A twofold inter­woven two-dimensional[rightwards arrow]two-dimen­sional (2-D[rightwards arrow]2-D) cluster-organic network based on the [Cu₂I₂] cluster and the 4,4'-(diazene­di­yl)dipyridine ligand: poly[[[mu]₂-4,4'-(diazenedi­yl)dipyridine]-[mu]₂-iodido-copper(I)]

In the polymeric title compound, [CuI(C₁₀H₈N₄)]_n, the Cu^I atom is in a four-coordinated tetra­hedral geometry, formed by two I atoms and two pyridine N atoms from two different 4,4'-(diazenedi­yl)dipyridine (4,4'-azpy) ligands. Two [mu]₂-I atoms link two Cu^I atoms to form a planar rhomboid [Cu₂I₂] cluster located on an inversion centre, where the distance between two Cu^I atoms is 2.7781 (15) Å and the Cu-I bond lengths are 2.6290 (13) and 2.7495 (15) Å. The bridging 4,4'-azpy ligands connect the [Cu₂I₂] clusters into a two-dimensional (2-D) double-layered grid-like network [parallel to the (10) plane], with a (4,4)-connected topology. Two 2-D grid-like networks inter­weave each other by long 4,4'-azpy bridging ligands to form a dense 2-D double-layered network. To the best of our knowledge, this inter­woven 2-D[rightwards arrow]2-D network is observed for the first time in [Cu₂I₂]-organic compounds.

S1. Comment

In recent years, the construction of multidimensional cluster-based coordination polymers have been a major focus of research in the field of chemistry and materials science, due to not only their aesthetically intriguing structural features (Schubert, 2011; Zhang, Song et al., 2008) but also because of their potentially useful applications, such as magnetism (Imai et al., 2009), photoluminescence (Perruchas et al., 2011), ion exchange (Mrutu et al., 2011), catalysis (Tan et al., 2012), adsorption (Li et al., 2010) and nonlinear optical properties (Zhang, Cao et al., 2008; Zhang, Meng et al., 2010). The strategy popularly used is a building-block approach (Hu et al., 2005; Eddaoudi et al., 2001) and much effort has been devoted to the connection of suitable predetermined building blocks into frameworks in order to obtain desired structures and properties.

As an important kind of cluster, copper(I) halide clusters have been widely studied due to their diverse structures and applications (Peng et al., 2010; Zhang, Wu et al., 2010). Up to now, copper(I) halide cluster-based coordination polymers with various structural motifs have been constructed, such as rhomboid [Cu₂I₂] dimers (Niu et al., 2006; Araki et al., 2005), cubane-like [Cu₄I₄] tetramers (Blake et al., 2001; Chen et al., 2008), zigzag chains (Graham et al., 2000; Cheng et al., 2004), double-stranded ladders (Graham et al., 2000) and two-dimensional [CuI]_n layers (Peng et al., 2005). Various bridging ligands, such as phosphines, anilines, pyridine-type ligands and thioethers, have been applied in constructing CuX-based coordination polymers (Peng et al., 2010). Herein, we have used 4,4'-(diazenediyl)dipyridine (4,4'-azpy) ligands as long bridges to construct the CuI-based coordination polymer poly[[µ-4,4'-(diazenediyl)dipyridine]-µ₂-iodido-copper(I)], (I), which is formed by [Cu₂I₂] clusters and single 4,4'-azpy bridges, and exhibits a novel twofold interwoven two-dimensional → two-dimensional (2-D → 2-D) network.

X-ray crystallographic analysis revealed that (I) crystallizes in the monoclinic space group P2/c with each [Cu₂I₂] cluster linked to four other [Cu₂I₂] clusters through long single 4,4'-azpy bridges, furnishing a 2-D double-layered grid-like network with a (4,4)-connected topology (Figs. 2 and 3). As shown in Fig. 1, the Cu^I atom is bonded by two I atoms and two pyridine N atoms from two 4,4'-azpy ligands, forming a four-coordinated tetrahedral geometry. The Cu1—N1 and Cu1—N2 bond lengths are 2.037 (6) and 2.045 (6) Å, respectively, and the N1—Cu1—N2 angle is 123.7 (3)°. The planar rhomboid [Cu₂I₂] cluster is formed by two µ₂-I atoms linking two Cu^I atoms. In the [Cu₂I₂] cluster, the distance between two Cu^I atoms is 2.7781 (15) Å, and the Cu—I bonds lengths are 2.6290 (13) and 2.7495 (15) Å. The I—Cu—I and Cu—I—Cu angles are 117.85 (4) and 62.15 (4)°, respectively.

The 4,4'-azpy ligands connect the [Cu₂I₂] clusters into a 2-D double-layered grid-like network with a (4,4)-connected topology. The N═N bond length is 1.240 (9) Å and the average distances between C and N atoms in the pyridine rings is 1.331 (9) Å. In the (4,4) network, the [Cu₂I₂] clusters shows a unique ABAB arrangement (Fig. 2) and the 4,4'-azpy ligand is slightly distorted because the angle between the planes of the two pyridine is 8.9 (4)°. Interestingly, the 2-D net exhibits a rare double-layered structure (Fig. 3a), which should be due to the distances between the two Cu^I atoms in the [Cu₂I₂] clusters. The lengths of the two diagonals in the grid, constructed by four [Cu₂I₂] clusters and four 4,4'-azpy bridges, are 16.149 (2) and 22.883 (3) Å (Fig. 2). Therefore, each layer has enough empty space, which results in two layers interweaving each other by long 4,4'-azpy bridging ligands to form a new dense two-dimensional double-layered network (Fig. 3b).

In previous work, the phenomena of interpenetration and catenation have appeared in CuX-based coordination polymers. In [Cu₂Br₂{1,2-bis(pyridin-4-yl)ethane}₂]_n (Hu et al., 2006), two sets of (4,4) layers adopt the diagonal–diagonal fourfold interpenetration mode, giving high catenation and generating a 2-D → 3-D (three-dimensional) interpenetrating framework. In [Cu₂Br₂{1,3-bis(pyridin-4-yl)propane}₂]_n (Hu et al., 2006), the 2-D polycatenane network is formed by interlocking of 1-D (one-dimensional) double-stranded tubular chains. However, interwoven 2-D → 2-D networks are very scarce in coordination polymers and, to the best of our knowledge, the novel interwoven 2-D → 2-D network in (I) is the first to be found in a [Cu₂X₂]–organic compound.

In fact, this experiment was designed to synthesize W/S/Cu cluster-based coordination polymers. In the first step of the preparation, the cubane-shaped {[(t-Bu)₄N]₃[WOS₃(CuI)₃I]} W/S/Cu cluster was synthesized. It was hoped that in the next step the W/S/Cu clusters would be bridged by long 4,4'-azpy ligands to form a cubane-shaped W/S/Cu cluster-based coordination polymer. However, in the second step, the W/S/Cu clusters were decomposed by water from the acetonitrile or dimethylformamide solvent in the solvothermal reaction. As a result, the unexpected [Cu₂I₂]-based coordination polymer (I) was obtained.

In summary, an unexpected [Cu₂I₂]-based coordination polymer, (I), with a two-dimensional double-layered grid-like (4,4) network is obtained from a solvothermal reaction which was originally designed to synthesize W/S/Cu cluster-based coordination polymers. This interwoven two-dimensional → two-dimensional network in (I) is firstly found in [Cu₂I₂]-organic compounds.

Related literature

For related literature, see: Araki et al. (2005); Blake et al. (2001); Chen et al. (2008); Cheng et al. (2004); Eddaoudi et al. (2001); Graham et al. (2000); Hu et al. (2005, 2006); Imai et al. (2009); Li et al. (2010); Mrutu et al. (2011); Niu et al. (2006); Peng et al. (2005, 2010); Perruchas et al. (2011); Schubert (2011); Tan et al. (2012); Zhang, Cao, Zhang, Meng, Matsumoto, Song, Ma, Chen, Tatsumi & Humphrey (2008); Zhang, Meng, Song, Zhao, Li, Qu, Sun, Humphrey & Zhang (2010); Zhang, Song, Yang, Humphrey & Zhang (2008); Zhang, Wu, Liu, Dou, Bu & Feng (2010).

S2. Experimental

(NH₄)₂WOS₃ (0.335 g, 1 mmol), CuSCN (0.568 g, 3 mmol) and (t-Bu)₄NI (1.119 g, 3 mmol) were added to dimethylformamide (DMF, 2 ml) and the resulting solution was stirred thoroughly for 5 min. After filtration, i-PrOH (5 ml) was carefully layered on the surface of the the red filtrate. Red block-shaped crystals were obtained after two weeks. These crystals (0.0734 g) and 4,4'-(diazenediyl)dipyridine (0.0183 g, 0.1 mmol) were added to acetonitrile (2 ml) and DMF (1 ml) and the resulting solution was stirred thoroughly for 10 min in a vacuum. The solution was then sealed and heated in an oven at 373 K for 48 h, and then cooled to room temperature at a rate of 3 K h^-1, producing brown block-shaped crystals (yield 0.0287 g). Analysis calculated for C₁₀H₈CuIN₄: C 32.06, H 2.15, N 14.95%; found: C 31.88, H 2.19, N 15.15%. IR (KBr, cm^-1): 3053 (w), 2108 (s h), 1595 (s h), 1563 (w), 1413 (s h), 1224 (m), 1048 (w), 928 (s h), 841 (s h), 569 (m), 430 (m). [What does the "h" represent in the peak assignments?]

S3. Refinement

H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C).

Computing details

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

Figures

	Fig. 1. The structure of a portion of the title compound, showing the atom-labelling scheme and 50% probability displacement ellipsoids. All H atoms have been omitted. [Symmetry codes: (i) -x, -y+1, -z+1; (ii) x+1, -y+2, z+1/2.]
	Fig. 2. A fragment of the two-dimensional (4,4) network showing the [Cu2I2] clusters in a unique ABAB arrangement. The diagonal distances between the centers of the [Cu2I2] clusters are 16.149 (2) and 22.883 (3) Å.
	Fig. 3. (a) A packing diagram of the two-dimensional (4,4) networks showing the double-layer structures. (In the electronic version of the paper, Cu^I atoms are green, I atoms are purple, C atoms are grey and N atoms are blue.) (b) The novel two-dimensional twofold interwoven networks. (In the electronic version of the paper, the different layers layers are highlighted in red and blue.)

poly[[µ-4,4'-(diazenediyl)dipyridine]-µ₂-iodido-copper(I)]

Crystal data

[CuI(C10H8N4)]	F(000) = 712
Mr = 374.65	Dx = 2.085 Mg m^−3
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yc	Cell parameters from 3410 reflections
a = 9.7137 (19) Å	θ = 2.5–28.9°
b = 8.0745 (16) Å	µ = 4.39 mm^−1
c = 15.396 (3) Å	T = 150 K
β = 98.73 (3)°	Block, brown
V = 1193.6 (4) Å^3	0.2 × 0.18 × 0.15 mm
Z = 4

Data collection

Rigaku Saturn724+ (2x2 bin mode) diffractometer	2171 independent reflections
Radiation source: fine-focus sealed tube	1674 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.053
ω scans	θmax = 25.3°, θmin = 2.9°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2008)	h = −11→9
Tmin = 0.795, Tmax = 1.000	k = −9→8
6682 measured reflections	l = −17→18

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H-atom parameters constrained
S = 1.17	w = 1/[σ^2(Fo^2) + (0.0198P)^2 + 2.6592P] where P = (Fo^2 + 2Fc^2)/3
2171 reflections	(Δ/σ)max < 0.001
145 parameters	Δρmax = 0.80 e Å^−3
0 restraints	Δρmin = −0.63 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
I1	0.10063 (6)	0.31252 (6)	0.41593 (4)	0.0507 (2)
Cu1	0.05260 (10)	0.62373 (12)	0.45162 (7)	0.0496 (3)
N1	−0.0745 (6)	0.7213 (8)	0.3467 (4)	0.0404 (16)
N2	0.2398 (6)	0.7250 (8)	0.5042 (4)	0.0440 (17)
N3	0.5868 (7)	0.9279 (10)	0.6661 (4)	0.056 (2)
N4	0.6006 (7)	1.0804 (10)	0.6633 (4)	0.0525 (19)
C1	−0.0876 (8)	0.8843 (10)	0.3362 (5)	0.046 (2)
H1A	−0.0247	0.9520	0.3713	0.056*
C2	−0.1888 (8)	0.9597 (10)	0.2763 (5)	0.050 (2)
H2A	−0.1931	1.0744	0.2708	0.059*
C3	−0.2833 (8)	0.8588 (10)	0.2249 (5)	0.042 (2)
C4	−0.2708 (9)	0.6913 (11)	0.2340 (6)	0.068 (3)
H4A	−0.3336	0.6213	0.2003	0.081*
C5	−0.1640 (8)	0.6267 (11)	0.2936 (5)	0.060 (3)
H5A	−0.1536	0.5123	0.2971	0.072*
C6	0.2540 (8)	0.8884 (10)	0.5123 (5)	0.048 (2)
H6A	0.1845	0.9550	0.4823	0.057*
C7	0.3652 (8)	0.9648 (10)	0.5625 (5)	0.050 (2)
H7A	0.3699	1.0796	0.5665	0.060*
C8	0.4689 (7)	0.8682 (11)	0.6067 (5)	0.045 (2)
C9	0.4586 (9)	0.6984 (11)	0.5976 (6)	0.073 (3)
H9A	0.5280	0.6294	0.6259	0.087*
C10	0.3424 (8)	0.6326 (11)	0.5452 (6)	0.069 (3)
H10A	0.3363	0.5182	0.5386	0.083*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0569 (4)	0.0338 (3)	0.0588 (4)	0.0023 (3)	0.0007 (3)	−0.0019 (3)
Cu1	0.0447 (6)	0.0386 (6)	0.0579 (7)	−0.0023 (5)	−0.0164 (5)	0.0030 (5)
N1	0.041 (4)	0.031 (4)	0.047 (4)	0.000 (3)	−0.001 (3)	−0.001 (3)
N2	0.039 (4)	0.035 (4)	0.052 (4)	0.000 (3)	−0.010 (3)	0.001 (3)
N3	0.041 (4)	0.062 (5)	0.063 (5)	−0.010 (4)	−0.005 (4)	−0.008 (4)
N4	0.043 (4)	0.061 (5)	0.050 (4)	−0.010 (4)	−0.005 (3)	−0.005 (4)
C1	0.045 (5)	0.044 (6)	0.046 (5)	−0.003 (4)	−0.008 (4)	−0.004 (4)
C2	0.054 (5)	0.040 (5)	0.052 (5)	0.011 (4)	0.000 (4)	0.009 (4)
C3	0.044 (5)	0.042 (5)	0.036 (4)	0.009 (4)	−0.004 (4)	0.002 (4)
C4	0.058 (6)	0.057 (6)	0.074 (6)	0.004 (5)	−0.035 (5)	−0.003 (5)
C5	0.061 (6)	0.037 (5)	0.072 (6)	0.003 (4)	−0.020 (5)	−0.001 (4)
C6	0.048 (5)	0.041 (6)	0.049 (5)	−0.003 (4)	−0.008 (4)	0.002 (4)
C7	0.051 (5)	0.047 (6)	0.048 (5)	−0.016 (4)	−0.005 (4)	−0.003 (4)
C8	0.030 (4)	0.060 (6)	0.044 (5)	0.000 (4)	−0.001 (4)	−0.002 (4)
C9	0.058 (6)	0.043 (6)	0.102 (8)	0.009 (5)	−0.035 (6)	−0.018 (5)
C10	0.053 (6)	0.041 (6)	0.101 (7)	0.000 (4)	−0.032 (5)	−0.016 (5)

Geometric parameters (Å, º)

I1—Cu1	2.6290 (13)	C2—H2A	0.9300
I1—Cu1^i	2.7495 (15)	C3—C4	1.364 (11)
Cu1—N1	2.037 (6)	C3—N4^iii	1.444 (9)
Cu1—N2	2.045 (6)	C4—C5	1.379 (10)
N1—C1	1.330 (9)	C4—H4A	0.9300
N1—C5	1.338 (9)	C5—H5A	0.9300
N2—C10	1.326 (9)	C6—C7	1.375 (9)
N2—C6	1.330 (9)	C6—H6A	0.9300
N3—N4	1.240 (9)	C7—C8	1.370 (10)
N3—C8	1.435 (9)	C7—H7A	0.9300
N4—C3^ii	1.444 (9)	C8—C9	1.381 (11)
C1—C2	1.382 (9)	C9—C10	1.389 (10)
C1—H1A	0.9300	C9—H9A	0.9300
C2—C3	1.383 (10)	C10—H10A	0.9300
Cu1—I1—Cu1^i	62.15 (4)	C4—C3—C2	119.0 (7)
N1—Cu1—N2	123.7 (3)	C4—C3—N4^iii	117.0 (7)
N1—Cu1—I1	108.02 (18)	C2—C3—N4^iii	124.0 (7)
N2—Cu1—I1	106.82 (19)	C3—C4—C5	119.3 (7)
N1—Cu1—I1^i	100.64 (19)	C3—C4—H4A	120.3
N2—Cu1—I1^i	100.42 (19)	C5—C4—H4A	120.3
I1—Cu1—I1^i	117.85 (4)	N1—C5—C4	122.9 (8)
N1—Cu1—Cu1^i	118.39 (18)	N1—C5—H5A	118.5
N2—Cu1—Cu1^i	116.93 (18)	C4—C5—H5A	118.5
I1—Cu1—Cu1^i	61.05 (4)	N2—C6—C7	124.0 (7)
I1^i—Cu1—Cu1^i	56.80 (4)	N2—C6—H6A	118.0
C1—N1—C5	116.7 (6)	C7—C6—H6A	118.0
C1—N1—Cu1	121.0 (5)	C8—C7—C6	118.6 (8)
C5—N1—Cu1	121.5 (5)	C8—C7—H7A	120.7
C10—N2—C6	116.9 (6)	C6—C7—H7A	120.7
C10—N2—Cu1	121.5 (5)	C7—C8—C9	118.6 (7)
C6—N2—Cu1	120.5 (5)	C7—C8—N3	125.5 (8)
N4—N3—C8	113.1 (7)	C9—C8—N3	115.9 (7)
N3—N4—C3^ii	113.1 (7)	C8—C9—C10	118.6 (7)
N1—C1—C2	124.2 (7)	C8—C9—H9A	120.7
N1—C1—H1A	117.9	C10—C9—H9A	120.7
C2—C1—H1A	117.9	N2—C10—C9	123.2 (8)
C1—C2—C3	117.7 (7)	N2—C10—H10A	118.4
C1—C2—H2A	121.1	C9—C10—H10A	118.4
C3—C2—H2A	121.1
Cu1^i—I1—Cu1—N1	−113.0 (2)	Cu1—N1—C1—C2	−168.1 (6)
Cu1^i—I1—Cu1—N2	111.9 (2)	N1—C1—C2—C3	0.8 (13)
Cu1^i—I1—Cu1—I1^i	0.0	C1—C2—C3—C4	−1.5 (13)
N2—Cu1—N1—C1	−37.0 (7)	C1—C2—C3—N4^iii	176.3 (7)
I1—Cu1—N1—C1	−162.6 (6)	C2—C3—C4—C5	−0.4 (14)
I1^i—Cu1—N1—C1	73.3 (6)	N4^iii—C3—C4—C5	−178.3 (8)
Cu1^i—Cu1—N1—C1	131.1 (6)	C1—N1—C5—C4	−3.8 (13)
N2—Cu1—N1—C5	153.7 (6)	Cu1—N1—C5—C4	166.0 (7)
I1—Cu1—N1—C5	28.0 (7)	C3—C4—C5—N1	3.2 (15)
I1^i—Cu1—N1—C5	−96.1 (6)	C10—N2—C6—C7	−2.2 (13)
Cu1^i—Cu1—N1—C5	−38.2 (7)	Cu1—N2—C6—C7	166.0 (6)
N1—Cu1—N2—C10	−152.1 (7)	N2—C6—C7—C8	0.5 (13)
I1—Cu1—N2—C10	−26.0 (7)	C6—C7—C8—C9	1.2 (13)
I1^i—Cu1—N2—C10	97.5 (7)	C6—C7—C8—N3	−175.7 (8)
Cu1^i—Cu1—N2—C10	39.6 (8)	N4—N3—C8—C7	−11.7 (12)
N1—Cu1—N2—C6	40.2 (7)	N4—N3—C8—C9	171.4 (9)
I1—Cu1—N2—C6	166.3 (6)	C7—C8—C9—C10	−1.0 (14)
I1^i—Cu1—N2—C6	−70.2 (6)	N3—C8—C9—C10	176.2 (9)
Cu1^i—Cu1—N2—C6	−128.1 (6)	C6—N2—C10—C9	2.4 (14)
C8—N3—N4—C3^ii	178.2 (6)	Cu1—N2—C10—C9	−165.7 (8)
C5—N1—C1—C2	1.8 (12)	C8—C9—C10—N2	−0.8 (16)

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