μ-Acetato-μ-aqua-μ-hydroxido-bis­[(1,10-phenanthroline)copper(II)] dinitrate monohydrate

Abud, J.E.; Sartoris, R.P.; Calvo, R.; Baggio, R.

doi:10.1107/S0108270111011048

metal-organic compounds

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 67| Part 5| May 2011| Pages m130-m133

doi:10.1107/S0108270111011048

μ-Acetato-μ-aqua-μ-hydroxido-bis[(1,10-phenanthroline)copper(II)] dinitrate monohydrate

Julian E. Abud,^a Rosana P. Sartoris,^a ^* Rafael Calvo ^a and Ricardo Baggio ^b ^*

^aDepartamento de Física, Facultad de Bioquímica y Ciencias Biológicas and INTEC (CONICET–Universidad Nacional del Litoral), Ciudad Universitaria 3000, Santa Fe, Argentina, and ^bGerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
^*Correspondence e-mail: rosanasartoris@gmail.com, baggio@cnea.gov.ar

(Received 15 February 2011; accepted 24 March 2011; online 13 April 2011)

The triply bridged title dinuclear copper(II) compound, [Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O, (I), consists of a [Cu₂(μ₂-CH₃COO)(μ₂-OH)(phen)₂(μ₂-OH₂)]²⁺ cation (phen is 1,10-phenanthroline), two uncoordinated nitrate anions and one water molecule. The title cation contains a distorted square-pyramidal arrangement around each metal centre with a CuN₂O₃ chromophore. In the dinuclear unit, both Cu^II ions are linked through a hydroxide bridge and a triatomic bridging carboxylate group, and at the axial positions through a water molecule. The phenanthroline groups in neighbouring dinuclear units interdigitate along the [010] direction, generating several π–π contacts which give rise to planar arrays parallel to (001). These are in turn connected by hydrogen bonds involving the aqua and hydroxide groups as donors with the nitrate anions as acceptors. Comparisons are made with isostructural compounds having similar cationic units but different counter-ions; the role of hydrogen bonding in the overall three-dimensional structure and its ultimate effect on the cell dimensions are discussed.

Comment

Since the seminal work on copper acetate monohydrate reported by Bleaney & Bowers (1952 ), interest in magnetic dimeric (or dinuclear) compounds has been maintained for the past 60 years from different perspectives. This work has contributed to the field of molecular magnetic materials (Kahn, 1993 ) and to the understanding of correlations between exchange couplings and bond structure, and has helped in the design of new polynuclear molecular magnets. The fact that weakly interacting AFM (antiferromagnetic) dimeric magnetic materials display Bose–Einstein condensation at relatively high temperature (T) triggered considerable research by the materials and physics communities (Giamarchi et al., 2008 ). The discovery of high-T_c superconductors also stimulated interest in interacting quantum spin systems, providing information about elementary excitations, quantum phase transitions and critical phenomena. Many studies of dimeric materials have been reported in this context. Our interest in dimeric materials is directed towards the effects of weak interactions between molecular units (Napolitano et al., 2008 ; Perec et al., 2010 ). Since the stacking of phenanthroline rings is a potential source of weak intermolecular exchange couplings, we have been looking for new compounds where dinuclear units are coupled by this type of interaction. During our studies, the triply bridged dinuclear copper(II) title compound, μ-acetato-μ-aqua-μ-hydroxido-bis[(1,10-phenanthroline)copper(II)] dinitrate monohydrate, (I), was obtained (Figs. 1–3 ).

The asymmetric unit of (I) consists of a [Cu₂(μ₂-CH₃COO)(μ₂-OH)(phen)₂(μ₂-OH₂)]²⁺ dinuclear cation (phen is 1,10-phenanthroline), two uncoordinated nitrate anions and one solvent water molecule (Fig. 1). The cation has a distorted square-pyramidal arrangement at each Cu^II ion, in such a way that the two pyramidal CuN₂O₃ chromophores share one edge. Both Cu^II ions are linked [Cu1⋯Cu2 = 2.9559 (5) Å] at two equatorial positions through a hydroxide bridge [Cu—O = 1.928 (2) and 1.919 (2) Å for atoms Cu1 and Cu2, respectively] and a triatomic carboxylate bridge [Cu—O = 1.935 (2) and 1.940 (2) Å for atoms Cu1 and Cu2, respectively], and at the axial position through a water molecule [Cu—O = 2.344 (2) and 2.332 (2) Å for atoms Cu1 and Cu2, respectively]. The coordination of each Cu^II centre is completed by an N,N′-chelating phen ligand [Cu—N = 2.007 (3) and 2.023 (2) Å for Cu1, and 1.994 (3) and 2.016 (2) Å for Cu2]; the resulting bond valencies for the two cations are 2.16 and 2.20, respectively (PLATON; Spek, 2009 ). The polyhedron around Cu1 is slightly more regular than that about Cu2, displaying clear differences in the (ideally equal) trans O—Cu—N basal angles [6.56 (16) versus 16.48 (18)°, respectively], the deviation from planarity in the basal plane [0.032 (2) Å for N2A versus 0.205 (2) Å for N1B], the departure of the apical axis from the vertical [8.22 (12) versus 20.4 (2)°] and (perhaps as a summary) their τ parameters [as defined by Addison et al. (1984 ) and calculated using PLATON; 0.11 versus 0.27].

The ligands are featureless: neither of the phen groups departs significantly from planarity [maximum deviations = 0.028 (3) Å for C2A and 0.037 (3) Å for C11B] and the C—O bonds in the acetate group display an almost perfect resonance [O1C C1C = 1.249 (4) Å and O2C C1C = 1.252 (4) Å].

{Cu₂(OH)(H₂O)(carboxylate)} is a well known cluster and a search of the Cambridge Structural Database (CSD, Version 5.32 of 2011; Allen, 2002 ) revealed several structures incorporating the moiety [e.g. CSD refcodes CITLOH, CITLEX and YAFZUA01 (Youngme et al., 2008 ); YEMNIO and YEMNEK (Chailuecha et al., 2006 ); DIXGEX (Chen et al., 2008 ); JEJCIK (Christou et al., 1990 ); OLOVOA (Chadjistamatis et al., 2003 ); QAHDUY (Sgarabotto et al., 1999 ); YINJEL (Chen et al., 2007 ), to mention just a few]. A comparative analysis within this set shows coordination distances over modest ranges (Cu—O_hydroxy = 1.908–1.933 Å, Cu—O_carboxylate = 1.925–1.993 Å and Cu—O_water = 2.321–2.415 Å), the values found for (I) being within these ranges. On the other hand, the intercationic distance for (I) appears distinctly shorter [Cu⋯Cu = 2.990–3.124 Å in the CSD versus Cu1⋯Cu2 = 2.9559 (5) Å in (I)].

A view of the {Cu₂(OH)(H₂O)(carboxylate)} clusters is provided in Fig. 4, presented as overlapping {Cu₂(OH)(H₂O)(carboxylate)} clusters where only the Cu–(OH)–Cu bridge has been fitted, the remaining atoms having been omitted for clarity. It is obvious that a very reasonable match is observed for the carboxylates, while a much larger spread is observed for the aqua bridge. This may have to do with the weaker binding of the O_water atom to the cations, as well as the hydrogen-bonding ability of water. This makes it prone to disrupting interactions and modifying the ideal geometry.

Regarding the packing arrangement, the way in which the dinuclear units aggregate into a three-dimensional supramolecular structure can be described (for clarity) as a two-step process. The first step is achieved via the stacking of interwoven dinuclear units to form two-dimensional structures parallel to (001) (Fig. 2). The forces involved are several π–π interactions between the stacked phenanthroline groups, summarized in Table 2. These interactions are not evenly distributed. Firstly, there are zones with additional stronger bonds (labelled `A' in Fig. 2, entries 1–3 in Table 2) defining chains which run along the b-axis direction, and these chains are in turn connected by weaker/fewer links (zones labelled `B' in Fig. 2, entries 4–5 in Table 2) to form a broad two-dimensional structure. Secondly, a number of hydrogen bonds are present involving the NO₃⁻ counter-ions as acceptors and the hydroxy/aqua (Table 1, entries 1–6) and the outermost phen C—H groups (Table 1, entries 7–9) as donors. Fig. 3 shows a packing view rotated by 90° compared with that presented in Fig. 2, where the planar arrays are seen in projection, and the hydrogen-bonding network can be clearly observed. It is apparent that the cohesion provided by these interactions is partly intraplanar (providing for the plane stability) and partly interplanar, assisting the plane-to-plane linkage.

More detailed comparisons can be made of the three-dimensional structure in (I) with two isostructural analogues (mentioned earlier) which have the same phen ligand but different counter-anions (L), viz. L = BF₄⁻, (II) (CITLOH; Youngme et al., 2008), and L = ClO₄⁻, (III) (YEMNIO; Chailuecha et al., 2006). Both structures share the same dinuclear unit as (I) [mean square deviations of the fit of all non-H atoms = 0.075 (2) and 0.116 (2) Å, respectively] and are also interwoven in analogous π-bonded layers, but differ in the remaining interactions aggregating the components into a three-dimensional structure. It is relevant to stress for the following discussion that this hydrogen-bonding system appears stronger and more clearly defined in (I) than in either of the analogues (II) and (III), since the O-atom acceptors in the NO₃⁻ counter-ion of (I) are fairly well defined, while those in the BF₄⁻ and ClO₄⁻ analogues, (II) and (III), appear heavily disordered.

Comparison of the cell dimensions for all three structures (Table 3) yields information regarding the interactions governing the crystal packing and the way they operate [numbers in parentheses give the percentage differences from (I)]. It can be seen that, along the c axis, there are negligible differences between the three structures, while significant differences are noted along a and b. This fact correlates with the disposition and structure of the packing `leitmotiv' shown in Fig. 2. The c direction is, in principle, defined by the width of the planes and this is basically associated with the volume occupied by the dinuclear unit; counter-ions are lodged in the intermolecular voids and, even though they provide interplanar cohesion, they do not appear to affect the mean planar width. Thus, the `c'-axis length would be limited by the `bumping' of basically uncompressible planes. The remaining two directions, on the other hand, are contained in the plane, and along them the structure shows no significant cohesion forces able to oppose the strain introduced by any additional forces, e.g. hydrogen bonding. Thus, structure (I), with stronger and better defined intraplanar hydrogen-bonding interactions than (II) and (III) (see above), presents a detectable shrinkage of the planes in both the a and b directions, a fact directly ascribable to the internal hydrogen-bonding network and the flexibility of the π–π interactions to adapt to them. It is worth noting the highly hydrophilic character of both NO₃⁻ anions, in particular nitrate D, where atom O3D, for instance, accepts four hydrogen bonds of different type and strength.

Our structural results show promise in the search for new dinuclear materials with weak interactions between moieties. However, we have not yet overcome the problem of the specimens being too small for EPR (electron paramagnetic resonance) measurements, and are at present devoting our efforts to the growth of single crystals of adequate size and quality for this purpose.

Figure 1
A molecular view of (I)

, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and hydrogen bonds are shown as double dashed lines. [Symmetry codes: (i) x − 1, y, z; (ii) −x + $[{3\over 2}]$ , −y + 1, z − $[{1\over 2}]$ .]

Figure 2
A packing diagram for (I)

, viewed along [001], showing how the dinuclear units are linked by π–π interactions into planes parallel to (001).

Figure 3
A packing diagram for (I)

, viewed along [100] and rotated by 90° compared with the view in Fig. 2

, showing the hydrogen-bonding interactions (dashed lines). The (001) sheets are shown in projection as vertical structures (marked by square brackets).

Figure 4
Comparison of the {Cu₂(OH)(H₂O)(carboxylate)} cluster in (I)

(heavy lines) with examples from the literature. Structure codes a–j correspond to the following CSD refcodes and references: a = CITLOH, c = CITLEX and i = YAFZUA01 (Youngme et al., 2008

); b = YEMNIO and h = YEMNEK (Chailuecha et al., 2006

); d = DIXGEX (Chen et al., 2008

); e = JEJCIK (Christou et al., 1990

); f = OLOVOA (Chadjistamatis et al., 2003

); g = QAHDUY (Sgarabotto et al., 1999

); j = YINJEL (Chen et al., 2007

Experimental

All chemicals were purchased from Sigma and were used as received. A solution of sodium acetate, NaCH₃COO (4 mM, 0.328 g), in water (40 ml) was prepared and its pH adjusted to 3.5–4 with a 10% solution of HNO₃. Under continuous agitation, equimolar quantities of 1,10-phenanthroline and copper nitrate were added to this solution. After complete dissolution, the pH was adjusted to 4.5–5 with a 1 N solution of NaOH and 10% HNO₃, and the solution was then filtered and left to evaporate at room temperature. Small crystals of (I) suitable for X-ray diffraction were obtained after approximately three weeks.

Crystal data

[Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O
M_r = 723.59
Orthorhombic, P 2₁ 2₁ 2₁
a = 8.15051 (15) Å
b = 17.4091 (3) Å
c = 19.7447 (4) Å
V = 2801.63 (9) Å³
Z = 4
Mo Kα radiation
μ = 1.59 mm⁻¹
T = 292 K
0.35 × 0.20 × 0.15 mm

Data collection

Oxford Gemini CCD S Ultra diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ) T_min = 0.54, T_max = 0.73
16045 measured reflections
5135 independent reflections
3791 reflections with I > 2σ(I)
R_int = 0.029

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.054
S = 0.91
5135 reflections
422 parameters
7 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.25 e Å⁻³
Absolute structure: Flack (1983 ), with 1687 Friedel pairs
Flack parameter: 0.001 (9)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O3Dⁱ	0.83 (3)	2.28 (3)	3.107 (4)	174 (3)
O1W—H1WA⋯O2D	0.84 (4)	2.21 (3)	2.943 (5)	145 (3)
O1W—H1WA⋯O3D	0.84 (4)	2.22 (3)	2.994 (5)	153 (3)
O1W—H1WB⋯O2E	0.84 (4)	1.91 (3)	2.745 (4)	171 (3)
O2W—H2WA⋯O1D	0.87 (4)	2.05 (3)	2.881 (6)	161 (6)
O2W—H2WB⋯O3Eⁱⁱ	0.87 (4)	1.99 (2)	2.835 (6)	164 (7)
C5A—H5A⋯O3Dⁱⁱⁱ	0.93	2.52	3.408 (5)	160
C5B—H5B⋯O3D^iv	0.93	2.52	3.402 (5)	158
C6B—H6B⋯O3E^v	0.93	2.51	3.359 (6)	152
Symmetry codes: (i) x-1, y, z; (ii) $[-x+{\script{3\over 2}}, -y+1, z-{\script{1\over 2}}]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ .

Table 2
π–π contacts (Å, °) for (I)

Centroid codes are as defined in Fig. 1. c.c.d. is the centroid–centroid distance, d.a. is the dihedral angle between rings and p.c.d. is the (mean) perpendicular distance from the centroid to the opposite plane (for details, see Janiak 2000 ).

Group 1/group 2	c.c.d. (Å)	d.a. (°)	p.c.d. (Å)
Cg1⋯Cg2ⁱ	3.533 (2)	1.87 (17)	3.37 (2)
Cg5⋯Cg6ⁱ	3.614 (2)	2.29 (17)	3.35 (3)
Cg1⋯Cg4ⁱ	4.093 (2)	3.06 (17)	3.37 (4)
Cg2⋯Cg3ⁱⁱ	3.628 (2)	1.32 (17)	3.35 (2)
Cg3⋯Cg6ⁱ	3.578 (2)	1.68 (17)	3.39 (2)
Cg4⋯Cg5ⁱⁱⁱ	4.070 (2)	3.16 (17)	3.33 (2)
Symmetry codes: (i) −x, − $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (ii) 1 − x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (iii) −x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z.

Table 3
Comparison of the unit-cell parameters for (I), (II) and (III)

Percentage values refer to differences from compound (I) reported herein.

Compound	a (Å)	b (Å)	c (Å)
(I)^a	8.1505 (2)	17.4091 (3)	19.7447 (4)
(II)^b	8.3452 (2) (2.38%)	17.7730 (2) (2.21%)	19.8477 (2) (0.52%)
(III)^c	8.3526 (5) (2.48%)	17.8236 (12) (2.38%)	19.9074 (13) (0.82%)
References: (a) this work; (b) Youngme et al. (2008); (c) Chailuecha et al. (2006).

Even though the geometry of the counter-ions allowed the groups to be initially interpreted as either acetate or nitrate, the final bond lengths and the lack of methyl H atoms in the difference maps confirmed nitrate as the correct assignment. All H atoms could be found in a difference Fourier map. Those attached to C atoms were placed in calculated positions, with phen C—H = 0.93 Å and methyl C—H = 0.96 Å, and allowed to ride. Those attached to O atoms were further refined with restrained O—H distances of 0.85 (1) Å and H⋯H distances of 1.35 (1) Å. The isotropic displacement parameter of the hydroxy H atom was refined. In all other cases, displacement parameters were taken as U_iso(H) = 1.5U_eq(C,O) for methyl groups and water molecules, and as U_iso(H) = 1.2U_eq(C) otherwise.

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S0108270111011048/gg3255sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270111011048/gg3255Isup2.hkl

Comment top

Since the seminal work on copper acetate monohydrate reported by Bleaney & Bowers (1952), interest in magnetic dimeric (or dinuclear) compounds has been maintained for the past 60 years, from different perspectives. This work has contributed to the field of molecular magnetic materials (Kahn, 1993), to the understanding of correlations between exchange couplings and bond structure, and helped in the design of new polynuclear molecular magnets. The fact that weakly interacting AFM dimeric magnetic materials display Bose–Einstein condensation at relatively high T [T = temperature?] triggered considerable research by the materials and physics community (Giamarchi et al., 2008). The discovery of high-T superconductors also stimulated interest in interacting quantum spin systems providing information about elementary excitations, quantum phase transitions and critical phenomena. Many studies of dimeric materials have been reported in this context. Our interest in dimeric materials is directed towards the effects of weak interactions between molecular units (Napolitano et al., 2008; Perec et al., 2010). Since the stacking of phenanthroline rings is a potential source of weak intermolecular exchange couplings we have been looking for new compounds where dinuclear units are coupled by this type of interaction. During our study the triply bridged dinuclear copper(II) title compound, [Cu₂(C₂H₃O₂)(OH)(H₂O)(C₁₂H₈N₂)₂] .2NO₃.H₂O, (I), was obtained (Figs. 1–3).

The molecule consists of a [Cu₂(µ₂-CH₃COO-κ²-O',O")(µ₂-OH)(µ₂-OH₂)(phen)₂]²⁺ dinuclear cation (phen = 1,10-phenanthroline), two uncoordinated L^- anions (L = NO₃) and one water molecule of crystallization (Fig. 1). It contains a distorted square-pyramidal arrangement at each copper(II) ion, in such a way that the two pyramidal CuN₂O₃ chromophores share one edge. Both Cu^II ions are linked [Cu1···Cu2 2.9559 (5) Å] at two equatorial positions through a hydroxo bridge [Cu—O_hydroxo 1.928 (2), 1.919 (2) Å for Cu1, Cu2, respectively], a triatomic carboxylato bridge [Cu—O_carboxylato 1.935 (2), 1.940 (2) Å for Cu1, Cu2, respectively], and at the axial position through a water molecule [Cu—O_water 2.344 (2), 2.332 (2) Å for Cu1, Cu2, respectively]. The coordination of each copper centre is completed by a chelating phen-N,N' [Cu—N_phen 2.007 (3), 2.023 (2) Å and 1.994 (3), 2.016 (2) Å, [for Cu1 and Cu2 ?], respectively]; the resulting bond valency for both cations is 2.16, 2.20 as calculated using PLATON (Spek, 2009). The polyhedron around Cu1 is slightly more regular than the Cu2 one, displaying clear differences in the (ideally equal) trans O—Cu—N basal angles [6.62 (16)° versus 16.48 (18)°, respectively], the deviation from planarity in the basal plane [0.032 (2) Å for N2A versus 0.205 (2) Å for N1B], the departure of the apical axis from the vertical [8.22 (12) versus. 20.4 (2)°], and (perhaps as a summary) their τ parameters (as defined in Addison et al., 1984, and calculated with the program PLATON): 0.11 versus 0.27.

The ligands are basically featureless; none of the phen groups depart significantly from planarity [maximum deviations 0.028 (3) Å for C2A; 0.037 (3) Å for C11B] and the C—O bonds in the acetato group display an almost perfect resonance [O1C ≐ C1C 1.249 (4); O2C ≐ C1C 1.252 (4) Å].

Cu₂(OH)(H₂O)(carboxylate) is a well known cluster and a search in the v5.32 (2011) version of the Cambridge Structural Database (CSD; Allen, 2002) revealed several structures incorporating the moiety [e.g. CITLOH, CITLEX and YAFZUA01 (Youngme et al., 2008); YEMNIO and YEMNEK (Chailuecha et al., 2006); DIXGEX (Chen et al., 2008); JEJCIK (Christou et al., 1990); OLOVOA (Chadjistamatis et al., 2003); QAHDUY (Sgarabotto et al., 1999); YINJEL (Chen et al., 2007) etc., just to mention a few]. The comparative analysis within this set discloses coordination distances in a modest spread (Cu—O_hydroxo 1.908–1.933 Å; Cu—O_carboxylato 1.925–1.993 Å; Cu—O_water 2.321–2.415 Å) showing the values found for (I) to be within these ranges; the intercationic distance for (I), instead, appears distinctly shorter [Cu···Cu range 2.990–3.124 Å, versus Cu1···Cu2 2.9559 (5) Å in (I)].

A view of the Cu₂(OH)(H₂O)(carboxylate) clusters is provided in Fig. 4 and presented as overlapping Cu₂(OH)(H₂O)(carboxylate) clusters, where only the Cu–(OH)–Cu bridge has been fitted, the remaining atoms omitted for clarity: it is obvious that a very reasonable match is observed for the carboxylates, while a much larger spread is observed for the aqua bridge. This may have to do with the weaker binding of the O_water to the cations as well as the hydrogen-bonding ability of water. This makes it prone to disrupting interactions and modifying the ideal geometry.

Regarding the packing arrangement, the way in which the dinuclear units aggregate into a three-dimensional supramolecular structure is describable (for clarity) as a two-step process. The first step is achieved via the stacking of interweaved dinuclear units to form two-dimensional structures parallel to (001) (Fig. 2). The forces involved are several π···π interactions between the stacked phenanthroline groups, as summarized in Table 2. These interactions are not evenly distributed, but there are zones with additional stronger bonds (labelled `A' in Fig. 2, entries 1–3 in Table 2) defining chains which run along the b-axis direction; these chains are in turn connected by weaker/fewer links (zones labelled `B', entries 4–5 in Table 2) to form a broad two-dimensional structure. Secondly, a number of hydrogen bonds involving the hydroxido/aqueous groups as donors and the O atoms of the NO₃^- counterions as acceptors are present (Table 1). Fig. 3 shows a packing view rotated by 90° [compared] to that presented in Fig. 2, where the planar arrays are seen in projection, and the hydrogen-bonding network can be clearly observed. It is apparent that the cohesion provided by these interactions is partly `intra'-planar (providing for the plane stability) as well as `inter'-planar, assisting the plane-to-plane linkage.

More detailed comparisons can be made of the three-dimensional structure in (I) with two isostructural analogues (already considered earlier) which have the same phenanthroline ligand but different L counteranions, viz. L = BF₄^-, (II) (CITLOH, Youngme et al., 2008), and L = ClO₄^-, (III) (YEMNIO, Chailuecha et al., 2006). Both structures share the same dinuclear unit as (I) [mean square deviations 0.075 (2), and 0.116 (2) Å, respectively] and are also interweaved in analogous π-bonded layers, but differing in the remaining interactions aggregating into a three-dimensional structure. It is relevant to stress for the following discussion that this hydrogen-bonding system appears stronger and more clearly defined in (I) than in either of the (II), (III) analogues, since the O-atom acceptors in the NO₃^- counterions (I) are fairly well behaved while those in the BF₄^- (II) and ClO₄^- (III) analogues appear heavily disordered.

Comparison of the cell dimensions for all three structures (Table 3) yields information regarding the interactions governing the crystal packing and the way they operate [figures in brackets give the percentage differences with (I)]. It can be seen that along the c axis there are negligible differences between all three structures, while significant differences are noted along a and b. This fact correlates with the disposition and structure of the packing `leitmotiv' shown in Fig 2. The c direction is, in principle, defined by the width of the planes and this is basically associated with the volume occupied by the dinuclear unit; counterions lodge at the intermolecular voids and even if they provide interplanar cohesion, they do not appear to affect the mean planar width. Thus, the `c'-axis length would be limited by the `bumping' of basically uncompressible planes. The remaining two directions, on the other hand, are contained in the plane and along them the structure shows no significant cohesion forces able to oppose the strain introduced by any additional forces, e.g. hydrogen bonding. Thus, structure (I), with stronger and better defined `intra'-planar hydrogen-bonding interactions than (II) and (III) (see above) presents a detectable `shrinkage' of the planes in both the a and b directions, a fact directly ascribable to the internal hydrogen-bonding network and the flexibility of π···π interactions to adapt to them. It is worth noting the highly hydrophilic character of both NO₃ ^- anions, in particular nitrate D, where O3D, for instance, accepts four hydrogen bonds of different types and strength.

Our structural results show promise in the search for new dinuclear materials with weak interactions between moieties; however, we have not yet overcome the problem of the specimens being too small for EPR measurements, and are at present devoted to the growth of single crystals of adequate size and quality.

Related literature top

For related literature, see: Addison et al. (1984); Allen (2002); Bleaney & Bowers (1952); Chadjistamatis et al. (2003); Chailuecha et al. (2006); Chen et al. (2007, 2008); Christou et al. (1990); Giamarchi et al. (2008); Kahn (1993); Napolitano et al. (2008); Perec et al. (2010); Sgarabotto et al. (1999); Spek (2009); Youngme et al. (2008).

Experimental top

All chemicals were purchased from Sigma and used as received. A solution of sodium acetate NaCH₃COO (4 mM, 0.328 g) in 40 ml of water was prepared and its pH adjusted to 3.5–4 with a 10% solution of HNO₃. Under continuous agitation, equimolar quantities of 1,10-phenanthroline and copper nitrate were added to this solution; after complete dissolution its pH was adjusted to 4.5–5 with 1 N solution of NaOH and 10% HNO₃. This solution was filtered and left to evaporate at room temperature. Small crystals suitable for X-ray diffraction were obtained after circa 3 weeks.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97, PLATON (Spek, 2009).

Figures top

	Fig. 1. Molecular view of (I) with displacement ellipsoids drawn at the 30% level. Hydrogen bonds are shown as double broken lines. Symmetry codes: (i) x - 1, y, z; (ii) -x + 3/2, -y + 1, z - 1/2.
	Fig. 2. Packing diagram of (I) viewed along [001], showing how the dinuclear units are linked by π···π bonding into planes parallel to (001).
	Fig. 3. Packing diagram of (I), viewed along [100] and rotated by 90° to the view in Fig. 2 showing the hydrogen-bonding interactions. The (001) sheets are shown in projection as vertical structures (marked by square brackets).
	Fig. 4. Comparison of the Cu₂(OH)(H₂O)(carboxylate) group in (I) (heavy lining) with similar ones from the literature, (the structure code (s) and within brackets the CSD RefCode(s) and Reference are stated). a, c, i: (CITLOH; CITLEX; YAFZUA01; Youngme et al., 2008); b, h: (YEMNIO; YEMNEK; Chailuecha et al., 2006); d: (DIXGEX; Chen et al., 2008); e: (JEJCIK; Christou et al., 1990; f: (OLOVOA; Chadjistamatis et al., 2003); g: (QAHDUY; Sgarabotto et al., 1999); j: (YINJEL; Chen et al., 2007).

µ-Acetato-µ-aqua-µ-hydroxido-bis[(1,10-phenanthroline)copper(II)] dinitrate monohydrate top

Crystal data top

[Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O	F(000) = 1472
M_r = 723.59	D_x = 1.716 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 7244 reflections
a = 8.15051 (15) Å	θ = 4.1–25.6°
b = 17.4091 (3) Å	µ = 1.59 mm⁻¹
c = 19.7447 (4) Å	T = 292 K
V = 2801.63 (9) Å³	Block, blue
Z = 4	0.35 × 0.20 × 0.15 mm

Data collection top

Oxford Diffraction Gemini CCD S Ultra diffractometer	5135 independent reflections
Radiation source: fine-focus sealed tube	3791 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
ω scans, thick slices	θ_max = 26.3°, θ_min = 2.6°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	h = −10→9
T_min = 0.54, T_max = 0.73	k = −21→21
16045 measured reflections	l = −23→24

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.054	w = 1/[σ²(F_o²) + (0.0274P)²] where P = (F_o² + 2F_c²)/3
S = 0.91	(Δ/σ)_max = 0.001
5135 reflections	Δρ_max = 0.26 e Å⁻³
422 parameters	Δρ_min = −0.25 e Å⁻³
7 restraints	Absolute structure: Flack, 1983. 1687 Friedel pairs measured
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.001 (9)

Crystal data top

[Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O	V = 2801.63 (9) Å³
M_r = 723.59	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 8.15051 (15) Å	µ = 1.59 mm⁻¹
b = 17.4091 (3) Å	T = 292 K
c = 19.7447 (4) Å	0.35 × 0.20 × 0.15 mm

Data collection top

Oxford Diffraction Gemini CCD S Ultra diffractometer	5135 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	3791 reflections with I > 2σ(I)
T_min = 0.54, T_max = 0.73	R_int = 0.029
16045 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.054	Δρ_max = 0.26 e Å⁻³
S = 0.91	Δρ_min = −0.25 e Å⁻³
5135 reflections	Absolute structure: Flack, 1983. 1687 Friedel pairs measured
422 parameters	Absolute structure parameter: 0.001 (9)
7 restraints

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cu1	0.09622 (5)	0.532730 (19)	0.181451 (18)	0.03940 (11)
Cu2	0.04714 (5)	0.695859 (19)	0.217691 (18)	0.03840 (11)
O1	−0.0627 (3)	0.59866 (10)	0.22448 (11)	0.0387 (5)
H1	−0.153 (2)	0.5978 (16)	0.2049 (13)	0.030 (9)*
N1A	0.1297 (3)	0.46454 (14)	0.26321 (12)	0.0403 (6)
N2A	0.2467 (4)	0.45533 (14)	0.13881 (14)	0.0433 (7)
C1A	0.0727 (4)	0.47228 (18)	0.32564 (16)	0.0530 (8)
H1A	0.0102	0.5153	0.3364	0.064*
C2A	0.1043 (6)	0.4170 (2)	0.37637 (18)	0.0646 (11)
H2A	0.0626	0.4230	0.4199	0.078*
C3A	0.1962 (5)	0.3551 (2)	0.3602 (2)	0.0640 (12)
H3A	0.2167	0.3183	0.3933	0.077*
C4A	0.2615 (5)	0.34476 (18)	0.29565 (19)	0.0492 (9)
C5A	0.3601 (5)	0.28082 (18)	0.2737 (3)	0.0645 (12)
H5A	0.3830	0.2413	0.3040	0.077*
C6A	0.4197 (5)	0.27719 (18)	0.2102 (2)	0.0661 (11)
H6A	0.4837	0.2353	0.1979	0.079*
C7A	0.3879 (5)	0.33519 (17)	0.16159 (19)	0.0507 (9)
C8A	0.4440 (5)	0.3360 (2)	0.0950 (2)	0.0682 (11)
H8A	0.5109	0.2965	0.0794	0.082*
C9A	0.4018 (5)	0.3939 (2)	0.0528 (2)	0.0641 (11)
H9A	0.4395	0.3942	0.0083	0.077*
C10A	0.3023 (4)	0.45284 (19)	0.07600 (19)	0.0551 (9)
H10A	0.2736	0.4921	0.0463	0.066*
C11A	0.2883 (4)	0.39749 (17)	0.18166 (19)	0.0413 (8)
C12A	0.2256 (4)	0.40279 (16)	0.24843 (19)	0.0420 (9)
N1B	0.1693 (3)	0.79646 (14)	0.22013 (14)	0.0415 (6)
N2B	0.0001 (3)	0.72297 (13)	0.31385 (13)	0.0374 (6)
C1B	0.2522 (5)	0.83158 (18)	0.1721 (2)	0.0519 (9)
H1B	0.2577	0.8087	0.1296	0.062*
C2B	0.3319 (5)	0.9013 (2)	0.1818 (2)	0.0623 (10)
H2B	0.3925	0.9238	0.1471	0.075*
C3B	0.3189 (5)	0.9362 (2)	0.2439 (2)	0.0566 (11)
H3B	0.3675	0.9839	0.2506	0.068*
C4B	0.2345 (4)	0.90151 (17)	0.29681 (18)	0.0458 (9)
C5B	0.2111 (5)	0.9323 (2)	0.3632 (2)	0.0584 (11)
H5B	0.2579	0.9796	0.3738	0.070*
C6B	0.1252 (5)	0.8959 (2)	0.4102 (2)	0.0622 (11)
H6B	0.1135	0.9183	0.4527	0.075*
C7B	0.0494 (5)	0.82292 (18)	0.39747 (16)	0.0470 (9)
C8B	−0.0457 (5)	0.78212 (19)	0.44369 (16)	0.0547 (9)
H8B	−0.0618	0.8010	0.4872	0.066*
C9B	−0.1150 (5)	0.71428 (19)	0.42458 (16)	0.0527 (9)
H9B	−0.1793	0.6867	0.4549	0.063*
C10B	−0.0888 (5)	0.68649 (18)	0.35924 (15)	0.0464 (8)
H10B	−0.1364	0.6399	0.3472	0.056*
C11B	0.0699 (4)	0.79070 (16)	0.33261 (15)	0.0393 (8)
C12B	0.1608 (4)	0.83026 (16)	0.28255 (18)	0.0400 (8)
O1C	0.0622 (3)	0.57733 (12)	0.09282 (10)	0.0496 (6)
O2C	0.0325 (3)	0.70113 (11)	0.11975 (10)	0.0485 (6)
C1C	0.0387 (5)	0.6464 (2)	0.07864 (17)	0.0484 (9)
C2C	0.0125 (6)	0.6669 (2)	0.00525 (17)	0.0838 (16)
H2CA	0.0900	0.6395	−0.0222	0.126*
H2CB	0.0278	0.7211	−0.0008	0.126*
H2CC	−0.0969	0.6531	−0.0080	0.126*
N1D	0.5583 (6)	0.62141 (19)	0.0885 (2)	0.0694 (10)
O1D	0.6265 (8)	0.5984 (3)	0.0407 (2)	0.168 (2)
O2D	0.4321 (5)	0.6575 (2)	0.0863 (2)	0.1437 (17)
O3D	0.6074 (5)	0.60806 (17)	0.14612 (18)	0.0964 (11)
N1E	0.4211 (5)	0.5970 (2)	0.38412 (17)	0.0704 (10)
O1E	0.3242 (6)	0.6491 (2)	0.38830 (19)	0.1283 (15)
O2E	0.4594 (5)	0.57261 (18)	0.33056 (16)	0.1121 (13)
O3E	0.4739 (7)	0.5703 (3)	0.4343 (2)	0.185 (2)
O1W	0.2877 (3)	0.62337 (13)	0.21961 (13)	0.0465 (5)
H1WA	0.365 (3)	0.6326 (19)	0.1926 (12)	0.070*
H1WB	0.331 (4)	0.609 (2)	0.2563 (9)	0.070*
O2W	0.6949 (5)	0.4782 (3)	−0.0556 (2)	0.1205 (12)
H2WA	0.697 (7)	0.512 (3)	−0.023 (3)	0.181*
H2WB	0.798 (2)	0.472 (4)	−0.063 (3)	0.181*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0451 (2)	0.03186 (19)	0.0412 (2)	0.00363 (18)	0.00070 (19)	0.00110 (16)
Cu2	0.0461 (3)	0.0317 (2)	0.0375 (2)	0.00065 (19)	0.00004 (18)	0.00016 (16)
O1	0.0360 (15)	0.0397 (12)	0.0404 (13)	−0.0002 (10)	0.0018 (12)	−0.0036 (9)
N1A	0.0398 (16)	0.0349 (14)	0.0462 (17)	−0.0043 (14)	−0.0058 (12)	0.0033 (12)
N2A	0.0482 (18)	0.0333 (15)	0.0483 (17)	0.0039 (14)	−0.0027 (14)	−0.0022 (13)
C1A	0.060 (2)	0.053 (2)	0.046 (2)	−0.004 (2)	−0.0040 (19)	0.0058 (17)
C2A	0.082 (3)	0.061 (2)	0.050 (2)	−0.015 (3)	−0.006 (2)	0.0122 (18)
C3A	0.068 (3)	0.051 (3)	0.073 (3)	−0.021 (2)	−0.034 (2)	0.025 (2)
C4A	0.045 (2)	0.042 (2)	0.060 (3)	−0.0103 (17)	−0.0183 (19)	0.0061 (17)
C5A	0.063 (3)	0.0284 (18)	0.102 (3)	−0.0005 (17)	−0.037 (3)	0.007 (2)
C6A	0.057 (3)	0.038 (2)	0.104 (3)	0.0094 (18)	−0.034 (3)	−0.015 (2)
C7A	0.043 (2)	0.0311 (17)	0.078 (3)	−0.0005 (16)	−0.016 (2)	−0.0119 (17)
C8A	0.053 (3)	0.056 (2)	0.096 (3)	0.009 (2)	0.002 (2)	−0.035 (2)
C9A	0.059 (3)	0.056 (2)	0.077 (3)	0.003 (2)	0.020 (2)	−0.020 (2)
C10A	0.059 (2)	0.045 (2)	0.062 (3)	0.0027 (18)	0.0057 (19)	−0.0059 (18)
C11A	0.0328 (19)	0.0343 (18)	0.057 (2)	−0.0064 (15)	−0.0125 (19)	−0.0070 (17)
C12A	0.037 (2)	0.0248 (18)	0.064 (2)	−0.0085 (16)	−0.0166 (18)	0.0026 (15)
N1B	0.0458 (16)	0.0342 (14)	0.0446 (16)	−0.0001 (12)	−0.0023 (14)	0.0089 (15)
N2B	0.0418 (16)	0.0300 (13)	0.0403 (14)	0.0051 (11)	−0.0039 (13)	0.0023 (12)
C1B	0.052 (2)	0.047 (2)	0.056 (2)	0.0092 (17)	0.005 (2)	0.0053 (17)
C2B	0.044 (2)	0.057 (2)	0.086 (3)	−0.0016 (18)	−0.005 (2)	0.024 (2)
C3B	0.046 (2)	0.0313 (19)	0.093 (3)	0.0042 (17)	−0.010 (2)	0.007 (2)
C4B	0.035 (2)	0.0362 (19)	0.066 (3)	0.0065 (16)	−0.0145 (17)	0.0028 (17)
C5B	0.053 (3)	0.040 (2)	0.083 (3)	0.0015 (19)	−0.022 (2)	−0.016 (2)
C6B	0.067 (3)	0.055 (2)	0.065 (3)	0.010 (2)	−0.022 (2)	−0.021 (2)
C7B	0.049 (2)	0.045 (2)	0.047 (2)	0.0154 (18)	−0.0167 (19)	−0.0050 (15)
C8B	0.070 (3)	0.056 (2)	0.0381 (19)	0.024 (2)	−0.0118 (19)	−0.0042 (16)
C9B	0.064 (3)	0.056 (2)	0.0383 (19)	0.0179 (19)	0.0061 (18)	0.0078 (16)
C10B	0.050 (2)	0.0412 (19)	0.0481 (19)	0.0131 (19)	−0.0031 (17)	0.0048 (15)
C11B	0.041 (2)	0.0325 (16)	0.0447 (19)	0.0117 (15)	−0.0156 (16)	−0.0012 (14)
C12B	0.0408 (19)	0.0292 (16)	0.050 (2)	0.0067 (14)	−0.0091 (18)	−0.0018 (16)
O1C	0.0681 (18)	0.0401 (13)	0.0404 (13)	0.0073 (13)	−0.0013 (12)	0.0015 (9)
O2C	0.0723 (17)	0.0350 (11)	0.0381 (12)	0.0057 (13)	−0.0045 (11)	0.0026 (10)
C1C	0.051 (2)	0.055 (2)	0.039 (2)	0.0018 (19)	0.0025 (18)	0.0013 (17)
C2C	0.142 (5)	0.074 (3)	0.036 (2)	0.010 (3)	−0.003 (2)	0.0054 (17)
N1D	0.080 (3)	0.064 (2)	0.064 (2)	0.000 (2)	0.005 (2)	0.0021 (18)
O1D	0.215 (5)	0.189 (4)	0.099 (3)	0.018 (4)	0.066 (4)	−0.036 (3)
O2D	0.081 (3)	0.167 (4)	0.183 (4)	0.041 (3)	0.011 (3)	0.081 (3)
O3D	0.108 (3)	0.079 (2)	0.102 (2)	0.017 (2)	−0.018 (2)	−0.0126 (17)
N1E	0.084 (3)	0.083 (2)	0.044 (2)	0.023 (2)	−0.018 (2)	−0.0060 (18)
O1E	0.148 (4)	0.121 (3)	0.116 (3)	0.058 (3)	0.019 (3)	0.004 (2)
O2E	0.159 (4)	0.114 (2)	0.063 (2)	0.066 (2)	−0.015 (2)	−0.0183 (17)
O3E	0.217 (6)	0.259 (5)	0.080 (3)	0.132 (4)	−0.057 (3)	−0.019 (3)
O1W	0.0427 (14)	0.0495 (13)	0.0474 (14)	−0.0005 (11)	0.0012 (12)	0.0018 (12)
O2W	0.123 (3)	0.134 (3)	0.104 (3)	0.010 (2)	−0.009 (2)	0.017 (2)

Geometric parameters (Å, º) top

Cu1—O1	1.928 (2)	N2B—C11B	1.361 (4)
Cu1—O1C	1.935 (2)	C1B—C2B	1.391 (5)
Cu1—N2A	2.007 (3)	C1B—H1B	0.9300
Cu1—N1A	2.022 (2)	C2B—C3B	1.372 (5)
Cu1—O1W	2.344 (2)	C2B—H2B	0.9300
Cu2—O1	1.919 (2)	C3B—C4B	1.389 (5)
Cu2—O2C	1.940 (2)	C3B—H3B	0.9300
Cu2—N2B	1.994 (3)	C4B—C12B	1.407 (4)
Cu2—N1B	2.015 (2)	C4B—C5B	1.429 (5)
Cu2—O1W	2.332 (2)	C5B—C6B	1.324 (5)
O1—H1	0.83 (3)	C5B—H5B	0.9300
N1A—C1A	1.324 (4)	C6B—C7B	1.435 (5)
N1A—C12A	1.360 (4)	C6B—H6B	0.9300
N2A—C10A	1.321 (4)	C7B—C8B	1.392 (5)
N2A—C11A	1.358 (4)	C7B—C11B	1.408 (4)
C1A—C2A	1.413 (4)	C8B—C9B	1.362 (5)
C1A—H1A	0.9300	C8B—H8B	0.9300
C2A—C3A	1.349 (6)	C9B—C10B	1.394 (4)
C2A—H2A	0.9300	C9B—H9B	0.9300
C3A—C4A	1.394 (5)	C10B—H10B	0.9300
C3A—H3A	0.9300	C11B—C12B	1.414 (4)
C4A—C12A	1.406 (4)	O1C—C1C	1.249 (4)
C4A—C5A	1.440 (5)	O2C—C1C	1.253 (4)
C5A—C6A	1.346 (5)	C1C—C2C	1.508 (4)
C5A—H5A	0.9300	C2C—H2CA	0.9600
C6A—C7A	1.418 (5)	C2C—H2CB	0.9600
C6A—H6A	0.9300	C2C—H2CC	0.9600
C7A—C8A	1.393 (5)	N1D—O1D	1.166 (5)
C7A—C11A	1.412 (4)	N1D—O2D	1.206 (5)
C8A—C9A	1.352 (5)	N1D—O3D	1.229 (4)
C8A—H8A	0.9300	N1E—O3E	1.176 (4)
C9A—C10A	1.386 (5)	N1E—O2E	1.182 (4)
C9A—H9A	0.9300	N1E—O1E	1.205 (4)
C10A—H10A	0.9300	O1W—H1WA	0.84 (4)
C11A—C12A	1.417 (5)	O1W—H1WB	0.84 (4)
N1B—C1B	1.315 (4)	O2W—H2WA	0.87 (4)
N1B—C12B	1.367 (4)	O2W—H2WB	0.87 (4)
N2B—C10B	1.316 (4)

O1—Cu1—O1C	93.62 (9)	C1B—N1B—Cu2	129.8 (2)
O1—Cu1—N2A	174.29 (10)	C12B—N1B—Cu2	111.7 (2)
O1C—Cu1—N2A	88.72 (10)	C10B—N2B—C11B	117.6 (3)
O1—Cu1—N1A	95.08 (10)	C10B—N2B—Cu2	129.8 (2)
O1C—Cu1—N1A	167.71 (10)	C11B—N2B—Cu2	112.6 (2)
N2A—Cu1—N1A	81.85 (11)	N1B—C1B—C2B	123.1 (4)
O1—Cu1—O1W	84.55 (8)	N1B—C1B—H1B	118.4
O1C—Cu1—O1W	96.67 (9)	C2B—C1B—H1B	118.4
N2A—Cu1—O1W	100.36 (10)	C3B—C2B—C1B	118.2 (4)
N1A—Cu1—O1W	92.79 (9)	C3B—C2B—H2B	120.9
O1—Cu2—O2C	94.74 (9)	C1B—C2B—H2B	120.9
O1—Cu2—N2B	93.00 (9)	C2B—C3B—C4B	121.3 (3)
O2C—Cu2—N2B	157.88 (9)	C2B—C3B—H3B	119.4
O1—Cu2—N1B	174.35 (10)	C4B—C3B—H3B	119.4
O2C—Cu2—N1B	90.76 (10)	C3B—C4B—C12B	116.3 (3)
N2B—Cu2—N1B	82.33 (10)	C3B—C4B—C5B	126.4 (3)
O1—Cu2—O1W	85.07 (8)	C12B—C4B—C5B	117.3 (3)
O2C—Cu2—O1W	95.37 (9)	C6B—C5B—C4B	122.2 (3)
N2B—Cu2—O1W	105.93 (9)	C6B—C5B—H5B	118.9
N1B—Cu2—O1W	93.12 (9)	C4B—C5B—H5B	118.9
Cu2—O1—Cu1	100.41 (10)	C5B—C6B—C7B	122.0 (3)
Cu2—O1—H1	113 (2)	C5B—C6B—H6B	119.0
Cu1—O1—H1	112 (2)	C7B—C6B—H6B	119.0
C1A—N1A—C12A	118.8 (3)	C8B—C7B—C11B	117.3 (3)
C1A—N1A—Cu1	129.5 (2)	C8B—C7B—C6B	125.2 (3)
C12A—N1A—Cu1	111.7 (2)	C11B—C7B—C6B	117.4 (3)
C10A—N2A—C11A	118.3 (3)	C9B—C8B—C7B	119.4 (3)
C10A—N2A—Cu1	128.7 (2)	C9B—C8B—H8B	120.3
C11A—N2A—Cu1	112.9 (2)	C7B—C8B—H8B	120.3
N1A—C1A—C2A	121.8 (3)	C8B—C9B—C10B	119.6 (3)
N1A—C1A—H1A	119.1	C8B—C9B—H9B	120.2
C2A—C1A—H1A	119.1	C10B—C9B—H9B	120.2
C3A—C2A—C1A	118.5 (4)	N2B—C10B—C9B	123.2 (3)
C3A—C2A—H2A	120.7	N2B—C10B—H10B	118.4
C1A—C2A—H2A	120.7	C9B—C10B—H10B	118.4
C2A—C3A—C4A	122.1 (3)	N2B—C11B—C7B	122.9 (3)
C2A—C3A—H3A	118.9	N2B—C11B—C12B	116.8 (3)
C4A—C3A—H3A	118.9	C7B—C11B—C12B	120.3 (3)
C3A—C4A—C12A	115.7 (3)	N1B—C12B—C4B	122.6 (3)
C3A—C4A—C5A	126.1 (4)	N1B—C12B—C11B	116.6 (3)
C12A—C4A—C5A	118.2 (4)	C4B—C12B—C11B	120.9 (3)
C6A—C5A—C4A	121.2 (3)	C1C—O1C—Cu1	127.7 (2)
C6A—C5A—H5A	119.4	C1C—O2C—Cu2	127.4 (2)
C4A—C5A—H5A	119.4	O1C—C1C—O2C	126.4 (3)
C5A—C6A—C7A	122.1 (3)	O1C—C1C—C2C	117.7 (3)
C5A—C6A—H6A	118.9	O2C—C1C—C2C	115.9 (3)
C7A—C6A—H6A	118.9	C1C—C2C—H2CA	109.4
C8A—C7A—C11A	116.5 (3)	C1C—C2C—H2CB	109.5
C8A—C7A—C6A	126.0 (4)	H2CA—C2C—H2CB	109.5
C11A—C7A—C6A	117.5 (4)	C1C—C2C—H2CC	109.5
C9A—C8A—C7A	120.4 (3)	H2CA—C2C—H2CC	109.5
C9A—C8A—H8A	119.8	H2CB—C2C—H2CC	109.5
C7A—C8A—H8A	119.8	O1D—N1D—O2D	123.9 (5)
C8A—C9A—C10A	119.8 (4)	O1D—N1D—O3D	122.0 (5)
C8A—C9A—H9A	120.1	O2D—N1D—O3D	114.1 (4)
C10A—C9A—H9A	120.1	O3E—N1E—O2E	121.0 (4)
N2A—C10A—C9A	122.4 (3)	O3E—N1E—O1E	118.7 (4)
N2A—C10A—H10A	118.8	O2E—N1E—O1E	120.3 (4)
C9A—C10A—H10A	118.8	Cu2—O1W—Cu1	78.42 (7)
N2A—C11A—C7A	122.6 (3)	Cu2—O1W—H1WA	121 (2)
N2A—C11A—C12A	116.2 (3)	Cu1—O1W—H1WA	115 (2)
C7A—C11A—C12A	121.2 (3)	Cu2—O1W—H1WB	122 (2)
N1A—C12A—C4A	123.0 (3)	Cu1—O1W—H1WB	111 (2)
N1A—C12A—C11A	117.3 (3)	H1WA—O1W—H1WB	107 (3)
C4A—C12A—C11A	119.7 (3)	H2WA—O2W—H2WB	102 (3)
C1B—N1B—C12B	118.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3Dⁱ	0.83 (3)	2.28 (3)	3.107 (4)	174 (3)
O1W—H1WA···O2D	0.84 (4)	2.21 (3)	2.943 (5)	145 (3)
O1W—H1WA···O3D	0.84 (4)	2.22 (3)	2.994 (5)	153 (3)
O1W—H1WB···O2E	0.84 (4)	1.91 (3)	2.745 (4)	171 (3)
O2W—H2WA···O1D	0.87 (4)	2.05 (3)	2.881 (6)	161 (6)
O2W—H2WB···O3Eⁱⁱ	0.87 (4)	1.99 (2)	2.835 (6)	164 (7)
C5A—H5A···O3Dⁱⁱⁱ	0.93	2.52	3.408 (5)	160
C5B—H5B···O3D^iv	0.93	2.52	3.402 (5)	158
C6B—H6B···O3E^v	0.93	2.51	3.359 (6)	152

Symmetry codes: (i) x−1, y, z; (ii) −x+3/2, −y+1, z−1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1, y+1/2, −z+1/2; (v) x−1/2, −y+3/2, −z+1.

Experimental details

Crystal data
Chemical formula	[Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O
M_r	723.59
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	292
a, b, c (Å)	8.15051 (15), 17.4091 (3), 19.7447 (4)
V (Å³)	2801.63 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.59
Crystal size (mm)	0.35 × 0.20 × 0.15

Data collection
Diffractometer	Oxford Diffraction Gemini CCD S Ultra diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)
T_min, T_max	0.54, 0.73
No. of measured, independent and observed [I > 2σ(I)] reflections	16045, 5135, 3791
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.623

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.054, 0.91
No. of reflections	5135
No. of parameters	422
No. of restraints	7
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.26, −0.25
Absolute structure	Flack, 1983. 1687 Friedel pairs measured
Absolute structure parameter	0.001 (9)

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), SHELXL97, PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3Dⁱ	0.83 (3)	2.28 (3)	3.107 (4)	174 (3)
O1W—H1WA···O2D	0.84 (4)	2.21 (3)	2.943 (5)	145 (3)
O1W—H1WA···O3D	0.84 (4)	2.22 (3)	2.994 (5)	153 (3)
O1W—H1WB···O2E	0.84 (4)	1.91 (3)	2.745 (4)	171 (3)
O2W—H2WA···O1D	0.87 (4)	2.05 (3)	2.881 (6)	161 (6)
O2W—H2WB···O3Eⁱⁱ	0.87 (4)	1.99 (2)	2.835 (6)	164 (7)
C5A—H5A···O3Dⁱⁱⁱ	0.93	2.52	3.408 (5)	160
C5B—H5B···O3D^iv	0.93	2.52	3.402 (5)	158
C6B—H6B···O3E^v	0.93	2.51	3.359 (6)	152

Symmetry codes: (i) x−1, y, z; (ii) −x+3/2, −y+1, z−1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1, y+1/2, −z+1/2; (v) x−1/2, −y+3/2, −z+1.

Table 2. π-π contacts (Å, °) for (1) top

Group_1/Group_2	ccd(Å)	da(°)	pcd(Å)
Cg1···Cg2ⁱ	3.533 (2)	1.87 (17)	3.37 (2)
Cg5···Cg6ⁱ	3.614 (2)	2.29 (17)	3.35 (3)
Cg1···Cg4ⁱ	4.093 (2)	3.06 (17)	3.37 (5)
Cg2···Cg3ⁱⁱ	3.628 (2)	1.32 (17)	3.35 (2)
Cg3···Cg6ⁱ	3.578 (2)	1.68 (17)	3.39 (2)
Cg4···Cg5ⁱⁱⁱ	4.070 (2)	3.16 (17)	3.33 (2)

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

Centroid code: as in Fig. 1.

ccd: centroid-to-centroid distance; da: dihedral angle between rings; pcd: (mean) centroid to opposite plane distance. (For details, see Janiak 2000)

Table 3. Comparison of cell parameters for I, II and III. top

Compound	a (Å)	b (Å)	c (Å)
I ^*	8.1505 (2)	17.4091 (3)	19.7447 (4)
II ^**	8.3452 (2) (2.38%)	17.7730 (2) (2.21%)	19.8477 (2) (0.52%)
III ^***	8.3526 (5) (2.48%)	17.8236 (12) (2.38%)	19.9074 (13) (0.82%)

Percent values refer to differences with compound I herein reported

^* This work ;^** Youngme et al., 2008; ^*** Chailuecha et al., 2006.

Acknowledgements

The authors acknowledge ANPCyT (project No. PME 01113) for the purchase of the CCD diffractometer and the Spanish Research Council (CSIC) for providing a free-of-charge licence to the Cambridge Strcutural Database (Allen, 2002). This work was also supported by CAI+D and UNL. RC is a member of the research staff of CONICET.

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