Aqua­di­chloro­(di-2-pyridyl­di­azene)copper(II) monohydrate

The crystal structure of the mononuclear title complex, [CuCl₂(C₁₀H₈N₄)(H₂O)]·H₂O, shows an s-cis/E/s-trans-configured di-2-pyridyl­diazene ligand, with the square-pyramidal Cu^II ion coordinated to one pyridyl and one diazene N atom together with two Cl atoms and one aqua ligand. The crystal packing involves both hydrogen-bonding and [pi]-[pi] interactions. The solvent water mol­ecule links three monomers to one another through hydrogen-bonding interactions in which two monomers are linked via chloro ligands and the third via the aqua ligand. Face-to-face and weak slipped [pi]-[pi] interactions also occur between di-2-pyridyl­diazene moieties, and these interactions are responsible for the interchain packing.

S1. Comment

Non-covalent interactions, particularly versatile hydrogen bonds (Desiraju, 2000; Steiner & Desiraju, 1998; Bertolasi et al., 2001; Mathew et al., 2002), play vital roles in constructing organic and inorganic supramolecular architectures. During the past few years, several types of non-covalent interactions, such as π stacking interactions (Harrowfield, 1996; Roesky & Andruh, 2003;), weak coordination interactions (Grove et al., 2001) and electrostatic interactions (Reddy et al., 1993; Dong et al., 1999), have been recognized and used in constructing extended networks of supramolecular architectures. These types of interactions have attracted attention especially in fields such as developing new functional materials, crystal engineering, molecular recognition and self-assembly of organometallic compounds (Desiraju, 1996; Braga et al., 1998). Organic molecules containing two donor N atoms, such as pyrazine, bipyridine and azobispyridine, have been extensively employed for this purpose, and a number of extended structures with diverse topologies have been synthesized (Li et al., 2001; Moliner et al., 1999; Wong et al., 2000). The 2,2'-azobispyridine (abpy) ligand, which is known to form an unusual complex (Baldwin et al., 1969), was selected for the present study. The abpy ligand has several different coordination modes involving five-membered chelate ring formation (NNCNM), as shown in the first scheme below. When one 2-pyridyl ring remains uncoordinated, because of the repulsion effects between azo N-atom lone pairs and ortho-CH or pyridyl N-atom lone pairs, a singly chelating complex can form, as in (IIa) or (IIb). In the present study, apby is used as the building block and an interesting supramolecular architecture containing the Cu^II complex corresponding to (IIb) in the scheme is obtained.

The asymmetric unit of the title complex, (I), consists of one unit of [CuCl₂(C₁₀H₈N₄)H₂O]·H₂O. In the complex, the Cu^II ion is coordinated in a distorted square-pyramidal mode to two N atoms (one pyridyl and one azo N) of the abpy ligand, one chloro ligand and one water molecule in the basal plane, with a second chloro ligand in the apical position (Fig. 1 and Table 1). The abpy ligand adopts an s-cis/E/s-trans conformation. The second pyridyl N atom is not coordinated to the Cu^II ion but is the acceptor in a strong intramolecular hydrogen bond from the coordinated water molecule (Table 2). The stabilizing effect of the formation of this hydrogen bond is probably largely responsible for the abpy ligand adopting the conformation (IIb), with a dihedral angle between the coordinated and uncoordinated pyridyl planes of 7.03 (2)°. Hartmann et al. (2000) reported that the N═N distance [1.272 (9) Å] in an abpy ligand deviates significantly from that in free abpy [1.246 (2) Å; Bock et al., 1998], while the Re—N distance is shorter [2.143 (5) Å]. Hartmann et al. (2000)? attributed the shortening of the Re—N bond length and the extension of the N═N bond length to the effect of substantial π back donation from the metal ion centers into the π^*(abpy) orbital. This effect, nevertheless, is not observed to be significant in our complex [N═N = 1.254 (3) Å] because of the high effective charge of the Cu^IIion.

Both intermolecular hydrogen bonding and π–π interactions combine to stabilize the extended structure (Fig. 2). The water molecule of crystallization links three monomers to one another, acting as a hydrogen-bond donor to chloro ligands of two monomers and as a hydrogen-bond acceptor to the coordinated water molecule of a third monomer (Table 2). These interactions are responsible for forming a ladder-type structure (Fig. 2). The abpy moieties are also subject to π–π non-covalent interactions, which are either strong face-to-face interactions [Cg1···Cg3 = 3.415 (3) Å; Cg1 is the center of the chelate ring and Cg3 is the center of the uncoordinated pyridyl ring] or weak slipped interactions [Cg2···Cg3 = 3.944 (3) Å; Cg2 is the center of coordinated pyridyl ring]. These π—π interactions link the hydorgen-bonded chains. The five-membered chelate ring and uncoordinated pyridyl ring are stacked so as to be nearly parallel, with a dihedral angle of 4.68 (2)°. The interplanar separation of these rings is 3.414 (s.u.?)–3.404 (s.u.?) Å, the closest interatomic distance being C1···C10ⁱⁱⁱ [3.330 (5) Å; symmetry code: (iii) 1 − x, −y, 1 − z]. The other π–π interaction is between the coordinated and uncoordinated pyridyl rings. The interplanar separation of these rings ranges from 3.464 (s.u.?) to 3.232 (s.u.?)Å, the closest interatomic distance being C1···C10ⁱⁱⁱ [3.330 (5) Å]. Thus, an extensive network of hydrogen bonds and π–π stacking interactions stabilizes the crystal structure and forms an infinite three-dimensional lattice.

S2. Experimental

2,2'-Azobispyridine (abpy) was prepared according to the method of Rivarola et al. (1985). Solutions of CuCl₂·5H₂O (0.12 g, 1 equivalent) in water (20 ml) and 2,2'-azobispyridine (0.1 g, 1 equivalent) in terahydrofuran (THF) were mixed and the resulting dark-green solution was refluxed for 3 h. After the mixture was cooled to ambient temperature, a dark-green precipitate was obtained. The solid was then filtered off and washed with water. Dark-green crystals suitable for X-ray analysis were obtained by slow evaporation of THF/H₂O solution over a period of one week (yield 77%).

S3. Refinement

H atoms on C atoms were placed at calculated positions (C—H = 0.93 Å) and were allowed to ride on the parent atoms [U_iso(H)=1.2U(C)]. Other H atoms were placed from a difference map and were included in the refinement with O—H distances restrained to 0.84 (3) Å. Δρ_max and Δρ_min of 0.79 and −1.08 ų were found at distances of 0.63 and 0.83 Å from atoms N1 and Cu1, respectively.

Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2001); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. : A view of the copper coordination of the title compound, with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. : The hydrogen bonding (dashed lines) and π–π interactions, with 10% probability displacement ellipsoids.

Aquadichloro(di-2-pyridyldiazene)copper(II) monohydrate

Crystal data

[CuCl2(C10H8N4)(H2O)]·H2O	Z = 2
Mr = 354.69	F(000) = 358
Triclinic, P1	Dx = 1.716 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71069 Å
a = 8.072 (5) Å	Cell parameters from 21779 reflections
b = 8.279 (5) Å	θ = 2.6–28.8°
c = 11.327 (5) Å	µ = 1.98 mm^−1
α = 76.195 (5)°	T = 293 K
β = 73.134 (5)°	Prism, dark green
γ = 74.199 (5)°	0.42 × 0.33 × 0.21 mm
V = 686.5 (7) Å^3

Data collection

STOE IPDS-II diffractometer	3480 independent reflections
Radiation source: fine-focus sealed tube	2752 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.043
Detector resolution: 6.67 pixels mm^-1	θmax = 28.9°, θmin = 2.6°
ω scans	h = −10→10
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −11→11
Tmin = 0.295, Tmax = 0.477	l = −15→15
12369 measured reflections

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)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.102	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0663P)^2] where P = (Fo^2 + 2Fc^2)/3
3480 reflections	(Δ/σ)max < 0.001
188 parameters	Δρmax = 0.79 e Å^−3
4 restraints	Δρmin = −1.08 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
Cu1	0.33574 (4)	0.21037 (4)	0.72403 (3)	0.03760 (11)
Cl1	0.43448 (13)	0.26076 (11)	0.87471 (7)	0.0655 (2)
Cl2	0.05376 (8)	0.41774 (8)	0.71134 (6)	0.04598 (16)
C1	0.2007 (3)	−0.0863 (3)	0.7638 (3)	0.0441 (6)
C2	0.1430 (4)	−0.2355 (4)	0.8180 (4)	0.0596 (8)
H1	0.1098	−0.2946	0.7715	0.071*
C3	0.1362 (5)	−0.2944 (4)	0.9445 (4)	0.0680 (9)
H2	0.0979	−0.3943	0.9846	0.082*
C4	0.1864 (4)	−0.2039 (5)	1.0091 (3)	0.0620 (8)
H3	0.1826	−0.2419	1.0939	0.074*
C5	0.2428 (4)	−0.0556 (4)	0.9482 (3)	0.0500 (6)
H4	0.2778	0.0045	0.9930	0.060*
C6	0.3014 (3)	0.1529 (3)	0.4577 (3)	0.0409 (5)
C7	0.2444 (4)	0.0751 (4)	0.3862 (3)	0.0541 (7)
H5	0.1892	−0.0161	0.4219	0.065*
C8	0.2728 (4)	0.1386 (5)	0.2593 (3)	0.0643 (9)
H6	0.2402	0.0876	0.2072	0.077*
C9	0.3492 (4)	0.2768 (5)	0.2101 (3)	0.0609 (8)
H7	0.3658	0.3225	0.1252	0.073*
C10	0.4008 (4)	0.3465 (4)	0.2890 (3)	0.0536 (7)
H8	0.4522	0.4405	0.2558	0.064*
N1	0.2488 (3)	0.0041 (3)	0.8271 (2)	0.0407 (5)
N2	0.2141 (3)	−0.0300 (3)	0.6342 (2)	0.0469 (5)
N3	0.2857 (3)	0.0953 (3)	0.5899 (2)	0.0373 (4)
N4	0.3796 (3)	0.2840 (3)	0.4118 (2)	0.0444 (5)
O1	0.4847 (3)	0.3478 (3)	0.59747 (19)	0.0501 (5)
O2	0.1604 (3)	0.6811 (3)	0.4497 (2)	0.0547 (5)
H9	0.472 (5)	0.338 (5)	0.530 (3)	0.076 (12)*
H10	0.591 (3)	0.338 (5)	0.591 (4)	0.073 (12)*
H11	0.140 (6)	0.627 (5)	0.519 (3)	0.077 (13)*
H12	0.113 (5)	0.662 (5)	0.400 (3)	0.079 (13)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.04230 (18)	0.03948 (18)	0.03624 (18)	−0.01588 (13)	−0.01338 (12)	−0.00350 (12)
Cl1	0.1007 (6)	0.0701 (5)	0.0475 (4)	−0.0442 (5)	−0.0361 (4)	0.0012 (3)
Cl2	0.0419 (3)	0.0466 (3)	0.0491 (4)	−0.0079 (3)	−0.0120 (3)	−0.0085 (3)
C1	0.0410 (13)	0.0382 (13)	0.0566 (16)	−0.0148 (10)	−0.0147 (12)	−0.0042 (11)
C2	0.0609 (18)	0.0493 (16)	0.076 (2)	−0.0269 (14)	−0.0196 (16)	−0.0031 (15)
C3	0.064 (2)	0.0558 (18)	0.083 (2)	−0.0307 (16)	−0.0197 (18)	0.0143 (17)
C4	0.0571 (18)	0.067 (2)	0.0566 (18)	−0.0255 (16)	−0.0145 (15)	0.0152 (15)
C5	0.0524 (16)	0.0535 (16)	0.0443 (14)	−0.0200 (13)	−0.0142 (12)	0.0039 (12)
C6	0.0375 (12)	0.0450 (13)	0.0424 (13)	−0.0038 (10)	−0.0119 (10)	−0.0147 (11)
C7	0.0524 (16)	0.0607 (17)	0.0582 (18)	−0.0076 (13)	−0.0193 (14)	−0.0253 (14)
C8	0.0616 (19)	0.086 (2)	0.0552 (18)	−0.0025 (17)	−0.0242 (15)	−0.0352 (18)
C9	0.0605 (18)	0.074 (2)	0.0415 (15)	0.0061 (16)	−0.0151 (14)	−0.0182 (15)
C10	0.0586 (17)	0.0550 (16)	0.0406 (14)	−0.0039 (13)	−0.0095 (13)	−0.0089 (12)
N1	0.0393 (11)	0.0401 (11)	0.0434 (11)	−0.0126 (9)	−0.0118 (9)	−0.0018 (9)
N2	0.0496 (13)	0.0429 (12)	0.0554 (14)	−0.0147 (10)	−0.0172 (11)	−0.0111 (10)
N3	0.0369 (10)	0.0368 (10)	0.0414 (11)	−0.0088 (8)	−0.0119 (9)	−0.0092 (8)
N4	0.0521 (13)	0.0436 (11)	0.0381 (11)	−0.0111 (10)	−0.0118 (10)	−0.0066 (9)
O1	0.0519 (12)	0.0670 (13)	0.0400 (10)	−0.0317 (10)	−0.0142 (9)	−0.0003 (9)
O2	0.0551 (12)	0.0583 (13)	0.0579 (14)	−0.0245 (10)	−0.0153 (11)	−0.0076 (11)

Geometric parameters (Å, º)

Cu1—Cl1	2.2433 (14)	C6—C7	1.382 (5)
Cu1—Cl2	2.4684 (13)	C6—N3	1.438 (4)
Cu1—N1	1.999 (3)	C6—N4	1.327 (4)
Cu1—N3	2.153 (3)	C7—H5	0.930
Cu1—O1	1.940 (2)	C7—C8	1.382 (4)
C1—C2	1.380 (4)	C8—H6	0.930
C1—N1	1.342 (5)	C8—C9	1.371 (6)
C1—N2	1.412 (4)	C9—H7	0.930
C2—H1	0.930	C9—C10	1.378 (6)
C2—C3	1.389 (6)	C10—H8	0.930
C3—H2	0.930	C10—N4	1.341 (4)
C3—C4	1.364 (7)	N2—N3	1.254 (3)
C4—H3	0.931	O1—H9	0.83 (4)
C4—C5	1.381 (5)	O1—H10	0.82 (3)
C5—H4	0.930	O2—H11	0.80 (3)
C5—N1	1.334 (4)	O2—H12	0.83 (5)
Cl1—Cu1—Cl2	107.93 (4)	C7—C6—N4	124.0 (3)
Cl1—Cu1—N1	94.94 (9)	N3—C6—N4	113.3 (3)
Cl1—Cu1—N3	164.56 (6)	C6—C7—H5	121.5
Cl1—Cu1—O1	90.60 (9)	C6—C7—C8	117.2 (3)
Cl2—Cu1—N1	101.42 (8)	H5—C7—C8	121.4
Cl2—Cu1—N3	86.39 (7)	C7—C8—H6	120.0
Cl2—Cu1—O1	95.40 (8)	C7—C8—C9	120.0 (4)
N1—Cu1—N3	76.12 (10)	H6—C8—C9	120.0
N1—Cu1—O1	159.69 (9)	C8—C9—H7	120.6
N3—Cu1—O1	93.81 (11)	C8—C9—C10	118.6 (3)
C2—C1—N1	123.4 (3)	H7—C9—C10	120.7
C2—C1—N2	117.7 (3)	C9—C10—H8	118.7
N1—C1—N2	118.9 (2)	C9—C10—N4	122.5 (3)
C1—C2—H1	121.2	H8—C10—N4	118.8
C1—C2—C3	117.7 (4)	Cu1—N1—C1	115.03 (18)
H1—C2—C3	121.1	Cu1—N1—C5	127.0 (3)
C2—C3—H2	120.4	C1—N1—C5	117.9 (3)
C2—C3—C4	119.2 (3)	C1—N2—N3	113.5 (3)
H2—C3—C4	120.4	Cu1—N3—C6	129.6 (2)
C3—C4—H3	120.1	Cu1—N3—N2	115.95 (18)
C3—C4—C5	119.7 (3)	C6—N3—N2	114.0 (3)
H3—C4—C5	120.1	C6—N4—C10	117.7 (3)
C4—C5—H4	119.0	Cu1—O1—H9	105 (3)
C4—C5—N1	122.1 (4)	Cu1—O1—H10	125 (3)
H4—C5—N1	118.9	H9—O1—H10	108 (4)
C7—C6—N3	122.7 (2)	H11—O2—H12	115 (5)
N1—C1—C2—C3	−0.5 (5)	Cl1—Cu1—N1—C1	−170.00 (18)
N2—C1—C2—C3	177.6 (3)	Cl2—Cu1—N1—C1	80.57 (19)
C1—C2—C3—C4	−0.1 (5)	N1—C1—N2—N3	5.6 (4)
C2—C3—C4—C5	0.0 (5)	C2—C1—N2—N3	−172.6 (3)
C3—C4—C5—N1	0.6 (5)	C1—N2—N3—C6	179.5 (2)
N4—C6—C7—C8	0.5 (4)	C1—N2—N3—Cu1	−7.8 (3)
N3—C6—C7—C8	−177.6 (2)	N4—C6—N3—N2	−179.1 (2)
C6—C7—C8—C9	−2.2 (5)	C7—C6—N3—N2	−0.8 (3)
C7—C8—C9—C10	1.9 (5)	N4—C6—N3—Cu1	9.5 (3)
C8—C9—C10—N4	0.2 (5)	C7—C6—N3—Cu1	−172.1 (2)
C4—C5—N1—C1	−1.2 (4)	O1—Cu1—N3—N2	168.27 (19)
C4—C5—N1—Cu1	−177.4 (2)	N1—Cu1—N3—N2	6.14 (18)
C2—C1—N1—C5	1.1 (4)	Cl1—Cu1—N3—N2	62.0 (3)
N2—C1—N1—C5	−176.9 (2)	Cl2—Cu1—N3—N2	−96.55 (18)
C2—C1—N1—Cu1	177.8 (2)	O1—Cu1—N3—C6	−20.5 (2)
N2—C1—N1—Cu1	−0.3 (3)	N1—Cu1—N3—C6	177.4 (2)
O1—Cu1—N1—C5	111.6 (3)	Cl1—Cu1—N3—C6	−126.8 (2)
N3—Cu1—N1—C5	173.5 (2)	Cl2—Cu1—N3—C6	74.68 (19)
Cl1—Cu1—N1—C5	6.3 (2)	C7—C6—N4—C10	1.5 (4)
Cl2—Cu1—N1—C5	−103.2 (2)	N3—C6—N4—C10	179.8 (2)
O1—Cu1—N1—C1	−64.7 (3)	C9—C10—N4—C6	−1.9 (4)
N3—Cu1—N1—C1	−2.77 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H12···Cl2^i	0.83 (3)	2.39 (3)	3.210 (3)	170 (4)
O1—H10···O2^ii	0.82 (2)	1.89 (3)	2.710 (4)	172 (4)
O2—H11···Cl2	0.80 (3)	2.49 (3)	3.277 (3)	167 (4)
O1—H9···N4	0.82 (2)	1.90 (3)	2.689 (3)	161 (4)

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