Bis(2-methyl­benzoato-κ2 O,O′)(1,10′-phenanthroline-κ2 N,N′)copper(II)

Sheng-Liang Ni; Feng Zhou; Jin-Li Qi

doi:10.1107/S1600536811018162

. 2011 May 20;67(Pt 6):m779. doi: 10.1107/S1600536811018162

Bis(2-methylbenzoato-κ² O,O′)(1,10′-phenanthroline-κ² N,N′)copper(II)

Sheng-Liang Ni ^a,^*, Feng Zhou ^a, Jin-Li Qi ^a

PMCID: PMC3120328 PMID: 21754662

Abstract

In the title compound, [Cu(C₈H₇O₂)₂(C₁₂H₈N₂)], the Cu^II atom assumes a distorted octahedral coordination geometry, chelated by two N atoms from the 1,10′-phenanthroline ligand and four O atoms from two 2-methylbenzoate anions. A significant Jahn–Teller distortion is observed with two axial Cu—O distances significantly longer than those in the equatorial CuO₂N₂ plane. In the crystal, π–π stacking interactions, with centroid–centroid distances of 3.547 (3) or 3.728 (3) Å between the phenanthroline rings, form layers parallel to (011).

Related literature

For Jahn–Teller distortions in copper complexes, see: Yang & Vittal (2003 ▶); Su et al. (2005 ▶); Liu et al. (2010 ▶). For phenanthroline complexes, see: Wang et al. (1996 ▶); Wall et al. (1999 ▶); Naing et al. (1995 ▶). For related structures, see: Cano et al. (1997 ▶); Rodrigues et al. (1999 ▶) Xu & Xu (2004 ▶).

Experimental

Crystal data

[Cu(C₈H₇O₂)₂(C₁₂H₈N₂)]
M _r = 514.02
Monoclinic,
a = 16.245 (3) Å
b = 10.136 (2) Å
c = 14.048 (3) Å
β = 99.15 (3)°
V = 2283.7 (8) Å³
Z = 4
Mo Kα radiation
μ = 1.00 mm⁻¹
T = 293 K
0.15 × 0.10 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.866, T _max = 0.900
17441 measured reflections
4021 independent reflections
2509 reflections with I > 2σ(I)
R _int = 0.063

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.150
S = 1.13
4021 reflections
319 parameters
H-atom parameters constrained
Δρ_max = 0.74 e Å⁻³
Δρ_min = −1.04 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 ▶); 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: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811018162/sj5144sup1.cif

e-67-0m779-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811018162/sj5144Isup2.hkl

e-67-0m779-Isup2.hkl^{(197.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Cu—O3	1.919 (4)
Cu—O1	1.927 (4)
Cu—N2	2.010 (4)
Cu—N1	2.025 (4)

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Acknowledgments

This project was supported by the Foundation of the Education Department of Zhejiang Province (ZC200805662).

supplementary crystallographic information

Comment

The Jahn-Teller distortion of copper(II) complexes is well known. Most copper(II) complexes display an elongated distortion, and the coordinate bonds in the axial direction are usually longer than those in the equatorial coordination plane by 0.2–0.6 Å (Yang & Vittal, 2003; Su et al., 2005; Liu et al., 2010). Metal-phenanthroline complexes and their derivatives have also attracted much attention (Wang et al., 1996; Wall et al., 1999; Naing et al., 1995). In the title copper(II) phenanthroline complex, (I), a pair of long Cu-O bonds is observed.

The molecular structure of the title complex is shown in Fig. 1. The Cu^II ion binds to a phenanthroline molecule and two 2-methylbenzoate anions in a distorted octahedral geometry. Two N atoms from phen and two O atoms from carboxyl groups form a tetrahedrally distorted equatorial coordination plane, with a dihedral angle of 7.3 (2) ° between the Cu/O1/O3 and Cu/N1/N2 planes. The bond lengths in the equatorial plane are normal (Table 1). In the axial direction, the Cu-O distances (Cu-O2 2.609 (4) Å, Cu-O4 2.666 (4) Å) are longer than the Cu-O distances(Cu-O1 1.927 (4) Å, Cu-O3 1.919 (4) Å) equatorial plane.

The Cu-O-C angles of (Cu-O1-C13 105.9 (3) °, Cu-O3-C21 108.2 (3) °) are similar to values found in copper(II) complexes with a chelating benzoate ligand, for example, 106.1 (4) ° (Cano et al., 1997) and 104.5 (1) ° (Xu & Xu, 2004), but are much smaller than those in copper(II) complexes with a monodentate benzoate ligand, for example, 131.8 (1) ° (Rodrigues et al., 1999). This suggests the existence of a bonding interaction between atoms Cu and O2, Cu and O4. Besides the elongated Jahn-Teller distortion, the smaller O2-Cu-O4 angle of 132.1 (1) Å is also a possible reason for the larger differences within the same carboxylate group.

In the crystal structure two-dimensional layers form parallel to (011) through π–π packing interactions with centroid to centroid distances 3.547 (3) Å and 3.728 (3) Å between the phenanthroline rings, as shown in Fig. 2.

Experimental

Freshly prepared CuCO₃ was essential for an optimal synthesis. 1.0 cm³ (1 M) aqueous Na₂CO₃ was added dropwise to a stirred aqueous solution of (0.2490 g, 1.0 mmol)CuSO₄.5H₂O in 4 cm³ of doubly distilled water. This produced a blue precipitate, of Cu(OH)_2-2x(CO₃)_x.yH₂O, which was centrifuged and washed with doubly distilled water until no SO₄^-2 anions were detected in the supernatant liquid. The fresh blue precipitate was subsequently added to a stirred solution of 2-methylbenzoic acid (0.2725 g, 2.0 mmol) and 1,10'-phenanthroline (0.1982 g, 1.0 mmol) in 20 cm³ C₂H₅OH-H₂O (1:1, v/v). The mixture was stirred for 30 min and filtered. The insoluble solid was then filtered off, and the resulting blue filtrate (pH = 5.20) was allowed to stand at room temperature. Blue block-like crystals were grown by slow evaporation over a week. Yield: 45% based on the initial CuSO₄.5 H₂O.