Poly[tetra­methyl­ammonium [μ₄-bromido-di-μ₂-bromido-dicuprate(I)]]

The title compound, {(C₄H₁₂N)[Cu₂Br₃]}_n, consists of Cu^I-bromide complex anions and tetra­methyl­ammonium cations. The bromide ions bridge Cu^I ions to form one-dimensional polymeric chains. Both the cation and the anion have mirror symmetries; in the cation, the N atom and two C atoms are located on a mirror plane, while in the complex anion, the three bromide ions are located on two different mirror planes. No hydrogen bonding occurs in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](N-C) = 0.006 Å
• R factor = 0.036
• wR factor = 0.097
• Data-to-parameter ratio = 18.9

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for         N1

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        Cu1
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.17 Ratio

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu1         (1)       1.10

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Great interest is presently being focused on the controllable preparation of copper(I)-halide-based compounds due to their various structures (Subramanian & Hoffmann, 1992) and photophysical properties (Ford et al., 1999). The various structural features may be ascribed to the diversity of the Cu(I) coordination geometry and the capability of the halide ions to bridge between the diamagnetic metal ions (Place et al., 1998); while the photophysical properties may be associated with the d¹⁰ electronic configuration of the Cu(I) (Cariati et al., 2000). In present paper, we report the synthesis and crystal structure of a CuBr-based complex, {[Me₄N][Cu₂Br₃]}_n (I).

The title compound is isomorphous with its chloride analogue (Andersson & Jagner, 1986). The crystal consists of one-dimensional [Cu₂Br₃]_n^n- anionic chain accompanying with isolated [Me₄N]⁺ cations (Figure 1). The Cu^I ion displays a slightly distorted tetrahedral geometry formed by two µ-Br and two µ₄-Br atoms. The Cu—Br bond distances rang from 2.4068 (6) to 2.6389 (6) Å, and the Br—Cu—Br bond angels vary between 98.23 (2) to 122.07 (3)° (Table 1), which are comparable to those in the [Cu_aBr_b]^n– clusters (Andersson & Jagner, 1989; Liu et al., 2005). Two adjacent [CuBr₄]^3- tetrahedra along the a direction form a repeating unit of tetrahedra pair with inversion center through Br—Br edge-sharing. These tetrahedra pairs further connect each other through Br—Br edge-sharing to yield a one-dimensional [Cu₂Br₃]_n^n– anionic chain along the b direction. The [Me₄N]⁺ cations reside between these anionic chains without obvious C—H···Br hydrogen bonding interactions but electrostatic interactions and van der Waals force (Figure 2).

Related literature

For general background, see: Subramanian & Hoffmann (1992); Ford et al. (1999); Place et al. (1998); Cariati et al. (2000). For related structures, see: Andersson & Jagner (1986, 1989); Liu et al. (2005).

S2. Experimental

A mixture of CuCN (90 mg, 1.0 mmol) and Me₄NBr (231 mg, 1.5 mmol) in 10 ml of dry and distilled tetrahydrofuran was sealed into a 25 ml polytetrafluoroethylene-lined stainless steel containers under autogenous pressure and heated at 433 K for 4 d, followed by cooling at 0.1 K.min^-1 to room temperature. The resulted orange crystals were collected with ca 40% yield (based on CuCN). Calc. for C₄H₁₂Br₃Cu₂N: C, 10.90; H, 2.74; N, 3.18(%); Found: C, 10.83; H, 2.69; N, 3.25(%).

S3. Refinement

H atoms were added according to the theoretical models and torsion angles were refined with C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2002); cell refinement: CrystalClear (Rigaku, 2002); data reduction: CrystalClear (Rigaku, 2002); program(s) used to solve structure: SHELXTL (Siemens, 1994); program(s) used to refine structure: SHELXTL (Siemens, 1994); molecular graphics: SHELXTL (Siemens, 1994); software used to prepare material for publication: SHELXTL (Siemens, 1994).

Figures

	Fig. 1. The structure of the anionic chain with 30% probability of thermal ellipsoids [symmetry code A: -x, -y, -z].
	Fig. 2. A view of the unit cell structure.

Poly[tetramethylammonium [µ₄-bromido-di-µ₂-bromido-dicopper(I)]]

Crystal data

(C4H12N)[Cu2Br3]	F(000) = 824
Mr = 440.96	Dx = 2.719 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 2070 reflections
a = 17.018 (2) Å	θ = 3.1–27.5°
b = 6.5466 (7) Å	µ = 15.01 mm^−1
c = 9.6698 (13) Å	T = 293 K
V = 1077.3 (2) Å^3	Prism, orange
Z = 4	0.20 × 0.10 × 0.08 mm

Data collection

Rigaku Mercury CCD diffractometer	1039 independent reflections
Radiation source: rotating-anode generator	878 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
ω scans	θmax = 25.0°, θmin = 3.2°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2002)	h = −20→20
Tmin = 0.080, Tmax = 0.300	k = −7→7
6754 measured reflections	l = −11→8

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.097	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0635P)^2] where P = (Fo^2 + 2Fc^2)/3
1039 reflections	(Δ/σ)max = 0.001
55 parameters	Δρmax = 0.68 e Å^−3
0 restraints	Δρmin = −0.86 e Å^−3

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.

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 > σ(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	Occ. (<1)
Cu1	0.07375 (3)	0.50134 (6)	0.43157 (5)	0.06294 (15)
Br1	0.04183 (2)	0.7500	0.63282 (4)	0.03593 (11)
Br2	0.09825 (3)	0.7500	0.24868 (5)	0.05354 (14)
Br3	0.16999 (2)	0.2500	0.49720 (5)	0.04730 (13)
N1	0.15065 (18)	0.2500	−0.0327 (3)	0.0352 (9)
C1	0.1572 (3)	0.4365 (5)	−0.1174 (4)	0.0848 (15)
H1A	0.2077	0.4396	−0.1616	0.127*
H1B	0.1516	0.5545	−0.0593	0.127*
H1C	0.1167	0.4368	−0.1864	0.127*
C2	0.2111 (3)	0.2500	0.0796 (5)	0.0642 (16)
H2A	0.2626	0.2500	0.0392	0.096*
H2B	0.2047	0.1303	0.1358	0.096*	0.50
H2C	0.2047	0.3697	0.1358	0.096*	0.50
C3	0.0709 (3)	0.2500	0.0330 (7)	0.079 (2)
H3A	0.0313	0.2500	−0.0377	0.118*
H3B	0.0651	0.3697	0.0895	0.118*	0.50
H3C	0.0651	0.1303	0.0895	0.118*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0740 (3)	0.0491 (3)	0.0658 (3)	0.00909 (19)	0.0015 (3)	0.0110 (2)
Br1	0.0419 (2)	0.0317 (2)	0.0343 (2)	0.000	−0.00283 (17)	0.000
Br2	0.0905 (3)	0.0326 (2)	0.0376 (2)	0.000	0.0095 (2)	0.000
Br3	0.0437 (2)	0.0351 (2)	0.0631 (3)	0.000	−0.0052 (2)	0.000
N1	0.0446 (17)	0.0263 (16)	0.0346 (19)	0.000	−0.0041 (15)	0.000
C1	0.137 (4)	0.055 (2)	0.063 (2)	−0.019 (2)	−0.021 (2)	0.031 (2)
C2	0.066 (3)	0.069 (3)	0.058 (3)	0.000	−0.023 (3)	0.000
C3	0.052 (3)	0.079 (4)	0.104 (5)	0.000	0.018 (3)	0.000

Geometric parameters (Å, º)

Cu1—Br1	2.5946 (6)	N1—C2	1.496 (6)
Cu1—Br1^i	2.6389 (6)	N1—C3	1.499 (5)
Cu1—Br2	2.4396 (6)	C1—H1A	0.9600
Cu1—Br3	2.4068 (6)	C1—H1B	0.9600
Cu1—Cu1^i	2.8377 (10)	C1—H1C	0.9600
Br1—Cu1^ii	2.5946 (6)	C2—H2A	0.9600
Br1—Cu1^i	2.6389 (6)	C2—H2B	0.9600
Br1—Cu1^iii	2.6389 (6)	C2—H2C	0.9600
Br2—Cu1^ii	2.4396 (6)	C3—H3A	0.9600
Br3—Cu1^iv	2.4068 (6)	C3—H3B	0.9600
N1—C1^iv	1.474 (4)	C3—H3C	0.9600
N1—C1	1.474 (4)
Br3—Cu1—Br2	122.07 (3)	C1^iv—N1—C3	107.7 (2)
Br3—Cu1—Br1	111.94 (2)	C1—N1—C3	107.7 (2)
Br2—Cu1—Br1	99.257 (19)	C2—N1—C3	108.3 (4)
Br3—Cu1—Br1^i	98.228 (19)	N1—C1—H1A	109.5
Br2—Cu1—Br1^i	111.87 (2)	N1—C1—H1B	109.5
Br1—Cu1—Br1^i	114.337 (19)	H1A—C1—H1B	109.5
Br3—Cu1—Cu1^i	118.34 (3)	N1—C1—H1C	109.5
Br2—Cu1—Cu1^i	119.57 (3)	H1A—C1—H1C	109.5
Br1—Cu1—Cu1^i	57.919 (18)	H1B—C1—H1C	109.5
Br1^i—Cu1—Cu1^i	56.418 (18)	N1—C2—H2A	109.5
Cu1—Br1—Cu1^ii	77.72 (2)	N1—C2—H2B	109.5
Cu1—Br1—Cu1^i	65.663 (19)	H2A—C2—H2B	109.5
Cu1^ii—Br1—Cu1^i	111.735 (17)	N1—C2—H2C	109.5
Cu1—Br1—Cu1^iii	111.735 (17)	H2A—C2—H2C	109.5
Cu1^ii—Br1—Cu1^iii	65.663 (19)	H2B—C2—H2C	109.5
Cu1^i—Br1—Cu1^iii	77.15 (2)	N1—C3—H3A	109.5
Cu1^ii—Br2—Cu1	83.71 (3)	N1—C3—H3B	109.5
Cu1^iv—Br3—Cu1	86.26 (3)	H3A—C3—H3B	109.5
C1^iv—N1—C1	111.8 (4)	N1—C3—H3C	109.5
C1^iv—N1—C2	110.5 (2)	H3A—C3—H3C	109.5
C1—N1—C2	110.5 (2)	H3B—C3—H3C	109.5
Br3—Cu1—Br1—Cu1^ii	128.459 (17)	Cu1^i—Cu1—Br1—Cu1^iii	−63.70 (2)
Br2—Cu1—Br1—Cu1^ii	−1.76 (3)	Br3—Cu1—Br2—Cu1^ii	−121.45 (2)
Br1^i—Cu1—Br1—Cu1^ii	−120.959 (16)	Br1—Cu1—Br2—Cu1^ii	1.84 (3)
Cu1^i—Cu1—Br1—Cu1^ii	−120.959 (16)	Br1^i—Cu1—Br2—Cu1^ii	122.857 (18)
Br3—Cu1—Br1—Cu1^i	−110.58 (3)	Cu1^i—Cu1—Br2—Cu1^ii	60.09 (4)
Br2—Cu1—Br1—Cu1^i	119.20 (3)	Br2—Cu1—Br3—Cu1^iv	−119.47 (2)
Br1^i—Cu1—Br1—Cu1^i	0.0	Br1—Cu1—Br3—Cu1^iv	123.330 (17)
Br3—Cu1—Br1—Cu1^iii	−174.28 (2)	Br1^i—Cu1—Br3—Cu1^iv	2.85 (3)
Br2—Cu1—Br1—Cu1^iii	55.50 (2)	Cu1^i—Cu1—Br3—Cu1^iv	59.01 (4)
Br1^i—Cu1—Br1—Cu1^iii	−63.70 (2)

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