Poly[dichloridobis[μ-1-(4-pyridyl­meth­yl)-1,2,4-triazole]cadmium(II)]

In the title coordination polymer, [CdCl₂(C₈H₈N₄)₂]_n, the Cd^II atom, lying on an inversion center, is coordinated by two Cl atoms and two triazole N atoms and two pyridyl N atoms from four 1-(4-pyridyl­meth­yl)-1,2,4-triazole (pmta) ligands in a distorted trans-CdCl₂N₄ octa­hedral arrangement. The bridg­ing pmta ligands, with a dihedral angle between the triazole and pyridyl rings of 71.86 (8)°, link the Cd atoms into a 4⁴ sheet parallel to (02). π–π inter­actions between the triazole rings [centroid–centroid distance = 3.428 (2) Å] connect the sheets.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.022
• wR factor = 0.048
• Data-to-parameter ratio = 17.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       3.34
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          6
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          2
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          6

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

Recently, our group has focused on the design and synthesis of some unsymmetric flexible ligands (Huang et al., 2006; Liu et al., 2005), and we have got a heterocyclic ligand 1-(4-pyridylmethyl)-1,2,4-triazole (pmta). In order to explore the architectural styles and coordination chemistry of this kind of ligands, we selected cadmium chloride as representative subject for stereoregular coordination. Among our attempts, the title compound, a new coordination polymer, was obtained as crystals suitable for single-crystal X-ray analysis.

The title compound is isomorphic to the complex we have reported (Li et al., 2009; Wang et al., 2008). The crystallographic analysis reveals that the asymmetric unit contains one Cd^II atom lying on an inversion center, one Cl anion and one bridging pmta ligand, as shown in Fig. 1. The Cd^II atom lies in an octahedral [CdCl₂N₄] environment, with the axial positions occupied by two Cl atoms and the equatorial positions occupied by two trans triazole N atoms and two trans pyridyl N atoms, which belong to four different pmta ligands. The bond angles about Cd1 atom range from 85.82 (6) to 94.18 (6)° and deviate slightly from those of a perfect octahedron. Due to the existence of the –CH₂– spacer between the triazole and pyridyl rings with a dihedral angle of 71.86 (8)°, sufficient flexibility makes it possible for pmta to be twisted to meet the requirment of coordination geometries of the Cd center.

As shown in Fig. 2, the title compound exhibits a two-dimensional rhombohedral sheet containing 36-membered sandglass rings. The sp³ configuration of C3 forces the pmta ligand to be non-linear, generating the non-linear grid sides and thereby the sandglass grids. Every complementary four [Cd₄(pmta)₄] grids are joined together by sharing the Cd apices, giving a 4⁴ topology with a side length of 11.022 Å and diagonal measurements of 14.096 and 16.949 Å.

Related literature

For our previous studies on the design and synthesis of some unsymmetric flexible ligands, see: Huang et al. (2006); Liu et al. (2005). For related structures, see: Li et al. (2009); Wang et al. (2008).

S2. Experimental

A solution of pmta (0.021 g, 0.10 mmol) in MeOH (5 ml) was carefully layered on a solution of CdCl₂.2.5H₂O (0.023 g, 0.10 mmol) in H₂O (5 ml). Diffusion between the two phases over a period of two weeks produced colorless block crystals.

S3. Refinement

H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (CH) and 0.97 (CH₂) Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2007); cell refinement: CrystalClear (Rigaku, 2007); data reduction: CrystalClear (Rigaku, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The structure of the title compound, showing 30% probability displacement ellipsoids. H atoms have been omitted for clarity. [Symmetry codes: (A) -x, -y+1, -z; (B) -x+1, y-1/2, -z+1/2; (C) x-1, -y+3/2, z-1/2.]
	Fig. 2. The two-dimensional structure of the title compound, constructed of rhombus-shaped grids.

Poly[dichloridobis[µ-1-(4-pyridylmethyl)-1,2,4-triazole]cadmium(II)]

Crystal data

[CdCl2(C8H8N4)2]	F(000) = 500
Mr = 503.67	Dx = 1.725 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2546 reflections
a = 7.5795 (5) Å	θ = 2.7–27.5°
b = 16.9491 (10) Å	µ = 1.42 mm^−1
c = 8.2215 (5) Å	T = 293 K
β = 113.325 (3)°	Prism, colorless
V = 969.86 (10) Å^3	0.20 × 0.18 × 0.04 mm
Z = 2

Data collection

Rigaku Mercury CCD diffractometer	2214 independent reflections
Radiation source: fine-focus sealed tube	2079 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ω scans	θmax = 27.5°, θmin = 3.0°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2007)	h = −9→9
Tmin = 0.841, Tmax = 1.000	k = −15→22
6994 measured reflections	l = −9→10

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)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.048	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.016P)^2 + 0.9435P] where P = (Fo^2 + 2Fc^2)/3
2214 reflections	(Δ/σ)max < 0.001
124 parameters	Δρmax = 0.78 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.0000	0.5000	0.0000	0.02465 (6)
Cl1	0.18617 (7)	0.53526 (3)	−0.19411 (7)	0.03766 (12)
N2	0.4333 (3)	0.60582 (12)	0.5065 (2)	0.0416 (4)
C2	0.4379 (3)	0.56302 (12)	0.2553 (3)	0.0309 (4)
H2	0.4822	0.5515	0.1674	0.037*
C3	0.7421 (3)	0.62024 (12)	0.4780 (3)	0.0387 (5)
H3A	0.8033	0.5921	0.4116	0.046*
H3B	0.8016	0.6027	0.6000	0.046*
C4	0.7814 (3)	0.70736 (11)	0.4718 (3)	0.0315 (4)
C5	0.6464 (3)	0.76634 (13)	0.4358 (3)	0.0404 (5)
H5	0.5187	0.7540	0.4106	0.048*
C6	0.7022 (3)	0.84449 (12)	0.4373 (3)	0.0385 (5)
H6	0.6094	0.8836	0.4141	0.046*
C7	1.0109 (3)	0.80837 (14)	0.5028 (4)	0.0501 (6)
H7	1.1368	0.8221	0.5239	0.060*
C8	0.9684 (3)	0.72969 (13)	0.5070 (4)	0.0496 (6)
H8	1.0646	0.6919	0.5332	0.060*
N3	0.2643 (2)	0.54659 (10)	0.2469 (2)	0.0306 (4)
C1	0.2694 (3)	0.57354 (12)	0.4037 (3)	0.0356 (4)
H1	0.1653	0.5695	0.4360	0.043*
N1	0.5399 (2)	0.59858 (9)	0.4081 (2)	0.0309 (4)
N4	0.8817 (3)	0.86600 (10)	0.4702 (2)	0.0351 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.02100 (10)	0.02176 (10)	0.03014 (10)	0.00065 (7)	0.00902 (7)	−0.00232 (7)
Cl1	0.0338 (3)	0.0460 (3)	0.0388 (3)	0.0022 (2)	0.0204 (2)	0.0020 (2)
N2	0.0476 (11)	0.0420 (11)	0.0385 (10)	−0.0133 (9)	0.0205 (9)	−0.0113 (8)
C2	0.0264 (9)	0.0316 (10)	0.0330 (10)	−0.0031 (8)	0.0097 (8)	−0.0057 (8)
C3	0.0261 (10)	0.0265 (10)	0.0511 (13)	−0.0061 (8)	0.0022 (9)	−0.0011 (9)
C4	0.0307 (10)	0.0257 (9)	0.0331 (10)	−0.0049 (8)	0.0073 (8)	−0.0019 (8)
C5	0.0274 (10)	0.0317 (11)	0.0579 (14)	−0.0051 (8)	0.0125 (10)	0.0022 (10)
C6	0.0320 (11)	0.0276 (10)	0.0534 (13)	0.0007 (8)	0.0141 (10)	0.0039 (9)
C7	0.0315 (11)	0.0284 (11)	0.094 (2)	−0.0065 (9)	0.0285 (12)	−0.0064 (12)
C8	0.0338 (12)	0.0250 (11)	0.0862 (19)	−0.0009 (9)	0.0197 (12)	−0.0064 (11)
N3	0.0246 (8)	0.0318 (9)	0.0334 (8)	−0.0030 (7)	0.0095 (7)	−0.0038 (7)
C1	0.0390 (11)	0.0336 (11)	0.0387 (11)	−0.0064 (9)	0.0202 (9)	−0.0052 (9)
N1	0.0283 (8)	0.0235 (8)	0.0365 (9)	−0.0051 (6)	0.0082 (7)	−0.0010 (7)
N4	0.0345 (9)	0.0246 (8)	0.0479 (10)	−0.0036 (7)	0.0180 (8)	−0.0005 (7)

Geometric parameters (Å, º)

Cd1—N3	2.3531 (16)	C4—C8	1.383 (3)
Cd1—N4^i	2.4183 (16)	C5—C6	1.389 (3)
Cd1—Cl1	2.5842 (5)	C5—H5	0.9300
N2—C1	1.313 (3)	C6—N4	1.329 (3)
N2—N1	1.357 (3)	C6—H6	0.9300
C2—N3	1.320 (2)	C7—N4	1.333 (3)
C2—N1	1.330 (2)	C7—C8	1.375 (3)
C2—H2	0.9300	C7—H7	0.9300
C3—N1	1.454 (2)	C8—H8	0.9300
C3—C4	1.511 (3)	N3—C1	1.353 (3)
C3—H3A	0.9700	C1—H1	0.9300
C3—H3B	0.9700	N4—Cd1^ii	2.4183 (16)
C4—C5	1.376 (3)
N3^iii—Cd1—N3	180.0	C5—C4—C3	125.27 (19)
N3^iii—Cd1—N4^i	85.82 (6)	C8—C4—C3	117.38 (19)
N3—Cd1—N4^i	94.18 (6)	C4—C5—C6	119.5 (2)
N3^iii—Cd1—N4^iv	94.18 (6)	C4—C5—H5	120.2
N3—Cd1—N4^iv	85.82 (6)	C6—C5—H5	120.2
N4^i—Cd1—N4^iv	180.00 (10)	N4—C6—C5	123.2 (2)
N3^iii—Cd1—Cl1	91.79 (4)	N4—C6—H6	118.4
N3—Cd1—Cl1	88.21 (4)	C5—C6—H6	118.4
N4^i—Cd1—Cl1	90.49 (5)	N4—C7—C8	123.7 (2)
N4^iv—Cd1—Cl1	89.51 (5)	N4—C7—H7	118.1
N3^iii—Cd1—Cl1^iii	88.21 (4)	C8—C7—H7	118.1
N3—Cd1—Cl1^iii	91.79 (4)	C7—C8—C4	119.4 (2)
N4^i—Cd1—Cl1^iii	89.51 (5)	C7—C8—H8	120.3
N4^iv—Cd1—Cl1^iii	90.49 (5)	C4—C8—H8	120.3
Cl1—Cd1—Cl1^iii	180.0	C2—N3—C1	103.13 (16)
C1—N2—N1	102.33 (17)	C2—N3—Cd1	127.31 (13)
N3—C2—N1	109.85 (18)	C1—N3—Cd1	128.94 (14)
N3—C2—H2	125.1	N2—C1—N3	114.62 (19)
N1—C2—H2	125.1	N2—C1—H1	122.7
N1—C3—C4	115.10 (17)	N3—C1—H1	122.7
N1—C3—H3A	108.5	C2—N1—N2	110.07 (17)
C4—C3—H3A	108.5	C2—N1—C3	127.96 (19)
N1—C3—H3B	108.5	N2—N1—C3	121.64 (18)
C4—C3—H3B	108.5	C6—N4—C7	116.82 (18)
H3A—C3—H3B	107.5	C6—N4—Cd1^ii	125.95 (14)
C5—C4—C8	117.34 (19)	C7—N4—Cd1^ii	117.03 (14)

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