Crystal structure of the monoclinic phase (phase IV) of bis­(tetra­methyl­ammonium) tetra­chlorido­cuprate(II)

Seck, G.A.; Diop, L.; Oliver, A.G.

doi:10.1107/S2056989017002146

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Volume 73| Part 3| March 2017| Pages 358-360

https://doi.org/10.1107/S2056989017002146

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Crystal structure of the monoclinic phase (phase IV) of bis(tetramethylammonium) tetrachloridocuprate(II)

Gorgui Awa Seck,^a Libasse Diop ^a ^* and Allen G. Oliver ^b

^aLaboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, and ^bDepartment of Chemistry and Biochemistry, University of Notre Dame, IN 46557-5670, USA
^*Correspondence e-mail: dlibasse@gmail.com

Edited by H. Ishida, Okayama University, Japan (Received 12 December 2016; accepted 9 February 2017; online 14 February 2017)

The crystal structure of the low-temperature monoclinic phase of the title compound, [(CH₃)₄N]₂[CuCl₄], was determined at 120 K. The structure of the room-temperature phase has been determined in the orthorhombic space group Pmcm [Morosin & Lingafelter (1961 ). J. Phys. Chem. 50–51; Clay et al. (1975 ). Acta Cryst. B31 289–290]. The asymmetric unit consists of one discrete tetrachloridocuprate anion with a distorted tetrahedral geometry and two tetramethylammonium cations. In the crystal, the cations and the anions are linked via weak C—H⋯Cl hydrogen bonds.

Keywords: crystal structure; tetrahedral tetrachloridocuprate ion; tetramethylammonium ion.

CCDC reference: 1531866

1. Chemical context

The title compound undergoes successive phase transitions at 297, 291 and 263 K (Sugiyama et al., 1980 ). The room temperature phase (phase I) crystallizes in the orthorhombic space group Pmcm with Z = 4 (Morosin & Lingafelter, 1961; Clay et al., 1975). Three low-temperature phases, named phases II, III and IV in the order of decreasing temperature, show incommensurate, ferroelastic commensurate monoclinic and monoclinic structures, respectively (Sugiyama et al., 1980; Gesi & Iizumi, 1980 ). We allowed [(CH₃)₄N]Cl, CuCl₂ and thioacetamide to react in ethanol. The expected mixed ligand complex was not crystallized but instead the title compound was obtained accidentally. The crystal structure of phase IV of the title compound was determined at 120 K and is reported herein.

2. Structural commentary

The asymmetric unit of the title compound consists of a discrete [CuCl₄]²⁻ anion and two crystallographically tetramethylammonium cations (Fig. 1). In the anion, the four Cl atoms are inequivalent with Cu—Cl distances ranging from 2.2313 (15) to 2.2538 (16) Å. The Cl—Cu—Cl angles vary from 98.44 (7) to 133.69 (7)°, indicating a distorted tetrahedral geometry around the Cu^II atom. Using Houser's τ₄ metric [τ₄ = 360 − (α + β)/141], where α and β are the largest angles about the metal atom (Yang et al., 2007 ), we obtain a value of 0.658 for phase IV and 0.792 for the orthorhombic phase I. This indicates a greater deviation from an ideal tetrahedron in phase IV compared with phase I, tending towards a `see-saw' geometry.

Figure 1
The asymmetric unit of the title compound showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are depicted as spheres of an arbitrary radius.

3. Supramolecular features

In the crystal, the cations and the anions are linked via weak C—H⋯Cl hydrogen bonds (Table 1 and Fig. 2), forming a three-dimensional network.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1C⋯Cl2ⁱ	0.98	2.69	3.585 (7)	153
C2—H2A⋯Cl1ⁱⁱ	0.98	2.79	3.675 (7)	151
C2—H2A⋯Cl3ⁱⁱ	0.98	2.80	3.555 (7)	134
C2—H2B⋯Cl1ⁱ	0.98	2.79	3.674 (7)	150
C3—H3B⋯Cl4	0.98	2.74	3.670 (7)	159
C4—H4A⋯Cl3ⁱⁱⁱ	0.98	2.59	3.555 (7)	166
C5—H5A⋯Cl2^iv	0.98	2.68	3.635 (7)	165
C5—H5B⋯Cl3^v	0.98	2.81	3.587 (6)	137
C5—H5C⋯Cl4ⁱ	0.98	2.63	3.610 (6)	173
C8—H8B⋯Cl1ⁱⁱⁱ	0.98	2.76	3.650 (6)	151
C8—H8C⋯Cl2^v	0.98	2.82	3.763 (7)	162
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) x-1, y, z; (iii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) x, y-1, z; (v) -x+2, -y+1, -z+1.

Figure 2
A packing diagram of the title compound, viewed along the a axis, showing the C—H⋯Cl hydrogen bonds (blue dashed lines).

4. Database survey

A substructure search for compounds that incorporate a tetramethylammonium ion and a copper tetrachloride species reveals thirteen structures (CSD November 2016; Groom et al., 2016 ). Of these, three are structures of (Me₄N)₂[CuCl₄] with a discrete [CuCl₄]²⁻ anion (Morosin & Lingafelter, 1961; Clay et al., 1975; Hlel et al., 2008 ).

5. Synthesis and crystallization

On mixing [(CH₃)₄N]Cl (0.465 g, 4.2 mmol) in ethanol (10 ml) with CuCl₂·2H₂O (0.365 g, 2.1 mmol) in ethanol (10 ml) and thioacetamide (0.160 g, 2.1 mmol) in ethanol (10 ml), a clear solution is obtained. Slow evaporation at room temperature (301 K) yielded pale-green crystals of [(CH₃)₄N]₂[CuCl₄] suitable for X-ray determination.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were included in idealized geometries and allowed to rotate to minimize their electron-density contribution with C—H = 0.98 Å and U_iso(H) = 1.5U_eq(C). The crystal used was found to be twinned through a 180° rotation about the reciprocal a axis with a twin component ratio of 0.76:0.24 (matrix: [1.000 −0.003 0.004 0.001 −1.000 −0.003 −0.093 0.005 −1.000]) . The diffraction data were integrated routinely applying this matrix and were scaled for absorption effects using TWINABS (Krause et al., 2015 ). In the final model, incorporation of the twinned data did not significantly alter the model, thus the final model was refined using the majority component data.

Table 2
Experimental details

Crystal data
Chemical formula	(C₄H₁₂N)₂[CuCl₄]
M_r	353.63
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	120
a, b, c (Å)	8.9901 (5), 12.0059 (7), 14.9570 (9)
β (°)	91.719 (3)
V (Å³)	1613.65 (16)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	1.99
Crystal size (mm)	0.15 × 0.12 × 0.11

Data collection
Diffractometer	Bruker APEXII
Absorption correction	Multi-scan (TWINABS; Krause et al., 2015)
T_min, T_max	0.659, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	7842, 4019, 2862
R_int	0.057
(sin θ/λ)_max (Å⁻¹)	0.669

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.066, 0.141, 1.12
No. of reflections	4019
No. of parameters	144
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.16, −1.03
Computer programs: APEX3 and SAINT (Bruker, 2015 ), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), XP in SHELXTL (Sheldrick, 2008 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1531866

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989017002146/is5469sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017002146/is5469Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2015); cell refinement: SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Bis(tetramethylammonium) tetrachloridocuprate(II) top

Crystal data top

(C₄H₁₂N)₂[CuCl₄]	F(000) = 732
M_r = 353.63	D_x = 1.456 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.9901 (5) Å	Cell parameters from 6598 reflections
b = 12.0059 (7) Å	θ = 2.6–24.7°
c = 14.9570 (9) Å	µ = 1.99 mm⁻¹
β = 91.719 (3)°	T = 120 K
V = 1613.65 (16) Å³	Block, pale green
Z = 4	0.15 × 0.12 × 0.11 mm

Data collection top

Bruker APEXII diffractometer	4019 independent reflections
Radiation source: fine-focus sealed tube	2862 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.057
Detector resolution: 8.33 pixels mm^-1	θ_max = 28.4°, θ_min = 2.2°
combination of ω and φ–scans	h = −12→12
Absorption correction: multi-scan (TWINABS; Krause et al., 2015)	k = −16→16
T_min = 0.659, T_max = 0.746	l = 0→19
7842 measured reflections

Refinement top

Refinement on F²	Primary atom site location: real-space vector search
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.141	H-atom parameters constrained
S = 1.12	w = 1/[σ²(F_o²) + 15.8242P] where P = (F_o² + 2F_c²)/3
4019 reflections	(Δ/σ)_max < 0.001
144 parameters	Δρ_max = 1.16 e Å⁻³
0 restraints	Δρ_min = −1.03 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	U_iso*/U_eq
Cu1	0.77037 (7)	0.71890 (6)	0.60734 (5)	0.01762 (17)
Cl1	0.78370 (15)	0.53786 (11)	0.64164 (10)	0.0211 (3)
Cl2	0.79189 (17)	0.81507 (13)	0.47896 (10)	0.0275 (3)
Cl3	0.97801 (15)	0.77628 (13)	0.67958 (10)	0.0267 (3)
Cl4	0.52836 (16)	0.74708 (14)	0.62755 (13)	0.0363 (4)
N1	0.2548 (5)	0.4839 (4)	0.6659 (3)	0.0183 (10)
C1	0.1601 (7)	0.3893 (5)	0.6925 (5)	0.0322 (15)
H1A	0.0671	0.4177	0.7162	0.048*
H1B	0.2128	0.3452	0.7386	0.048*
H1C	0.1378	0.3422	0.6403	0.048*
C2	0.1815 (7)	0.5491 (6)	0.5923 (4)	0.0328 (15)
H2A	0.0840	0.5750	0.6113	0.049*
H2B	0.1685	0.5017	0.5392	0.049*
H2C	0.2436	0.6133	0.5779	0.049*
C3	0.2801 (7)	0.5574 (6)	0.7446 (5)	0.0344 (16)
H3A	0.1846	0.5868	0.7639	0.052*
H3B	0.3451	0.6192	0.7284	0.052*
H3C	0.3273	0.5146	0.7935	0.052*
C4	0.4008 (6)	0.4411 (6)	0.6347 (5)	0.0296 (14)
H4A	0.4516	0.4002	0.6834	0.044*
H4B	0.4629	0.5038	0.6167	0.044*
H4C	0.3836	0.3912	0.5836	0.044*
N2	0.7505 (5)	0.1309 (4)	0.5840 (3)	0.0198 (10)
C5	0.7809 (7)	0.1175 (6)	0.4871 (4)	0.0279 (14)
H5A	0.7882	0.0381	0.4727	0.042*
H5B	0.8748	0.1545	0.4738	0.042*
H5C	0.6998	0.1511	0.4512	0.042*
C6	0.6058 (7)	0.0788 (6)	0.6059 (5)	0.0334 (16)
H6A	0.6112	−0.0018	0.5957	0.050*
H6B	0.5264	0.1106	0.5675	0.050*
H6C	0.5846	0.0931	0.6687	0.050*
C7	0.7444 (8)	0.2520 (5)	0.6048 (5)	0.0347 (16)
H7A	0.7225	0.2622	0.6681	0.052*
H7B	0.6661	0.2872	0.5676	0.052*
H7C	0.8405	0.2863	0.5925	0.052*
C8	0.8722 (7)	0.0776 (6)	0.6381 (4)	0.0304 (15)
H8A	0.8733	−0.0026	0.6260	0.046*
H8B	0.8558	0.0901	0.7018	0.046*
H8C	0.9678	0.1102	0.6222	0.046*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0169 (3)	0.0172 (3)	0.0188 (3)	0.0000 (3)	0.0018 (2)	0.0003 (3)
Cl1	0.0216 (7)	0.0157 (6)	0.0261 (7)	0.0009 (5)	0.0031 (5)	0.0006 (5)
Cl2	0.0355 (8)	0.0277 (8)	0.0195 (7)	−0.0040 (6)	0.0024 (6)	0.0043 (6)
Cl3	0.0227 (7)	0.0268 (8)	0.0304 (8)	−0.0034 (6)	−0.0019 (6)	−0.0028 (6)
Cl4	0.0169 (7)	0.0303 (8)	0.0621 (12)	0.0049 (6)	0.0097 (7)	0.0129 (8)
N1	0.014 (2)	0.018 (2)	0.022 (3)	0.0001 (18)	−0.0003 (18)	0.0018 (19)
C1	0.028 (3)	0.022 (3)	0.047 (4)	−0.010 (3)	0.012 (3)	−0.005 (3)
C2	0.030 (3)	0.048 (4)	0.020 (3)	0.013 (3)	−0.004 (3)	0.007 (3)
C3	0.038 (4)	0.037 (4)	0.028 (4)	−0.016 (3)	−0.001 (3)	−0.001 (3)
C4	0.020 (3)	0.030 (4)	0.038 (4)	0.006 (3)	0.008 (3)	0.007 (3)
N2	0.020 (2)	0.020 (2)	0.019 (3)	0.0022 (19)	0.0043 (19)	0.0018 (19)
C5	0.036 (4)	0.031 (3)	0.016 (3)	0.009 (3)	0.002 (3)	0.001 (3)
C6	0.021 (3)	0.031 (4)	0.048 (4)	−0.006 (3)	0.007 (3)	0.005 (3)
C7	0.051 (4)	0.022 (3)	0.032 (4)	0.001 (3)	0.009 (3)	−0.002 (3)
C8	0.025 (3)	0.043 (4)	0.023 (3)	0.009 (3)	0.001 (2)	0.010 (3)

Geometric parameters (Å, º) top

Cu1—Cl4	2.2313 (15)	C4—H4B	0.9800
Cu1—Cl1	2.2357 (15)	C4—H4C	0.9800
Cu1—Cl3	2.2374 (15)	N2—C8	1.486 (7)
Cu1—Cl2	2.2538 (16)	N2—C7	1.488 (8)
N1—C1	1.481 (7)	N2—C6	1.488 (7)
N1—C3	1.483 (8)	N2—C5	1.491 (7)
N1—C2	1.488 (7)	C5—H5A	0.9800
N1—C4	1.498 (7)	C5—H5B	0.9800
C1—H1A	0.9800	C5—H5C	0.9800
C1—H1B	0.9800	C6—H6A	0.9800
C1—H1C	0.9800	C6—H6B	0.9800
C2—H2A	0.9800	C6—H6C	0.9800
C2—H2B	0.9800	C7—H7A	0.9800
C2—H2C	0.9800	C7—H7B	0.9800
C3—H3A	0.9800	C7—H7C	0.9800
C3—H3B	0.9800	C8—H8A	0.9800
C3—H3C	0.9800	C8—H8B	0.9800
C4—H4A	0.9800	C8—H8C	0.9800

Cl4—Cu1—Cl1	99.33 (6)	N1—C4—H4C	109.5
Cl4—Cu1—Cl3	133.69 (7)	H4A—C4—H4C	109.5
Cl1—Cu1—Cl3	98.64 (6)	H4B—C4—H4C	109.5
Cl4—Cu1—Cl2	98.44 (7)	C8—N2—C7	109.7 (5)
Cl1—Cu1—Cl2	133.48 (6)	C8—N2—C6	109.5 (5)
Cl3—Cu1—Cl2	99.32 (6)	C7—N2—C6	109.1 (5)
C1—N1—C3	108.6 (5)	C8—N2—C5	109.2 (4)
C1—N1—C2	110.9 (5)	C7—N2—C5	108.5 (5)
C3—N1—C2	109.2 (5)	C6—N2—C5	110.8 (5)
C1—N1—C4	109.7 (5)	N2—C5—H5A	109.5
C3—N1—C4	109.6 (5)	N2—C5—H5B	109.5
C2—N1—C4	108.9 (5)	H5A—C5—H5B	109.5
N1—C1—H1A	109.5	N2—C5—H5C	109.5
N1—C1—H1B	109.5	H5A—C5—H5C	109.5
H1A—C1—H1B	109.5	H5B—C5—H5C	109.5
N1—C1—H1C	109.5	N2—C6—H6A	109.5
H1A—C1—H1C	109.5	N2—C6—H6B	109.5
H1B—C1—H1C	109.5	H6A—C6—H6B	109.5
N1—C2—H2A	109.5	N2—C6—H6C	109.5
N1—C2—H2B	109.5	H6A—C6—H6C	109.5
H2A—C2—H2B	109.5	H6B—C6—H6C	109.5
N1—C2—H2C	109.5	N2—C7—H7A	109.5
H2A—C2—H2C	109.5	N2—C7—H7B	109.5
H2B—C2—H2C	109.5	H7A—C7—H7B	109.5
N1—C3—H3A	109.5	N2—C7—H7C	109.5
N1—C3—H3B	109.5	H7A—C7—H7C	109.5
H3A—C3—H3B	109.5	H7B—C7—H7C	109.5
N1—C3—H3C	109.5	N2—C8—H8A	109.5
H3A—C3—H3C	109.5	N2—C8—H8B	109.5
H3B—C3—H3C	109.5	H8A—C8—H8B	109.5
N1—C4—H4A	109.5	N2—C8—H8C	109.5
N1—C4—H4B	109.5	H8A—C8—H8C	109.5
H4A—C4—H4B	109.5	H8B—C8—H8C	109.5

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1C···Cl2ⁱ	0.98	2.69	3.585 (7)	153
C2—H2A···Cl1ⁱⁱ	0.98	2.79	3.675 (7)	151
C2—H2A···Cl3ⁱⁱ	0.98	2.80	3.555 (7)	134
C2—H2B···Cl1ⁱ	0.98	2.79	3.674 (7)	150
C3—H3B···Cl4	0.98	2.74	3.670 (7)	159
C4—H4A···Cl3ⁱⁱⁱ	0.98	2.59	3.555 (7)	166
C5—H5A···Cl2^iv	0.98	2.68	3.635 (7)	165
C5—H5B···Cl3^v	0.98	2.81	3.587 (6)	137
C5—H5C···Cl4ⁱ	0.98	2.63	3.610 (6)	173
C8—H8B···Cl1ⁱⁱⁱ	0.98	2.76	3.650 (6)	151
C8—H8C···Cl2^v	0.98	2.82	3.763 (7)	162

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) −x+3/2, y−1/2, −z+3/2; (iv) x, y−1, z; (v) −x+2, −y+1, −z+1.

Acknowledgements

The authors acknowledge the Cheikh Anta Diop University of Dakar (Senegal) and the University of Notre Dame (USA) for equipment support.

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