Bis(μ-1,10-phenanthrolin-2-olato-κ³N,N′:O)­dicopper(I)(Cu—Cu) monohydrate

The crystal structure of the title compound, [Cu₂(C₁₂H₇­N₂O)₂]·H₂O, shows that this dinuclear complex has shorter Cu—N, Cu—O and Cu—Cu distances within the coordination sphere than similar reported complexes. The complex mol­ecule is located on a centre of symmetry and the water mol­ecule is on a twofold axis of the space group C2/c. The discrete complex mol­ecules are extended into a two-dimensional supramolecular array via π–π stacking interactions, intermolecular Cu...Cu interactions and C—H...O hydrogen bonds.

S1. Comment

The copper(II) complex of 1,10-phenanthroline, the first artificial nuclease, has been well investigated over the past two decades. Although [(phen)₂Cu]⁺ or [(phen)₂Cu₂]⁺ (phen is 1,10-phenanthroline) are thought to be the active species for DNA cleavage (Sigman et al., 1993; Lu et al., 2003), it is still not known how these complexes bind to DNA. Therefore, investigating the structures of [(phen)₂Cu]⁺ and [(phen)₂Cu₂]⁺ would be helpful for understanding the binding mode. Recently, three supramolecular isomers of dinuclear copper(I) 2-hydroxy-1,10-phenanthroline complexes, [Cu₂(ophen)₂], synthesized from 1,10-phenanthroline (ophen is? Please define) were studied by Zhang Tong et al. (2002). In our experiments, we have obtained a similar complex, the title compound, (I), and we report its crystal structure here. \sch

The geometric parameters of (I) are listed in Table 1 and the molecular conformation is illustrated in Fig. 1. The compound contains a [Cu₂(oxo-phen)₂] complex and a water molecule. The complex molecule is located on a centre of symmetry and the water molecule on a twofold axis of the space group C2/c. Each Cu⁺ ion adopts a square-planar geometry, being coordinated by two N atoms from an oxo-phen ligand and one O atom from another oxo-phen ligand, as well as one Cu atom. This structure is not much different from that reported by Zhang Tong et al. (2002). However, all coordination bonds around the Cu atoms [Cu—N 1.913 (4) and 2.110 (4) Å, Cu—O 1.883 (3) Å and Cu—Cu 2.497 (1) Å] are shorter than the corresponding bonds [Cu—N 1.953 (5)–2.274 (6) Å, Cu—O 1.916 (5)–1.923 (5) Å and Cu—Cu 2.661 (2)–2.679 (3) Å] in [Cu₂(ophen)₂] supramolecular isomers, especially the Cu—Cu distance, which is shorter by 0.164–0.182 Å but much closer to the values observed in mixed-valence Cu⁺/Cu²⁺ complexes [Cu—Cu 2.402 (1)–2.443 (2) Å; Zhang Tong et al., 2002; Zhang Tong & Chen, 2002]. Thus the coordination sphere of (I) is tighter and the interaction of both Cu⁺ ions is stronger.

The hydrogen-bonding geometry in (I) is listed in Table 2 and illustrated in Fig. 2. In the crystal packing, aromatic π–π stacking interactions are present between the ligand rings of the complex packed along y. These can be best described by considering the C6/C9—C12/N2 ring at (x, y, z) and the C4—C9 ring at (x, y − 1, z), with a centroid-centroid distance of 3.587 (7) Å. The weighted least-squares planes through these two rings are very nearly parallel, as the dihedral angle they form is only 0.40 (13)°. The interplanar spacing is 3.28 (5) Å and the centroid shift is 1.45 (11) Å. Along y, the shortest Cu···Cu contact is b = 3.6676 (3) Å. The coordination plane through atoms Cu1/N1/N2/O1 at (x, y, z) and the equivalent atoms at (1/2 − x, 1/2 + y, 3/2 − z) form a dihedral angle of 48.03 (13)°. This is the direction along which the complex molecules are joined via weak C—H···O hydrogen interactions (Table 2), giving rise to a zigzag chain that, together with the π–π stacking and Cu···Cu interactions, generates a supramolecular two-dimensional array extended along the length of the crystal.

S2. Experimental

All chemicals were of reagent grade and commercially available from the Beijing Chemical Reagents Company of China; they were used without further purification. Cu(NO₃)₂·3H₂O (0.12 g), 1,10-phenanthroline (0.117 g), 4-aminobenzoic acid (0.034 g) and NaOH (0.02 g) were mixed with water (10 ml) and stirred at room temperature for 30 min. The mixture was then sealed in air and heated at 443 K for 6 d in a 30-ml Teflon-lined autoclave. After cooling, the black crystals of (I) were collected.

S3. Refinement

The residual electron density has a maximum located 0.85 Å from atom O1W. H atoms attached to C atoms were placed in geometrically idealized positions with Csp²—H = 0.93 Å and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C). The water O atom is on a twofold axis, so one H atom is related to the other by symmetry. A peak was found 0.85 Å from the O atom but it forms an unacceptable angle of 150° with its symmetry relative. On the other hand, the O atom is affected by a rather large U_eq value of 0.380 (14) Ų, indicative of disorder, the probable cause of which is the lack of hydrogen-bonding interactions involving this water molecule, which is simply occluded in a hole of the structure. These are the reasons why the water H atoms were not considered in the present refinement.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1999); software used to prepare material for publication: SHELXTL/PC.

Figures

	Fig. 1. The structure of (I), with displacement ellipsoids drawn at the 30% probability level. Atoms labelled with the suffix A are at the symmetry position (1/2 − x, 3/2 − y, 2 − z).
	Fig. 2. The two-dimensional supramolecular array of (I). Dashed lines between cross-hatched spheres represent Cu···Cu interactions and the remaining dashed lines indicate hydrogen bonds.

Bis(µ-1,10-phenanthrolin-2-olato-κ³N,N',O)dicopper(I) monohydrate

Crystal data

[Cu2(C12H7N2O)2]·H2O	F(000) = 1080
Mr = 535.49	Dx = 1.751 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1851 reflections
a = 30.344 (3) Å	θ = 2.2–23.7°
b = 3.6676 (3) Å	µ = 2.13 mm^−1
c = 19.1508 (17) Å	T = 293 K
β = 107.578 (1)°	Plate, black
V = 2031.7 (3) Å^3	0.28 × 0.15 × 0.04 mm
Z = 4

Data collection

Bruker SMART 1K CCD area-detector diffractometer	1780 independent reflections
Radiation source: fine-focus sealed tube	1506 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
ϕ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = −36→35
Tmin = 0.587, Tmax = 0.920	k = −4→4
6470 measured reflections	l = −22→22

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)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.198	H-atom parameters constrained
S = 1.14	w = 1/[σ^2(Fo^2) + (0.143P)^2] where P = (Fo^2 + 2Fc^2)/3
1780 reflections	(Δ/σ)max < 0.001
150 parameters	Δρmax = 1.48 e Å^−3
6 restraints	Δρmin = −0.52 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.

The water molecule in the compound shows positional disorder near the crystallographic symmetry (1 − x, y, 1.5 − z). After refined several cycles, O1w atom was determined by its average between the atom and symmetry correlational atom. The occupation factor of the water O atom is 0.5.

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

	x	y	z	Uiso*/Ueq
Cu1	0.265841 (19)	0.64296 (15)	0.95050 (3)	0.0418 (4)
N1	0.30823 (14)	0.5181 (11)	0.8844 (2)	0.0410 (9)
N2	0.32309 (15)	0.8069 (10)	1.0168 (2)	0.0369 (9)
O1	0.29373 (12)	1.0007 (10)	1.10659 (18)	0.0478 (9)
C1	0.2991 (2)	0.3813 (12)	0.8173 (3)	0.0497 (14)
H1	0.2689	0.3160	0.7923	0.060*
C2	0.3331 (2)	0.3320 (13)	0.7830 (3)	0.0580 (16)
H2	0.3253	0.2424	0.7354	0.070*
C3	0.3781 (2)	0.4158 (14)	0.8195 (3)	0.0507 (13)
H3	0.4010	0.3815	0.7972	0.061*
C4	0.3894 (2)	0.5564 (13)	0.8922 (3)	0.0460 (12)
C5	0.35247 (19)	0.6082 (12)	0.9209 (3)	0.0403 (12)
C6	0.36095 (17)	0.7600 (13)	0.9919 (3)	0.0377 (11)
C7	0.4347 (2)	0.6544 (13)	0.9343 (4)	0.0531 (15)
H7	0.4592	0.6227	0.9153	0.064*
C8	0.44224 (19)	0.7949 (14)	1.0025 (3)	0.0485 (13)
H8	0.4723	0.8526	1.0300	0.058*
C9	0.40577 (19)	0.8568 (11)	1.0333 (3)	0.0416 (12)
C10	0.41170 (18)	1.0063 (13)	1.1040 (3)	0.0449 (12)
H10	0.4410	1.0703	1.1338	0.054*
C11	0.37373 (19)	1.0556 (13)	1.1283 (3)	0.0445 (12)
H11	0.3776	1.1576	1.1742	0.053*
C12	0.32904 (18)	0.9533 (13)	1.0844 (3)	0.0401 (11)
O1W	0.5000	0.451 (8)	0.7500	0.380 (14)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0402 (5)	0.0510 (5)	0.0299 (5)	−0.0033 (2)	0.0044 (3)	−0.0026 (2)
N1	0.046 (2)	0.038 (2)	0.029 (2)	−0.0013 (18)	−0.0028 (18)	0.0011 (17)
N2	0.043 (2)	0.038 (2)	0.027 (2)	−0.0059 (17)	0.0056 (18)	−0.0007 (16)
O1	0.048 (2)	0.062 (2)	0.0305 (18)	−0.0073 (18)	0.0072 (16)	−0.0097 (17)
C1	0.064 (4)	0.038 (3)	0.039 (3)	0.004 (2)	0.001 (3)	−0.004 (2)
C2	0.093 (5)	0.042 (3)	0.035 (3)	0.011 (3)	0.014 (3)	−0.001 (2)
C3	0.069 (4)	0.049 (3)	0.036 (3)	0.012 (3)	0.018 (3)	0.002 (2)
C4	0.058 (3)	0.037 (2)	0.044 (3)	0.009 (2)	0.017 (3)	0.009 (2)
C5	0.047 (3)	0.030 (2)	0.039 (3)	0.0037 (18)	0.005 (2)	0.0071 (18)
C6	0.044 (3)	0.031 (2)	0.034 (2)	0.002 (2)	0.006 (2)	0.008 (2)
C7	0.059 (4)	0.044 (3)	0.060 (4)	0.007 (2)	0.022 (3)	0.009 (2)
C8	0.042 (3)	0.049 (3)	0.049 (3)	−0.003 (2)	0.005 (2)	0.005 (2)
C9	0.046 (3)	0.034 (2)	0.037 (3)	−0.0016 (19)	0.002 (2)	0.0075 (19)
C10	0.046 (3)	0.043 (3)	0.038 (3)	−0.008 (2)	0.000 (2)	0.006 (2)
C11	0.060 (3)	0.039 (3)	0.030 (2)	−0.010 (2)	0.007 (2)	0.000 (2)
C12	0.049 (3)	0.039 (2)	0.029 (2)	−0.006 (2)	0.007 (2)	0.001 (2)
O1W	0.380 (14)	0.380 (14)	0.380 (14)	0.000	0.114 (4)	0.000

Geometric parameters (Å, º)

Cu1—O1^i	1.883 (3)	C3—H3	0.9300
Cu1—N2	1.913 (4)	C4—C5	1.403 (8)
Cu1—N1	2.109 (4)	C4—C7	1.412 (9)
Cu1—Cu1^i	2.4971 (11)	C5—C6	1.419 (7)
N1—C1	1.328 (7)	C6—C9	1.397 (7)
N1—C5	1.354 (7)	C7—C8	1.358 (8)
N2—C12	1.361 (6)	C7—H7	0.9300
N2—C6	1.382 (7)	C8—C9	1.420 (8)
O1—C12	1.279 (6)	C8—H8	0.9300
O1—Cu1^i	1.883 (3)	C9—C10	1.422 (8)
C1—C2	1.393 (9)	C10—C11	1.378 (8)
C1—H1	0.9300	C10—H10	0.9300
C2—C3	1.366 (9)	C11—C12	1.414 (7)
C2—H2	0.9300	C11—H11	0.9300
C3—C4	1.425 (8)
O1^i—Cu1—N2	173.36 (16)	N1—C5—C4	123.4 (5)
O1^i—Cu1—N1	104.07 (15)	N1—C5—C6	117.0 (5)
N2—Cu1—N1	82.57 (16)	C4—C5—C6	119.6 (5)
O1^i—Cu1—Cu1^i	90.38 (11)	N2—C6—C9	122.7 (4)
N2—Cu1—Cu1^i	82.98 (13)	N2—C6—C5	116.8 (5)
N1—Cu1—Cu1^i	165.50 (11)	C9—C6—C5	120.5 (5)
C1—N1—C5	118.3 (5)	C8—C7—C4	119.9 (6)
C1—N1—Cu1	132.6 (4)	C8—C7—H7	120.0
C5—N1—Cu1	109.1 (3)	C4—C7—H7	120.0
C12—N2—C6	119.5 (4)	C7—C8—C9	122.2 (6)
C12—N2—Cu1	126.0 (4)	C7—C8—H8	118.9
C6—N2—Cu1	114.5 (3)	C9—C8—H8	118.9
C12—O1—Cu1^i	121.5 (3)	C6—C9—C8	118.1 (5)
N1—C1—C2	122.6 (6)	C6—C9—C10	117.4 (5)
N1—C1—H1	118.7	C8—C9—C10	124.5 (5)
C2—C1—H1	118.7	C11—C10—C9	119.6 (5)
C3—C2—C1	119.7 (5)	C11—C10—H10	120.2
C3—C2—H2	120.2	C9—C10—H10	120.2
C1—C2—H2	120.2	C10—C11—C12	120.9 (5)
C2—C3—C4	119.5 (5)	C10—C11—H11	119.5
C2—C3—H3	120.3	C12—C11—H11	119.5
C4—C3—H3	120.3	O1—C12—N2	119.1 (4)
C5—C4—C7	119.7 (5)	O1—C12—C11	121.0 (4)
C5—C4—C3	116.4 (5)	N2—C12—C11	119.9 (5)
C7—C4—C3	123.8 (5)
O1^i—Cu1—N1—C1	1.9 (5)	C12—N2—C6—C5	−179.6 (4)
N2—Cu1—N1—C1	−178.0 (5)	Cu1—N2—C6—C5	1.6 (5)
Cu1^i—Cu1—N1—C1	−173.5 (3)	N1—C5—C6—N2	−1.0 (6)
O1^i—Cu1—N1—C5	−179.4 (3)	C4—C5—C6—N2	179.5 (4)
N2—Cu1—N1—C5	0.7 (3)	N1—C5—C6—C9	179.4 (4)
Cu1^i—Cu1—N1—C5	5.2 (7)	C4—C5—C6—C9	−0.1 (7)
N1—Cu1—N2—C12	−179.9 (4)	C5—C4—C7—C8	0.6 (7)
Cu1^i—Cu1—N2—C12	1.2 (4)	C3—C4—C7—C8	178.4 (5)
N1—Cu1—N2—C6	−1.3 (3)	C4—C7—C8—C9	−1.5 (8)
Cu1^i—Cu1—N2—C6	179.9 (3)	N2—C6—C9—C8	179.7 (4)
C5—N1—C1—C2	−0.8 (7)	C5—C6—C9—C8	−0.7 (6)
Cu1—N1—C1—C2	177.8 (3)	N2—C6—C9—C10	0.6 (7)
N1—C1—C2—C3	2.0 (8)	C5—C6—C9—C10	−179.8 (4)
C1—C2—C3—C4	−0.6 (7)	C7—C8—C9—C6	1.6 (7)
C2—C3—C4—C5	−1.6 (7)	C7—C8—C9—C10	−179.4 (4)
C2—C3—C4—C7	−179.4 (5)	C6—C9—C10—C11	−1.2 (7)
C1—N1—C5—C4	−1.7 (7)	C8—C9—C10—C11	179.8 (4)
Cu1—N1—C5—C4	179.4 (4)	C9—C10—C11—C12	1.2 (7)
C1—N1—C5—C6	178.9 (4)	Cu1^i—O1—C12—N2	2.3 (7)
Cu1—N1—C5—C6	−0.1 (5)	Cu1^i—O1—C12—C11	−178.7 (3)
C7—C4—C5—N1	−179.3 (4)	C6—N2—C12—O1	179.0 (4)
C3—C4—C5—N1	2.8 (7)	Cu1—N2—C12—O1	−2.4 (7)
C7—C4—C5—C6	0.2 (7)	C6—N2—C12—C11	0.0 (7)
C3—C4—C5—C6	−177.7 (4)	Cu1—N2—C12—C11	178.6 (3)
C12—N2—C6—C9	0.0 (7)	C10—C11—C12—O1	−179.6 (5)
Cu1—N2—C6—C9	−178.8 (3)	C10—C11—C12—N2	−0.6 (7)

Symmetry code: (i) −x+1/2, −y+3/2, −z+2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O1^ii	0.93	2.52	3.448 (7)	173

Symmetry code: (ii) x, −y+1, z−1/2.