The complex salt benzodiimidazolium tetra­chloro­zincate

The title compound, (C₈H₈N₄)[ZnCl₄], consists of the benzo­diimidazolium cation and tetra­chloro­zincate anion. As expected, the benzodiimidazolium is essentially planar, while the [ZnCl₄]^2- unit has a regular tetrahedral geometry; they have approximate C_2h and T_d symmetry, respectively. The hydrogen bonding formed by the chloride ligand with the HN moiety leads to an extended two-dimensional structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.026
• wR factor = 0.072
• Data-to-parameter ratio = 12.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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Computing details

Data collection: CAD-4 VAX/PC Diffractometer Control Software (Enraf-Nonius, 1988); cell refinement: CAD-4 VAX/PC Diffractometer Control Software; data reduction: NRCVAX (Gabe et al., 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

(I)

Crystal data

C8H8N4^+·ZnCl4^−	F(000) = 728
Mr = 367.35	Dx = 1.981 Mg m^−3
Orthorhombic, Cmcm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2c 2	Cell parameters from 25 reflections
a = 8.719 (2) Å	θ = 1–25°
b = 9.276 (2) Å	µ = 2.84 mm^−1
c = 15.226 (3) Å	T = 293 K
V = 1231.4 (5) Å^3	Plate, colourless
Z = 4	0.4 × 0.4 × 0.1 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	539 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.017
Graphite monochromator	θmax = 25.0°, θmin = 2.7°
ω scans	h = −10→0
Absorption correction: ψ scans (North et al., 1968)	k = −11→11
Tmin = 0.33, Tmax = 0.75	l = 0→18
1169 measured reflections	3 standard reflections every 97 reflections
607 independent reflections	intensity decay: <1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.026	Only H-atom displacement parameters refined
wR(F^2) = 0.073	w = 1/[σ^2(Fo^2) + (0.0536P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
607 reflections	Δρmax = 0.71 e Å^−3
50 parameters	Δρmin = −0.41 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0081 (10)

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
N1	0.3754 (2)	0.21154 (17)	0.60050 (15)	0.0332 (5)
C2	0.5000	0.2760 (3)	0.6304 (2)	0.0354 (8)
C1	0.4192 (3)	0.0969 (2)	0.54709 (15)	0.0275 (5)
C3	0.3322 (4)	0.0000	0.5000	0.0290 (7)
H1A	0.2757	0.2335	0.6184	0.050 (8)*
H3A	0.2241	0.0000	0.5000	0.050 (11)*
H2A	0.5000	0.3571	0.6586	0.058 (13)*
Zn1	0.0000	0.29266 (5)	0.7500	0.0299 (3)
Cl1	0.0000	0.16128 (8)	0.62204 (6)	0.0319 (3)
Cl2	0.21445 (10)	0.42793 (8)	0.7500	0.0374 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0314 (11)	0.0349 (10)	0.0334 (12)	0.0023 (8)	0.0065 (10)	−0.0023 (8)
C2	0.049 (2)	0.0312 (18)	0.0256 (19)	0.000	0.000	−0.0025 (13)
C1	0.0263 (11)	0.0305 (10)	0.0256 (12)	0.0002 (9)	0.0035 (10)	0.0032 (9)
C3	0.0186 (15)	0.0382 (16)	0.0303 (19)	0.000	0.000	0.0029 (14)
Zn1	0.0244 (4)	0.0374 (4)	0.0279 (4)	0.000	0.000	0.000
Cl1	0.0278 (5)	0.0374 (5)	0.0306 (5)	0.000	0.000	−0.0040 (3)
Cl2	0.0300 (5)	0.0405 (5)	0.0417 (5)	−0.0068 (3)	0.000	0.000

Geometric parameters (Å, º)

N1—C1	1.392 (3)	C3—C1^ii	1.378 (3)
N1—C2	1.321 (3)	C3—H3A	0.9426
N1—H1A	0.9340	Zn1—Cl1	2.2980 (9)
C2—N1^i	1.321 (3)	Zn1—Cl1^iii	2.2980 (9)
C2—H2A	0.8659	Zn1—Cl2	2.2517 (9)
C1—C3	1.378 (3)	Zn1—Cl2^iv	2.2517 (9)
C1—C1^i	1.409 (4)
C2—N1—C1	108.8 (2)	C1—C3—C1^ii	113.2 (3)
C2—N1—H1A	124.5	C1—C3—H3A	123.4
C1—N1—H1A	126.3	C1^ii—C3—H3A	123.4
N1—C2—N1^i	110.6 (3)	Cl1—Zn1—Cl1^iii	115.95 (5)
N1—C2—H2A	124.3	Cl2—Zn1—Cl1	107.188 (16)
N1^i—C2—H2A	124.3	Cl2^iv—Zn1—Cl1	107.188 (16)
C3—C1—N1	130.6 (2)	Cl2—Zn1—Cl1^iii	107.188 (16)
C3—C1—C1^i	123.42 (15)	Cl2^iv—Zn1—Cl1^iii	107.188 (16)
N1—C1—C1^i	105.91 (12)	Cl2—Zn1—Cl2^iv	112.27 (5)
C1—N1—C2—N1^i	−0.1 (4)	N1—C1—C3—C1^ii	178.5 (3)
C2—N1—C1—C3	−178.6 (2)	C1^i—C1—C3—C1^ii	0.0
C2—N1—C1—C1^i	0.1 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1	0.93	2.50	3.323 (2)	148
N1—H1A···Cl2	0.93	2.75	3.344 (2)	123