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The coordination geometry of the ZnII atom in the title complex, [Zn(C2N3)2(C6H8N6)2]n or [Zn(dca)2(bte)2]n, where bte is [mu]-1,2-bis(1,2,4-triazol-1-yl)­ethane and dca is dicyan­amide, is distorted compressed octahedral, in which the ZnII atom lies on an inversion center and coordinates four N atoms from the triazole rings of four symmetry-related bte ligands and two N atoms from two symmetry-related monodentate dca ligands. The structure is polymeric, with 18-membered spiro-fused rings extending in the b direction and each 18-membered ring involving two inversion-related bte mol­ecules.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103012435/sk1645sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103012435/sk1645Isup2.hkl
Contains datablock I

CCDC reference: 221055

Comment top

The syntheses of new organic-inorganic polymers has been a rapidly developing area of research in recent years because their unusual properties, such as electronic, optical, magnetic and catalytic properties (Batten et al., 1998; Blake et al., 1999).

The design of coordination polymers is greatly influenced by several factors, such as the metal coordination preference, the structural characteristics of the polydentate organic ligand, the metal–ligand ratio, the solvent system and the counter-ion. The most widely used ligands are rigid rod-like organic building blocks, such as 4,4'-bipyridine (Fujita et al., 1994) and 4,4'-azobispyridine (Li et al., 2001), while flexible ligands have been studied relatively little. The flexible ligand bis(1,2,4-triazole-1-yl)ethane (Torres et al., 1988) is an excellent alternative for further research. The dicyanamide ligand, [N(CN)2] is also a remarkably versatile building block for the construction of supramolecular architectures, since it can act in a mono-, bi- or tridentate manner (Riggio et al., 2001; Li et al., 2002). We report here the crystal structure of a novel infinite double-stranded chain polymer, [Zn(bte)2(dca)2]n, (I), which has been synthesized from a mixed-ligand system of bis(1,2,4-triazole-1-yl)ethane (bte) and dicyanamide (dca).

Fig. 1 shows the local coordination about the zinc centre in (I). The complex molecules have a center of symmetry and the Zn atom lies on an inversion centre. The coordination geometry of the ZnII atom is a distorted compressed octahedron and it coordinates with four N atoms from the triazole rings of four symmetry-related bte ligands and two N atoms from two symmetry-related monodentate dca ligands. The equatorial plane contains two N atoms from the triazole rings of two bte ligands [Zn1—N3 2.1948 (14) Å and Zn1—N3iii 2.1948 (14) Å; symmetry code: (iii) 1 − x, −y, 1 − z] and two N atoms from two dca ligands [Zn1—N7 = 2.1734 (16) Å and Zn1—N7iii = 2.1734 (16) Å], and the axial positions are occupied by two triazole N atoms of two bte ligands [Zn1—N6i = 2.1263 (13) Å and Zn1—N6ii = 2.1263 (13) Å; symmetry codes: (i) x, y − 1, z; (ii) 1 − x, 1 − y, 1 − z]. The bte ligands exhibit gauch conformation in complex (I). Zn atoms are linked by bte ligands via the N atoms in the 4-positions of two triazole rings, and a rhombic network of size 5.601 (2) × 6.687 (2) Å is formed. The diagonal lengths of the rhomb are 8.369 (2) Å for Zn1···Zn11 and 9.063 (2) Å for C6iii···C6i. The rhombic angles are 94.6 (2) and 85.4 (2)°.

Compound (I) has an infinite double-stranded chain structure (Fig. 1). The r.m.s. deviation of the triazole ring atoms from the mean planes of the rings containing atoms N3 and N6 are 0.0024 (9) and 0.0009 (8) Å, respectively, and the dihedral angle between the planes of the N3- and N6-triazole rings is 58.05 (6)°. The bte ligand is twisted during coordination and the N1—C5—C6—N4 torsion angle is 58.11 (16)°. Two strands of bte ligands are wrapped around one another and are held together by ZnII atoms, forming an infinite double-stranded chain structure. Each chain consists of 18-membered spiro-fused rings, in which two ZnII atoms are joined via two bte molecules. The chains extend along the b axis, and all of the Zn atoms in one chain are on the axial line. The Zn···Zn separation across the bridging bte ligand is equal to the b axis translation [8.369 (2) Å], which is shorter than the intermetallic distance founded for [Cu(TTA)2]2(bte) [TTA = 1,1,1-trifluoro-3-(2-thenoyl)acetone], which exhibits M(anti-bte)M bridging [12.473 (2) Å; Li et al., 1999]. The dicyanamide is coordinated to metal atoms in a monodentate manner via the nitrile N atom. Free dicyanamide ligands possess C2v symmetry, while the dicyanamide ligand in (I) possesses pseudo-C2v symmetry, with nitrile C—N bond distances of 1.156 (3) Å for N7—C7 and 1.154 (2) Å for N9—C8 (Table 1). The amide C7—N8—C8 bond angle is 119.49 (15)° and the The nitrile N7—C7—N8 and N9—C8—N8 bond angles are 173.85 (16) and 174.38 (19)°, respectively. There are weak interactions N2···H5A—C5v and N9···H2A—C2vi interactions [symmetry codes: (v) −x, −y + 1, −z + 1; (vi) −x, −y, −z + 1] between trazole (dca) N atoms and alkane (triazole) H atoms in neighboring chains [N2···H5A—C5v = 2.511 Å and N9···H2A—C2vi = 2.537 Å]. There is also a weak interaction between a nitrile N atom and a triazole H atom from a neighboring chains [N9···H4A—C4vii = 2.435 (3) Å; symmetry code: (vii) −1/2 + x, 1/2 − y, 1/2 + z]. The adjacent chains are linked via these weak interactions in the solid state in (I). Although many one-dimensional chain polymers have been reported (Dong et al., 1999; Claramunt et al., 2000), double-stranded chain polymers are rare (Zhao et al., 2002). The synthesis of (I) is a successful example of the synthesis of novel polymers using the flexible bis(1,2,4-triazol-1-yl)alkane ligand.

Experimental top

A aqueous solution (10 ml) of NaN(CN)2 (1 mmol, 0.090 g) was mixed with an aqueous solution (10 ml) of Zn(NO3)2·6H2O (0.5 mmol, 0.149 g) and stirred for 20 min. A methanol solution (10 ml) of 1,2-bis(1,2,4-triazol-yl)ethane (0.082 g, 0.5 mmol) was then added slowly. The mixture was stirred at room temperature for 30 min and the resulting solution was filtered. After the filtrate had been allowed to stand in air at room temperature for two weeks, well shaped colorless single crystals of (I) were obtained. The product was stable under ambient atmospheric conditions and insoluble in most common inorganic and organic solvents. Found: C 36.46, H 2.98, N 47.73%; calculated for C16H16N18Zn: C 36.55, H 3.07, N 47.98%.

Refinement top

Compound (I) crystallized in the monoclinic system and space group P21/n was assigned from the systematic absences. H atoms were placed in idealized positions and refined as riding, with C—H distances of 0.93 Å (triazole) and 0.97 Å (ethane).

Computing details top

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The coordination environment of the Zn atom of (I) at the showing displacement ellipsoids at the 30% probability level. [Symmetry codes: (i) x, −1 + y, z; (ii) 1 − x, −y, 1 − z; (iii) 1 − x, 1 − y, 1 − z; (iv) x, 1 + y, z.]
catena-poly[[bis(dicyanamido)zinc(II)]-di-µ-bis(1,2,4-triazol-1-yl)ethane- κ4N4:N4'] top
Crystal data top
[Zn(C2N3)2(C6H8N6)2]F(000) = 536
Mr = 525.84Dx = 1.595 Mg m3
Monoclinic, P21/n(#14)Mo Kα radiation, λ = 0.71070 Å
a = 8.501 (4) ÅCell parameters from 3445 reflections
b = 8.369 (4) Åθ = 3.5–27.5°
c = 15.403 (6) ŵ = 1.17 mm1
β = 92.463 (6)°T = 193 K
V = 1094.8 (8) Å3Chunk, colorless
Z = 20.55 × 0.39 × 0.20 mm
Data collection top
Rigaku CCD
diffractometer
2386 independent reflections
Radiation source: fine-focus sealed tube2296 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
ω scansθmax = 27.5°, θmin = 3.6°
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2000)
h = 1110
Tmin = 0.612, Tmax = 0.802k = 1010
8103 measured reflectionsl = 1918
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.028Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.063H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0313P)2 + 0.5747P]
where P = (Fo2 + 2Fc2)/3
2386 reflections(Δ/σ)max < 0.001
160 parametersΔρmax = 0.26 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
[Zn(C2N3)2(C6H8N6)2]V = 1094.8 (8) Å3
Mr = 525.84Z = 2
Monoclinic, P21/n(#14)Mo Kα radiation
a = 8.501 (4) ŵ = 1.17 mm1
b = 8.369 (4) ÅT = 193 K
c = 15.403 (6) Å0.55 × 0.39 × 0.20 mm
β = 92.463 (6)°
Data collection top
Rigaku CCD
diffractometer
2386 independent reflections
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2000)
2296 reflections with I > 2σ(I)
Tmin = 0.612, Tmax = 0.802Rint = 0.023
8103 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0280 restraints
wR(F2) = 0.063H-atom parameters constrained
S = 1.04Δρmax = 0.26 e Å3
2386 reflectionsΔρmin = 0.24 e Å3
160 parameters
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
Zn10.50000.00000.50000.01477 (8)
N10.18263 (13)0.37693 (14)0.41637 (8)0.0162 (2)
N20.24862 (15)0.45436 (15)0.48686 (8)0.0207 (3)
N30.37012 (14)0.21927 (14)0.46558 (8)0.0194 (3)
N40.13340 (14)0.71885 (14)0.38136 (8)0.0161 (2)
N50.04728 (14)0.77867 (15)0.44665 (8)0.0210 (3)
N60.29658 (14)0.87063 (14)0.45601 (8)0.0175 (2)
N70.40691 (16)0.02740 (16)0.62838 (9)0.0240 (3)
N80.21224 (17)0.0937 (2)0.73570 (10)0.0332 (3)
N90.03779 (19)0.0497 (2)0.75295 (11)0.0399 (4)
C10.36050 (17)0.35500 (17)0.51375 (10)0.0212 (3)
H1A0.42750.37590.56170.025*
C20.25508 (17)0.23807 (17)0.40524 (9)0.0186 (3)
H2A0.22900.16480.36160.022*
C30.15140 (16)0.86857 (17)0.48949 (10)0.0201 (3)
H3A0.12740.92620.53880.024*
C40.27970 (16)0.77446 (16)0.38787 (9)0.0171 (3)
H4A0.35870.74960.35020.021*
C50.04098 (16)0.43993 (17)0.37144 (10)0.0181 (3)
H5A0.03870.45830.41350.022*
H5B0.00040.36070.33030.022*
C60.07054 (17)0.59532 (17)0.32310 (9)0.0194 (3)
H6A0.14430.57570.27800.023*
H6B0.02740.63230.29540.023*
C70.31020 (17)0.05377 (19)0.67694 (10)0.0205 (3)
C80.0812 (2)0.01225 (19)0.74243 (10)0.0255 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.01220 (12)0.01346 (12)0.01859 (13)0.00019 (8)0.00017 (8)0.00059 (8)
N10.0164 (6)0.0139 (5)0.0183 (6)0.0007 (4)0.0012 (5)0.0009 (4)
N20.0210 (6)0.0171 (6)0.0234 (6)0.0004 (5)0.0052 (5)0.0030 (5)
N30.0183 (6)0.0154 (6)0.0244 (6)0.0021 (5)0.0007 (5)0.0011 (5)
N40.0161 (6)0.0136 (5)0.0184 (6)0.0009 (4)0.0010 (5)0.0005 (4)
N50.0170 (6)0.0209 (6)0.0251 (6)0.0009 (5)0.0020 (5)0.0045 (5)
N60.0157 (6)0.0150 (6)0.0217 (6)0.0006 (4)0.0001 (5)0.0017 (4)
N70.0224 (7)0.0281 (7)0.0219 (6)0.0019 (5)0.0029 (6)0.0008 (5)
N80.0244 (7)0.0444 (9)0.0316 (8)0.0070 (6)0.0084 (6)0.0119 (7)
N90.0324 (9)0.0509 (10)0.0370 (9)0.0101 (7)0.0084 (7)0.0058 (7)
C10.0209 (7)0.0166 (7)0.0254 (7)0.0006 (5)0.0057 (6)0.0001 (6)
C20.0215 (7)0.0148 (6)0.0195 (7)0.0032 (5)0.0006 (6)0.0008 (5)
C30.0156 (6)0.0194 (7)0.0255 (7)0.0010 (5)0.0015 (6)0.0058 (6)
C40.0148 (6)0.0162 (6)0.0204 (7)0.0009 (5)0.0000 (5)0.0010 (5)
C50.0155 (6)0.0156 (6)0.0228 (7)0.0004 (5)0.0040 (5)0.0022 (5)
C60.0217 (7)0.0165 (7)0.0194 (7)0.0007 (5)0.0048 (6)0.0014 (5)
C70.0182 (7)0.0236 (7)0.0193 (7)0.0029 (6)0.0036 (6)0.0010 (6)
C80.0237 (8)0.0320 (8)0.0210 (7)0.0021 (6)0.0034 (6)0.0040 (6)
Geometric parameters (Å, º) top
Zn1—N6i2.1263 (13)N6—C41.3256 (19)
Zn1—N6ii2.1263 (13)N6—C31.3580 (19)
Zn1—N7iii2.1734 (16)N6—Zn1iv2.1263 (13)
Zn1—N72.1734 (16)N7—C71.156 (2)
Zn1—N3iii2.1948 (14)N8—C71.300 (2)
Zn1—N32.1948 (14)N8—C81.314 (2)
N1—C21.3297 (19)N9—C81.154 (2)
N1—N21.3643 (17)C1—H1A0.9300
N1—C51.4612 (18)C2—H2A0.9300
N2—C11.3167 (19)C3—H3A0.9300
N3—C21.3292 (19)C4—H4A0.9300
N3—C11.361 (2)C5—C61.525 (2)
N4—C41.3277 (19)C5—H5A0.9700
N4—N51.3643 (18)C5—H5B0.9700
N4—C61.4555 (18)C6—H6A0.9700
N5—C31.3172 (19)C6—H6B0.9700
N6i—Zn1—N6ii180.00 (6)C7—N7—Zn1154.89 (12)
N6i—Zn1—N7iii88.81 (5)C7—N8—C8119.49 (15)
N6ii—Zn1—N7iii91.19 (5)N2—C1—N3114.53 (13)
N6i—Zn1—N791.19 (5)N2—C1—H1A122.7
N6ii—Zn1—N788.81 (5)N3—C1—H1A122.7
N7iii—Zn1—N7180.0N3—C2—N1110.14 (13)
N6i—Zn1—N3iii92.59 (5)N3—C2—H2A124.9
N6ii—Zn1—N3iii87.41 (5)N1—C2—H2A124.9
N7iii—Zn1—N3iii86.13 (5)N5—C3—N6114.78 (13)
N7—Zn1—N3iii93.87 (5)N5—C3—H3A122.6
N6i—Zn1—N387.41 (5)N6—C3—H3A122.6
N6ii—Zn1—N392.59 (5)N6—C4—N4109.99 (13)
N7iii—Zn1—N393.87 (5)N6—C4—H4A125.0
N7—Zn1—N386.13 (5)N4—C4—H4A125.0
N3iii—Zn1—N3180.0N1—C5—C6112.91 (12)
C2—N1—N2109.92 (12)N1—C5—H5A109.0
C2—N1—C5129.13 (12)C6—C5—H5A109.0
N2—N1—C5120.52 (11)N1—C5—H5B109.0
C1—N2—N1102.54 (12)C6—C5—H5B109.0
C2—N3—C1102.86 (12)H5A—C5—H5B107.8
C2—N3—Zn1127.97 (10)N4—C6—C5111.62 (12)
C1—N3—Zn1127.40 (10)N4—C6—H6A109.3
C4—N4—N5110.27 (12)C5—C6—H6A109.3
C4—N4—C6127.84 (12)N4—C6—H6B109.3
N5—N4—C6121.38 (12)C5—C6—H6B109.3
C3—N5—N4102.03 (12)H6A—C6—H6B108.0
C4—N6—C3102.93 (12)N7—C7—N8173.85 (16)
C4—N6—Zn1iv128.34 (10)N9—C8—N8174.38 (19)
C3—N6—Zn1iv128.71 (10)
C2—N1—N2—C10.60 (16)C1—N3—C2—N10.55 (16)
C5—N1—N2—C1173.79 (13)Zn1—N3—C2—N1166.17 (10)
N6i—Zn1—N3—C227.48 (13)N2—N1—C2—N30.76 (17)
N6ii—Zn1—N3—C2152.52 (13)C5—N1—C2—N3173.19 (13)
N7iii—Zn1—N3—C261.16 (13)N4—N5—C3—N60.27 (17)
N7—Zn1—N3—C2118.84 (13)C4—N6—C3—N50.19 (17)
N6i—Zn1—N3—C1134.77 (13)Zn1iv—N6—C3—N5178.59 (10)
N6ii—Zn1—N3—C145.23 (13)C3—N6—C4—N40.01 (15)
N7iii—Zn1—N3—C1136.60 (13)Zn1iv—N6—C4—N4178.77 (9)
N7—Zn1—N3—C143.40 (13)N5—N4—C4—N60.15 (16)
C4—N4—N5—C30.25 (15)C6—N4—C4—N6171.59 (12)
C6—N4—N5—C3172.12 (12)C2—N1—C5—C6119.31 (16)
N6i—Zn1—N7—C743.7 (3)N2—N1—C5—C668.96 (17)
N6ii—Zn1—N7—C7136.3 (3)C4—N4—C6—C5106.59 (16)
N3iii—Zn1—N7—C7136.4 (3)N5—N4—C6—C564.33 (16)
N3—Zn1—N7—C743.6 (3)N1—C5—C6—N458.11 (16)
N1—N2—C1—N30.26 (17)Zn1—N7—C7—N8130.7 (2)
C2—N3—C1—N20.17 (18)C8—N8—C7—N7168.8 (2)
Zn1—N3—C1—N2165.90 (10)C7—N8—C8—N9170.1 (2)
Symmetry codes: (i) x, y1, z; (ii) x+1, y+1, z+1; (iii) x+1, y, z+1; (iv) x, y+1, z.

Experimental details

Crystal data
Chemical formula[Zn(C2N3)2(C6H8N6)2]
Mr525.84
Crystal system, space groupMonoclinic, P21/n(#14)
Temperature (K)193
a, b, c (Å)8.501 (4), 8.369 (4), 15.403 (6)
β (°) 92.463 (6)
V3)1094.8 (8)
Z2
Radiation typeMo Kα
µ (mm1)1.17
Crystal size (mm)0.55 × 0.39 × 0.20
Data collection
DiffractometerRigaku CCD
diffractometer
Absorption correctionMulti-scan
(CrystalClear; Rigaku, 2000)
Tmin, Tmax0.612, 0.802
No. of measured, independent and
observed [I > 2σ(I)] reflections
8103, 2386, 2296
Rint0.023
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.063, 1.04
No. of reflections2386
No. of parameters160
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.26, 0.24

Computer programs: CrystalClear (Rigaku, 2000), CrystalClear, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1998), SHELXTL.

Selected geometric parameters (Å, º) top
Zn1—N6i2.1263 (13)Zn1—N32.1948 (14)
Zn1—N6ii2.1263 (13)N7—C71.156 (2)
Zn1—N7iii2.1734 (16)N8—C71.300 (2)
Zn1—N72.1734 (16)N8—C81.314 (2)
Zn1—N3iii2.1948 (14)N9—C81.154 (2)
N6i—Zn1—N6ii180.00 (6)N7iii—Zn1—N393.87 (5)
N6i—Zn1—N791.19 (5)N7—Zn1—N386.13 (5)
N6ii—Zn1—N788.81 (5)N3iii—Zn1—N3180.0
N7iii—Zn1—N7180.0C7—N8—C8119.49 (15)
N6i—Zn1—N387.41 (5)N7—C7—N8173.85 (16)
N6ii—Zn1—N392.59 (5)N9—C8—N8174.38 (19)
Symmetry codes: (i) x, y1, z; (ii) x+1, y+1, z+1; (iii) x+1, y, z+1.
 

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