Aqua(2,2'-bipyrid­yl)­chloro­nitrato­copper(II)

In a new hydrogen-bonded three-dimensional complex, [CuCl(NO₃)(C₁₀H₈N₂)(H₂O)], the Cu atom has an elongated tetra­gonal octa­hedral environment, with two 2,2'-bipyridyl N atoms, one nitrate O atom and one Cl atom forming the equatorial plane, and a second O atom of the nitrate anion and a water mol­ecule in the axial positions. The complex mol­ecules are linked to form a three-dimensional supra­molecular array by hydrogen-bonding inter­actions both between the water O atom and nitrate O atoms, and between the water O atom and the Cl atom of a neighboring mol­ecule.

S1. Comment

In the past decade, the design and synthesis of metal-organic compounds based on the principles of crystal engineering have made rapid progress (Li et al., 2006). Furthermore, the rational design and construction of specific architectures are beneficial for preparing functional materials. Self-assembly of metal compounds by hydrogen bonds into one-, two- and three-dimensional supramolecular architectures connects with biological chemistry, materials chemistry (such as organic films and magnetic materials) and supramolecular chemistry (Chen et al., 2001). Hydrogen bonds play vital roles in highly efficient and specific biological reactions and are essential for molecular recognition and self-organization of molecules in supramolecular chemistry. Copper complexes have been studied extensively in recent years. Their flexibility, facility of preparation and capacity for stabilizing unusual oxidation states can explain their successful performance in mimicking peculiar geometries around the metal, leading to very interesting spectroscopic properties and varied reactivities (Hathaway, 1987). Moreover, copper complexes have extensively been used as catalysts for a wide variety of reactions, including olefin polymerization (Killian et al., 1996) and oxygen activation (Jung et al., 1996). The stereochemistry of a series of mono(chelate) copper(II) complexes containing an oxoanion and a halide is currently of interest to us. With the flexible di-2-pyridylamine (dpyam) ligand, the complexes [Cu(dpyam)(NO₃)Cl]·0.5H₂O (Mathews & Manohar, 1991), [Cu(dpyam)(O₂CCH₃)Cl] (Ugozzoli et al., 1997) and [Cu(dpyam)(O₂CCH₂CH₃)Cl]·H₂O (Youngme et al., 1999) have been found so far. The former involves a polymeric structure bridged by a chloride ion, while the latter two compounds exhibit monomeric units. In the present paper, we report the crystal structure of the less flexible 2,2'-bipyridyl (bpy) complex [Cu(bpy)(NO₃)Cl(H₂O)], (I), in which a three-dimensional supramolecular array is formed by hydrogen-bonding interactions. Structural comparison with related complexes has been made and the spectroscopic properties of the complexes are discussed.

The structure of (I) is made up of discrete [Cu(bpy)(NO₃)Cl(H₂O)] units. The Cu atom is six-coordinated in a distorted octahedral arrangement (Table 1), with two N atoms of the bpy ligand, one O atom of the nitrate anion (atom O2) and a chloride anion forming the equatorial plane, while a second nitrate O atom [Cu1—O3 = 2.6262 (16) Å] and a water O atom occupy the tetragonal positions, thus giving an elongated octahedral geometry with tetragonality (T = mean in-plane distance/mean out-of-plane distance) of 0.84. The tetragonal octahedral arrangement is typical and expected for Cu^II in view of the Jahn–Teller effect (Jahn & Teller, 1937). However, the title compound is further distorted with regard to the coordination of atom O3 from the nitrate ligand, which occupies the off-axis tetragonal position with an axial O1—Cu1—O3 angle much lesser than 180° [144.17 (1)°], leading to semicoordination to the Cu^II ion. The equatorial plane shows a slight tetrahedral twist, as is evident from the dihedral angle of 10.0 (1)° at which the N1—Cu1—N2 and Cl1—Cu1—O2 planes cross. The local molecular geometry of (I) is best described as elongated octahedral with a long off-axis axial bond giving a (4 + 1 + 1') structure. The equatorial Cu—Cl distance is normal, in agreement with a previous report (Hathaway, 1987). The structure of the title complex is found to be different from that of the closely related dpyam complex [Cu(dpyam)(NO₃)Cl]·0.5H₂O (Mathews & Manohar, 1991). This compound consists of polymeric [Cu(dpyam)(NO₃)Cl]_n zigzag chains with monodentate nitrate and bridging chloride ligands and involves a distorted square-based pyramidal geometry. The copper environment in (I) is also different from those of the related dpyam complexes with monovalent acetate and propionate oxoanions, viz. [Cu(dpyam)(O₂CCH₃)Cl] (Ugozzoli, et al., 1997) and [Cu(dpyam)(O₂CCH₂CH₃)Cl]·H₂O (Youngme et al., 1999), involving mononuclear units with bidentate acetate or propionate ligands and, in the latter, an uncoordinated water molecule, giving a distorted square-based pyramidal geometry. The most similarity to compound (I) is found in the square-pyramidal complex [Cu(dpyam)(O₂CCH₃)(NCS)(H₂O)] (Youngme et al., 2006), containing a pseudohalide, a coordinated water molecule and a monodentate acetate ligand. The second O atom of the acetate anion coordinates to Cu^II ion in a similar fashion to that of the nitrate in compound (I), but with a very long Cu—O distance, 3.064 (1) Å. These observations indicate that both the chelate function of the bpy and dpyam ligands, and the coordination nature of oxoanions, are responsible for the structure of this complex system. This implies that the more flexible dpyam ligand results in a greater variety of geometries and structures (Amournjarusiri & Hathaway, 1991). The electronic reflectance spectrum of (I) involves a single broad peak at 13 850 cm⁻¹, corresponding to an elongated tetragonal octahedral geometry with off-axial-direction coordination from the normal to the N1/N2/O2/Cl1 plane (Procter et al., 1972). The electronic spectrum of (I) is similar to those found in complexes with similar Cu^II environments [Cu(dpyam)(O₂CCH₃)₂]·2H₂O (13 510 cm⁻¹), [Cu(dpyam)(O₂CCH₃)(NO₂)]·H₂O (13 880 cm⁻¹), [Cu(dpyam)(NO₂)₂] (13 890 cm⁻¹), [Cu(dpyam)(NO₃)₂]·2H₂O (13 580 cm⁻¹) (Youngme et al., 2002) and [Cu(dpyam)(O₂CCH₃)(NCS)(OH₂)] (15 980 cm⁻¹) (Youngme et al., 2006). The symmetric and antisymmetric NO stretchings appear as the strong bands at 1310 and 1384 cm⁻¹, respectively, consistent with the asymmetric bidentate nitrate group (Lewis et al., 1972). The complex molecules are linked to form a three-dimensional supramolecular array by hydrogen-bonding interactions between water molecule and the coordinated nitrate O atoms and Cl atom of neighboring molecules (Table 2 and Fig. 2).

S2. Experimental

The title complex was prepared by adding a warming solution containing Cu(NO₃)₂. 3H₂O (0.241 g, 1.0 mmol) in water (5 ml) to a warming solution of 2,2'-bipyridine (0.156 g, 1.0 mmol) in ethanol (20 ml), and then solid NaCl (0.029 g, 0.5 mmol) was added. The blue solution was slowly evaporated at room temperature. After several days, blue–green crystals were formed. The crystals were filtered off, washed with mother liquor and air-dried.

S3. Refinement

H atoms in the bpy ligand were placed in idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.93 Å and U_iso(H) values of 1.2U_eq(C). H atoms bonded to the water O atom were visible in a difference map and were refined with a DFIX (SHELXTL; Sheldrick, 2000b) restraint of O—H = 0.85 (1) Å and with U_iso(H) values of 1.5U_eq(O) [not in accordance with CIF].

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2000b); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The molecular structure of (I), with 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The packing of (I), with hydrogen bonds shown as dashed lines, showing the two-dimensional structure along the a axis. The bpy ligand has been omitted for clarity.

Aquachloronitrato(2,2'-bipyridyl)copper(II)

Crystal data

[Cu(NO3)Cl(C10H8N2)(H2O)]	F(000) = 676
Mr = 335.20	Dx = 1.810 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 5409 reflections
a = 10.8944 (3) Å	θ = 2.3–27.1°
b = 10.6760 (3) Å	µ = 2.01 mm^−1
c = 11.0496 (3) Å	T = 273 K
β = 106.860 (1)°	Rhombus, blue–green
V = 1229.92 (6) Å^3	0.43 × 0.35 × 0.28 mm
Z = 4

Data collection

Siemens SMART CCD area-detector diffractometer	2718 independent reflections
Radiation source: fine-focus sealed tube	2466 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ω scans	θmax = 27.1°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000a)	h = −8→13
Tmin = 0.441, Tmax = 0.576	k = −13→13
7471 measured reflections	l = −14→13

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)] = 0.024	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.066	w = 1/[σ^2(Fo^2) + (0.0371P)^2 + 0.3286P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.001
2716 reflections	Δρmax = 0.30 e Å^−3
180 parameters	Δρmin = −0.63 e Å^−3
3 restraints	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods

Special details

Experimental. The diffuse reflectance spectrum at room temperature was measured on polycrystalline samples using a UV–vis–NIR scanning spectrophotometer UV 3101PC, SHIMADZU spectrophotometer in the 3000–52000 cm⁻¹ spectral range, while the infrared spectrum was recorded on a Spectrum One Perkin-Elmer FTIR spectrophotometer as KBr pressed pellets in the 4000–450 cm⁻¹ spectral range.

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	1.106626 (19)	0.23305 (2)	0.312412 (18)	0.02746 (8)
Cl1	1.25668 (5)	0.38517 (4)	0.36620 (5)	0.04124 (12)
N1	1.03622 (14)	0.25937 (13)	0.46030 (13)	0.0272 (3)
N2	0.97162 (13)	0.09852 (13)	0.27390 (13)	0.0275 (3)
N3	1.02555 (14)	0.31279 (15)	0.06990 (13)	0.0336 (3)
O1	1.25361 (12)	0.07209 (13)	0.36197 (13)	0.0365 (3)
H11	1.3272 (16)	0.095 (2)	0.3975 (19)	0.043 (6)*
H12	1.258 (2)	0.022 (2)	0.3046 (19)	0.054 (7)*
O2	1.11173 (13)	0.23544 (12)	0.13027 (12)	0.0344 (3)
O3	0.95133 (15)	0.35805 (16)	0.12510 (15)	0.0529 (4)
O4	1.01975 (16)	0.33962 (16)	−0.03994 (13)	0.0511 (4)
C1	1.07267 (18)	0.34788 (18)	0.54989 (17)	0.0360 (4)
H1	1.1403	0.4006	0.5487	0.043*
C2	1.01326 (19)	0.36358 (19)	0.64415 (18)	0.0399 (4)
H2	1.0401	0.4260	0.7048	0.048*
C3	0.91341 (19)	0.2847 (2)	0.64622 (18)	0.0394 (4)
H3	0.8723	0.2931	0.7087	0.047*
C4	0.87500 (17)	0.19269 (18)	0.55421 (16)	0.0330 (4)
H4	0.8078	0.1389	0.5542	0.040*
C5	0.93813 (15)	0.18207 (15)	0.46235 (14)	0.0249 (3)
C6	0.90431 (15)	0.08839 (15)	0.35942 (14)	0.0255 (3)
C7	0.81242 (17)	−0.00449 (17)	0.34850 (17)	0.0341 (4)
H7	0.7667	−0.0106	0.4075	0.041*
C8	0.78992 (18)	−0.08790 (18)	0.24829 (19)	0.0398 (4)
H8	0.7288	−0.1507	0.2394	0.048*
C9	0.85883 (19)	−0.07728 (19)	0.16157 (19)	0.0408 (4)
H9	0.8448	−0.1324	0.0938	0.049*
C10	0.94910 (18)	0.01723 (18)	0.17791 (17)	0.0355 (4)
H10	0.9959	0.0245	0.1199	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.02813 (12)	0.03186 (13)	0.02634 (12)	−0.00398 (8)	0.01413 (9)	−0.00044 (7)
Cl1	0.0436 (3)	0.0415 (2)	0.0445 (2)	−0.01587 (19)	0.0220 (2)	−0.00319 (19)
N1	0.0291 (7)	0.0291 (7)	0.0272 (7)	−0.0026 (5)	0.0142 (6)	−0.0008 (5)
N2	0.0260 (6)	0.0304 (7)	0.0275 (6)	0.0002 (5)	0.0101 (5)	−0.0005 (5)
N3	0.0322 (7)	0.0380 (8)	0.0297 (7)	−0.0020 (6)	0.0076 (6)	0.0018 (6)
O1	0.0316 (7)	0.0376 (7)	0.0386 (7)	−0.0009 (6)	0.0076 (6)	−0.0031 (6)
O2	0.0320 (6)	0.0445 (7)	0.0294 (6)	0.0078 (5)	0.0132 (5)	0.0070 (5)
O3	0.0487 (8)	0.0604 (9)	0.0551 (9)	0.0213 (8)	0.0239 (7)	0.0075 (7)
O4	0.0617 (9)	0.0618 (9)	0.0274 (6)	0.0019 (8)	0.0092 (6)	0.0108 (6)
C1	0.0394 (9)	0.0368 (9)	0.0363 (9)	−0.0113 (8)	0.0181 (8)	−0.0076 (7)
C2	0.0456 (10)	0.0431 (10)	0.0355 (9)	−0.0065 (9)	0.0187 (8)	−0.0128 (8)
C3	0.0406 (10)	0.0508 (11)	0.0342 (9)	−0.0006 (9)	0.0225 (8)	−0.0055 (8)
C4	0.0306 (8)	0.0390 (9)	0.0340 (9)	−0.0030 (7)	0.0168 (7)	0.0003 (7)
C5	0.0226 (7)	0.0275 (7)	0.0261 (7)	0.0013 (6)	0.0093 (6)	0.0034 (6)
C6	0.0227 (7)	0.0275 (7)	0.0262 (7)	0.0022 (6)	0.0070 (6)	0.0032 (6)
C7	0.0293 (8)	0.0373 (9)	0.0370 (9)	−0.0055 (7)	0.0118 (7)	0.0012 (7)
C8	0.0335 (9)	0.0350 (9)	0.0478 (10)	−0.0087 (8)	0.0070 (8)	−0.0045 (8)
C9	0.0404 (10)	0.0381 (10)	0.0404 (10)	−0.0008 (8)	0.0065 (8)	−0.0114 (8)
C10	0.0361 (9)	0.0401 (9)	0.0323 (8)	0.0009 (8)	0.0130 (7)	−0.0056 (7)

Geometric parameters (Å, º)

Cu1—N2	2.0110 (14)	C2—C3	1.381 (3)
Cu1—N1	2.0161 (14)	C2—H2	0.9300
Cu1—O2	2.0296 (13)	C3—C4	1.388 (3)
Cu1—Cl1	2.2581 (5)	C3—H3	0.9300
Cu1—O1	2.3040 (13)	C4—C5	1.386 (2)
N1—C1	1.343 (2)	C4—H4	0.9300
N1—C5	1.356 (2)	C5—C6	1.479 (2)
N2—C10	1.337 (2)	C6—C7	1.389 (2)
N2—C6	1.358 (2)	C7—C8	1.386 (3)
N3—O4	1.2307 (19)	C7—H7	0.9300
N3—O3	1.243 (2)	C8—C9	1.383 (3)
N3—O2	1.283 (2)	C8—H8	0.9300
O1—H11	0.821 (15)	C9—C10	1.384 (3)
O1—H12	0.842 (15)	C9—H9	0.9300
C1—C2	1.387 (2)	C10—H10	0.9300
C1—H1	0.9300
N2—Cu1—N1	81.03 (6)	C3—C2—H2	120.7
N2—Cu1—O2	91.60 (6)	C1—C2—H2	120.7
N1—Cu1—O2	158.17 (6)	C2—C3—C4	119.40 (16)
N2—Cu1—Cl1	176.88 (4)	C2—C3—H3	120.3
N1—Cu1—Cl1	95.91 (4)	C4—C3—H3	120.3
O2—Cu1—Cl1	91.49 (4)	C5—C4—C3	119.09 (16)
N2—Cu1—O1	86.15 (5)	C5—C4—H4	120.5
N1—Cu1—O1	108.23 (5)	C3—C4—H4	120.5
O2—Cu1—O1	91.60 (5)	N1—C5—C4	121.57 (15)
Cl1—Cu1—O1	94.22 (4)	N1—C5—C6	114.87 (13)
C1—N1—C5	118.82 (14)	C4—C5—C6	123.55 (15)
C1—N1—Cu1	126.51 (12)	N2—C6—C7	121.15 (15)
C5—N1—Cu1	114.57 (11)	N2—C6—C5	114.65 (13)
C10—N2—C6	119.24 (14)	C7—C6—C5	124.20 (14)
C10—N2—Cu1	125.88 (12)	C8—C7—C6	118.94 (16)
C6—N2—Cu1	114.77 (11)	C8—C7—H7	120.5
O4—N3—O3	122.60 (17)	C6—C7—H7	120.5
O4—N3—O2	118.89 (16)	C9—C8—C7	119.68 (17)
O3—N3—O2	118.51 (14)	C9—C8—H8	120.2
Cu1—O1—H11	114.1 (15)	C7—C8—H8	120.2
Cu1—O1—H12	119.0 (16)	C8—C9—C10	118.52 (17)
H11—O1—H12	106.4 (18)	C8—C9—H9	120.7
N3—O2—Cu1	107.29 (10)	C10—C9—H9	120.7
N1—C1—C2	122.43 (16)	N2—C10—C9	122.46 (17)
N1—C1—H1	118.8	N2—C10—H10	118.8
C2—C1—H1	118.8	C9—C10—H10	118.8
C3—C2—C1	118.68 (17)
N2—Cu1—N1—C1	−177.52 (16)	C1—C2—C3—C4	−0.3 (3)
O2—Cu1—N1—C1	−106.1 (2)	C2—C3—C4—C5	0.1 (3)
Cl1—Cu1—N1—C1	3.14 (16)	C1—N1—C5—C4	0.1 (2)
O1—Cu1—N1—C1	99.58 (15)	Cu1—N1—C5—C4	−176.63 (13)
N2—Cu1—N1—C5	−1.04 (11)	C1—N1—C5—C6	179.55 (15)
O2—Cu1—N1—C5	70.42 (19)	Cu1—N1—C5—C6	2.78 (18)
Cl1—Cu1—N1—C5	179.62 (11)	C3—C4—C5—N1	−0.1 (3)
O1—Cu1—N1—C5	−83.94 (12)	C3—C4—C5—C6	−179.40 (16)
N1—Cu1—N2—C10	−177.27 (15)	C10—N2—C6—C7	−0.2 (2)
O2—Cu1—N2—C10	23.38 (15)	Cu1—N2—C6—C7	−176.75 (13)
O1—Cu1—N2—C10	−68.12 (15)	C10—N2—C6—C5	179.27 (15)
N1—Cu1—N2—C6	−1.04 (11)	Cu1—N2—C6—C5	2.77 (17)
O2—Cu1—N2—C6	−160.38 (11)	N1—C5—C6—N2	−3.7 (2)
O1—Cu1—N2—C6	108.12 (11)	C4—C5—C6—N2	175.72 (15)
O4—N3—O2—Cu1	172.54 (14)	N1—C5—C6—C7	175.83 (15)
O3—N3—O2—Cu1	−7.22 (19)	C4—C5—C6—C7	−4.8 (3)
N2—Cu1—O2—N3	87.68 (11)	N2—C6—C7—C8	0.1 (3)
N1—Cu1—O2—N3	18.1 (2)	C5—C6—C7—C8	−179.38 (16)
Cl1—Cu1—O2—N3	−91.86 (11)	C6—C7—C8—C9	0.0 (3)
O1—Cu1—O2—N3	173.87 (11)	C7—C8—C9—C10	0.1 (3)
C5—N1—C1—C2	−0.3 (3)	C6—N2—C10—C9	0.3 (3)
Cu1—N1—C1—C2	176.03 (15)	Cu1—N2—C10—C9	176.40 (14)
N1—C1—C2—C3	0.4 (3)	C8—C9—C10—N2	−0.2 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O3^i	0.82 (2)	2.54 (2)	3.165 (2)	134 (2)
O1—H11···O4^i	0.82 (2)	2.13 (2)	2.941 (2)	171 (2)
O1—H12···Cl1^ii	0.84 (2)	2.36 (2)	3.1918 (15)	173 (2)
C1—H1···Cl1	0.93	2.68	3.265 (2)	122
C10—H10···O2	0.93	2.57	3.064 (2)	114

Symmetry codes: (i) x+1/2, −y+1/2, z+1/2; (ii) −x+5/2, y−1/2, −z+1/2.