Bis(1-methyl­piperazine-1,4-diium) tetra­bromidocuprate(II)

Abstract

The title compound, (C₅H₁₄N₂)[CuBr₄], was synthesized by hydro­thermal reaction of CuBr₂ with 1-methyl­piperazine in an HBr/water solution. Both amine N atoms are protonated. The Cu—Br distances in the tetrahedral anion are in the range 2.3809 (11)–2.4131 (11) Å. In the crystal, moderately strong and weak inter­molecular N—H⋯Br hydrogen bonds link the anion and cation units into an infinite two-dimensional network parallel to the ab plane.

Related literature

For related amino coordination compounds, see: Fu et al. (2009 ▶); Aminabhavi et al. (1986 ▶); Dai & Fu (2008a ▶,b ▶). For halogen atoms as hydrogen-bond acceptors, see: Brammer et al. (2001 ▶). For the chlorine analogue of the title compound, see: Peng (2011 ▶).

Experimental

Crystal data

• (C₅H₁₄N₂)[CuBr₄]

• M _r = 485.36

• Orthorhombic,

• a = 9.1933 (18) Å

• b = 10.341 (2) Å

• c = 14.255 (3) Å

• V = 1355.2 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 13.37 mm⁻¹

• T = 298 K

• 0.20 × 0.05 × 0.05 mm

Data collection

• Rigaku Mercury2 diffractometer

• Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ▶) T _min = 0.89, T _max = 1.00

• 14009 measured reflections

• 3092 independent reflections

• 2545 reflections with I > 2σ(I)

• R _int = 0.079

Refinement

• R[F ² > 2σ(F ²)] = 0.044

• wR(F ²) = 0.088

• S = 1.08

• 3092 reflections

• 109 parameters

• H-atom parameters constrained

• Δρ_max = 0.92 e Å⁻³

• Δρ_min = −0.71 e Å⁻³

• Absolute structure: Flack (1983 ▶), 1312 Friedel pairs

• Flack parameter: 0.05 (2)

Data collection: CrystalClear (Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2C⋯Br3i	0.90	2.50	3.339 (6)	154
N2—H2D⋯Br1ii	0.90	2.68	3.354 (5)	133
N2—H2D⋯Br2ii	0.90	2.76	3.457 (5)	135
N1—H1⋯Br4	0.90	2.55	3.345 (5)	148

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

Amino derivatives of piperazine have found a wide range of applications in material science, due to their magnetic, fluorescent and dielectric properties. There has also been an increased interest in the preparation of amino coordination compounds (Aminabhavi et al. 1986; Dai & Fu 2008a; Dai & Fu 2008b; Fu, et al. 2009). We report here the crystal structure of the title compound, bis-(1-methylpiperazine-1,4-diium) tetrabromide copper(II).

The asymmetric unit is composed of one CuBr₄^2- anion and one 1-methylpiperazine-1,4-diium cation (Fig.1). Both amine N atoms are protonated, indicating thus two positive charges on the cation that balance the two negative charges on the CuBr₄^2- anion. Geometric parameters of the title compound are in the normal range.

In the crystal structure, all H atoms of the amine groups are involved in intermolecular N—H···Br hydrogen bonds with the bond angles ranging from 132.7° to 154.3° and N···Br distances from 3.339 (6)Å to 3.457 (5)Å, respectively. Following the survey by Brammer et al. (2001) the N2—H2D···Br1 and N2—H2D···Br2 H-bonds should be considered to be clearly weaker than the N2—H2C···Br3 and N1—H1···Br4 interactions (Table 1). The hydrogen bonds link the cations and anions into an infinite two-dimensional network parallel to the ab-plane (Fig.2). The chlorine analogue of the title compound is reported elsewhere in this issue (Peng, 2011).

Experimental

A mixture of 1-methylpiperazine (0.4 mmol), CuBr₂ (0.4 mmol) and HBr/distilled water (10ml,1:4) sealed in a teflon-lined stainless steel vessel, was maintained at 100 °C. Blue block -shaped crystals suitable for X-ray analysis were obtained after 3 days.

Refinement

All H atoms attached to C atoms were fixed geometrically and treated as riding on the parent atoms with C-H = 0.97 Å (methylene) and C-H = 0.96 Å (methyl) with U_iso(H) = 1.2U_eq (methylene) and U_iso(H) = 1.5U_eq (methyl). The positional parameters of the H atoms (N1, N2) were initially refined freely, subsequently restrained using a distance of 0.90 Å and in the final refinements treated in riding motion on their parent nitrogen atoms with U_iso(H)=1.2U_eq(N).

Figures

Fig. 1.

Molecular view of the title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Fig. 2.

The crystal packing of the title compound viewed along the c axis showing the two-dimensional hydrogen bond network (dashed lines). Hydrogen atoms not involved in hydrogen bonding have been omitted for clarity.

Crystal data

(C5H14N2)[CuBr4]	F(000) = 908
Mr = 485.36	Dx = 2.379 Mg m−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3092 reflections
a = 9.1933 (18) Å	θ = 3.3–27.5°
b = 10.341 (2) Å	µ = 13.37 mm−1
c = 14.255 (3) Å	T = 298 K
V = 1355.2 (5) Å3	Block, blue
Z = 4	0.20 × 0.05 × 0.05 mm

Data collection

Rigaku Mercury2 diffractometer	3092 independent reflections
Radiation source: fine-focus sealed tube	2545 reflections with I > 2σ(I)
graphite	Rint = 0.079
Detector resolution: 13.6612 pixels mm-1	θmax = 27.5°, θmin = 3.3°
profile data from φ scans	h = −11→11
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −13→13
Tmin = 0.89, Tmax = 1.00	l = −18→18
14009 measured reflections

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044	H-atom parameters constrained
wR(F2) = 0.088	w = 1/[σ2(Fo2) + (0.0277P)2] where P = (Fo2 + 2Fc2)/3
S = 1.08	(Δ/σ)max < 0.001
3092 reflections	Δρmax = 0.92 e Å−3
109 parameters	Δρmin = −0.71 e Å−3
0 restraints	Absolute structure: Flack (1983), 1312 Friedel pairs
Primary atom site location: structure-invariant direct methods	Flack parameter: 0.05 (2)

Special details

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.

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 > 2sigma(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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.99472 (8)	0.08523 (7)	0.59527 (5)	0.0496 (2)
Br2	0.89670 (8)	−0.22010 (7)	0.49622 (5)	0.0430 (2)
Br3	0.72439 (8)	−0.21019 (7)	0.72661 (5)	0.04138 (19)
Cu1	0.79551 (9)	−0.06642 (7)	0.60209 (5)	0.0365 (2)
Br4	0.60073 (8)	0.08567 (7)	0.61127 (6)	0.0501 (2)
N2	0.6726 (5)	0.5289 (5)	0.5927 (4)	0.0367 (14)
H2C	0.7150	0.5985	0.6190	0.044*
H2D	0.6225	0.5519	0.5411	0.044*
N1	0.7844 (6)	0.3272 (4)	0.7129 (3)	0.0298 (12)
H1	0.7703	0.2609	0.6731	0.036*
C4	0.8043 (7)	0.4533 (7)	0.5656 (5)	0.0384 (16)
H4A	0.8684	0.5069	0.5281	0.046*
H4B	0.7756	0.3793	0.5281	0.046*
C5	0.8841 (7)	0.4074 (6)	0.6529 (5)	0.0364 (16)
H5A	0.9680	0.3564	0.6348	0.044*
H5B	0.9181	0.4815	0.6884	0.044*
C2	0.6566 (7)	0.4061 (7)	0.7413 (4)	0.0413 (17)
H2A	0.6892	0.4790	0.7786	0.050*
H2B	0.5922	0.3541	0.7798	0.050*
C3	0.5744 (7)	0.4550 (7)	0.6565 (5)	0.0397 (17)
H3A	0.5329	0.3824	0.6228	0.048*
H3B	0.4953	0.5104	0.6769	0.048*
C1	0.8613 (8)	0.2694 (7)	0.7956 (5)	0.050 (2)
H1A	0.7941	0.2181	0.8312	0.075*
H1B	0.8992	0.3374	0.8344	0.075*
H1C	0.9398	0.2159	0.7741	0.075*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0533 (5)	0.0344 (4)	0.0610 (5)	−0.0140 (4)	0.0190 (4)	−0.0117 (4)
Br2	0.0539 (4)	0.0333 (4)	0.0418 (4)	−0.0101 (4)	0.0066 (3)	−0.0080 (3)
Br3	0.0424 (4)	0.0365 (4)	0.0452 (4)	0.0005 (3)	0.0098 (3)	0.0034 (3)
Cu1	0.0389 (5)	0.0269 (4)	0.0436 (5)	−0.0011 (4)	0.0015 (4)	−0.0011 (4)
Br4	0.0374 (4)	0.0322 (4)	0.0805 (5)	0.0010 (3)	−0.0113 (4)	−0.0026 (4)
N2	0.033 (3)	0.035 (3)	0.041 (3)	0.002 (3)	−0.003 (3)	−0.001 (3)
N1	0.032 (3)	0.024 (3)	0.033 (3)	0.000 (2)	0.000 (2)	−0.002 (2)
C4	0.043 (4)	0.033 (4)	0.040 (4)	0.008 (3)	0.010 (3)	0.002 (3)
C5	0.026 (4)	0.027 (4)	0.057 (4)	0.006 (3)	0.003 (3)	−0.003 (3)
C2	0.038 (4)	0.046 (4)	0.040 (4)	0.009 (3)	0.011 (3)	0.003 (4)
C3	0.025 (4)	0.047 (4)	0.047 (4)	0.004 (3)	0.005 (3)	0.009 (4)
C1	0.053 (5)	0.048 (4)	0.049 (4)	0.015 (4)	−0.007 (3)	0.007 (4)

Geometric parameters (Å, °)

Br1—Cu1	2.4131 (11)	C4—H4A	0.9700
Br2—Cu1	2.3809 (11)	C4—H4B	0.9700
Br3—Cu1	2.4059 (10)	C5—H5A	0.9700
Cu1—Br4	2.3869 (11)	C5—H5B	0.9700
N2—C3	1.492 (8)	C2—C3	1.513 (9)
N2—C4	1.493 (7)	C2—H2A	0.9700
N2—H2C	0.9000	C2—H2B	0.9700
N2—H2D	0.9000	C3—H3A	0.9700
N1—C2	1.486 (8)	C3—H3B	0.9700
N1—C1	1.499 (8)	C1—H1A	0.9600
N1—C5	1.503 (8)	C1—H1B	0.9600
N1—H1	0.9000	C1—H1C	0.9600
C4—C5	1.520 (9)
Br2—Cu1—Br4	140.15 (4)	N1—C5—C4	110.1 (5)
Br2—Cu1—Br3	99.28 (4)	N1—C5—H5A	109.6
Br4—Cu1—Br3	99.38 (4)	C4—C5—H5A	109.6
Br2—Cu1—Br1	96.41 (4)	N1—C5—H5B	109.6
Br4—Cu1—Br1	98.24 (4)	C4—C5—H5B	109.6
Br3—Cu1—Br1	129.61 (4)	H5A—C5—H5B	108.2
C3—N2—C4	112.3 (5)	N1—C2—C3	111.1 (5)
C3—N2—H2C	114.7	N1—C2—H2A	109.4
C4—N2—H2C	100.1	C3—C2—H2A	109.4
C3—N2—H2D	109.0	N1—C2—H2B	109.4
C4—N2—H2D	109.9	C3—C2—H2B	109.4
H2C—N2—H2D	110.6	H2A—C2—H2B	108.0
C2—N1—C1	112.2 (5)	N2—C3—C2	110.9 (5)
C2—N1—C5	109.5 (5)	N2—C3—H3A	109.5
C1—N1—C5	112.3 (5)	C2—C3—H3A	109.5
C2—N1—H1	118.5	N2—C3—H3B	109.5
C1—N1—H1	105.1	C2—C3—H3B	109.5
C5—N1—H1	98.6	H3A—C3—H3B	108.1
N2—C4—C5	110.1 (5)	N1—C1—H1A	109.5
N2—C4—H4A	109.7	N1—C1—H1B	109.5
C5—C4—H4A	109.7	H1A—C1—H1B	109.5
N2—C4—H4B	109.7	N1—C1—H1C	109.5
C5—C4—H4B	109.7	H1A—C1—H1C	109.5
H4A—C4—H4B	108.2	H1B—C1—H1C	109.5

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2C···Br3i	0.90	2.50	3.339 (6)	154
N2—H2D···Br1ii	0.90	2.68	3.354 (5)	133
N2—H2D···Br2ii	0.90	2.76	3.457 (5)	135
N1—H1···Br4	0.90	2.55	3.345 (5)	148

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