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Crystal structure of bis­­(N,N,N′,N′-tetra­methyl­guanidinium) tetra­chlorido­cuprate(II)

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aLaboratoire des Produits Naturels, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, bLaboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, and cDépartement de Chimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montréal, Québec, H3C 3J7, Canada
*Correspondence e-mail: dlibasse@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 13 June 2016; accepted 21 June 2016; online 24 June 2016)

In the structure of the title salt, (C5H14N3)2[CuCl4], the CuII atom in the anion lies on a twofold rotation axis. The tetra­chlorido­cuprate(II) anion adopts a flattened tetra­hedral coordination environment and inter­acts electrostatically with the tetra­methyl­guanidinium cation. The crystal packing is additionally consolidated through N—H⋯Cl and C—H⋯Cl hydrogen bonds, resulting in a three-dimensional network structure.

1. Chemical context

The title compound belongs to the series of hybrid organic–inorganic materials of general formula A2[MX4] where A is an organic cation, M a divalent transition metal and X a halide. The copper representatives of these families have been extensively studied for their magnetic, dielectric and fluorescent properties in relation to their solid-state structures (Halvorson et al., 1990[Halvorson, K. E., Patterson, C. & Willett, R. D. (1990). Acta Cryst. B46, 508-519.]). Recent studies include examination of polymorphism in relation to electrostatic properties (Awwadi & Haddad, 2012[Awwadi, F. F. & Haddad, S. F. (2012). J. Mol. Struct. 1020, 28-32.]) or thermochroism (Aldrich et al., 2016[Aldrich, E. P., Bussey, K. A., Connell, J. R., Reinhart, E. F., Oshin, K. D., Mercado, B. Q. & Oliver, A. G. (2016). Acta Cryst. E72, 40-43.]), sometimes in relation to phase transitions (Kelley et al., 2015[Kelley, A., Nalla, S. & Bond, M. R. (2015). Acta Cryst. B71, 48-60.]).

[Scheme 1]

Following our report on the crystal structure of bis-tetra­methyl­guanidinium tri­chlorido­cadmate (Ndiaye et al., 2016[Ndiaye, M., Samb, A., Diop, L. & Maris, T. (2016). Acta Cryst. E72, 1-3.]), we have investigated the inter­actions between tetra­methyl­guanidine and CuCl2·2H2O which has yielded the title salt, (C5H14N3)2[CuCl4], (I)[link].

2. Structural commentary

The asymmetric unit of (I)[link] contains a complete N,N,N′,N′-tetra­methyl­guanidinium cation and half of a [CuCl4]2− anion held together by an N—H⋯Cl hydrogen bond (Fig. 1[link]). In the anion, the Cu—Cl distances range from 2.2396 (4) Å to 2.2557 (4) Å. They are shorter than those usually found in tetra­chlorido­cuprate(II) anions with a square-planar configuration (Guo et al., 2015[Guo, B., Zhang, X., Yu, J.-H. & Xu, J.-Q. (2015). Dalton Trans. 44, 11470-11481.]). The distortion of the flattened tetra­chlorido­cuprate(II) anion in (I)[link] from the ideal tetra­hedral configuration can be asserted by the values of the two trans Cl—Cu—Cl angles, 135.62 (3)° and 133.31 (3)°. These two angles can also be used to calculate the τ4 geometry index developed by Yang et al. (2007[Yang, L., Powell, D. R. & Houser, R. P. (2007). Dalton Trans. pp. 955-964.]) for complexes with coordination number four to qu­antify such a distortion. The τ4 parameter is defined as [360 - (α+β)] / 141 where α and β are the two largest Cl—Cu—Cl angles. A τ4 index value of 1 corresponds to an ideal tetra­hedral configuration while a value of 0 is for a perfect square-planar configuration. Here the value obtained (0.65) indicates a `see-saw' (bis­phenoidal) configuration with point group symmetry 2.

[Figure 1]
Figure 1
The structures of the mol­ecular entities in (I)[link], drawn with displacement parameters at the 50% probability level. The N—H⋯Cl hydrogen bond is indicated by a dashed line. [Symmetry code: (i) −x + 1, y, −z + [{3\over 2}].]

In the organic cation, the C—N distances in the central CN3 unit [1.332 (2), 1.335 (2) and 1.342 (2) Å] are consistent with a partial double-bond character and a positive charge delocalization, as usually found in structures involving tetra­methyl­guanidinium cations. The central core of the cation has an almost planar–trigonal geometry, as reflected by the values for the three N—C—N angles close to 120° and the r.m.s deviation from the least-squares plane calculated for atoms C1, N1, N2 and N3 that is only 0.0006 Å. The di­methyl­ammonium groups are twisted by 29.38 (16)° (C2, C3) and 25.08 (16)° (C4, C5) with respect to this plane.

3. Supra­molecular features

Anions and cations are connected through electrostatic inter­actions and via classical N—H⋯Cl hydrogen bonds involving atom Cl1 whereby only one of the H atoms of the amine group is involved; the remaining H atom has no acceptor atom (Fig. 1[link], Table 1[link]). In addition, each Cl atom of the anion is engaged in three C—H⋯Cl hydrogen bonds, leading to the formation of a three-dimensional network structure (Fig. 2[link], Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C4—H4B⋯Cl2i 0.95 (2) 2.77 (2) 3.5902 (19) 145.3 (18)
C2—H2C⋯Cl1ii 0.98 (3) 2.90 (3) 3.745 (2) 144.5 (18)
C2—H2D⋯Cl1iii 0.91 (2) 2.91 (2) 3.818 (2) 173.3 (19)
C3—H3B⋯Cl2iv 0.99 (3) 2.82 (3) 3.793 (2) 168 (2)
C5—H5C⋯Cl2v 0.93 (3) 2.80 (3) 3.5992 (18) 144.9 (19)
C2—H2E⋯Cl2vi 0.96 (3) 2.85 (3) 3.6491 (18) 140.5 (19)
N2—H2B⋯Cl1 0.86 (3) 2.53 (3) 3.3417 (16) 157 (2)
Symmetry codes: (i) [-x+1, y, -z+{\script{3\over 2}}]; (ii) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iii) [x, -y+1, z-{\script{1\over 2}}]; (iv) [-x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]; (v) [-x+1, y-1, -z+{\script{3\over 2}}]; (vi) [x-{\script{1\over 2}}, y-{\script{1\over 2}}, z-1].
[Figure 2]
Figure 2
Packing diagram of (I)[link] viewed along [001].

4. Database survey

A search in the Cambridge Structural Database (Version 5.37 with two updates; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) for isolated tetra­chlorido­cuprate(II) anions without disorder returned 342 hits for a total of 389 fragments. The configurations of these fragments were analysed using the τ4 index as described above. Around 60 of these (15%) have a τ4 index value less than 0.1, including 29 that have a τ4 index of 0 (ideal square-planar configuration). Only four were found to have a configuration close to the ideal tetra­hedral one with a τ4 index value larger than 0.9. A large number of fragments (72%) has a geometry index τ4 value in the 0.6–0.8 range and feature a bis­phenoidal configuration as found for (I)[link]. An analysis with the modified version of the τ4 index [τ4′, as defined by Okuniewski et al. (2015[Okuniewski, A., Rosiak, D., Chojnacki, J. & Becker, B. (2015). Polyhedron, 90, 47-57.])] gives a similar distribution with only minor variation.

The title compound is isostructural with bis­(N,N,N′,N′-tetra­methyl­guanidinium) tetra­bromido­nickelate(II) (Jones & Thonnessen, 2006[Jones, P. G. & Thonnessen, H. (2006). Private communication (refcode CEPXIF). CCDC, Cambridge, England.]) and shows similarities in terms of the space-group and cell parameters with tetra­methyl­guanidinium bis­ulfite (Heldebrant et al., 2009[Heldebrant, D. J., Yonker, C. R., Jessop, P. G. & Phan, L. (2009). Chem. Eur. J. 15, 7619-7627.]).

5. Synthesis and crystallization

Yellowish-green crystals were obtained by mixing in stoichiometric amounts tetra­methyl­guanidine with CuCl2·2H2O in ethanol.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. All hydrogen atoms were located from a Fourier difference map and were refined freely.

Table 2
Experimental details

Crystal data
Chemical formula (C5H14N3)2[CuCl4]
Mr 437.72
Crystal system, space group Monoclinic, C2/c
Temperature (K) 100
a, b, c (Å) 18.9274 (5), 8.2441 (2), 14.8654 (4)
β (°) 124.165 (1)
V3) 1919.28 (9)
Z 4
Radiation type Ga Kα, λ = 1.34139 Å
μ (mm−1) 9.51
Crystal size (mm) 0.16 × 0.10 × 0.06
 
Data collection
Diffractometer Bruker Venture Metaljet
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.449, 0.752
No. of measured, independent and observed [I > 2σ(I)] reflections 14222, 2208, 2178
Rint 0.036
(sin θ/λ)max−1) 0.650
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.071, 1.11
No. of reflections 2208
No. of parameters 152
H-atom treatment All H-atom parameters refined
Δρmax, Δρmin (e Å−3) 0.84, −0.35
Computer programs: APEX2 and SAINT (Bruker, 2014[Bruker (2014). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009) and publCIF (Westrip, 2010).

Bis(N,N,N',N'-tetramethylguanidinium) tetrachloridocuprate(II) top
Crystal data top
(C5H14N3)2[CuCl4]F(000) = 908
Mr = 437.72Dx = 1.515 Mg m3
Monoclinic, C2/cGa Kα radiation, λ = 1.34139 Å
a = 18.9274 (5) ÅCell parameters from 9968 reflections
b = 8.2441 (2) Åθ = 4.9–60.7°
c = 14.8654 (4) ŵ = 9.51 mm1
β = 124.165 (1)°T = 100 K
V = 1919.28 (9) Å3Block, clear yellowish green
Z = 40.16 × 0.10 × 0.06 mm
Data collection top
Bruker Venture Metaljet
diffractometer
2208 independent reflections
Radiation source: Metal Jet, Gallium Liquid Metal Jet Source2178 reflections with I > 2σ(I)
Helios MX Mirror Optics monochromatorRint = 0.036
Detector resolution: 10.24 pixels mm-1θmax = 60.7°, θmin = 4.9°
ω and φ scansh = 2424
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
k = 1010
Tmin = 0.449, Tmax = 0.752l = 1619
14222 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.028All H-atom parameters refined
wR(F2) = 0.071 w = 1/[σ2(Fo2) + (0.0315P)2 + 2.7253P]
where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max = 0.001
2208 reflectionsΔρmax = 0.84 e Å3
152 parametersΔρmin = 0.35 e Å3
0 restraints
Special details top

Experimental. X-ray crystallographic data for I were collected from a single crystal sample, which was mounted on a loop fiber. Data were collected using a Bruker Venture diffractometer equipped with a Photon 100 CMOS Detector, a Helios MX optics and a Kappa goniometer. The crystal-to-detector distance was 4.0 cm, and the data collection was carried out in 1024 x 1024 pixel mode.

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
xyzUiso*/Ueq
N10.18244 (9)0.33219 (19)0.30111 (11)0.0202 (3)
N20.24981 (11)0.5129 (2)0.44495 (13)0.0277 (4)
N30.32977 (9)0.32615 (17)0.42260 (11)0.0164 (3)
C10.25428 (10)0.3903 (2)0.38962 (13)0.0173 (3)
C20.17917 (12)0.2676 (2)0.20725 (14)0.0215 (3)
C30.09950 (12)0.3500 (3)0.28512 (17)0.0314 (4)
C40.40978 (11)0.4132 (2)0.49381 (15)0.0235 (4)
C50.33922 (12)0.1564 (2)0.40153 (15)0.0208 (3)
Cu10.50000.71829 (4)0.75000.01698 (11)
Cl10.37443 (3)0.61496 (7)0.70754 (4)0.03106 (13)
Cl20.54835 (3)0.82595 (5)0.91317 (3)0.02989 (13)
H4A0.4363 (15)0.380 (3)0.569 (2)0.030 (6)*
H5A0.2894 (16)0.099 (3)0.3780 (19)0.029 (6)*
H4B0.4000 (14)0.526 (3)0.4851 (18)0.024 (5)*
H2C0.1702 (16)0.150 (3)0.2047 (19)0.030 (6)*
H2D0.2285 (15)0.291 (3)0.2132 (18)0.022 (5)*
H3A0.0693 (18)0.248 (4)0.260 (2)0.040 (7)*
H2A0.2102 (18)0.568 (4)0.418 (2)0.037 (7)*
H3B0.0655 (19)0.432 (4)0.228 (2)0.050 (8)*
H5B0.3539 (15)0.147 (3)0.349 (2)0.028 (6)*
H5C0.3857 (16)0.111 (3)0.465 (2)0.028 (6)*
H2E0.1316 (16)0.319 (3)0.143 (2)0.028 (6)*
H4C0.4454 (16)0.389 (3)0.468 (2)0.033 (6)*
H2B0.2934 (17)0.536 (3)0.509 (2)0.035 (6)*
H3C0.1050 (17)0.373 (3)0.352 (2)0.040 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0176 (6)0.0242 (7)0.0155 (6)0.0023 (6)0.0072 (5)0.0054 (6)
N20.0225 (7)0.0289 (8)0.0186 (7)0.0092 (7)0.0036 (6)0.0097 (6)
N30.0174 (6)0.0135 (6)0.0163 (6)0.0003 (5)0.0083 (5)0.0008 (5)
C10.0196 (7)0.0167 (7)0.0130 (7)0.0028 (6)0.0075 (6)0.0001 (6)
C20.0273 (9)0.0215 (9)0.0134 (8)0.0026 (7)0.0102 (7)0.0044 (6)
C30.0182 (8)0.0432 (12)0.0264 (9)0.0061 (8)0.0086 (7)0.0100 (9)
C40.0194 (8)0.0228 (9)0.0223 (8)0.0040 (7)0.0079 (7)0.0029 (7)
C50.0234 (8)0.0132 (7)0.0253 (9)0.0028 (7)0.0135 (7)0.0000 (7)
Cu10.01872 (18)0.01483 (18)0.01209 (17)0.0000.00542 (14)0.000
Cl10.0201 (2)0.0510 (3)0.0243 (2)0.00970 (18)0.01383 (17)0.01532 (19)
Cl20.0501 (3)0.0180 (2)0.01273 (19)0.00519 (18)0.01222 (18)0.00224 (14)
Geometric parameters (Å, º) top
N1—C11.342 (2)C3—H3B0.99 (3)
N1—C21.462 (2)C3—H3C0.96 (3)
N1—C31.457 (2)C4—H4A0.97 (3)
N2—C11.335 (2)C4—H4B0.95 (2)
N2—H2A0.77 (3)C4—H4C0.97 (3)
N2—H2B0.86 (3)C5—H5A0.93 (3)
N3—C11.332 (2)C5—H5B0.96 (2)
N3—C41.459 (2)C5—H5C0.93 (3)
N3—C51.467 (2)Cu1—Cl1i2.2557 (4)
C2—H2C0.98 (3)Cu1—Cl12.2557 (4)
C2—H2D0.91 (2)Cu1—Cl2i2.2396 (4)
C2—H2E0.96 (3)Cu1—Cl22.2396 (4)
C3—H3A0.96 (3)
C1—N1—C2122.85 (14)H3A—C3—H3B108 (2)
C1—N1—C3121.97 (14)H3A—C3—H3C105 (2)
C3—N1—C2114.63 (14)H3B—C3—H3C113 (2)
C1—N2—H2A120 (2)N3—C4—H4A110.4 (14)
C1—N2—H2B119.9 (17)N3—C4—H4B110.0 (14)
H2A—N2—H2B120 (3)N3—C4—H4C106.3 (15)
C1—N3—C4122.24 (14)H4A—C4—H4B112 (2)
C1—N3—C5122.31 (14)H4A—C4—H4C112 (2)
C4—N3—C5115.01 (14)H4B—C4—H4C106 (2)
N2—C1—N1119.64 (15)N3—C5—H5A110.2 (15)
N3—C1—N1120.38 (15)N3—C5—H5B111.8 (15)
N3—C1—N2119.98 (15)N3—C5—H5C109.2 (15)
N1—C2—H2C108.1 (14)H5A—C5—H5B110 (2)
N1—C2—H2D109.8 (14)H5A—C5—H5C111 (2)
N1—C2—H2E107.2 (15)H5B—C5—H5C104 (2)
H2C—C2—H2D111 (2)Cl1—Cu1—Cl1i135.62 (3)
H2C—C2—H2E110 (2)Cl2—Cu1—Cl1100.265 (17)
H2D—C2—H2E110 (2)Cl2i—Cu1—Cl196.958 (19)
N1—C3—H3A109.1 (16)Cl2—Cu1—Cl1i96.959 (19)
N1—C3—H3B109.1 (17)Cl2i—Cu1—Cl1i100.264 (17)
N1—C3—H3C111.8 (16)Cl2—Cu1—Cl2i133.31 (3)
C2—N1—C1—N2146.94 (18)C4—N3—C1—N1159.80 (16)
C2—N1—C1—N333.3 (3)C4—N3—C1—N220.4 (2)
C3—N1—C1—N224.1 (3)C5—N3—C1—N128.2 (2)
C3—N1—C1—N3155.67 (18)C5—N3—C1—N2151.61 (17)
Symmetry code: (i) x+1, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H4B···Cl2i0.95 (2)2.77 (2)3.5902 (19)145.3 (18)
C2—H2C···Cl1ii0.98 (3)2.90 (3)3.745 (2)144.5 (18)
C2—H2D···Cl1iii0.91 (2)2.91 (2)3.818 (2)173.3 (19)
C3—H3B···Cl2iv0.99 (3)2.82 (3)3.793 (2)168 (2)
C5—H5C···Cl2v0.93 (3)2.80 (3)3.5992 (18)144.9 (19)
C2—H2E···Cl2vi0.96 (3)2.85 (3)3.6491 (18)140.5 (19)
N2—H2B···Cl10.86 (3)2.53 (3)3.3417 (16)157 (2)
Symmetry codes: (i) x+1, y, z+3/2; (ii) x+1/2, y+1/2, z+1; (iii) x, y+1, z1/2; (iv) x+1/2, y+3/2, z+1; (v) x+1, y1, z+3/2; (vi) x1/2, y1/2, z1.
 

Acknowledgements

The authors acknowledge the Cheikh Anta Diop University of Dakar (Sénégal), the Canada Foundation for Innovation and the Université de Montréal for financial support.

References

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