2—H2	121.5 (11)	C10—C9—C8	122.03 (13)
C4—C3—C2	119.84 (17)	C12—C9—C8	119.01 (15)
C4—C3—H3	121.9 (12)	C9—C10—C9ⁱ	120.90 (18)
C2—C3—H3	118.2 (12)	C9—C10—H10	119.55 (9)
C5—C4—C3	119.65 (16)	C9ⁱ—C10—H10	119.55 (9)
C5—C4—H4	120.0 (12)	C12ⁱ—C11—C12	120.2 (2)
C3—C4—H4	120.4 (12)	C12ⁱ—C11—H11	119.90 (10)
C4—C5—C6	120.69 (17)	C12—C11—H11	119.90 (10)
C4—C5—H5	120.4 (12)	C11—C12—C9	120.48 (17)
C6—C5—H5	118.8 (12)	C11—C12—H12	121.4 (11)
C1—C6—C5	120.45 (16)	C9—C12—H12	118.1 (11)
C1—C6—H6	117.4 (11)	C7—C13—H13A	111.8 (10)
C5—C6—H6	122.1 (11)	C7—C13—H13B	108.4 (11)
N1—C7—C1	109.44 (12)	H13A—C13—H13B	107.4 (14)
N1—C7—C13	108.55 (12)	C7—C13—H13C	111.2 (9)
C1—C7—C13	112.35 (13)	H13A—C13—H13C	108.1 (13)
N1—C7—H7	111.8 (10)	H13B—C13—H13C	109.8 (15)

C6—C1—C2—C3	0.1 (2)	C2—C1—C7—N1	−49.69 (19)
C7—C1—C2—C3	−178.53 (16)	C6—C1—C7—C13	−107.63 (17)
C1—C2—C3—C4	0.6 (3)	C2—C1—C7—C13	70.97 (19)
C2—C3—C4—C5	−0.9 (3)	C7—N1—C8—C9	179.55 (12)
C3—C4—C5—C6	0.4 (3)	N1—C8—C9—C10	12.2 (2)
C2—C1—C6—C5	−0.6 (2)	N1—C8—C9—C12	−167.04 (14)
C7—C1—C6—C5	178.06 (16)	C12—C9—C10—C9ⁱ	0.71 (10)
C4—C5—C6—C1	0.3 (3)	C8—C9—C10—C9ⁱ	−178.53 (14)
C8—N1—C7—C1	−110.27 (15)	C12ⁱ—C11—C12—C9	0.73 (10)
C8—N1—C7—C13	126.80 (15)	C10—C9—C12—C11	−1.4 (2)
C6—C1—C7—N1	131.72 (14)	C8—C9—C12—C11	177.83 (10)

Symmetry code: (i) −x, −y+1, z.

Hydrogen-bond geometry (Å, º) top

Cg is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···Cgⁱⁱ	0.92 (2)	2.97 (2)	3.7265 (18)	140.7 (18)

Symmetry code: (ii) −x+1/2, y−1/2, −z+1.

Experimental details

Crystal data
Chemical formula	C₂₄H₂₄N₂
M_r	340.45
Crystal system, space group	Orthorhombic, P2₁2₁2
Temperature (K)	130
a, b, c (Å)	21.1309 (7), 5.6572 (2), 8.2290 (3)
V (Å³)	983.71 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.07
Crystal size (mm)	0.33 × 0.26 × 0.14

Data collection
Diffractometer	Oxford Diffraction Xcalibur Atlas Gemini diffractometer
Absorption correction	Analytical [CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]
T_min, T_max	0.980, 0.991
No. of measured, independent and observed [I > 2σ(I)] reflections	6971, 1161, 1027
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.618

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.073, 1.06
No. of reflections	1161
No. of parameters	154
H-atom treatment	Only H-atom coordinates refined
Δρ_max, Δρ_min (e Å⁻³)	0.09, −0.17

Computer programs: CrysAlis CCD (Oxford Diffraction, 2009), CrysAlis RED (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006)', SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

Cg is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···Cgⁱ	0.92 (2)	2.97 (2)	3.7265 (18)	140.7 (18)

Symmetry code: (i) −x+1/2, y−1/2, −z+1.

Acknowledgements

Support from VIEP-UAP: GUPJ-NAT10-G (2011) is acknowledged.

References

Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887–897. CrossRef CAS Web of Science IUCr Journals Google Scholar
Espinosa Leija, A., Hernández, G., Cruz, S., Bernès, S. & Gutiérrez, R. (2009). Acta Cryst. E65, o1316. Web of Science CSD CrossRef IUCr Journals Google Scholar
Fossey, J. S., Russell, M. L., Abdul Malik, K. M. & Richards, C. J. (2007). J. Organomet. Chem. 692, 4843–4848. CrossRef CAS Google Scholar
García, T., Bernès, S., Hernández, G., Gutiérrez, R. & Vázquez, J. (2010). Quím. Hoy Chem. Sci. 1, 10–13. Google Scholar
Jeon, S.-J., Li, H. & Walsh, P. J. (2005). J. Am. Chem. Soc. 127, 16416–16425. Web of Science CrossRef PubMed CAS Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CrossRef CAS IUCr Journals Google Scholar
Oxford Diffraction (2009). CrysAlis CCD, CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tanaka, K. & Toda, F. (2000). Chem. Rev. 100, 1025–1074. Web of Science CrossRef PubMed CAS Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 7| July 2011| Pages o1648-o1649

doi:10.1107/S1600536811021556

Open

access