A novel three-dimensional copper(I) coordination polymer constructed from a copper–bromide net and nicotinic acid ligands

The title compound, poly[μ₃-bromido-(pyridine-3-carboxyl­ato-κN)copper(I)], [CuBr(C₆H₅NO₂)]_n, is a novel coordination polymer based on a copper–bromide net and nicotinic acid ligands. The asymmetric unit contains one copper(I) ion, one bromide ligand and one nicotinic acid ligand, all on general positions. The Cu^I atom is tetra­hedral and coordinated by three bridging Br atoms and the N atom from the nicotinic acid ligand. The Cu–Br units form alternating six-membered chair-patterned rings in net-like layers. The attached nicotinic acid units point alternately up and down. The layers are assembled into a three-dimensional network via inter­molecular O—H...O and C—H...Br hydrogen-bonding inter­actions.

S1. Comment

Metal halides have been of increasing interest for their rich photoluminescent properties and intriguing topologies (Subramanian & Hoffmann, 1992; Ye et al., 2005; Lu, 2003; Cheng et al., 2005). In the past decade, experiments have proved that an effective approach for increasing the dimensionality is to use aromatic multi-dentate bridging N-donor molecules to link the oligomers into one-, two- or three-dimensional coordination polymers (Zhong et al., 2000; Larionova et al., 2000). In the structural investigations of compounds of nicotinic acid, it has been found that nicotinic acid can act as such a multidentate ligand (Luo et al., 2004; Evans & Lin, 2001; Li et al., 2007) with versatile binding and coordination modes. A novel net-like two-dimensional copper(I) coordination polymer, (I), resulted from the hydrothermal treatment of CuBr with nicotinic acid in alkaline aqueous solution.

As depicted in Fig. 1, the asymmetric unit consists of one copper(I) ion, one bromide ligand and one nicotinic acid ligand per asymmetric unit. The Cu^I center has a tetrahedral coordination geometry defined by three Br atoms and one N atom from the nicotinic acid ligand. The Cu–Br unit forms an alternating six-membered chair-patterned ring. The ring is further extended into a net-like layer (Fig. 2) through edge-sharing. Each Cu atom is bonded to nicotinic acid ligands arranged alternatingly pointing up and down around the ring. Finally, these layers are further assembled into a three-dimensional supramolecular network via intermolecular O—H···O and C—H···Br hydrogen-bonding stacking interactions (Fig. 3). The overall structural motif in (I) is unprecedented.

Copper(I) halide complexes with nitrogen bases have long been of interest because of the diversity of structure types formed (Gill et al., 1976; Camus et al., 1975; Healy et al., 1983, 1989). Typically, either discrete tetranuclear clusters (Dyason et al., 1985) or polymers are produced (Healy et al., 1989; Graham et al., 1989). The two common polymer frameworks are often termed the `chain' and the `stair'. The `chain' polymer has linear chains consisting of –(CuX)– repeat units. These chains can form two-dimensional sheets when the pendant ligands are bidentate, by bridging Cu atoms in adjacent chains (as seen in the polymer [CuClPz]; Pz is pyrazine; Moreno et al., 1995). Alternatively, the `stair' polymer has square –(Cu₂X₂)– units that form the step of a stair (Healy et al., 1989; Massaux et al., 1971; Jasinski et al., 1985; Wilsson & Oskarsson, 1985). However, the title compound differs from these `chain' and `stair' frameworks, forming a net-like layer constructed by edge-sharing of –(CuBr)– alternating six-membered chair-patterned rings.

Related literature

For related literature, see: Subramanian & Hoffmann (1992); Ye et al. (2005); Lu (2003); Cheng et al. (2005); Zhong et al. (2000); Larionova et al. (2000); Luo et al. (2004); Evans & Lin (2001); Li et al. (2007); Gill et al. (1976); Camus et al. (1975); Healy et al. (1983); Healy et al. (1989); Dyason et al. (1985); Graham et al. (1989); Moreno et al. (1995); Massaux et al. (1971); Jasinski et al. (1985); Wilsson Oskarsson (1985);

S2. Experimental

A mixture of cuprous bromide (0.14 g, 1 mmol), nicotinic acid (0.134 g, 1 mmol), NaOH (0.06 g, 1.5 mmol) and water (12 ml) was placed in a 23 ml Teflon reactor, which was heated to 433 K for three days and then cooled to room temperature at a rate of 10 K h^-1. The crystals obtained were washed with water and dried in air (yield 0.33 g, 90.2%).

S3. Refinement

H atoms were placed at calculated positions and were treated as riding on the parent atoms, with C—H distances of 0.93 Å, O—H distances of 0.82 Å and U_iso(H) values of 1.2U_eq(C) and 1.5U_eq(O). Please check changes to text made in accordance with CIF data.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A perspective view of the asymmetric unit of (I). [Symmetry codes: (iii) x - 1/2, -y + 1/2, z + 1/2; (iv) x - 1, y, z.]
	Fig. 2. A view of a net-like layer of Cu–Br units in (I).
	Fig. 3. A three-dimensional view of (I) in the bc plane. Hydrogen bonds are shown as dashed lines.

poly[µ₃-bromido-(pyridine-3-carboxylato-κN)copper(I)]

Crystal data

[CuBr(C6H5NO2)]	F(000) = 512
Mr = 266.56	Dx = 2.389 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3600 reflections
a = 3.8738 (5) Å	θ = 1.4–28°
b = 30.379 (4) Å	µ = 8.28 mm^−1
c = 6.3055 (1) Å	T = 273 K
β = 93.001 (1)°	Block, blue
V = 741.03 (2) Å^3	0.24 × 0.19 × 0.15 mm
Z = 4

Data collection

Bruker APEXII area-detector diffractometer	1604 independent reflections
Radiation source: fine-focus sealed tube	1314 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
ϕ and ω scan	θmax = 27.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −4→4
Tmin = 0.169, Tmax = 0.295	k = −34→38
9966 measured reflections	l = −7→8

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.092	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0354P)^2 + 2.5675P] where P = (Fo^2 + 2Fc^2)/3
1604 reflections	(Δ/σ)max < 0.001
101 parameters	Δρmax = 1.05 e Å^−3
0 restraints	Δρmin = −0.73 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Br1	0.99845 (12)	0.219200 (16)	−0.10234 (7)	0.03378 (17)
C1	0.6805 (11)	0.12646 (14)	0.1950 (7)	0.0281 (9)
H1	0.7649	0.1303	0.0608	0.034*
Cu1	0.51855 (17)	0.22119 (2)	0.14298 (10)	0.0403 (2)
N1	0.5638 (10)	0.16183 (12)	0.2960 (6)	0.0291 (8)
O1	0.7960 (11)	0.00908 (11)	0.2337 (6)	0.0528 (11)
C2	0.6818 (11)	0.08460 (14)	0.2797 (7)	0.0285 (9)
O2	0.9427 (11)	0.05548 (11)	−0.0182 (6)	0.0467 (9)
H2	1.0120	0.0325	−0.0697	0.070*
C3	0.5551 (13)	0.07851 (15)	0.4806 (7)	0.0337 (10)
H3	0.5511	0.0507	0.5418	0.040*
C4	0.4359 (12)	0.11470 (16)	0.5864 (7)	0.0353 (11)
H4	0.3496	0.1117	0.7205	0.042*
C5	0.4466 (12)	0.15557 (16)	0.4904 (7)	0.0333 (10)
H5	0.3689	0.1799	0.5640	0.040*
C6	0.8158 (12)	0.04736 (15)	0.1578 (7)	0.0332 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0335 (3)	0.0370 (3)	0.0315 (3)	0.0006 (2)	0.00779 (18)	0.0037 (2)
C1	0.036 (2)	0.025 (2)	0.024 (2)	0.0011 (19)	0.0057 (17)	−0.0019 (18)
Cu1	0.0523 (4)	0.0306 (3)	0.0386 (4)	0.0063 (3)	0.0089 (3)	0.0020 (3)
N1	0.036 (2)	0.0244 (19)	0.0272 (19)	0.0017 (16)	0.0048 (15)	−0.0025 (15)
O1	0.089 (3)	0.0208 (18)	0.051 (2)	0.0066 (18)	0.028 (2)	0.0037 (16)
C2	0.032 (2)	0.024 (2)	0.030 (2)	−0.0020 (18)	0.0023 (18)	−0.0008 (18)
O2	0.075 (3)	0.0257 (18)	0.042 (2)	0.0077 (18)	0.0220 (18)	−0.0024 (15)
C3	0.043 (3)	0.029 (2)	0.029 (2)	−0.002 (2)	0.0032 (19)	0.007 (2)
C4	0.044 (3)	0.037 (3)	0.025 (2)	−0.003 (2)	0.0079 (19)	0.001 (2)
C5	0.040 (3)	0.033 (3)	0.027 (2)	0.005 (2)	0.0061 (19)	−0.004 (2)
C6	0.041 (3)	0.028 (2)	0.031 (2)	−0.001 (2)	0.0048 (19)	0.0010 (19)

Geometric parameters (Å, º)

Br1—Cu1^i	2.4242 (8)	O1—C6	1.261 (6)
Br1—Cu1^ii	2.4757 (9)	C2—C3	1.394 (6)
Br1—Cu1	2.4806 (8)	C2—C6	1.477 (6)
C1—N1	1.340 (5)	O2—C6	1.261 (6)
C1—C2	1.380 (6)	O2—H2	0.8200
C1—H1	0.9300	C3—C4	1.378 (7)
Cu1—N1	2.049 (4)	C3—H3	0.9300
Cu1—Br1^iii	2.4242 (8)	C4—C5	1.383 (7)
Cu1—Br1^iv	2.4757 (8)	C4—H4	0.9300
N1—C5	1.343 (6)	C5—H5	0.9300
Cu1^i—Br1—Cu1^ii	110.02 (3)	C1—C2—C6	119.9 (4)
Cu1^i—Br1—Cu1	116.48 (3)	C3—C2—C6	121.4 (4)
Cu1^ii—Br1—Cu1	102.81 (3)	C6—O2—H2	109.5
N1—C1—C2	123.3 (4)	C4—C3—C2	118.5 (4)
N1—C1—H1	118.3	C4—C3—H3	120.8
C2—C1—H1	118.3	C2—C3—H3	120.8
N1—Cu1—Br1^iii	110.51 (10)	C3—C4—C5	119.1 (4)
N1—Cu1—Br1^iv	108.64 (11)	C3—C4—H4	120.5
Br1^iii—Cu1—Br1^iv	112.26 (3)	C5—C4—H4	120.5
N1—Cu1—Br1	102.93 (10)	N1—C5—C4	123.1 (4)
Br1^iii—Cu1—Br1	118.84 (3)	N1—C5—H5	118.5
Br1^iv—Cu1—Br1	102.81 (3)	C4—C5—H5	118.5
C1—N1—C5	117.3 (4)	O1—C6—O2	123.3 (4)
C1—N1—Cu1	120.3 (3)	O1—C6—C2	118.6 (4)
C5—N1—Cu1	122.0 (3)	O2—C6—C2	118.1 (4)
C1—C2—C3	118.7 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···Br1^v	0.93	2.87	3.716 (4)	152
O2—H2···O1^vi	0.82	1.82	2.620 (5)	166

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