metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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catena-Poly[[di­chloro­zinc(II)]-μ-cyano­guanidine]

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aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
*Correspondence e-mail: w.harrison@abdn.ac.uk

(Received 22 January 2007; accepted 23 January 2007; online 31 January 2007)

The one-dimensional title compound, [ZnCl2(C2H4N4)]n, contains ZnCl2N2 tetra­heda linked by N,N-bridging cyano­guanidine mol­ecules. A network of N—H⋯Cl hydrogen bonds help to establish the crystal packing.

Comment

The title compound, (I)[link] (Fig. 1[link]), is a one-dimensional coordination polymer containing cyano­guanidine mol­ecules, Zn2+ ions and Cl ions. The Zn2+ cation is tetra­hedrally coordinated by two terminal Cl ions and two cyano­guanidine mol­ecules (Table 1[link]), one bonded through the cyanide atom N4 and one from the imine atom N3. The C1—N3—C2 bond angle in (I)[link] is 116.22 (15)°, compared with the corresponding angle of 118.38 (2)° in the free ligand (Hirshfeld & Hope, 1980[Hirshfeld, F. L. & Hope, H. (1980). Acta Cryst. B36, 406-415.]). The C1—N3 [1.370 (2) Å] and C2—N3 [1.308 (3) Å] bond lengths in (I)[link] indicate that the conventional Lewis structure shown in the chemical scheme (C1=N3 a formal double bond and C2—N3 a formal single bond) is only a very approximate representation of the actual electron distribution in the mol­ecule (Hughes, 1940[Hughes, E. W. (1940). J. Am. Chem. Soc. 62, 1258-1267.]; Hirshfeld & Hope, 1980[Hirshfeld, F. L. & Hope, H. (1980). Acta Cryst. B36, 406-415.]).

[Scheme 1]

The connectivity of the building units in (I)[link] results in a polymeric chain of stoichiometry Zn(C2H4N4)Cl2 (Fig. 2[link]), which propagates in the polar [001] direction. The chain conformation is reinforced by an intra-chain N1—H2⋯Cl1 hydrogen bond. Further N—H⋯Cl bonds cross-link the polymeric strands (Table 2[link]). Atom H1 has no nearby Cl ions but possibly forms a weak bifurcated N—H⋯(Cl,Cl) inter­action (bond angle sum for H1 = 359°).

Two polymorphs of the mol­ecular compound Zn(C2H4N4)2Cl2 have been reported by Pickardt & Kuhn (1995[Pickardt, J. & Kuhn, B. (1995). Z. Kristallogr. 210, 901-901.]) and Fowkes & Harrison (2005[Fowkes, A. & Harrison, W. T. A. (2005). Acta Cryst. E61, m2021-m2022.]). These both contain ZnCl2N2 tetra­hedra, with the two cyanoguanidine molecules both bonding through their cyanide N atoms. Other compounds with the stoichiometry of the title compound, M(C2H4N4)X2 (M is a divalent metal cation and X is a halide) include Hg(C2H4N4)Cl2 and Cd(C2H4N4)Br2 (Pickardt & Kuhn, 1996[Pickardt, J. & Kuhn, B. (1996). Z. Naturforsch. Teil B, 51, 1701-1706.]). The mercury compound contains N,N-bonded cyano­guanidine molecues, as seen here in (I)[link], but the Cl ions also act as μ2 bridges between the irregularly-coordinated Hg2+ ions, leading to a layered polymeric network. The cadmium compound features cyanide-N-bonded cyano­guanidine mol­ecules and bridging Br ions, leading to one-dimensional chains of distorted tetra­hedral CdN2Br2 units.

[Figure 1]
Figure 1
The asymmetric unit of (I)[link], expanded to show the polymeric connectivity (open bonds) of the chain. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radius. The intra-chain hydrogen bond is indicated by a double-dashed line. [Symmetry codes: (i) 1 − x, −y, z − [{1\over 2}], (ii) 1 − x, −y, z + [{1\over 2}].]
[Figure 2]
Figure 2
Part of an [001] polymeric chain in (I)[link]. [Symmetry codes: (ii) 1 − x, −y, z + [{1\over 2}], (iii) x, y, z + 1.]

Experimental

An aqueous solution (10 ml) of cyano­guanidine (0.73 M) and a methano­lic solution (10 ml) of ZnCl2 (0.73 M) were mixed at 293 K in a Petri dish, resulting in a colourless mixture. Colourless blocks and slabs of (I)[link] grew over the course of a few days as the water/methanol evaporated at 293 K.

Crystal data
  • [ZnCl2(C2H4N4)]

  • Mr = 220.36

  • Orthorhombic, P c a 21

  • a = 13.6756 (8) Å

  • b = 7.3710 (5) Å

  • c = 7.4200 (5) Å

  • V = 747.96 (8) Å3

  • Z = 4

  • Dx = 1.957 Mg m−3

  • Mo Kα radiation

  • μ = 3.92 mm−1

  • T = 293 (2) K

  • Slab, colourless

  • 0.51 × 0.49 × 0.09 mm

Data collection
  • Bruker SMART1000 CCD area-detector diffractometer

  • ω scans

  • Absorption correction: multi-scan (SADABS; Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02a) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.240, Tmax = 0.720

  • 9597 measured reflections

  • 2612 independent reflections

  • 2481 reflections with I > 2σ(I)

  • Rint = 0.039

  • θmax = 32.5°

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.026

  • wR(F2) = 0.071

  • S = 1.05

  • 2612 reflections

  • 83 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.047P)2] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max < 0.001

  • Δρmax = 0.49 e Å−3

  • Δρmin = −0.57 e Å−3

  • Extinction correction: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.])

  • Extinction coefficient: 0.0218 (16)

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), with 1163 Friedel pairs

  • Flack parameter: 0.027 (11)

Table 1
Selected bond lengths (Å)

Zn1—N4iv 1.985 (2)
Zn1—N3 2.0887 (14)
Zn1—Cl2 2.2238 (7)
Zn1—Cl1 2.2252 (7)
Symmetry code: (iv) [-x+1, -y, z-{\script{1\over 2}}].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯Cl1v 0.86 2.92 3.6437 (18) 144
N1—H1⋯Cl2vi 0.86 2.92 3.389 (2) 116
N1—H2⋯Cl1 0.86 2.48 3.3050 (18) 161
N2—H3⋯Cl1v 0.86 2.42 3.262 (2) 166
N2—H4⋯Cl2vii 0.86 2.50 3.289 (2) 153
Symmetry codes: (v) [x+{\script{1\over 2}}, -y+1, z]; (vi) [-x+1, -y+1, z-{\script{1\over 2}}]; (vii) [x+{\script{1\over 2}}, -y, z].

H atoms were placed in idealized locations, with N—H = 0.86 Å, and refined as riding, with Uiso(H) = 1.2Ueq(N).

Data collection: SMART (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02a) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02a) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97.

Supporting information


Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

catena-Poly[[dichlorozinc(II)]-µ-cyanoguanidine] top
Crystal data top
[ZnCl2(C2H4N4)]F(000) = 432
Mr = 220.36Dx = 1.957 Mg m3
Orthorhombic, Pca21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2acCell parameters from 6450 reflections
a = 13.6756 (8) Åθ = 2.8–32.5°
b = 7.3710 (5) ŵ = 3.92 mm1
c = 7.4200 (5) ÅT = 293 K
V = 747.96 (8) Å3Slab, colourless
Z = 40.51 × 0.49 × 0.09 mm
Data collection top
Bruker SMART1000 CCD area-detector
diffractometer
2612 independent reflections
Radiation source: fine-focus sealed tube2481 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.039
ω scansθmax = 32.5°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 2020
Tmin = 0.240, Tmax = 0.720k = 1011
9597 measured reflectionsl = 119
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.026 w = 1/[σ2(Fo2) + (0.047P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.071(Δ/σ)max < 0.001
S = 1.05Δρmax = 0.49 e Å3
2612 reflectionsΔρmin = 0.57 e Å3
83 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0218 (16)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), with 1163 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.027 (11)
Special details top

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 (Å2) top
xyzUiso*/Ueq
Zn10.424511 (14)0.23356 (3)0.72398 (5)0.02943 (8)
Cl10.40928 (4)0.51909 (9)0.63074 (11)0.04953 (16)
Cl20.33515 (4)0.15972 (8)0.96339 (10)0.04576 (14)
C10.65364 (13)0.2735 (2)0.7454 (3)0.0276 (4)
C20.58011 (11)0.0556 (3)0.9148 (3)0.0307 (4)
N10.64494 (13)0.4213 (3)0.6480 (3)0.0420 (4)
H10.69630.47840.61260.050*
H20.58790.46110.61960.050*
N20.74078 (13)0.2115 (3)0.7896 (3)0.0390 (4)
H30.79240.26800.75450.047*
H40.74600.11460.85340.047*
N30.56986 (10)0.1852 (2)0.7959 (2)0.0265 (3)
N40.58423 (12)0.0587 (4)1.0211 (4)0.0471 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.02959 (11)0.02627 (11)0.03243 (13)0.00409 (6)0.00139 (11)0.00518 (13)
Cl10.0527 (3)0.0378 (3)0.0581 (4)0.0195 (2)0.0104 (3)0.0144 (3)
Cl20.0439 (2)0.0449 (3)0.0484 (3)0.0134 (2)0.0135 (2)0.0086 (3)
C10.0270 (7)0.0267 (7)0.0291 (11)0.0018 (5)0.0025 (6)0.0031 (7)
C20.0255 (7)0.0336 (10)0.0330 (10)0.0001 (6)0.0009 (6)0.0073 (8)
N10.0390 (8)0.0353 (9)0.0515 (12)0.0006 (7)0.0059 (8)0.0180 (9)
N20.0247 (7)0.0397 (9)0.0525 (12)0.0014 (7)0.0001 (7)0.0112 (8)
N30.0253 (6)0.0253 (7)0.0290 (8)0.0018 (5)0.0008 (5)0.0043 (6)
N40.0321 (8)0.0528 (13)0.0563 (15)0.0059 (7)0.0077 (7)0.0275 (11)
Geometric parameters (Å, º) top
Zn1—N4i1.985 (2)C2—N41.156 (3)
Zn1—N32.0887 (14)C2—N31.308 (3)
Zn1—Cl22.2238 (7)N1—H10.8600
Zn1—Cl12.2252 (7)N1—H20.8600
C1—N11.313 (3)N2—H30.8600
C1—N21.318 (3)N2—H40.8600
C1—N31.370 (2)N4—Zn1ii1.985 (2)
N4i—Zn1—N398.07 (7)C1—N1—H1120.0
N4i—Zn1—Cl2114.44 (8)C1—N1—H2120.0
N3—Zn1—Cl2106.09 (5)H1—N1—H2120.0
N4i—Zn1—Cl1111.87 (9)C1—N2—H3120.0
N3—Zn1—Cl1109.26 (5)C1—N2—H4120.0
Cl2—Zn1—Cl1115.37 (3)H3—N2—H4120.0
N1—C1—N2120.42 (18)C2—N3—C1116.22 (15)
N1—C1—N3117.97 (17)C2—N3—Zn1113.50 (11)
N2—C1—N3121.60 (18)C1—N3—Zn1130.18 (14)
N4—C2—N3176.63 (17)C2—N4—Zn1ii171.1 (2)
N1—C1—N3—C2169.9 (2)Cl2—Zn1—N3—C229.17 (17)
N2—C1—N3—C211.4 (3)Cl1—Zn1—N3—C2154.14 (16)
N1—C1—N3—Zn16.2 (3)N4i—Zn1—N3—C194.6 (2)
N2—C1—N3—Zn1172.58 (18)Cl2—Zn1—N3—C1146.97 (18)
N4i—Zn1—N3—C289.24 (19)Cl1—Zn1—N3—C122.0 (2)
Symmetry codes: (i) x+1, y, z1/2; (ii) x+1, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Cl1iii0.862.923.6437 (18)144
N1—H1···Cl2iv0.862.923.389 (2)116
N1—H2···Cl10.862.483.3050 (18)161
N2—H3···Cl1iii0.862.423.262 (2)166
N2—H4···Cl2v0.862.503.289 (2)153
Symmetry codes: (iii) x+1/2, y+1, z; (iv) x+1, y+1, z1/2; (v) x+1/2, y, z.
 

References

First citationBruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02a) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationFowkes, A. & Harrison, W. T. A. (2005). Acta Cryst. E61, m2021–m2022.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationHirshfeld, F. L. & Hope, H. (1980). Acta Cryst. B36, 406–415.  CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
First citationHughes, E. W. (1940). J. Am. Chem. Soc. 62, 1258–1267.  CrossRef CAS Google Scholar
First citationPickardt, J. & Kuhn, B. (1995). Z. Kristallogr. 210, 901–901.  CrossRef CAS Web of Science Google Scholar
First citationPickardt, J. & Kuhn, B. (1996). Z. Naturforsch. Teil B, 51, 1701–1706.  CAS Google Scholar
First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.  Google Scholar

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