Bis(μ-hexa­deca­noato-κ2 O:O)bis­[(2,2′-bipyridine-κ2 N,N′)(hexa­deca­noato-κO)copper(II)] methanol disolvate

Ahmad Nazeer Che Mat; Norbani Abdullah; Hamid Khaledi; Jia Ti Tee

doi:10.1107/S1600536811013559

. 2011 Apr 16;67(Pt 5):m599–m600. doi: 10.1107/S1600536811013559

Bis(μ-hexadecanoato-κ² O:O)bis[(2,2′-bipyridine-κ² N,N′)(hexadecanoato-κO)copper(II)] methanol disolvate

Ahmad Nazeer Che Mat ^a, Norbani Abdullah ^a,^*, Hamid Khaledi ^a,^*, Jia Ti Tee ^a

PMCID: PMC3089362 PMID: 21754319

Abstract

The asymmetric unit of the title compound, [Cu₂(C₁₆H₃₁O₂)₄(C₁₀H₈N₂)₂]·2CH₃OH, contains one half-molecule of the metal complex solvated by a methanol molecule. In the complex, two of the metal atoms are doubly bridged by two monodentate bridging hexadecanoate ligands around a center of inversion. The square-pyramidal geometry around each Cu^II ion is completed by a terminal hexadecanoate O atom and two N atoms from a 2,2′-bipyridine ligand. The alkyl chains of the carboxylate ligands are arranged in a parallel manner with an all-trans conformation. In the crystal, a π–π interaction formed by the bipyridine rings [centroid–centroid separation = 3.7723 (17) Å] and intermolecular C—H⋯O hydrogen bonds link the complex molecules into infinite chains along the b axis. An O—H⋯O interaction between the methanol solvate and one of the carboxylate O atoms is also observed.

Related literature

For background to metallomesogens, see: Giroud-Godquin (1998 ▶). For the structures of similar copper(II) complexes, see: Antolini et al. (1985 ▶); Zhang et al. (2006 ▶). For a description of the geometry of complexes with a five-coordinate metal atom, see: Addison et al. (1984 ▶).

Experimental

Crystal data

[Cu₂(C₁₆H₃₁O₂)₄(C₁₀H₈N₂)₂]·2CH₄O
M _r = 1525.16
Triclinic,
a = 9.6064 (3) Å
b = 9.7506 (3) Å
c = 24.0234 (8) Å
α = 92.559 (2)°
β = 98.681 (2)°
γ = 95.516 (2)°
V = 2210.14 (12) Å³
Z = 1
Mo Kα radiation
μ = 0.54 mm⁻¹
T = 296 K
0.40 × 0.27 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.814, T _max = 0.953
13457 measured reflections
8088 independent reflections
5498 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.127
S = 0.99
8088 reflections
466 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811013559/om2420sup1.cif

e-67-0m599-sup1.cif^{(31.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013559/om2420Isup2.hkl

e-67-0m599-Isup2.hkl^{(395.6KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C33—H33⋯O1ⁱ	0.93	2.50	3.093 (3)	122
C33—H33⋯O3ⁱ	0.93	2.57	3.071 (3)	114
C35—H35⋯O2ⁱⁱ	0.93	2.42	3.129 (3)	134
C39—H39⋯O4ⁱⁱⁱ	0.93	2.41	3.258 (4)	152
C41—H41⋯O5^iv	0.93	2.46	3.153 (4)	131
C42—H42⋯O1	0.93	2.59	3.096 (3)	115
O5—H5⋯O2	0.86 (2)	1.89 (3)	2.732 (4)	166 (6)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

The authors thank the Malaysian government for the Fundamental Research Grant Scheme (FRGS FP046/2008, FP017/2009), and the University of Malaya Grants (RG039/09SUS, PS339/2009 C).

supplementary crystallographic information

Comment

Metallomesogens are metal containing liquid crystals. Active research in this field started around 30 years ago (Giroud-Godquin, 1998), and these materials have found useful applications as ordered solvents, catalysts, and templates for synthesis, optical and ferroelectric systems, electronic or ionic conductors, and membranes. However, most metallomesogens have high melting points (greater than 523 K), high viscosity, and narrow isotropic range. Our research group is focused on functional low-temperature and thermally stable metallomesogens for spintronic, electronic, photonic and catalytic applications. To achieve this, we applied the concept of symmetry reduction and use of ligands with long (linear or branched) alkyl chains. Herein, we report the crystal structure of one such complex.

The title compound is a centrosymmetric dinuclear copper(II) complex in which the metal ions are five-coordinate in a square-pyramidal geometry with the τ value (Addison et al., 1984) of 0.016. The coordination geometry around each metal center is defined by two nitrogen atoms from a 2,2'-bipyridine and two O atoms from two monodentate hexadecanoato ligands at the basal positions. The square-pyramidal coordination of Cu(II) is completed by bonding to the bridging hexadecanoate O atom in the axial direction with Cu—O distance of 2.349 (2) Å. Within this double bridged dimer, the Cu···Cu distance [3.3740 (6) Å] is comparable to those observed in similar structures (Antolini et al., 1985; Zhang et al., 2006). The alkyl chains of the carboxylate ligands are arranged in a parallel manner with an all trans conformation. The methanol solvent molecule is a hydrogen bond donor to the carboxylate O2 atom. In the crystal, intermolecular C—H···O interactions (Table 1) connect the molecules into infinite chains along the b axis. The one-dimensional link is supplemented by a π-π stacking interaction between the anti-parallely arranged bipyridine rings of the adjacent molecules, the pyridyl rings centroid-centroid separation being 3.7723 (17) Å. Intramolecular C—H···O interactions are also observed.

Experimental

An aqueous solution of copper(II)nitrate trihydrate (5.7 g, 23.4 mmol) was added portionwise to a hot ethanolic solution (150 ml) of hexadecanoic acid (6 g, 23.4 mmol) and p-aminobenzoic acid (3.2 g, 23.6 mmol). The green solution formed was allowed to cool to room temperature, and then an excess amount of ammonia (30%) was added. The purple solution formed was stirred at room temperature overnight, and then heated gently to remove excess ammonia and get the pale blue precipitate of [Cu₂(p-H₂NC₆H₄COO)₂(CH₃(CH₂)₁₄COO)₂]. 2,2'-Bipyridine (0.19 g, 1.2 mmol) was added to a suspension of [Cu₂(p-H₂NC₆H₄COO)₂(CH₃(CH₂)₁₄COO)₂] (1 g, 1.1 mmol) in a 1:2 mixture of methanol-ethanol (60 ml). The mixture was heated for 30 minutes and the black precipitate was filtered off. The small blue crystals obtained from the filtrate, on standing overnight, were recrystallized from methanol-THF (1:1), to give the dark blue crystals of the title compound after two weeks.