catena-Poly[[(1,10-phenanthroline-κ²N,N′)cadmate(II)]-di-μ-bromido]

The title compound, [CdBr₂(C₁₂H₈N₂)]_n, is a 1:1 adduct of cadmium bromide with 1,10-phenanthroline (phen), which contains an infinite chain consisting of Cd₂Br₂ parallelograms sharing the Cd coners. The chain propagates along the c axis. Both the Cd^II atom and the phen mol­ecule lie on a twofold rotation axis. The Cd^II atom is coordinated by two N atoms from a chelating phen ligand and four Br atoms to complete a distorted octa­hedral geometry. The closest atom-to-atom distance of 3.35 (1) Å between the phen ligands of two adjacent chains indicates the existence of π–π inter­actions, which result in a two-dimensional layer parallel to the bc plane. The layers are associated through weak C—H...Br hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 290 K
• Mean [sigma](C-C) = 0.011 Å
• R factor = 0.029
• wR factor = 0.067
• Data-to-parameter ratio = 15.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.89
PLAT213_ALERT_2_C Atom C5      has ADP max/min Ratio .............       3.50 prola
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C3
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       3.73
PLAT335_ALERT_2_C Large Benzene C-C Range .......  C4     -C6            0.19 Ang.
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         11

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.894
            Tmax scaled      0.457 Tmin scaled      0.304
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cd1         (2)       1.97

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

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

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S1. Comment

Polynuclear d¹⁰ metal complexes have been found to exhibit intriguing structural and photoluminescent properties. Cl-bridged Cd^II polymeric complexes are of considerable interest because they may act as photoactive materials. Structures of Cl-bridged Cd^II polymeric complexes have been studied (Bell et al., 1982; Bigoli et al., 1983; Bonomo et al., 1989; Huang et al., 1998). However, Cd^II polymeric complexes with a CdBr₂N₂ coordination polydedron have been rarely reported. The phosphorescence and zero-field optically detected magnetic resonance studies with powder of CdX₂(phen), (phen = 1,10-phenanthroline; X = Cl, Br, and I) (Kimachi et al., 1995) and the crystal structures of CdCl₂(phen) and CdCl₂ (2,2'-bipyridine) have been reported (Chen et al., 2003; Zhou et al., 2003). We have introduced Br^- ion as a bridging ligand, and synthesized the Br-bridged Cd complex, [CdBr₂(phen)]_n, (I), by a hydrothermal reaction.

The structure of compound (I) (Fig. 1), contains one-dimensional chains extending in the c direction (Fig 2). Both Cd^II atom and phen molecule lie on the twofold rotation axis. The Cd^II atom is coordinated by two N atoms from a chelating phen ligand and four Br atoms to complete a distorted CdN₂Br₄ octahedral geometry. The average Cd—N bond length is 2.350 (3) Å and the bond lengths of Cd—Br are 2.6813 (5)Å and 2.9003 (5) Å. The Cd···Cd distance in the chain is 4.047 (1) Å, which is longer than that of the Cl-bridged Cd complex [3.931 (9) Å]. The closest atom-to-atom distance of 3.35 (1)Å between the phen ligands of two adjacent chains indicates the existence of π–π interactions, which result in a two-dimensional layer parallel to the bc plane (Fig. 3). The layers are associated through weak C—H···Br hydrogen bonds (Table 1).

Related literature

For related literature, see: Bell et al. (1982); Bigoli et al. (1983); Bonomo et al. (1989); Huang et al. (1998); Kimachi et al. (1995); Chen et al. (2003); Zhou et al. (2003).

S2. Experimental

Freshly prepared CdCO₃ (0.14 g, 0.812 mmol), phen.H₂O (0.10 g, 0.505 mmol), 2-bromobenzoic acid (0.10 g, 0.498 mmol), CH₃OH/H₂O (12 ml; v/v=1:2) were mixed and stirred for 2 h. The resulting suspension was heated in a 23 ml Teflon-lined stainless steel autoclave at 393 K for 7 d. After the autoclave was cooled to room temperature, colorless block crystals suitable for X-ray analysis were obtained.

S3. Refinement

All H atoms were positioned geometrically and treated as riding atoms, with C—H = 0.96 Å and U_iso(H) = 1.2U_eq(C).

Computing details

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

Figures

	Fig. 1. The structure of (I), showing the coordination geometry of Cd ^II atom. Displacement ellipsoids are drawn at the 40% probability level. H atoms have been omitted for clarity. [symmetry codes: (i) 1 - x, y, 1/2 - z; (ii) 1 - x, 1 - y, 1 - z; (iii) 1 - x, 1 - y, -z; (iv) x, 1 - y, z - 1/2.]
	Fig. 2. A view of the one-dimensional chain along the c axis in (I). H atoms have been omitted for clarity.
	Fig. 3. A packing diagram for (I), viewed down the c axis. Dashed lines indicate hydrogen bonds.

catena-Poly[[(1,10-phenanthroline-κ²N,N')cadmate(II)]-di-µ-bromido]

Crystal data

[CdBr2(C12H8N2)]	F(000) = 848
Mr = 452.42	Dx = 2.368 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 961 reflections
a = 16.7781 (7) Å	θ = 2.3–26.0°
b = 10.7594 (7) Å	µ = 7.99 mm^−1
c = 7.4213 (3) Å	T = 290 K
β = 108.664 (4)°	Block, colourless
V = 1269.26 (11) Å^3	0.23 × 0.12 × 0.10 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1247 independent reflections
Radiation source: fine-focus sealed tube	998 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
φ and ω scans	θmax = 26.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −20→18
Tmin = 0.340, Tmax = 0.511	k = −13→10
7231 measured reflections	l = −9→9

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.067	w = 1/[σ^2(Fo^2) + 3.3613P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max < 0.001
1247 reflections	Δρmax = 0.59 e Å^−3
79 parameters	Δρmin = −0.47 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: 0.00093 (19)

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

	x	y	z	Uiso*/Ueq
Cd1	0.5000	0.42497 (3)	0.2500	0.04136 (18)
Br1	0.60185 (3)	0.58225 (4)	0.49961 (6)	0.04905 (19)
N1	0.4258 (2)	0.2472 (3)	0.1038 (5)	0.0462 (9)
C1	0.3527 (3)	0.2477 (6)	−0.0359 (8)	0.0699 (15)
H1	0.3291	0.3253	−0.0919	0.084*
C2	0.3095 (5)	0.1378 (9)	−0.1055 (11)	0.105 (3)
H2	0.2563	0.1406	−0.2050	0.125*
C3	0.3414 (7)	0.0289 (8)	−0.0353 (13)	0.112 (4)
H3	0.3095	−0.0452	−0.0812	0.135*
C4	0.4194 (6)	0.0225 (5)	0.1050 (10)	0.085 (2)
C5	0.4646 (8)	−0.0905 (4)	0.1855 (12)	0.131 (7)
H5	0.4391	−0.1695	0.1417	0.157*
C6	0.4603 (3)	0.1372 (4)	0.1760 (6)	0.0534 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0494 (3)	0.0298 (2)	0.0357 (3)	0.000	0.00083 (19)	0.000
Br1	0.0535 (4)	0.0480 (3)	0.0414 (3)	−0.0127 (2)	0.0092 (2)	−0.00875 (17)
N1	0.049 (2)	0.044 (2)	0.051 (2)	−0.0127 (17)	0.0228 (18)	−0.0174 (16)
C1	0.053 (3)	0.093 (4)	0.065 (3)	−0.018 (3)	0.021 (3)	−0.037 (3)
C2	0.074 (5)	0.157 (7)	0.096 (5)	−0.061 (5)	0.044 (4)	−0.083 (5)
C3	0.150 (8)	0.110 (6)	0.120 (6)	−0.090 (6)	0.103 (6)	−0.083 (6)
C4	0.149 (7)	0.049 (3)	0.099 (5)	−0.049 (4)	0.098 (5)	−0.039 (3)
C5	0.29 (2)	0.032 (3)	0.151 (11)	−0.038 (5)	0.178 (12)	−0.027 (3)
C6	0.082 (4)	0.035 (2)	0.064 (3)	−0.018 (2)	0.052 (2)	−0.0149 (19)

Geometric parameters (Å, º)

Cd1—N1	2.349 (3)	C1—H1	0.9600
Cd1—N1^i	2.349 (3)	C2—C3	1.323 (12)
Cd1—Br1	2.6813 (5)	C2—H2	0.9600
Cd1—Br1^i	2.6813 (5)	C3—C4	1.389 (11)
Cd1—Br1^ii	2.9003 (5)	C3—H3	0.9600
Cd1—Br1^iii	2.9003 (5)	C4—C6	1.429 (7)
Br1—Cd1^ii	2.9003 (5)	C4—C5	1.456 (11)
N1—C1	1.328 (6)	C5—C5^i	1.27 (2)
N1—C6	1.351 (6)	C5—H5	0.9600
C1—C2	1.396 (8)	C6—C6^i	1.429 (10)
N1—Cd1—N1^i	71.03 (19)	N1—C1—C2	121.7 (6)
N1—Cd1—Br1	163.57 (9)	N1—C1—H1	119.4
N1^i—Cd1—Br1	93.92 (10)	C2—C1—H1	118.9
N1—Cd1—Br1^i	93.92 (10)	C3—C2—C1	120.5 (7)
N1^i—Cd1—Br1^i	163.57 (9)	C3—C2—H2	119.3
Br1—Cd1—Br1^i	101.73 (2)	C1—C2—H2	120.2
N1—Cd1—Br1^ii	86.58 (9)	C2—C3—C4	120.3 (6)
N1^i—Cd1—Br1^ii	90.92 (9)	C2—C3—H3	119.1
Br1—Cd1—Br1^ii	87.145 (15)	C4—C3—H3	120.6
Br1^i—Cd1—Br1^ii	94.797 (16)	C3—C4—C6	117.4 (7)
N1—Cd1—Br1^iii	90.92 (9)	C3—C4—C5	126.3 (7)
N1^i—Cd1—Br1^iii	86.58 (9)	C6—C4—C5	116.4 (8)
Br1—Cd1—Br1^iii	94.797 (16)	C5^i—C5—C4	123.4 (5)
Br1^i—Cd1—Br1^iii	87.145 (15)	C5^i—C5—H5	117.7
Br1^ii—Cd1—Br1^iii	176.93 (2)	C4—C5—H5	118.9
Cd1—Br1—Cd1^ii	92.855 (15)	N1—C6—C6^i	118.7 (3)
C1—N1—C6	119.0 (4)	N1—C6—C4	121.1 (6)
C1—N1—Cd1	125.3 (3)	C6^i—C6—C4	120.2 (4)
C6—N1—Cd1	115.7 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···Br1^iv	0.96	2.88	3.816 (12)	166
C5—H5···Br1^v	0.96	2.87	3.815 (5)	167

Symmetry codes: (iv) x−1/2, y−1/2, z−1; (v) −x+1, y−1, −z+1/2.