The crystal structure of the polymeric title complex, [CuCl
2(C
3H
6N
4)]
n, has been solved from laboratory X-ray powder diffraction data collected at room temperature. The structural model obtained was refined with the Rietveld method using geometric soft restraints. There are two Cu atoms, two Cl atoms and one 1,5-dimethyltetrazole ligand in the asymmetric unit. Both Cu atoms lie on inversion centres and adopt essentially elongated octahedral coordination. Within the octahedra, the elongated axial positions are occupied by Cl atoms, while two Cl and two N atoms (N3 and N4 of the tetrazole ring) are in equatorial sites. Each Cl atom forms an asymmetric bridge between neighbouring Cu atoms, which are also bridged
via the N3—N4 bond of the tetrazole ring. These bridges result in the formation of polymeric chains, running along the
a axis, with weak C—H
Cl hydrogen bonds crosslinking the chains.
Supporting information
CCDC reference: 632926
A solution of CuCl2·2H2O (0.94 g, 0.0055 mol) in methanol (10 ml) was added to a solution of 1,5-dimethyltetrazole (1.10 g, 0.011 mol) in a mixture of methanol and diethyl ether (1:2 v/v, 30 ml) with stirring at room temperature. The reaction mixture was stirred for 0.5 h. The resulting green–blue crystals of (I) were filtered, washed with a mixture of methanol and diethyl ether (1:3 v/v, 2 × 25 ml) and air dried (1.13 g, yield 89%). Calculated (%): Cu 27.3; found (%): Cu 27.1.
The TREOR90 program (Werner et al., 1985), was used to index the powder diffraction pattern to a triclinic cell [F20 = 88, M20 = 50, F39 = 92, M39 = 35]. The possible space groups, P1 and P1, were used for crystal structure solution with the direct methods package EXPO (Altomare et al., 1999). Only P1 was found to be appropriate. All non-H atoms were located by structure solution, with RF = 0.105.
The solved structure was then refined against the full data set using the Rietveld method as implemented in the FULLPROF program (Rodríguez-Carvajal, 2001). A correction for profile asymmetry was made for reflections up to 2θ = 40°. A Marsh–Dollase correction of intensities for the [100] preferred orientation of needle-like grains in the sample (Marsh, 1932; Dollase, 1986) was applied. The refined value of the preferred orientation coefficient G1 was 1.076 (3). The G2 parameter was found to be practically equal to 0 and was not included in the final refinement. The atomic displacement parameters were refined isotropically, those for N and C atoms being refined as one parameter. The H atoms were placed in calculated positions (C—H = 0.96 Å; Sheldrick, 1997), with displacement parameters Uiso(H) = 0.05 Å2, corresponding to the relationship Uiso(H) = 1.5Uiso(C) for the methyl group. The final structure was obtained as a result of refinement with soft restraints on the interatomic distances and bond angles of the ligand molecule. The distance and angle restraints were based on a geometric analysis of a large number of 1- and 1,5-substituted tetrazoles (CSD). The final Rietveld refinement plots are shown in Fig. 3.
Data collection: local program; cell refinement: FULLPROF (Rodríguez-Carvajal, 2001); data reduction: local program; program(s) used to solve structure: EXPO (Altomare et al., 1999); program(s) used to refine structure: FULLPROF; molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: FULLPROF and PLATON.
catena-poly[[di-µ-chloro-
κ21:2-µ-1,5-dimethyl-1
H-tetrazole-
κ2N3:
N4]copper(II)]
top
Crystal data top
[CuCl2(C3H6N4)] | V = 374.15 (4) Å3 |
Mr = 232.57 | Z = 2 |
Triclinic, P1 | F(000) = 230 |
Hall symbol: -P 1 | Dx = 2.064 Mg m−3 |
a = 6.8117 (4) Å | Co Kα radiation, λ = 1.79021 Å |
b = 7.4177 (4) Å | T = 295 K |
c = 8.6722 (4) Å | Particle morphology: needle |
α = 109.167 (2)° | green-blue |
β = 105.528 (3)° | flat sheet, 30 × 30 mm |
γ = 103.121 (3)° | Specimen preparation: Prepared at 295 K |
Data collection top
Carl Zeiss HZG-4A diffractometer | Data collection mode: reflection |
Radiation source: fine-focus sealed X-ray tube, BSV-29 | Scan method: step |
Fe filtered monochromator | 2θmin = 12°, 2θmax = 141.44°, 2θstep = 0.02° |
Specimen mounting: packed powder pellet | |
Refinement top
Refinement on Inet | Profile function: pseudo-Voigt profile function was used.
The refined value of the η-parameter is 0.779(14). |
Least-squares matrix: full with fixed elements per cycle | 52 parameters |
Rp = 0.078 | 16 restraints |
Rwp = 0.104 | 0 constraints |
Rexp = 0.136 | H-atom parameters constrained |
RBragg = 0.098 | Weighting scheme based on measured s.u.'s |
R(F2) = 0.066 | (Δ/σ)max = 0.05 |
χ2 = 0.578 | Background function: Polynomial background function was used.
The refined values of five coefficients are:
25.92(11), -16.65(19), 12.45(14), -0.34(5), -0.02(2). |
6473 data points | Preferred orientation correction: A Marsh–Dollase correction of intensities (Marsh, 1932; Dollase,
1986)
for the [100] preferred orientation of needle-like grains was applied.
The refined value of coefficient G1 is 1.076(3). The G2 parameter was found to be practically equal to 0 and was not included in the final refinement. |
Crystal data top
[CuCl2(C3H6N4)] | β = 105.528 (3)° |
Mr = 232.57 | γ = 103.121 (3)° |
Triclinic, P1 | V = 374.15 (4) Å3 |
a = 6.8117 (4) Å | Z = 2 |
b = 7.4177 (4) Å | Co Kα radiation, λ = 1.79021 Å |
c = 8.6722 (4) Å | T = 295 K |
α = 109.167 (2)° | flat sheet, 30 × 30 mm |
Data collection top
Carl Zeiss HZG-4A diffractometer | Scan method: step |
Specimen mounting: packed powder pellet | 2θmin = 12°, 2θmax = 141.44°, 2θstep = 0.02° |
Data collection mode: reflection | |
Refinement top
Rp = 0.078 | χ2 = 0.578 |
Rwp = 0.104 | 6473 data points |
Rexp = 0.136 | 52 parameters |
RBragg = 0.098 | 16 restraints |
R(F2) = 0.066 | H-atom parameters constrained |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cu1 | 0.00000 | 1.00000 | 0.00000 | 0.010 (1)* | |
Cu2 | 0.50000 | 1.00000 | 0.00000 | 0.009 (1)* | |
Cl1 | 0.5848 (8) | 0.7261 (6) | −0.1161 (6) | 0.022 (2)* | |
Cl2 | −0.0624 (7) | 1.1695 (6) | 0.2365 (6) | 0.027 (2)* | |
N1 | 0.2835 (6) | 0.7441 (13) | 0.3294 (10) | 0.033 (2)* | |
N2 | 0.4575 (6) | 0.8019 (17) | 0.2868 (11) | 0.033 (2)* | |
N3 | 0.4033 (6) | 0.8720 (18) | 0.1694 (13) | 0.033 (2)* | |
N4 | 0.1911 (5) | 0.8496 (18) | 0.1370 (9) | 0.033 (2)* | |
C5 | 0.1267 (2) | 0.8053 (5) | 0.2549 (4) | 0.033 (2)* | |
C6 | −0.0950 (8) | 0.7326 (18) | 0.2506 (17) | 0.033 (2)* | |
H6A | −0.0895 | 0.7140 | 0.3560 | 0.050* | |
H6B | −0.1772 | 0.6054 | 0.1502 | 0.050* | |
H6C | −0.1633 | 0.8309 | 0.2430 | 0.050* | |
C7 | 0.305 (3) | 0.6519 (19) | 0.4562 (14) | 0.033 (2)* | |
H7A | 0.4404 | 0.6278 | 0.4804 | 0.050* | |
H7B | 0.1873 | 0.5252 | 0.4080 | 0.050* | |
H7C | 0.3018 | 0.7423 | 0.5633 | 0.050* | |
Geometric parameters (Å, º) top
N1—N2 | 1.354 (10) | Cu1—Cl2 | 2.233 (5) |
N1—C5 | 1.344 (8) | Cu1—N4 | 2.248 (10) |
N1—C7 | 1.467 (16) | Cu1—Cl1i | 2.768 (5) |
N2—N3 | 1.295 (16) | Cu1—Cl2ii | 2.233 (5) |
N3—N4 | 1.356 (8) | Cu1—N4ii | 2.248 (10) |
N4—C5 | 1.320 (10) | Cu1—Cl1iii | 2.768 (5) |
C5—C6 | 1.470 (9) | Cu2—Cl1 | 2.231 (5) |
C6—H6A | 0.9600 | Cu2—N3 | 2.155 (12) |
C6—H6B | 0.9600 | Cu2—Cl2iv | 2.829 (5) |
C6—H6C | 0.9600 | Cu2—Cl2ii | 2.829 (5) |
C7—H7A | 0.9600 | Cu2—Cl1iii | 2.231 (5) |
C7—H7B | 0.9600 | Cu2—N3iii | 2.155 (12) |
C7—H7C | 0.9600 | | |
| | | |
N1—N2—N3 | 108.3 (6) | Cl2iv—Cu2—N3 | 90.9 (2) |
N1—C5—N4 | 102.4 (5) | Cl2ii—Cu2—N3 | 89.1 (2) |
N2—N3—N4 | 105.2 (9) | Cl1iii—Cu2—N3 | 91.8 (3) |
N2—N1—C5 | 109.4 (8) | N3—Cu2—N3iii | 180.00 |
N3—N4—C5 | 111.8 (8) | Cl2iv—Cu2—Cl2ii | 180.00 |
N2—N1—C7 | 117.9 (10) | Cl1iii—Cu2—Cl2iv | 95.29 (17) |
C5—N1—C7 | 132.3 (9) | Cl2iv—Cu2—N3iii | 89.1 (2) |
N1—C5—C6 | 121.6 (7) | Cl1iii—Cu2—Cl2ii | 84.71 (17) |
N4—C5—C6 | 129.0 (6) | Cl2ii—Cu2—N3iii | 90.9 (2) |
Cl2—Cu1—N4 | 93.6 (2) | Cl1iii—Cu2—N3iii | 88.2 (3) |
Cl1i—Cu1—Cl2 | 86.14 (16) | Cu1iv—Cl1—Cu2 | 85.17 (15) |
Cl2—Cu1—Cl2ii | 180.00 | Cu1—Cl2—Cu2i | 83.69 (14) |
Cl2—Cu1—N4ii | 86.4 (2) | Cu2—N3—N2 | 147.4 (5) |
Cl1iii—Cu1—Cl2 | 93.86 (16) | Cu2—N3—N4 | 107.4 (8) |
Cl1i—Cu1—N4 | 99.7 (3) | Cu1—N4—N3 | 126.8 (9) |
Cl2ii—Cu1—N4 | 86.4 (2) | Cu1—N4—C5 | 115.6 (4) |
N4—Cu1—N4ii | 180.00 | C5—C6—H6A | 109.00 |
Cl1iii—Cu1—N4 | 80.3 (3) | C5—C6—H6B | 110.00 |
Cl1i—Cu1—Cl2ii | 93.86 (16) | C5—C6—H6C | 109.00 |
Cl1i—Cu1—N4ii | 80.3 (3) | H6A—C6—H6B | 109.00 |
Cl1i—Cu1—Cl1iii | 180.00 | H6A—C6—H6C | 109.00 |
Cl2ii—Cu1—N4ii | 93.6 (2) | H6B—C6—H6C | 109.00 |
Cl1iii—Cu1—Cl2ii | 86.14 (16) | N1—C7—H7A | 109.00 |
Cl1iii—Cu1—N4ii | 99.7 (3) | N1—C7—H7B | 110.00 |
Cl1—Cu2—N3 | 88.2 (3) | N1—C7—H7C | 110.00 |
Cl1—Cu2—Cl2iv | 84.71 (17) | H7A—C7—H7B | 109.00 |
Cl1—Cu2—Cl2ii | 95.29 (17) | H7A—C7—H7C | 109.00 |
Cl1—Cu2—Cl1iii | 180.00 | H7B—C7—H7C | 110.00 |
Cl1—Cu2—N3iii | 91.8 (3) | | |
Symmetry codes: (i) x−1, y, z; (ii) −x, −y+2, −z; (iii) −x+1, −y+2, −z; (iv) x+1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6C···Cl2 | 0.96 | 2.4700 | 3.243 (15) | 137 |
C7—H7B···Cl2v | 0.96 | 2.4700 | 3.406 (15) | 165 |
C7—H7C···Cl2vi | 0.9600 | 2.7100 | 3.553 (18) | 147 |
Symmetry codes: (v) x, y−1, z; (vi) −x, −y+2, −z+1. |
Experimental details
Crystal data |
Chemical formula | [CuCl2(C3H6N4)] |
Mr | 232.57 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 295 |
a, b, c (Å) | 6.8117 (4), 7.4177 (4), 8.6722 (4) |
α, β, γ (°) | 109.167 (2), 105.528 (3), 103.121 (3) |
V (Å3) | 374.15 (4) |
Z | 2 |
Radiation type | Co Kα, λ = 1.79021 Å |
Specimen shape, size (mm) | Flat sheet, 30 × 30 |
|
Data collection |
Diffractometer | Carl Zeiss HZG-4A diffractometer |
Specimen mounting | Packed powder pellet |
Data collection mode | Reflection |
Scan method | Step |
2θ values (°) | 2θmin = 12 2θmax = 141.44 2θstep = 0.02 |
|
Refinement |
R factors and goodness of fit | Rp = 0.078, Rwp = 0.104, Rexp = 0.136, RBragg = 0.098, R(F2) = 0.066, χ2 = 0.578 |
No. of data points | 6473 |
No. of parameters | 52 |
No. of restraints | 16 |
H-atom treatment | H-atom parameters constrained |
Selected geometric parameters (Å, º) topN1—N2 | 1.354 (10) | Cu1—N4 | 2.248 (10) |
N1—C5 | 1.344 (8) | Cu1—Cl1i | 2.768 (5) |
N2—N3 | 1.295 (16) | Cu2—Cl1 | 2.231 (5) |
N3—N4 | 1.356 (8) | Cu2—N3 | 2.155 (12) |
N4—C5 | 1.320 (10) | Cu2—Cl2ii | 2.829 (5) |
Cu1—Cl2 | 2.233 (5) | | |
| | | |
Cl2—Cu1—N4 | 93.6 (2) | Cl1—Cu2—Cl2ii | 84.71 (17) |
Cl1i—Cu1—Cl2 | 86.14 (16) | Cl2ii—Cu2—N3 | 90.9 (2) |
Cl1i—Cu1—N4 | 99.7 (3) | Cu1ii—Cl1—Cu2 | 85.17 (15) |
Cl1—Cu2—N3 | 88.2 (3) | Cu1—Cl2—Cu2i | 83.69 (14) |
Symmetry codes: (i) x−1, y, z; (ii) x+1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6C···Cl2 | 0.96 | 2.4700 | 3.243 (15) | 137 |
C7—H7B···Cl2iii | 0.96 | 2.4700 | 3.406 (15) | 165 |
C7—H7C···Cl2iv | 0.9600 | 2.7100 | 3.553 (18) | 147 |
Symmetry codes: (iii) x, y−1, z; (iv) −x, −y+2, −z+1. |
In the last decade, the crystal structures of metal halide complexes with substituted tetrazoles have been investigated intensively [Cambridge Structural Database (CSD), Version 5.27 of November 2005; Allen, 2002], because these compounds are potential molecular magnets. However, very little has appeared in the literature on CuII chloride complexes with 1,5-disubstituted tetrazoles. Only four such compounds have been structurally characterized to date, namely CuCl2L complexes with L = 1,5-bis(1-methyl-1H-tetrazol-5-yl)-3-oxopentane (Lyakhov et al., 2001), L = N,N-dimethyl-1-(1-methyl-1H-tetrazol-5-yl)methanamine (Ivashkevich et al., 2002) and L = 1,2-bis(1-methyltetrazol-5-yl)ethane (Ivashkevich et al., 2003), and the CuCl2L2 complex with L = 1,5-diaminotetrazole (Gaponik et al., 2005). In these complexes, the ligand molecules may be considered as functionally substituted tetrazoles with additional electron-donor N and O atoms in the substituents [also including atom N4 of the tetrazole ring in bis(tetrazole) ligands]. In all these compounds, as they are molecular complexes (the first and the second compounds in the above list) or coordination polymers (the third and fourth compounds), only one tetrazole ring atom, N4, coordinates to the Cu atom, while additional coordination occurs through the amino N or O atom of the tetrazole ring substituents.
This paper presents the crystal structure of the title CuCl2L complex, (I), where L is 1,5-dimethyltetrazole. This is the first structure of a metal(II) halide complex with a 1,5-disubstituted tetrazole containing simple alkyl substituents. The synthesis and some physico–chemical properties of the complex have been described previously (Koren et al., 1988). However, no structural data have appeared in the literature to date because of the difficulty in growing single crystals suitable for structural analysis. In the present paper, the structure of (I) was solved and refined from X-ray powder diffraction data.
Compound (I) crystallizes in the triclinic space group P1 with two Cu atoms, two Cl atoms and one ligand molecule in the asymmetric unit. Both Cu atoms, Cu1 and Cu2, lie on inversion centres, while all remaining atoms are in general positions.
The tetrazole ring geometry in (I) is normal for 1- and 1,5-substituted tetrazoles (CSD). The formal double bonds N2═N3 and N4═C5 are the shortest in the ring (Table 1), while the formal single bonds lie in the range 1.344 (8)–1.356 (8) Å.
The Cu atoms adopt essentially elongated octahedral coordination (Fig. 1, Table 1). Within the octahedra, the elongated axial positions are occupied by Cl atoms, while two Cl and two N atoms (N3 and N4 of the tetrazole ring) are in the equatorial sites. The axial Cu—Cl bonds are on average about 0.57 Å longer than the equatorial Cu—Cl bonds.
Each Cl atom belongs to two neighbouring Cu octahedra and lies in an axial position of one octahedron and in the equatorial plane of a neighbouring one, thereby forming an asymmetric bridge between the Cu atoms. These metal atoms are also bridged via the N3—N4 bond of the tetrazole ring (see below). These bridges are responsible for the existence of polymeric ribbon-like chains running along the a axis (Fig. 1), with the ribbon planes close to (011) (Fig. 2). Within the chains, the Cu···Cu distance is 3.4059 (2) Å.
There are weak C—H···Cl hydrogen bonds in the structure of (I) (Table 2). One H atom of the C6 methyl group interacts with atom Cl2 within a polymeric chain, while two H atoms of the C7 methyl group participate in interactions that serve to cross-link the chains.
In the structure of (I), the connection between neighbouring Cu atoms within the polymeric chains is realised not only through the Cl atoms, but also via the N3—N4 bridge of the tetrazole ring. This result confirms the previously advanced hypothesis (Koren et al., 1988) of the polymeric structure of (I) and the presence of additional linking between the Cu atom via the tetrazole N—N bridge. More recently, this assumption was generalized in a review paper (Gaponik et al., 2006) where, by analysing some experimental data and the results of quantum-chemical calculations concerned with disubstituted tetrazoles, a general conclusion was reached that 1,5-dialkyltetrazoles should be able to link metal atoms together through the N3—N4 bridge. To date, among the CuII complexes of 1,5-substituted tetrazoles, only complex (I) shows linking between the Cu atoms through the N3—N4 bridge. However, such a bridge was found in the complex of AgI nitrate with pentamethylenetetrazole, which is composed of dimers [Ag(C12H20N8)NO3]2 (Bonder & Popov, 1972). It should be noted that similar ring bridges are typical of 1,2,4-triazole complexes (Haasnoot, 2000), with iron(II) complexes with 1,2,4-triazoles being spin-crossover compounds. Given the N3—N4 bridging in (I), one may expect that iron(II) complexes of 1,5-dialkyltetrazoles with such bridges may also reveal spin-crossover properties.