Chloro­(di­ethyl­enetri­amine)copper(II) chloride: a disordered quasi-one-dimensional structure

The title structure, [CuCl(C₄H₁₃N₃)]Cl, consists of alternating [CuCl(dien)]⁺ (dien is diethylene­triamine) and Cl⁻ ions arranged in quasi-one-dimensional stacks along the crystallographic a axis and forming tetragonally elongated octa­hedral coordination shells around each Cu atom [equatorial Cu—Cl = 2.2552 (8) Å, and axial Cu—Cl = 2.831 (1) and 3.341 (1) Å]. Crystallographic mirror planes bisect each stack vertically through the Cu, Cl and central N atoms, and horizontally through the [CuCl(dien)]⁺ cation. The horizontal mirrors lead to each atom in the puckered [CuCl(dien)]⁺ cations being disordered over two crystallographically equivalent sites. Comparison of the title structure with its Br and I analogues shows a growing influence of hydrogen bonding relative to coordination bonds on traversing the series I < Br < Cl.

Comment

The title structure, (I), is a member of an approximately isostructural series, the other members being [CuBr(dien)]Br (Boeyens et al., 1991) and the polymeric polymorph of [CuI₂(dien)]_n (Hodgson et al., 1991). The bromide and iodide crystal structures are almost identical, despite the bromide being described as ionic and the iodide as mol­ecular. Both compounds crystallize in the ortho­rhom­bic space group Pmn2₁ [Br: a = 8.716 (1), b = 8.588 (1) and c = 6.337 (1) Å; I: a = 8.873 (2), b = 8.890 (3) and c = 6.658 (1) Å]. In both cases, alternating [CuX(dien)] and capping X form quasi-one-dimensional stacks along c, which are bisected vertically by crystallographic mirror planes through the Cu, X and central N atoms. In contrast, the Cl analogue crystallizes in ortho­rhom­bic space group Pmmn, with a = 6.0925 (4), b = 8.6440 (4) and c = 8.3575 (4) Å. However, resolution of the disorder clearly shows a chemically sensible P2₁mn system (Fig. 1), isomorphous with the Br and I analogues, with an added mirror plane associated with the disordered [CuCl(dien)]⁺ group. The Cu⋯Cu separation along the stack corresponds to the shortest lattice repeat and, along with the geometry around the bridging halide, shows a steady progression from I to Cl (Table 3).

The increasing asymmetry of the two capping Cu⋯X distances arises because an N—H⋯X hydrogen bond (Fig. 1 and Table 2) replaces one of the direct Cu⋯X inter­actions. Accompanying these changes, the flattened five-membered rings of the iodide relax to a more typical puckered envelope shape in the Br and Cl structures. This ring conformation, in which the CH₂ adjacent to NH represents the flap of the envelope, is also the norm for the dimeric cations [CuCl(dien)]₂²⁺ (Draper et al., 2004; Urtiaga et al., 1996; Utz et al., 2003) and is even retained when additional capping ligands inter­act with the Cu atoms, e.g. H₂O (Willett, 2001; Zhu et al., 2003) and ClO₄⁻ in the Br analogue (Towle et al., 1985). Ironically, this is also the conformation seen in the monomeric polymorph of CuI₂(dien) (Hodgson et al., 1991)

The nature of the disorder is not clear from the current work. Weak inter­stitial reflections suggest that the determination may well be a subcell. However, attempts at working with larger and lower-symmetry unit cells did not reduce the disorder, and neither did refining the crystals as pseudo-tetra­gonal twins. It is also unclear whether the disorder is static or dynamic. The asymmetry introduced by the Cu⋯Cl and N—H⋯Cl inter­actions suggests a static system. However, it is worth noting that the direction of the central NH bond does not, in the case of the above dimeric cations, dictate on which side of the [CuCl(dien)]⁺ system the capping halide approaches the Cu atom. It is therefore possible to envisage the capping halide hopping from Cu to Cu with minimal conformational disturbance, so that at least part of the disorder may be dynamic.

Figure 1 A view of the [CuCl(dien)]Cl stack in (I), with 50% probability displacement ellipsoids. H atoms are shown as small spheres of arbitrary radii.

Experimental

Crystals suitable for crystallographic study were prepared by mixing equal volumes of 0.02 M methanol solutions of CuCl₂ and dien. The resulting solution was then subjected to vapour diffusion using diethyl ether as the anti-solvent.

Crystal data

• [CuCl(C₄H₁₃N₃)]Cl

• M_r = 237.61

• Orthorhombic, P m m n

• a = 6.0925 (4) Å

• b = 8.6440 (4) Å

• c = 8.3575 (4) Å

• V = 440.14 (4) ų

• Z = 2

• D_x = 1.793 Mg m⁻³

• Mo Kα radiation

• μ = 3.02 mm⁻¹

• T = 133 (2) K

• Plate, blue

• 0.25 × 0.25 × 0.05 mm

Data collection

• Nonius KappaCCD area-detector diffractometer

• φ and ω scans

• Absorption correction: multi-scan (SORTAV; Blessing, 1995, 1997) T_min = 0.519, T_max = 0.864

• 1086 measured reflections

• 579 independent reflections

• 576 reflections with I > 2σ(I)

• R_int = 0.023

• θ_max = 27.5°

Refinement

• Refinement on F²

• R[F² > 2σ(F²)] = 0.03

• wR(F²) = 0.080

• S = 1.21

• 579 reflections

• 77 parameters

• All H-atom parameters refined

• w = 1/[σ²(F_o²) + (0.0416P)² + 0.2888P] where P = (F_o² + 2F_c²)/3

• (Δ/σ)_max < 0.001

• Δρ_max = 0.47 e Å⁻³

• Δρ_min = −0.28 e Å⁻³

• Extinction correction: SHELXL97 (Sheldrick, 1997)

• Extinction coefficient: 0.045 (5)

Table 1
Selected geometric parameters (Å, °)

C1—N1	1.459 (3)
C1—C2	1.523 (4)
C2—N2	1.489 (4)
N1—Cu1	2.014 (3)
N2—Cu1	2.016 (2)
Cl1—Cu1	2.2552 (8)

N1—C1—C2	106.75 (19)
N2—C2—C1	106.6 (2)
C1—N1—Cu1	108.27 (14)
C2—N2—Cu1	109.86 (16)
N1—Cu1—N2	83.76 (7)

Cu1—N2—C2—C1	35.6 (3)
N2—C2—C1—N1	−53.7 (3)
C2—C1—N1—Cu1	46.2 (2)
C1—N1—Cu1—N2	−21.3 (2)
N1—Cu1—N2—C2	−8.8 (2)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1C⋯Cl2^i	0.83 (2)	2.48 (5)	3.188 (3)	144 (7)
N2—H2C⋯Cl1^ii	0.85 (2)	2.69 (3)	3.437 (2)	147 (4)
N2—H2D⋯Cl2^ii	0.83 (2)	2.68 (2)	3.429 (2)	150.8 (14)
Symmetry codes: (i) x-1, y, z; (ii) -x+1, -y, -z+1.

Table 3
Comparison of geometric parameters (Å, °) for [CuX₂(dien)] complexes

X	Cu⋯X	Cu⋯X	Cu⋯Cu	Cu⋯X⋯Cu
I†	3.328 (1)	3.368 (1)	6.658 (1)	167.7 (1)
Br‡	3.139 (4)	3.298 (4)	6.377 (1)	164.3 (1)
Cl§	2.831 (1)	3.341 (1)	6.092 (1)	161.6 (1)

†Hodgson et al. (1991).
‡Boeyens et al. (1991).
§This work.

The final refinement was carried out in the space group Pmmn, which resulted in each atom of the [CuCl(dien)]⁺ cation semi-occupying two sites on either side of the bc mirror plane. Decisions regarding which atoms constituted a mol­ecular fragment were made by selecting a combination that generated bond lengths and angles which matched those in similar previously published structures. Also, H atoms were subjected to DFIX rather than AFIX constraints, so that angles involving H atoms could also be used to avoid incorrect assignments. Although dihedral angles did not form part of the above selection process, their final values showed excellent agreement with those in similar structures.

Data collection: KappaCCD Server Software (Nonius, 1997) and COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supporting information

S1. Comment

The title structure, (I), is a member of an approximately isostructural series, the other members being [CuBr(dien)]Br (Boeyens et al., 1991) and the polymeric polymorph of [CuI₂(dien)]_n (Hodgson et al., 1991). The bromide and iodide crystal structures are almost identical, despite the bromide being described as ionic and the iodide as molecular. Both compounds crystallize in orthorhombic space group Pmn2₁ [Br: a = 8.716 (1), b = 8.588 (1) and c = 6.337 (1) Å; I: a = 8.873 (2), b = 8.890 (3) and c = 6.658 (1) Å]. In both cases, alternating [CuX(dien)] and capping X form quasi-one-dimensional stacks along c, which are bisected vertically by crystallographic mirror planes through the Cu, X and central N atoms. In contrast, the Cl analogue crystallizes in orthorhombic space group Pmmn, with a = 6.0925 (4), b = 8.6440 (4) and c = 8.3575 (4) Å. However, resolution of the disorder clearly shows a chemically sensible P2₁mn system (Fig. 1), isomorphous with the Br and I analogues, with an added mirror plane associated with the disordered [CuCl(dien)]⁺ group. The Cu···Cu separation along the stack corresponds to the shortest lattice repeat and, along with the geometry around the bridging halide, shows a steady progression from I to Cl (Table 3).

The increasing asymmetry of the two capping Cu···X distances arises because an N—H···X hydrogen bond (Fig 1, Table 2) replaces one of the direct Cu···X interactions. Accompanying these changes, the flattened five-membered rings of the iodide relax to a more typical puckered envelope shape in the Br and Cl structures. This ring conformation, in which the CH₂ adjacent to NH represents the flap of the envelope, is also the norm for the dimeric cations [CuCl(dien)]₂²⁺ (Draper et al., 2004; Urtiga et al., 1996; Utz et al., 2003) and is even retained when additional capping ligands interact with the Cu atoms, e.g. H₂O (Willett, 2001; Zhu et al., 2003) and ClO₄⁻ in the Br analogue (Towle et al., 1985). Ironically, this is also the conformation seen in the monomeric polymorph of CuI₂(dien) (Hodgson et al., 1991)

The nature of the disorder is not clear from the current work. Weak interstitial reflections suggest that the determination may well be a subcell. However, attempts at working with larger and lower-symmetry unit cells did not reduce the disorder, and neither did refining the crystals as pseudo-tetragonal twins. It is also unclear whether the disorder is static or dynamic. The asymmetry introduced by the Cu···Cl and N—H···Cl interactions suggests a static system. However, it is worth noting that the direction of the central NH bond does not, in the case of the above dimeric cations, dictate on which side of the [CuCl(dien)]⁺ system the capping halide approaches the Cu atom. It is therefore possible to envisage the capping halide hopping from Cu to Cu with minimal conformational disturbance, so that at least part of the disorder may be dynamic.

S2. Experimental

Crystals suitable for crystallographic study were prepared by mixing equal volumes of 0.02 M methanolic solutions of CuCl₂ and dien. This solution was then subjected to vapour diffusion using diethyl ether as the anti-solvent.

S3. Refinement

The final refinement was carried out in space group Pmmn, which resulted in each atom in the [CuCl(dien)]⁺ cation semi-occupying two sites on either side of the bc mirror plane. Decisions regarding which atoms constituted a molecular fragment were made by selecting a combination that generated bond lengths and angles which matched those in similar previously published structures. Also, H atoms were subjected to DFIX rather than AFIX constraints, so that angles involving H atoms could also be used to avoid incorrect assignments. Although dihedral angles did not form part of the above selection process, their final values showed excellent agreement with those in similar structures.

Computing details

Data collection: KappaCCD Server Software (Nonius, 1997) and COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK; data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Fig. 1. A view of the [CuCl(dien)]Cl stack in (I), with 50% probability displacement ellipsoids. H atoms are shown as small spheres of arbitrary radii.

Chloro(diethylenetriamine)copper(II) chloride

Crystal data

[CuCl(C4H13N3)]Cl	F(000) = 242
Mr = 237.61	Dx = 1.793 Mg m^−3
Orthorhombic, Pmmn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2a	Cell parameters from 1086 reflections
a = 6.0925 (4) Å	θ = 1–27.5°
b = 8.6440 (4) Å	µ = 3.02 mm^−1
c = 8.3575 (4) Å	T = 133 K
V = 440.14 (4) Å^3	Plate, blue
Z = 2	0.25 × 0.25 × 0.05 mm

Data collection

Nonius KappaCCD area-detector diffractometer	576 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.023
CCD scans	θmax = 27.5°, θmin = 4.1°
Absorption correction: multi-scan (SORTAV; Blessing, 1995, 1997)	h = 0→7
Tmin = 0.519, Tmax = 0.864	k = 0→11
1086 measured reflections	l = 0→10
579 independent reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0416P)^2 + 0.2888P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.03	(Δ/σ)max < 0.001
wR(F^2) = 0.080	Δρmax = 0.47 e Å^−3
S = 1.21	Δρmin = −0.28 e Å^−3
579 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
77 parameters	Extinction coefficient: 0.045 (5)
19 restraints

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
C1	0.2941 (4)	0.1060 (3)	0.0908 (3)	0.0264 (8)	0.5
C2	0.2262 (6)	−0.0237 (3)	0.2038 (3)	0.0335 (7)	0.5
N1	0.2147 (4)	0.25	0.1611 (3)	0.0216 (8)	0.5
N2	0.3107 (4)	0.0190 (3)	0.3651 (3)	0.0311 (6)	0.5
Cl1	0.2759 (2)	0.25	0.66488 (9)	0.0367 (3)	0.5
Cl2	0.75	0.25	0.33658 (8)	0.02624 (14)
Cu1	0.29242 (8)	0.25	0.39530 (4)	0.02485 (18)	0.5
H1A	0.25	0.089 (3)	−0.014 (2)	0.024 (6)*
H1B	0.448 (3)	0.110 (5)	0.077 (4)	0.032 (9)*	0.5
H1C	0.079 (4)	0.25	0.161 (9)	0.08 (2)*	0.5
H2A	0.25	−0.123 (3)	0.163 (4)	0.052 (8)*
H2B	0.070 (4)	−0.027 (5)	0.202 (5)	0.044 (10)*	0.5
H2C	0.444 (4)	−0.012 (5)	0.370 (4)	0.047 (12)*	0.5
H2D	0.25	−0.028 (3)	0.439 (3)	0.044 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.025 (2)	0.0267 (10)	0.0271 (10)	−0.0025 (9)	−0.0021 (8)	−0.0074 (8)
C2	0.0288 (16)	0.0231 (9)	0.0487 (12)	−0.0016 (13)	0.0004 (14)	−0.0082 (9)
N1	0.014 (2)	0.0252 (11)	0.0251 (11)	0	0.0012 (10)	0
N2	0.0375 (15)	0.0210 (9)	0.0348 (10)	−0.0018 (8)	0.0076 (8)	0.0090 (9)
Cl1	0.0338 (7)	0.0583 (5)	0.0181 (3)	0	0.0031 (4)	0
Cl2	0.0229 (2)	0.0244 (3)	0.0314 (3)	0	0	0
Cu1	0.0367 (5)	0.01915 (17)	0.01874 (18)	0	0.00409 (15)	0

Geometric parameters (Å, º)

C1—N1	1.459 (3)	N1—Cu1	2.014 (3)
C1—C2	1.523 (4)	N1—H1C	0.83 (2)
C1—H1A	0.926 (17)	N2—Cu1	2.016 (2)
C1—H1B	0.95 (2)	N2—H2C	0.85 (2)
C2—N2	1.489 (4)	N2—H2D	0.83 (2)
C2—H2A	0.93 (2)	Cl1—Cu1	2.2552 (8)
C2—H2B	0.95 (2)
N1—C1—C2	106.75 (19)	C1—N1—H1C	109 (2)
N1—C1—H1A	114.8 (13)	C1^i—N1—H1C	109 (2)
C2—C1—H1A	112.9 (14)	Cu1—N1—H1C	103 (5)
N1—C1—H1B	110 (2)	C2—N2—Cu1	109.86 (16)
C2—C1—H1B	112 (2)	C2—N2—H2C	107 (2)
H1A—C1—H1B	101 (2)	Cu1—N2—H2C	111 (3)
N2—C2—C1	106.6 (2)	C2—N2—H2D	113.7 (16)
N2—C2—H2A	120.5 (17)	Cu1—N2—H2D	111 (2)
C1—C2—H2A	113.8 (18)	H2C—N2—H2D	104 (3)
N2—C2—H2B	112 (2)	N1—Cu1—N2	83.76 (7)
C1—C2—H2B	107 (3)	N2—Cu1—N2^i	164.26 (13)
H2A—C2—H2B	97 (3)	N2^i—Cu1—N2^ii	159.98 (10)
C1—N1—C1^i	117.1 (3)	N2—Cu1—N2^iii	159.98 (10)
C1—N1—Cu1	108.27 (14)	N1—Cu1—Cl1	163.84 (8)
C1^i—N1—Cu1	108.27 (14)	N2—Cu1—Cl1	97.33 (7)
Cu1—N2—C2—C1	35.6 (3)	C1—N1—Cu1—N2	−21.3 (2)
N2—C2—C1—N1	−53.7 (3)	N1—Cu1—N2—C2	−8.8 (2)
C2—C1—N1—Cu1	46.2 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1C···Cl2^iv	0.83 (2)	2.48 (5)	3.188 (3)	144 (7)
N2—H2C···Cl1^v	0.85 (2)	2.69 (3)	3.437 (2)	147 (4)
N2—H2D···Cl2^v	0.83 (2)	2.68 (2)	3.429 (2)	151 (1)

Symmetry codes: (iv) x−1, y, z; (v) −x+1, −y, −z+1.