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The title compound, [CuCl2(C7H9N)4], lies on a site of crystallographic 42 (D4) symmetry in the space group P4/­nnc, and is isomorphous with the Ni and Co analogues. The Cu and Cl atoms thus lie on a fourfold axis, and the 3,5-­lutidine ligands lie on twofold axes. The Cu-Cl distance is 2.7649 (7) Å and the Cu-N distance is 2.0510 (12) Å. The space group of the Co analogue is revised from Pnnn to P4/­nnc.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107018471/gz3084sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107018471/gz3084Isup2.hkl
Contains datablock I

txt

Text file https://doi.org/10.1107/S0108270107018471/gz3084sup3.txt
Supplementary material

CCDC references: 652487; 653160

Comment top

The title compound, (I), was prepared during an investigation of the reactions of a cofacial binuclear bis(ketoenamine) complex, Cu2(BBI)2, where BBI is 5-tert-butyl-m-xylylenebis(acetylacetone iminate) (Bradbury et al., 1989), with 3,5-lutidine and related Lewis bases. Electronic spectroscopic changes during these reactions suggested that simple adducts, such as Cu2(BBI)2L2, were forming. However, these products could not be isolated. Instead, the complex apparently decomposed, and the title compound fortuitously crystallized after many years. No chloride was added to the Cu2(BBI)2–3,5-lutidine solution, nor were any other copper sources present. However, dichloromethane is known to be attacked by amines, with displacement of a Cl- anion (Fronczek et al., 1990; Maverick et al., 1990). Thus, formation of the title compound may have occurred by slow hydrolysis of Cu2(BBI)2 to release Cu2+, and subsequent combination with displaced Cl- anion and excess lutidine.

The molecule of (I) lies on a site of 42 symmetry and Z'= 1/8. Space group P4/nnc is uncommon, with only three occurrences reported by Brock & Dunitz (1994) in their compilation of well determined structures from the Cambridge Structural Database (CSD; Allen, 2002). All three have Z'= 1/8. A search of the complete database (Version 5.28, November 2006) yielded 101 hits, of which 65 have Z' = 1/8, 34 have Z' = 1/4, one has Z' = 9/8 and one has Z' = 2.

The crystallographic symmetry requires strict square-planar geometry of the CuN4 unit, and the axial octahedral elongation is likewise undistorted. The Cu—N distance is comparable with those in trans-dichlorotetrakis(pyridine)copper(II) dipyridine solvate [2.028 (3)–2.064 (4) Å; CSD refcode OMIROR; Bond et al., 2003], but that compound has a somewhat longer Cu—Cl distance [2.957 (2) Å] than in (I). Likewise, in trans-dichlorotetrakis(pyrid-3-ylmethanol-N) copper(II) (CSD refcode PACYUO; Moncol et al., 2004), the Cu—N distances are comparable, at 2.0322 (15)–2.0747 (17) Å, and the Cu—Cl distance is even longer, at 3.0752 (8) Å.

There are differences among these three structures with respect to the twisting of the pyridine ring out of the coordination plane, as measured by the Cl—Cu—N—C torsion angles. Compound (I) has a torsion angle of 42.35 (6)°, OMIROR has torsion angles of 25.4 and 32.0°, while PACYUO has torsion angles within the range 10.1–32.8°.

Compound (I) is isomorphous with the analogous NiII compound (Xu et al., 2005). The CoII analogue (refcode YIZSIJ; Kansikas et al., 1994) has been reported in space group Pnnn, with a = b, the molecule lying on a site of 222 (D2) symmetry and one full 3,5-lutidine ligand in the asymmetric unit. However, the coordinates of the lutidine conform to twofold symmetry, with a maximum deviation of 0.013 Å. Thus, it appears that the structure should be properly described in space group P4/nnc, isomorphous with the Ni and Cu compounds. Symmetrized coordinates for YIZSIJ in the tetragonal space group are provided as supplementary material.

Related literature top

For related literature, see: Allen (2002); Bond et al. (2003); Bradbury et al. (1989); Brock & Dunitz (1994); Fronczek et al. (1990); Kansikas et al. (1994); Maverick et al. (1990); Moncol et al. (2004); Xu et al. (2005).

Experimental top

The compound was prepared from a solution of Cu2(BBI)2.xDMF in CH2Cl2 by addition of an excess of 3,5-lutidine, where BBI is 5-tert-butyl-m-xylylenebis(acetylacetone iminate) (Bradbury et al., 1989). Over a period of 1–2 weeks, the CH2Cl2 evaporated, and blue crystals formed in the residual liquid. However, those crystals were not of sufficient quality for crystal structure determination, and the sample was retained in a sealed vial. After approximately 18 years, high-quality blue prisms of (I) were discovered in the sample.

Refinement top

For sp2 C atoms, a C—H distance of 0.95 Å was used, with Uiso(H) = 1.2Ueq(C). For the methyl group, C—H = 0.98 Å and Uiso(H) = 1.5Ueq(C), and a torsional parameter was refined.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor 1997); data reduction: DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The structure 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 asymmetric unit is labelled.
trans-Dichloridotetrakis(3,5-dimethylpyridine)copper(II) top
Crystal data top
[CuCl2(C7H9N)4]Dx = 1.337 Mg m3
Mr = 563.05Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/nncCell parameters from 3012 reflections
Hall symbol: -P 4a 2bcθ = 2.5–35.0°
a = 11.3324 (15) ŵ = 1.00 mm1
c = 10.894 (2) ÅT = 110 K
V = 1399.0 (4) Å3Prism, blue
Z = 20.20 × 0.20 × 0.17 mm
F(000) = 590
Data collection top
Nonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler
1547 independent reflections
Radiation source: fine-focus sealed tube1195 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
ω scans with κ offsetsθmax = 35.0°, θmin = 2.5°
Absorption correction: multi-scan
(SCALEPACK; Otwinowski & Minor, 1997)
h = 1818
Tmin = 0.826, Tmax = 0.849k = 1212
13834 measured reflectionsl = 1417
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.081 w = 1/[σ2(Fo2) + (0.034P)2 + 0.5672P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max < 0.001
1547 reflectionsΔρmax = 0.40 e Å3
45 parametersΔρmin = 0.65 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0064 (13)
Crystal data top
[CuCl2(C7H9N)4]Z = 2
Mr = 563.05Mo Kα radiation
Tetragonal, P4/nncµ = 1.00 mm1
a = 11.3324 (15) ÅT = 110 K
c = 10.894 (2) Å0.20 × 0.20 × 0.17 mm
V = 1399.0 (4) Å3
Data collection top
Nonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler
1547 independent reflections
Absorption correction: multi-scan
(SCALEPACK; Otwinowski & Minor, 1997)
1195 reflections with I > 2σ(I)
Tmin = 0.826, Tmax = 0.849Rint = 0.035
13834 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0300 restraints
wR(F2) = 0.081H-atom parameters constrained
S = 1.06Δρmax = 0.40 e Å3
1547 reflectionsΔρmin = 0.65 e Å3
45 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
xyzUiso*/Ueq
Cu10.75000.75000.25000.01052 (10)
Cl10.75000.75000.50380 (5)0.01531 (11)
N10.62202 (7)0.62202 (7)0.25000.0113 (2)
C10.62762 (9)0.53069 (9)0.17179 (11)0.01328 (19)
H10.69130.52750.11520.016*
C20.54443 (9)0.44044 (9)0.16975 (11)0.0144 (2)
C30.44920 (9)0.44920 (9)0.25000.0158 (3)
H30.38990.38990.25000.019*
C40.55841 (11)0.33732 (11)0.08414 (13)0.0238 (3)
H4A0.61200.27940.12080.036*
H4B0.59100.36470.00590.036*
H4C0.48130.30070.06990.036*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.00625 (11)0.00625 (11)0.01905 (18)0.0000.0000.000
Cl10.01361 (14)0.01361 (14)0.0187 (2)0.0000.0000.000
N10.0090 (3)0.0090 (3)0.0160 (5)0.0001 (4)0.0009 (3)0.0009 (3)
C10.0120 (4)0.0119 (4)0.0159 (5)0.0010 (3)0.0024 (4)0.0025 (4)
C20.0132 (4)0.0115 (4)0.0185 (5)0.0023 (3)0.0005 (4)0.0043 (4)
C30.0121 (3)0.0121 (3)0.0231 (7)0.0038 (4)0.0014 (4)0.0014 (4)
C40.0225 (5)0.0181 (5)0.0308 (6)0.0054 (4)0.0052 (5)0.0131 (5)
Geometric parameters (Å, º) top
Cu1—Cl12.7649 (7)C2—C41.5034 (16)
Cu1—N12.0510 (12)C3—H30.9500
N1—C11.3422 (12)C4—H4A0.9800
C1—C21.3912 (14)C4—H4B0.9800
C1—H10.9500C4—H4C0.9800
C2—C31.3924 (13)
N1i—Cu1—N190C1—N1—Cu1120.79 (6)
N1i—Cu1—N1ii180N1—C1—C2123.03 (10)
N1—Cu1—N1ii90N1—C1—H1118.5
N1i—Cu1—N1iii90C2—C1—H1118.5
N1—Cu1—N1iii180C1—C2—C3117.57 (10)
N1ii—Cu1—N1iii90C1—C2—C4120.66 (10)
N1i—Cu1—Cl1i90C3—C2—C4121.77 (10)
N1—Cu1—Cl1i90C2iv—C3—C2120.32 (13)
N1ii—Cu1—Cl1i90C2iv—C3—H3119.8
N1iii—Cu1—Cl1i90C2—C3—H3119.8
N1i—Cu1—Cl190C2—C4—H4A109.5
N1—Cu1—Cl190C2—C4—H4B109.5
N1ii—Cu1—Cl190H4A—C4—H4B109.5
N1iii—Cu1—Cl190C2—C4—H4C109.5
Cl1i—Cu1—Cl1180H4A—C4—H4C109.5
C1iv—N1—C1118.42 (12)H4B—C4—H4C109.5
C1iv—N1—Cu1120.79 (6)
N1i—Cu1—N1—C1iv47.65 (6)Cu1—N1—C1—C2178.68 (8)
Cl1i—Cu1—N1—C1iv137.65 (6)N1—C1—C2—C32.54 (16)
Cl1—Cu1—N1—C1iv42.35 (6)N1—C1—C2—C4177.05 (10)
N1i—Cu1—N1—C1132.35 (6)C1—C2—C3—C2iv1.19 (8)
Cl1—Cu1—N1—C1137.65 (6)C4—C2—C3—C2iv178.40 (13)
C1iv—N1—C1—C21.32 (8)
Symmetry codes: (i) x, y+3/2, z+1/2; (ii) x+3/2, y, z+1/2; (iii) x+3/2, y+3/2, z; (iv) y, x, z+1/2.

Experimental details

Crystal data
Chemical formula[CuCl2(C7H9N)4]
Mr563.05
Crystal system, space groupTetragonal, P4/nnc
Temperature (K)110
a, c (Å)11.3324 (15), 10.894 (2)
V3)1399.0 (4)
Z2
Radiation typeMo Kα
µ (mm1)1.00
Crystal size (mm)0.20 × 0.20 × 0.17
Data collection
DiffractometerNonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler
Absorption correctionMulti-scan
(SCALEPACK; Otwinowski & Minor, 1997)
Tmin, Tmax0.826, 0.849
No. of measured, independent and
observed [I > 2σ(I)] reflections
13834, 1547, 1195
Rint0.035
(sin θ/λ)max1)0.807
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.081, 1.06
No. of reflections1547
No. of parameters45
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.40, 0.65

Computer programs: COLLECT (Nonius, 2000), SCALEPACK (Otwinowski & Minor 1997), DENZO (Otwinowski & Minor 1997) and SCALEPACK, SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
Cu1—Cl12.7649 (7)C1—C21.3912 (14)
Cu1—N12.0510 (12)C2—C31.3924 (13)
N1—C11.3422 (12)C2—C41.5034 (16)
Cl1—Cu1—N1—C1i42.35 (6)
Symmetry code: (i) y, x, z+1/2.
 

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