[Cu(2-Me-imidH)₄Cl]Cl: a conflict between high symmetry and packing efficiency

The crystal and molecular structure of the monomeric title compound, chloro­tetrakis(2-methyl­imidazole)copper(II) chlor­ide, [CuCl(C₄H₆N₂)₄]Cl, is presented, and compared with those of two other closely related monomeric structures. The monomers are similar, but the supramolecular structures are very different. The influence that steric effects might have in determining crystal properties, such as space group symmetry or packing efficiency, is analysed.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.041
• wR factor = 0.085
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          8
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C16 H24 Cl Cu N8
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          2
              Cl

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.03
           From the CIF: _reflns_number_total                896
           Count of symmetry unique reflns          494
           Completeness (_total/calc)            181.38%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       402
           Fraction of Friedel pairs measured     0.814
           Are heavy atom types Z>Si present          yes

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

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

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Computing details

Data collection: SMART-NT (Bruker, 2001); cell refinement: SMART-NT; data reduction: SAINT-NT(Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Sheldrick, 1994); software used to prepare material for publication: SHELXL97.

Chlorotetrakis(2-methylimidazole)copper(II) chloride

Crystal data

[CuCl(C4H6N2)4]Cl	Dx = 1.471 Mg m^−3
Mr = 462.87	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4nc	Cell parameters from 134 reflections
a = 9.8106 (12) Å	θ = 3.1–22.9°
c = 10.8547 (19) Å	µ = 1.32 mm^−1
V = 1044.7 (3) Å^3	T = 293 K
Z = 2	Plates, blue
F(000) = 478	0.16 × 0.12 × 0.06 mm

Data collection

Bruker SMART CCD area-detector diffractometer	896 independent reflections
Radiation source: fine-focus sealed tube	670 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.072
φ and ω scans	θmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan [SADABS (Sheldrick, 1996) in SAINT-NT (Bruker, 2000)]	h = −11→11
Tmin = 0.83, Tmax = 0.92	k = −8→11
3889 measured reflections	l = −12→11

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.041	H-atom parameters constrained
wR(F^2) = 0.085	w = 1/[σ^2(Fo^2) + (0.0382P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.93	(Δ/σ)max = 0.004
896 reflections	Δρmax = 0.57 e Å^−3
64 parameters	Δρmin = −0.33 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.03 (3)

Special details

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
Cu	−0.5000	0.5000	1.09269 (8)	0.0315 (3)
Cl1	−0.5000	0.5000	0.8507 (2)	0.0489 (7)
Cl2	−0.5000	0.5000	1.4710 (3)	0.0442 (5)
N1	−0.3846 (3)	0.3318 (3)	1.1221 (4)	0.0322 (10)
C1	−0.4137 (6)	0.2365 (5)	1.2110 (6)	0.0484 (16)
H1A	−0.4877	0.2407	1.2645	0.058*
C2	−0.3208 (6)	0.1369 (6)	1.2097 (7)	0.0585 (19)
H2A	−0.3170	0.0608	1.2607	0.070*
N2	−0.2334 (4)	0.1708 (4)	1.1185 (6)	0.0558 (14)
H2B	−0.1637	0.1235	1.0963	0.067*
C3	−0.2717 (5)	0.2890 (4)	1.0680 (4)	0.0376 (13)
C4	−0.1958 (5)	0.3576 (5)	0.9678 (7)	0.0611 (17)
H4A	−0.2406	0.4413	0.9467	0.092*
H4B	−0.1928	0.2992	0.8969	0.092*
H4C	−0.1046	0.3767	0.9948	0.092*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0258 (4)	0.0258 (4)	0.0431 (7)	0.000	0.000	0.000
Cl1	0.0521 (10)	0.0521 (10)	0.0425 (17)	0.000	0.000	0.000
Cl2	0.0382 (7)	0.0382 (7)	0.0562 (15)	0.000	0.000	0.000
N1	0.0302 (19)	0.0268 (18)	0.040 (3)	−0.0019 (17)	0.0052 (19)	0.0055 (19)
C1	0.039 (3)	0.044 (3)	0.062 (4)	0.007 (3)	0.003 (3)	0.014 (3)
C2	0.056 (4)	0.049 (4)	0.071 (5)	0.007 (3)	−0.004 (4)	0.027 (4)
N2	0.039 (2)	0.038 (2)	0.089 (5)	0.017 (2)	0.002 (3)	0.004 (3)
C3	0.037 (3)	0.033 (3)	0.043 (4)	−0.002 (2)	0.000 (2)	−0.003 (2)
C4	0.052 (3)	0.064 (4)	0.068 (5)	0.012 (3)	0.020 (5)	0.005 (5)

Geometric parameters (Å, º)

Cu—N1^i	2.027 (3)	C2—N2	1.351 (7)
Cu—N1^ii	2.027 (3)	C2—H2A	0.9300
Cu—N1	2.027 (3)	N2—C3	1.337 (6)
Cu—N1^iii	2.027 (3)	N2—H2B	0.8600
Cu—Cl1	2.627 (3)	C3—C4	1.480 (7)
N1—C3	1.322 (5)	C4—H4A	0.9600
N1—C1	1.374 (6)	C4—H4B	0.9600
C1—C2	1.337 (7)	C4—H4C	0.9600
C1—H1A	0.9300
N1^i—Cu—N1^ii	161.9 (2)	C1—C2—N2	105.1 (6)
N1^i—Cu—N1	88.58 (4)	C1—C2—H2A	127.4
N1^ii—Cu—N1	88.58 (4)	N2—C2—H2A	127.4
N1^i—Cu—N1^iii	88.58 (4)	C3—N2—C2	109.6 (4)
N1^ii—Cu—N1^iii	88.58 (4)	C3—N2—H2B	125.2
N1—Cu—N1^iii	161.9 (2)	C2—N2—H2B	125.2
N1^i—Cu—Cl1	99.06 (12)	N1—C3—N2	109.2 (4)
N1^ii—Cu—Cl1	99.06 (12)	N1—C3—C4	127.2 (4)
N1—Cu—Cl1	99.06 (12)	N2—C3—C4	123.7 (5)
N1^iii—Cu—Cl1	99.06 (12)	C3—C4—H4A	109.5
C3—N1—C1	105.7 (4)	C3—C4—H4B	109.5
C3—N1—Cu	131.0 (3)	H4A—C4—H4B	109.5
C1—N1—Cu	123.3 (3)	C3—C4—H4C	109.5
C2—C1—N1	110.4 (6)	H4A—C4—H4C	109.5
C2—C1—H1A	124.8	H4B—C4—H4C	109.5
N1—C1—H1A	124.8

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2B···Cl2^iv	0.86	2.43	3.258 (5)	162

Symmetry code: (iv) x+1/2, −y+1/2, z−1/2.