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The structure of the title supramolecular complex, [Cu(C7H5O2)2(C5H6N2)2]·0.75C6H6, has been determined. The Cu2+ ion lies on an inversion centre and is coordinated by four O atoms of two opposing benzoate mol­ecules and two pyridine N atoms of two opposing amino­pyridine mol­ecules. The partially occupied benzene site lies across a twofold rotation axis. The crystal structure is dominated by two-dimensional networks containing two different hydrogen-bonded rings [R_2^2(16) and R_4^2(8)].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104003749/gd1293sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104003749/gd1293Isup2.hkl
Contains datablock I

CCDC reference: 237909

Comment top

The self-assembly of coordination-based entities is based on the implementation of ligands containing specific molecular information stored in the arrangement of suitable binding sites and of metal ions reading out the structural information through the algorithm defined by their coordination geometry (Lehn, 2000). One approach for addressing this problem is to design molecular components built from binding subunits of different types. Of special interest are the systems containing different binding units within their structure so as to combine several distinct coordination (Funeriu et al., 2001) or hydrogen-bonding (Etter, 1990) subprograms. Pyridine, carboxylate and amine as Cu{2+}$ coordination groups are selected as competitive partners in coordination or hydrogen-bonding events. On the basis of the stability constants in water of the simple complexes, we expect a selective complexation of CuII ions by carboxylate ($βeta _1$=2.46, Ablov and Nazarova, 1961) and of pyridine ($βeta _1$=3.30, Erlenmeyer et al., 1968) moieties in competition with the very unstable amine complexes used as hydrogen-bonding motifs. In this paper, we describe a coordination architecture that is built up by self-assembly of 4-aminopyridine ({ιt L}$_1$) and benzoic acid ({ιt L}$_2$) and Cu${2+}$ ions as metal-coordination and hydrogen-bond templating centres. The molecular structure of (I) is presented in Fig. 1. The Cu${2+}$ ion lies on an inversion centre and is sixfold coordinated by two N atoms (N2 and N2a) of inversion-related ligands {ιt L}$_1$ and four O atoms of inversion-related ligands {ιt L}$_2$ (O9, O11, O9a, and O11a), thus fulfilling the prediction based on the stability constants of the simple complexes. The Cu—O distances are short to the opposing O9 ions [1.962 (3) {AA}] and long to the opposing O11 atoms [2.706 (4) {AA}; just shorter than the sum of the Van der Waals radii of Cu and O]. The Cambridge Structural Database (Version 5.25; Allen 2002) gives for the shorter carboxylate Cu—O distance values between 1.951 and 2.180 {AA}, and for the longer distance 2.209–2.996 {AA}. Cu—N distances for {ιt L}$_1$ ligands range from 1.980–2.006 {AA} (eight structures); this distance is slightly shorter in (I): 1.974 (5) {AA}. Pertinent dimensions of the intramolecular structure are given in Table 1. The benzene site was found to be underoccupied (3/4), but the remaining atomic displacement parameters are still rather high, presumably as a result of some positional disorder. The straw-representation in Fig. 2 shows that the Cu atom and its coordinating ligands are stacked in two-dimensional arrangements in the ab plane, in which the {ιt L}$_1$ ligands are parallel to this plane and the {ιt L}$_2$ ligands are perpendicular to them. There are no interactions (hydrogen bonds or ππ interactions) between the phenyl groups of {ιt L}$_2$ ligands of adjacent stacks. It is interesting to note that bis(benzoato-{ιt O},{ιt O}')-bis(nicotinamide-{ιt N})-copper(II) [(II); Leban et al., 1996] shows a similar two-dimensional arrangement, with pyridine moieties lying within and parallel to the stacks, while the carboxylate and phenyl groups are perpendicular to the stacking plane. The difference between this structure and (I), apart from the slightly different {ιt L}$_1$ ligand, is the {ιt trans} arrangement of the two carboxylate groups in (I); they are {ιt cis} in (II). Another closely related compound, but this time with a {ιt trans} arrangement of the carboxylate groups, {ιt trans}-bis(benzoato-{ιt O},{ιt O}')-bis({ιt N},{ιt N}- diethylnicotinamide-{ιt N}$1$)-copper(ii) (Hökelek et al., 1996), does not show the typical two-dimensional structural arrangement of (I) and (II). Within each stack of the title compound, a two-dimensional network of R$_22$(16) and R$_42$(8) rings is present (Bernstein et al., 1995); the two rings are connected via the two H atoms of the amine group of {ιt L}$_1$ that are bonded to atoms O11 of the {ιt L}$_2$ ligands (Fig. 3), the H30$χdots$O11 and H31$χdots$O11 hydrogen–acceptor distances being 2.04 and 2.01 {AA}, respectively. Details of the hydrogen-bonding geometry are given in Table 2. The carbon displacement ellipsoids of the phenyl rings show a rather pronounced anisotropy in a direction perpendicular to plane of the rings, probably due to the absence of any steric chemical constraints in that direction.

Experimental top

A solution of 4-aminopyridine (10 mg, 1.06 mmol) {ιt L}$_1$ and benzoic acid (13 mg, 1.06 mmol) {ιt L}$_2$ in methanol (1 ml) was added to a solution of CuTf$_2$ (Tf=trifluoromethanesulfonate) (19.2 mg, 0.53 mmol) in methanol (1 ml) and the mixture was heated for 2 h at 333 K. Single crystals of the {ιt L}$_1$/{ιt L}$_2$-Cu complex were obtained by slow diffusion of suspended benzene in the resulted methanol solution at room temperature (yield 20.2 mg, 86.65 °).

Refinement top

H atoms were placed geometrically and allowed to ride on their parent C and N atoms, with C—H distances of 1.00–1.09 Å and N—H distances of 0.96–0.97 Å. The partial benzene solvent molecule, which lies across a twofold rotation axis, was constrained to be a rigid planar hexagon, and the C atoms were assigned a common isotropic displacement parameter. This displacement parameter was refined for a number of values of the site occupancy; the lowest value was obtained for an a occupancy of 0.75; this value is still high, possibly due to unresolved positional disorder. However, the quality of the diffraction data did not warrant more detailed treatment of the partial solvent molecule.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis RED (Oxford Diffraction, 2002); data reduction: CrysAlis RED; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Watkin et al., 2001); molecular graphics: PLATON (Spek, 1990); software used to prepare material for publication: PLATON (Spek, 1990).

Figures top
[Figure 1] Fig. 1. : The structure of (I) showing displacement ellipsoids at the 30° probability level. [Symmetry codes: (i) −x,-y,1 − z; (ii) 1 − x, y, 1/2 − z.]
[Figure 2] Fig. 2. : Straw representation of a projection of the crystal structure of (I) on to the bc plane. The benzene molecules in the cavities left open by the ligand phenyl rings have been omitted for the sake of clarity.
[Figure 3] Fig. 3. : The R$_22$(16) and R$_42$(8) ring network in the ab plane. [Symmetry code: (i) −x,-1 − y,1 − z.]
(I) top
Crystal data top
[Cu(C7H5O2)2(C5H6N2)2]·0.75C6H6F(000) = 1146
Mr = 552.59Dx = 1.339 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2367 reflections
a = 15.010 (1) Åθ = 4.3–21.6°
b = 9.0360 (8) ŵ = 0.84 mm1
c = 20.450 (2) ÅT = 173 K
β = 98.773 (9)°Prism, translucent pale blue
V = 2741.2 (4) Å30.20 × 0.08 × 0.05 mm
Z = 4
Data collection top
Xcalibur CCD
diffractometer
4535 independent reflections
Graphite monochromator1725 reflections with I > 2u(I)
Detector resolution: 17 pixels mm-1Rint = 0.08
area detector scansθmax = 32.3°, θmin = 2.9°
Absorption correction: gaussian
Schwarzenbach & Flack (1991)
h = 2222
Tmin = 0.910, Tmax = 0.950k = 1312
50463 measured reflectionsl = 2930
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.055H-atom parameters constrained
wR(F2) = 0.139 %Tp = P(6)*max(F$_o2$,0) + (1-P(6))F$_c2$. ηfillβreak Method = SHELXL 97 (Sheldrick, 1997). ηfillηbreak W = 1.0 / [$σigma 2(F*) + (P(1)p)2 + P(2)p + P(4) + P(5)σin(τheta)$]. ηfillβreak The P(1)-P(5) are 0.0859, 0.00, 0.00, 0.00, 0.00, and 0.333 respectively.
S = 0.95(Δ/σ)max = 0.006
1725 reflectionsΔρmax = 0.51 e Å3
161 parametersΔρmin = 0.61 e Å3
17 restraints
Crystal data top
[Cu(C7H5O2)2(C5H6N2)2]·0.75C6H6V = 2741.2 (4) Å3
Mr = 552.59Z = 4
Monoclinic, C2/cMo Kα radiation
a = 15.010 (1) ŵ = 0.84 mm1
b = 9.0360 (8) ÅT = 173 K
c = 20.450 (2) Å0.20 × 0.08 × 0.05 mm
β = 98.773 (9)°
Data collection top
Xcalibur CCD
diffractometer
4535 independent reflections
Absorption correction: gaussian
Schwarzenbach & Flack (1991)
1725 reflections with I > 2u(I)
Tmin = 0.910, Tmax = 0.950Rint = 0.08
50463 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05517 restraints
wR(F2) = 0.139H-atom parameters constrained
S = 0.95Δρmax = 0.51 e Å3
1725 reflectionsΔρmin = 0.61 e Å3
161 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cu10.00000.00000.50000.0329
N20.0622 (3)0.1926 (5)0.4992 (2)0.0327
C30.1170 (4)0.2247 (6)0.5437 (3)0.0451
C40.1617 (4)0.3556 (6)0.5451 (3)0.0500
C50.1509 (4)0.4654 (6)0.4993 (3)0.0404
N60.1920 (4)0.5982 (5)0.4998 (3)0.0674
C70.0931 (4)0.4328 (6)0.4538 (3)0.0371
C80.0531 (4)0.2978 (6)0.4547 (3)0.0339
O90.0323 (2)0.0093 (4)0.59658 (15)0.0328
C100.1081 (4)0.0739 (6)0.6100 (3)0.0345
O110.1492 (3)0.1286 (4)0.56737 (19)0.0459
C120.1479 (4)0.0795 (7)0.6811 (3)0.0382
C130.2260 (6)0.1492 (12)0.7029 (4)0.1050
C140.2638 (7)0.1490 (14)0.7705 (4)0.1318
C150.2209 (5)0.0858 (11)0.8146 (3)0.0791
C160.1458 (5)0.0094 (12)0.7949 (3)0.0839
C170.1085 (4)0.0035 (9)0.7279 (3)0.0627
H260.11120.15520.58590.0500*
H270.20340.37700.57890.0500*
H300.23100.61850.53210.0500*
H290.01400.26780.41570.0500*
H280.08660.50720.41580.0500*
C180.4804 (3)0.1525 (13)0.21740 (19)0.130 (3)*0.7500
C190.4601 (4)0.0226 (12)0.1854 (2)0.130 (3)*0.7500
C200.4802 (4)0.1104 (13)0.2183 (2)0.130 (3)*0.7500
H320.46600.24980.193460.0500*0.7500
H340.46440.20660.19460.0500*0.7500
H330.42930.02280.13790.0500*0.7500
H250.25720.20360.67020.0500*
H240.32350.19720.78480.0500*
H230.24460.09640.86280.0500*
H220.11630.04510.82840.0500*
H210.05310.05670.71360.0500*
H310.18150.67370.46810.0500*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0401 (6)0.0329 (5)0.0273 (4)0.0136 (6)0.0098 (4)0.0047 (6)
N20.039 (3)0.034 (2)0.026 (2)0.010 (2)0.008 (2)0.0031 (19)
C30.057 (4)0.042 (3)0.043 (3)0.018 (3)0.027 (3)0.013 (3)
C40.059 (4)0.040 (3)0.060 (4)0.017 (3)0.035 (3)0.012 (3)
C50.043 (3)0.029 (4)0.053 (3)0.013 (2)0.018 (3)0.010 (2)
N60.080 (4)0.037 (3)0.100 (5)0.033 (3)0.060 (4)0.029 (3)
C70.036 (3)0.032 (3)0.045 (3)0.011 (3)0.012 (3)0.013 (3)
C80.034 (3)0.037 (3)0.032 (3)0.008 (3)0.007 (2)0.005 (2)
O90.036 (2)0.0370 (19)0.0265 (16)0.010 (2)0.0089 (14)0.007 (2)
C100.042 (3)0.023 (3)0.041 (3)0.013 (3)0.013 (3)0.000 (3)
O110.056 (3)0.041 (2)0.046 (2)0.002 (2)0.025 (2)0.008 (2)
C120.032 (3)0.046 (4)0.038 (3)0.002 (3)0.013 (3)0.005 (3)
C130.102 (7)0.156 (9)0.063 (5)0.081 (7)0.032 (5)0.016 (6)
C140.092 (7)0.237 (14)0.066 (6)0.098 (9)0.010 (6)0.042 (7)
C150.047 (4)0.150 (8)0.038 (4)0.011 (5)0.001 (3)0.028 (5)
C160.072 (5)0.148 (8)0.031 (3)0.021 (7)0.005 (3)0.003 (5)
C170.053 (4)0.099 (5)0.036 (3)0.028 (5)0.005 (3)0.008 (5)
Geometric parameters (Å, º) top
Cu1—O91.962 (3)C13—C141.412 (12)
Cu1—O112.706 (4)C14—C151.316 (12)
Cu1—N21.974 (5)C15—C161.331 (12)
Cu1—O9i1.962 (3)C16—C171.400 (9)
Cu1—O11i2.706 (4)C3—H261.06
Cu1—N2i1.974 (5)C4—H271.02
O9—C101.271 (7)C7—H281.04
O11—C101.245 (7)C8—H291.09
N2—C31.348 (7)C13—H251.00
N2—C81.337 (7)C14—H241.00
N6—C51.350 (7)C15—H231.00
N6—H300.96C16—H221.00
N6—H310.97C17—H211.00
C3—C41.362 (8)C18—C191.356 (14)
C4—C51.391 (8)C18—C18ii1.373 (6)
C5—C71.397 (9)C19—C201.388 (14)
C7—C81.359 (8)C20—C20ii1.341 (6)
C10—C121.486 (9)C18—H321.01
C12—C171.382 (9)C19—H331.01
C12—C131.345 (11)C20—H341.01
O9—Cu1—O1153.91 (13)C10—C12—C17120.7 (5)
O9—Cu1—N290.83 (16)C13—C12—C17116.5 (6)
O9—Cu1—O9i180.00C12—C13—C14121.6 (8)
O9—Cu1—O11i126.09 (13)C13—C14—C15120.4 (9)
O9—Cu1—N2i89.17 (16)C14—C15—C16119.9 (7)
O11—Cu1—N288.81 (15)C15—C16—C17120.7 (7)
O9i—Cu1—O11126.09 (13)C12—C17—C16120.6 (7)
O11—Cu1—O11i180.00N2—C3—H26116.06
O11—Cu1—N2i91.19 (15)C4—C3—H26118.48
O9i—Cu1—N289.17 (16)C3—C4—H27122.30
O11i—Cu1—N291.19 (15)C5—C4—H27117.91
N2—Cu1—N2i180.00C5—C7—H28119.89
O9i—Cu1—O11i53.91 (13)C8—C7—H28119.83
O9i—Cu1—N2i90.83 (16)N2—C8—H29116.22
O11i—Cu1—N2i88.81 (15)C7—C8—H29119.85
Cu1—O9—C10108.2 (3)C12—C13—H25118.74
Cu1—O11—C1074.1 (3)C14—C13—H25119.68
Cu1—N2—C3121.4 (4)C13—C14—H24119.64
Cu1—N2—C8122.4 (4)C15—C14—H24119.96
C3—N2—C8116.3 (5)C14—C15—H23119.75
C5—N6—H30119.99C16—C15—H23120.37
C5—N6—H31119.93C15—C16—H22119.41
H30—N6—H31120.07C17—C16—H22119.93
N2—C3—C4123.7 (5)C12—C17—H21119.52
C3—C4—C5119.8 (6)C16—C17—H21119.86
N6—C5—C4121.9 (6)C18ii—C18—C19120.0 (9)
C4—C5—C7116.5 (5)C18—C19—C20120.0 (5)
N6—C5—C7121.6 (5)C19—C20—C20ii120.0 (10)
C5—C7—C8119.9 (5)C19—C18—H32120.15
N2—C8—C7123.8 (6)C18ii—C18—H32119.83
O9—C10—O11123.7 (5)C18—C19—H33119.92
O9—C10—C12116.1 (5)C20—C19—H33120.10
O11—C10—C12120.2 (5)C19—C20—H34119.80
C10—C12—C13122.7 (6)C20ii—C20—H34120.19
O11—Cu1—O9—C102.0 (3)C3—N2—C8—C72.1 (8)
N2—Cu1—O9—C1089.9 (4)N2—C3—C4—C50.8 (9)
O11i—Cu1—O9—C10178.0 (3)C3—C4—C5—N6178.3 (6)
N2i—Cu1—O9—C1090.1 (4)C3—C4—C5—C70.1 (9)
O9—Cu1—O11—C102.0 (3)C4—C5—C7—C82.0 (9)
N2—Cu1—O11—C1093.9 (3)N6—C5—C7—C8179.9 (6)
O9i—Cu1—O11—C10178.0 (3)C5—C7—C8—N23.1 (9)
N2i—Cu1—O11—C1086.1 (3)O9—C10—C12—C13177.4 (7)
O9—Cu1—N2—C344.0 (4)O9—C10—C12—C177.1 (9)
O9—Cu1—N2—C8136.4 (4)O11—C10—C12—C133.7 (10)
O11—Cu1—N2—C397.9 (4)O11—C10—C12—C17171.9 (6)
O11—Cu1—N2—C882.5 (4)C17—C12—C13—C142.3 (13)
O9i—Cu1—N2—C3136.0 (4)C10—C12—C17—C16179.7 (7)
O9i—Cu1—N2—C843.6 (4)C13—C12—C17—C164.5 (11)
O11i—Cu1—N2—C382.1 (4)C10—C12—C13—C14178.0 (8)
O11i—Cu1—N2—C897.5 (4)C12—C13—C14—C153.2 (17)
Cu1—O9—C10—O114.3 (7)C13—C14—C15—C166.5 (17)
Cu1—O9—C10—C12174.7 (4)C14—C15—C16—C174.2 (15)
Cu1—O11—C10—O93.1 (5)C15—C16—C17—C121.4 (13)
Cu1—O11—C10—C12175.9 (6)C18ii—C18—C19—C201.0 (8)
C8—N2—C3—C40.1 (8)C19—C18—C18ii—C19ii1.5 (7)
Cu1—N2—C8—C7178.3 (5)C18—C19—C20—C20ii0.1 (9)
Cu1—N2—C3—C4179.7 (5)C19—C20—C20ii—C19ii0.6 (9)
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N6—H30···O11iii0.962.042.945 (7)156
N6—H31···O11iv0.972.012.943 (6)159
C3—H26···O91.062.513.040 (7)110
C8—H29···O9i1.092.533.000 (7)105
Symmetry codes: (i) x, y, z+1; (iii) x1/2, y1/2, z; (iv) x, y1, z+1.

Experimental details

Crystal data
Chemical formula[Cu(C7H5O2)2(C5H6N2)2]·0.75C6H6
Mr552.59
Crystal system, space groupMonoclinic, C2/c
Temperature (K)173
a, b, c (Å)15.010 (1), 9.0360 (8), 20.450 (2)
β (°) 98.773 (9)
V3)2741.2 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.84
Crystal size (mm)0.20 × 0.08 × 0.05
Data collection
DiffractometerXcalibur CCD
diffractometer
Absorption correctionGaussian
Schwarzenbach & Flack (1991)
Tmin, Tmax0.910, 0.950
No. of measured, independent and
observed [I > 2u(I)] reflections
50463, 4535, 1725
Rint0.08
(sin θ/λ)max1)0.751
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.139, 0.95
No. of reflections1725
No. of parameters161
No. of restraints17
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.51, 0.61

Computer programs: CrysAlis CCD (Oxford Diffraction, 2002), CrysAlis RED (Oxford Diffraction, 2002), CrysAlis RED, SIR92 (Altomare et al., 1994), CRYSTALS (Watkin et al., 2001), PLATON (Spek, 1990).

Selected bond lengths (Å) top
Cu1—O91.962 (3)Cu1—O11i2.706 (4)
Cu1—O112.706 (4)Cu1—N2i1.974 (5)
Cu1—N21.974 (5)O9—C101.271 (7)
Cu1—O9i1.962 (3)O11—C101.245 (7)
Symmetry code: (i) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N6—H30···O11ii0.962.042.945 (7)156
N6—H31···O11iii0.972.012.943 (6)159
C3—H26···O91.062.513.040 (7)110
C8—H29···O9i1.092.533.000 (7)105
Symmetry codes: (i) x, y, z+1; (ii) x1/2, y1/2, z; (iii) x, y1, z+1.
 

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