catena-Poly[[(5,5′-dimethyl- 2,2′-bipyridine-κ²N,N′)cadmium(II)]-di-μ-chlorido]

The asymmetric unit of the title compound, [CdCl₂(C₁₂H₁₂N₂)]_n, contains one half-mol­ecule; a twofold rotation axis passes through the Cd atom. The Cd^II atom is six-coordinated in a distorted octa­hedral configuration by two N atoms from 2,2′-bipyridine-5,5′-dimethyl and four bridging Cl atoms. The bridging function of the chloro atoms leads to a one-dimensional chain structure. There is a π–π contact between the pyridine rings [centroid–centroid distance = 3.9807 (9) Å].

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.033
• wR factor = 0.090
• Data-to-parameter ratio = 22.1

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S1. Comment

In a recent paper, we reported the synthesis and crystal structure of [Zn(5,5'-dmbpy)Cl₂], (Khalighi et al., 2008) [where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine]. Several Cd^II polymer complexes, with formula, [Cd(N—N)(µ-Cl)₂]_n, such as [Cd(phen)(µ-Cl)₂]_n, (II) (Chen et al., 2003), {[Cd(5,5'-dabpy)(µ-Cl)₂].2H₂O}_n, (III) (Janiak et al., 1999) and [Cd(bipy)(µ-Cl)₂]_n, (IV) (Zhou et al., 2003) [where bipy is 2,2'-bipyridine, 5,5'-dabpy is 5,5'-diamino -2,2'-bipyridine and phen is 1,10-phenanthroline] have been synthesized and characterized by single-crystal X-ray diffraction methods. There are also several Cd^II polymer complexes, with formula, [Cd(µ-Cl)₂L₂]_n, such as [Cd(µ-Cl)₂(3,5-Me₂py)₂]_n, (V), [Cd(µ-Cl)₂(3,5-Br₂py)₂]_n, (VI) and [Cd(µ-Cl)₂(3,5-Cl₂py)₂]_n, (VII) (Hu & Englert, 2002), [Cd(µ-Cl)₂(3-Mepy)₂]_n, (VIII) (Satoh, et al., 2001) and [Cd(µ-Cl)₂(im)₂]_n, (IX) (Flook et al., 1973) [where py is pyridine and im is imidazole] have been synthesized and characterized by single-crystal X-ray diffraction methods. We report herein the synthesis and crystal structure of the title compound (I).

The asymmetric unit of the title compound, (I), contains one half-molecule (Fig. 1). The Cd^II atom is six-coordinated in a distorted octahedral configuration by two N atoms from 2,2'-bipyridine-5,5'-dimethyl and four bridging Cl atoms. The bridging function of chloro atoms leads to a one-dimensional chain structure. The Cd—Cl and Cd—N bond lengths and angles (Table 1) are within normal ranges, as in (II), (III) and (IV).

In the crystal structure, the π—π contact (Fig. 2) between the pyridine rings, Cg4···Cg4ⁱ [symmetry code: (i) x, 1/2- y, z, where Cg4 is centroid of the ring (N1/C1/C2/C4-C6)] may stabilize the structure, with centroid-centroid distance of 3.9807 (9) Å.

Related literature

For related literature, see: Chen et al. (2003); Flook et al. (1973); Hu & Englert (2002); Janiak et al. (1999); Satoh et al. (2001); Zhou et al. (2003); Khalighi et al. (2008).

S2. Experimental

For the preparation of the title compound, a solution of 5,5'-dimethyl-2,2' -bipyridine (0.25 g, 1.33 mmol) in methanol (10 ml) was added to a solution of CdCl₂.H₂O (0.27 g, 1.33 mmol) in methanol (10 ml) at room temperature. The suitable crystals for X-ray analysis were obtained by methanol diffusion to a colorless solution in DMSO. Suitable crystals were isolated after one week (yield; 0.35 g, 71.6%, m.p. < 573 K).

S3. Refinement

H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (a) -x, y, 3/2 - z].
	Fig. 2. A packing diagram of the title compound.

catena-Poly[[(5,5'-dimethyl-2,2'-bipyridine- κ²N,N')cadmium(II)]-di-µ-chlorido]

Crystal data

[CdCl2(C12H12N2)]	F(000) = 720
Mr = 367.55	Dx = 1.867 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1004 reflections
a = 20.365 (4) Å	θ = 4.1–29.2°
b = 9.3135 (19) Å	µ = 2.06 mm^−1
c = 7.2313 (14) Å	T = 298 K
β = 107.53 (3)°	Block, colorless
V = 1307.9 (5) Å^3	0.20 × 0.17 × 0.15 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1724 independent reflections
Radiation source: fine-focus sealed tube	1585 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
ϕ and ω scans	θmax = 29.2°, θmin = 4.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)	h = −27→18
Tmin = 0.666, Tmax = 0.740	k = −12→11
4283 measured reflections	l = −9→9

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.089	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0543P)^2 + 0.9451P] where P = (Fo^2 + 2Fc^2)/3
1724 reflections	(Δ/σ)max = 0.011
78 parameters	Δρmax = 0.68 e Å^−3
0 restraints	Δρmin = −0.76 e Å^−3

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
Cd1	0.0000	0.58047 (2)	0.7500	0.03912 (12)
Cl1	0.07886 (4)	0.41364 (6)	0.99832 (11)	0.04502 (17)
N1	0.06292 (10)	0.7876 (2)	0.8828 (3)	0.0383 (4)
C1	0.12723 (13)	0.7815 (3)	1.0067 (4)	0.0460 (5)
H1	0.1458	0.6918	1.0488	0.055*
C2	0.16716 (14)	0.9023 (3)	1.0746 (5)	0.0480 (6)
C3	0.23917 (17)	0.8878 (5)	1.2093 (6)	0.0674 (9)
H3A	0.2665	0.8339	1.1466	0.081*
H3B	0.2381	0.8389	1.3251	0.081*
H3C	0.2589	0.9815	1.2422	0.081*
C4	0.13695 (15)	1.0347 (3)	1.0145 (4)	0.0484 (6)
H4	0.1612	1.1187	1.0594	0.058*
C5	0.07094 (15)	1.0418 (3)	0.8883 (4)	0.0435 (5)
H5	0.0504	1.1303	0.8486	0.052*
C6	0.03548 (12)	0.9157 (2)	0.8213 (4)	0.0344 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.04181 (17)	0.02643 (15)	0.04102 (17)	0.000	0.00027 (11)	0.000
Cl1	0.0458 (3)	0.0370 (3)	0.0479 (3)	0.0092 (2)	0.0074 (3)	0.0073 (2)
N1	0.0373 (9)	0.0313 (9)	0.0426 (10)	0.0009 (8)	0.0064 (8)	−0.0023 (8)
C1	0.0381 (11)	0.0426 (13)	0.0501 (13)	0.0045 (10)	0.0024 (10)	−0.0068 (11)
C2	0.0364 (12)	0.0536 (16)	0.0507 (14)	−0.0035 (10)	0.0080 (11)	−0.0133 (11)
C3	0.0394 (14)	0.082 (2)	0.070 (2)	−0.0029 (15)	−0.0003 (14)	−0.0177 (18)
C4	0.0448 (13)	0.0457 (14)	0.0529 (15)	−0.0112 (11)	0.0117 (11)	−0.0135 (12)
C5	0.0487 (13)	0.0303 (10)	0.0533 (14)	−0.0046 (10)	0.0179 (12)	−0.0062 (10)
C6	0.0339 (10)	0.0296 (11)	0.0406 (11)	0.0012 (7)	0.0129 (9)	−0.0020 (8)

Geometric parameters (Å, º)

Cd1—Cl1^i	2.5457 (9)	C2—C3	1.502 (4)
Cd1—Cl1^ii	2.7668 (10)	C3—H3A	0.9600
Cd1—Cl1^iii	2.7668 (10)	C3—H3B	0.9600
Cl1—Cd1	2.5457 (9)	C3—H3C	0.9600
Cl1—Cd1^ii	2.7668 (10)	C4—C5	1.380 (4)
Cd1—N1^i	2.355 (2)	C4—H4	0.9300
N1—Cd1	2.355 (2)	C5—C6	1.387 (3)
C1—N1	1.347 (3)	C5—H5	0.9300
C1—C2	1.389 (4)	C6—N1	1.336 (3)
C1—H1	0.9300	C6—C6^i	1.501 (5)
C2—C4	1.388 (4)
Cd1—Cl1—Cd1^ii	94.82 (2)	N1—C1—H1	118.3
Cl1^i—Cd1—Cl1^ii	96.22 (3)	C2—C1—H1	118.3
Cl1—Cd1—Cl1^ii	85.18 (2)	C4—C2—C1	116.9 (3)
Cl1^i—Cd1—Cl1^iii	85.18 (2)	C4—C2—C3	122.5 (3)
Cl1—Cd1—Cl1^iii	96.22 (3)	C1—C2—C3	120.6 (3)
Cl1^ii—Cd1—Cl1^iii	177.73 (2)	C2—C3—H3A	109.5
Cl1^i—Cd1—Cl1	104.77 (4)	C2—C3—H3B	109.5
N1—Cd1—Cl1^i	159.71 (6)	H3A—C3—H3B	109.5
N1^i—Cd1—Cl1^i	93.57 (6)	C2—C3—H3C	109.5
N1—Cd1—Cl1	93.57 (6)	H3A—C3—H3C	109.5
N1^i—Cd1—Cl1	159.71 (6)	H3B—C3—H3C	109.5
N1—Cd1—Cl1^ii	93.89 (5)	C5—C4—C2	120.1 (3)
N1^i—Cd1—Cl1^ii	84.24 (5)	C5—C4—H4	120.0
N1—Cd1—Cl1^iii	84.24 (5)	C2—C4—H4	120.0
N1^i—Cd1—Cl1^iii	93.89 (5)	C4—C5—C6	119.4 (3)
N1—Cd1—N1^i	69.98 (10)	C4—C5—H5	120.3
C6—N1—C1	119.0 (2)	C6—C5—H5	120.3
C6—N1—Cd1	118.31 (15)	N1—C6—C5	121.2 (2)
C1—N1—Cd1	122.49 (18)	N1—C6—C6^i	116.64 (13)
N1—C1—C2	123.3 (3)	C5—C6—C6^i	122.15 (16)
N1—C1—C2—C4	2.3 (5)	C1—N1—Cd1—N1^i	−176.1 (3)
N1—C1—C2—C3	−178.6 (3)	C6—N1—Cd1—Cl1^i	36.2 (3)
C1—C2—C4—C5	−1.9 (4)	C1—N1—Cd1—Cl1^i	−138.71 (19)
C3—C2—C4—C5	179.1 (3)	C6—N1—Cd1—Cl1	−168.97 (17)
C2—C4—C5—C6	−0.5 (4)	C1—N1—Cd1—Cl1	16.1 (2)
C4—C5—C6—N1	2.8 (4)	C6—N1—Cd1—Cl1^ii	−83.57 (18)
C4—C5—C6—C6^i	−177.9 (3)	C1—N1—Cd1—Cl1^ii	101.5 (2)
C5—C6—N1—C1	−2.5 (4)	C6—N1—Cd1—Cl1^iii	95.14 (18)
C6^i—C6—N1—C1	178.2 (3)	C1—N1—Cd1—Cl1^iii	−79.8 (2)
C5—C6—N1—Cd1	−177.59 (18)	Cd1^ii—Cl1—Cd1—N1	93.61 (5)
C6^i—C6—N1—Cd1	3.0 (3)	Cd1^ii—Cl1—Cd1—N1^i	58.77 (15)
C2—C1—N1—C6	−0.1 (4)	Cd1^ii—Cl1—Cd1—Cl1^i	−95.17 (2)
C2—C1—N1—Cd1	174.8 (2)	Cd1^ii—Cl1—Cd1—Cl1^ii	0.0
C6—N1—Cd1—N1^i	−1.14 (13)	Cd1^ii—Cl1—Cd1—Cl1^iii	178.20 (2)

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