Di­bromo­tetrakis(4-methyl­imidazole)copper(II)

In the structure of the title compound, [CuBr₂(C₄H₆N₂)₄], the copper(II) cations are coordinated by four 4-methyl­imidazole ligands and two bromide anions within a distorted octahedron. The Cu—Br distances are elongated due to Jahn–Teller distortion. The two crystallographically independent 4-methyl­imidazole ligands and the single independent Br are located in general positions, whereas the copper(II) cation is located on a centre of inversion. There are short N—H...Br contacts to the bromide ligands, indicating hydrogen bonding.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.038
• wR factor = 0.104
• Data-to-parameter ratio = 25.8

checkCIF results

No syntax errors found
GLOBAL _publ field problems




 Alert Level A:


PUBL_002  Alert A The contact author's address is missing,
           _publ_contact_author_address.

ADDSYM reports no extra symmetry


 Alert Level C:



WEIGH_01  Alert C Extra text has been found in the
          _refine_ls_weighting_scheme field. This should be in the
          _refine_ls_weighting_details field.
          Weighting scheme given as calc w = 1/[\s^2^(Fo^2^)+(0.0461P)^2^+0.931
          Weighting scheme identified as calc

General Notes



ABSTM_02  The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
          Tmin and Tmax reported:      0.687     0.881
          Tmin' and Tmax expected:      0.627     0.696
          RR' =      0.865
          Please check that your absorption correction is appropriate.


 1 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

Computing details

Data collection: SDP (Enraf-Nonius, 1985); cell refinement: SDP; data reduction: XCAD4 in SDP; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Bruker, 1998); software used to prepare material for publication: CIFTAB in SHELXL97.

(I)

Crystal data

[CuBr2(C4H6N2)4]	F(000) = 550
Mr = 551.79	Dx = 1.626 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.2657 (9) Å	Cell parameters from 78 reflections
b = 12.053 (1) Å	θ = 10.0–17.5°
c = 11.338 (1) Å	µ = 4.53 mm^−1
β = 94.06 (1)°	T = 293 K
V = 1126.73 (18) Å^3	Block, blue
Z = 2	0.1 × 0.1 × 0.08 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	2136 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.039
Graphite monochromator	θmax = 30.1°, θmin = 2.5°
ω scans	h = 0→11
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1998)	k = −16→6
Tmin = 0.687, Tmax = 0.881	l = −15→15
5129 measured reflections	3 standard reflections every 240 min
3300 independent reflections	intensity decay: none

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	Calculated w = 1/[σ^2(Fo^2) + (0.0461P)^2 + 0.9319P] where P = (Fo^2 + 2Fc^2)/3
3300 reflections	(Δ/σ)max = 0.001
128 parameters	Δρmax = 1.23 e Å^−3
0 restraints	Δρmin = −0.95 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	0.5000	0.5000	0.5000	0.04036 (16)
Br1	0.33099 (4)	0.53646 (3)	0.74605 (4)	0.05020 (13)
N1	0.7068 (3)	0.4539 (2)	0.5916 (2)	0.0372 (5)
C1	0.8428 (4)	0.5093 (3)	0.6033 (3)	0.0417 (7)
H1	0.8607	0.5764	0.5659	0.050*
N2	0.9530 (3)	0.4576 (2)	0.6757 (3)	0.0437 (6)
H2	1.0500	0.4802	0.6948	0.052*
C2	0.8843 (4)	0.3628 (3)	0.7139 (3)	0.0455 (8)
C3	0.7326 (4)	0.3607 (3)	0.6611 (3)	0.0462 (8)
H3	0.6569	0.3048	0.6703	0.055*
C4	0.9701 (6)	0.2856 (4)	0.8006 (5)	0.0749 (14)
H4A	1.0730	0.3169	0.8276	0.112*	0.30 (6)
H4B	0.9870	0.2156	0.7631	0.112*	0.30 (6)
H4C	0.9055	0.2748	0.8668	0.112*	0.30 (6)
H4D	0.9040	0.2213	0.8107	0.112*	0.70 (6)
H4E	0.9900	0.3226	0.8752	0.112*	0.70 (6)
H4F	1.0715	0.2634	0.7715	0.112*	0.70 (6)
N3	0.5728 (3)	0.6598 (2)	0.5063 (2)	0.0370 (6)
C11	0.5418 (4)	0.7306 (3)	0.5884 (3)	0.0453 (8)
H11	0.4841	0.7140	0.6537	0.054*
N4	0.6040 (4)	0.8307 (2)	0.5666 (3)	0.0480 (7)
H4	0.5966	0.8891	0.6095	0.058*
C12	0.6810 (4)	0.8234 (3)	0.4644 (3)	0.0439 (8)
C13	0.6608 (4)	0.7183 (3)	0.4280 (3)	0.0420 (7)
H13	0.7003	0.6890	0.3598	0.050*
C14	0.7616 (6)	0.9219 (4)	0.4144 (4)	0.0701 (12)
H14A	0.8702	0.9026	0.3973	0.105*	0.57 (6)
H14B	0.7648	0.9815	0.4707	0.105*	0.57 (6)
H14C	0.7018	0.9449	0.3429	0.105*	0.57 (6)
H14D	0.6876	0.9834	0.4099	0.105*	0.43 (6)
H14E	0.7931	0.9045	0.3366	0.105*	0.43 (6)
H14F	0.8561	0.9411	0.4643	0.105*	0.43 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0383 (3)	0.0265 (3)	0.0536 (3)	−0.0072 (2)	−0.0157 (2)	0.0029 (2)
Br1	0.04270 (19)	0.0413 (2)	0.0652 (2)	−0.00560 (14)	−0.00567 (15)	0.01207 (16)
N1	0.0358 (12)	0.0335 (14)	0.0412 (14)	−0.0046 (11)	−0.0055 (10)	0.0006 (11)
C1	0.0377 (16)	0.0383 (17)	0.0487 (18)	−0.0029 (13)	−0.0003 (13)	0.0029 (14)
N2	0.0295 (12)	0.0441 (16)	0.0563 (17)	−0.0034 (11)	−0.0046 (11)	−0.0008 (13)
C2	0.0378 (16)	0.0401 (18)	0.057 (2)	−0.0005 (13)	−0.0094 (14)	0.0030 (15)
C3	0.0389 (17)	0.0377 (17)	0.060 (2)	−0.0076 (13)	−0.0094 (15)	0.0073 (15)
C4	0.058 (3)	0.063 (3)	0.099 (4)	−0.005 (2)	−0.029 (2)	0.026 (2)
N3	0.0367 (13)	0.0301 (13)	0.0427 (15)	−0.0071 (10)	−0.0072 (11)	−0.0002 (11)
C11	0.051 (2)	0.0389 (18)	0.0470 (19)	−0.0088 (15)	0.0070 (15)	−0.0018 (14)
N4	0.0564 (18)	0.0332 (15)	0.0542 (18)	−0.0072 (13)	0.0028 (14)	−0.0083 (13)
C12	0.0436 (17)	0.0371 (17)	0.0495 (19)	−0.0079 (14)	−0.0074 (14)	0.0060 (14)
C13	0.0491 (19)	0.0389 (18)	0.0377 (17)	−0.0058 (14)	0.0007 (14)	−0.0004 (13)
C14	0.081 (3)	0.054 (2)	0.075 (3)	−0.026 (2)	0.003 (2)	0.018 (2)

Geometric parameters (Å, º)

Cu1—N1^i	2.014 (3)	C4—H4E	0.9600
Cu1—N1	2.014 (3)	C4—H4F	0.9600
Cu1—N3	2.017 (2)	N3—C11	1.302 (4)
Cu1—N3^i	2.017 (2)	N3—C13	1.381 (4)
N1—C1	1.306 (4)	C11—N4	1.341 (4)
N1—C3	1.381 (4)	C11—H11	0.9300
C1—N2	1.337 (4)	N4—C12	1.364 (5)
C1—H1	0.9300	N4—H4	0.8600
N2—C2	1.360 (5)	C12—C13	1.339 (5)
N2—H2	0.8600	C12—C14	1.493 (5)
C2—C3	1.351 (4)	C13—H13	0.9300
C2—C4	1.495 (5)	C14—H14A	0.9600
C3—H3	0.9300	C14—H14B	0.9600
C4—H4A	0.9600	C14—H14C	0.9600
C4—H4B	0.9600	C14—H14D	0.9600
C4—H4C	0.9600	C14—H14E	0.9600
C4—H4D	0.9600	C14—H14F	0.9600
N1^i—Cu1—N1	180.0	H4C—C4—H4F	141.1
N1^i—Cu1—N3	89.70 (10)	H4D—C4—H4F	109.5
N1—Cu1—N3	90.30 (10)	H4E—C4—H4F	109.5
N1^i—Cu1—N3^i	90.30 (10)	C11—N3—C13	105.3 (3)
N1—Cu1—N3^i	89.70 (10)	C11—N3—Cu1	125.3 (2)
N3—Cu1—N3^i	180.0	C13—N3—Cu1	129.4 (2)
C1—N1—C3	105.1 (3)	N3—C11—N4	111.1 (3)
C1—N1—Cu1	127.2 (2)	N3—C11—H11	124.4
C3—N1—Cu1	127.6 (2)	N4—C11—H11	124.4
N1—C1—N2	111.6 (3)	C11—N4—C12	107.8 (3)
N1—C1—H1	124.2	C11—N4—H4	126.1
N2—C1—H1	124.2	C12—N4—H4	126.1
C1—N2—C2	107.8 (3)	C13—C12—N4	105.5 (3)
C1—N2—H2	126.1	C13—C12—C14	133.2 (4)
C2—N2—H2	126.1	N4—C12—C14	121.3 (3)
C3—C2—N2	105.7 (3)	C12—C13—N3	110.2 (3)
C3—C2—C4	131.4 (4)	C12—C13—H13	124.9
N2—C2—C4	122.9 (3)	N3—C13—H13	124.9
C2—C3—N1	109.8 (3)	C12—C14—H14A	109.5
C2—C3—H3	125.1	C12—C14—H14B	109.5
N1—C3—H3	125.1	H14A—C14—H14B	109.5
C2—C4—H4A	109.5	C12—C14—H14C	109.5
C2—C4—H4B	109.5	H14A—C14—H14C	109.5
H4A—C4—H4B	109.5	H14B—C14—H14C	109.5
C2—C4—H4C	109.5	C12—C14—H14D	109.5
H4A—C4—H4C	109.5	H14A—C14—H14D	141.1
H4B—C4—H4C	109.5	H14B—C14—H14D	56.3
C2—C4—H4D	109.5	H14C—C14—H14D	56.3
H4A—C4—H4D	141.1	C12—C14—H14E	109.5
H4B—C4—H4D	56.3	H14A—C14—H14E	56.3
H4C—C4—H4D	56.3	H14B—C14—H14E	141.1
C2—C4—H4E	109.5	H14C—C14—H14E	56.3
H4A—C4—H4E	56.3	H14D—C14—H14E	109.5
H4B—C4—H4E	141.1	C12—C14—H14F	109.5
H4C—C4—H4E	56.3	H14A—C14—H14F	56.3
H4D—C4—H4E	109.5	H14B—C14—H14F	56.3
C2—C4—H4F	109.5	H14C—C14—H14F	141.1
H4A—C4—H4F	56.3	H14D—C14—H14F	109.5
H4B—C4—H4F	56.3	H14E—C14—H14F	109.5

Symmetry code: (i) −x+1, −y+1, −z+1.