Crystal structure of bis­[μ-S-hexyl 3-(2-oxido­benzyl­idene)di­thio­carbazato-κ4 O,N 3,S:O]dicopper(II)

M S Begum; M B H Howlader; M C Sheikh; R Miyatake; E Zangrando

doi:10.1107/S2056989015022914

. 2015 Dec 9;71(Pt 12):m249–m250. doi: 10.1107/S2056989015022914

Crystal structure of bis[μ-S-hexyl 3-(2-oxidobenzylidene)dithiocarbazato-κ⁴ O,N ³,S:O]dicopper(II)

M S Begum ^a, M B H Howlader ^a,^*, M C Sheikh ^b, R Miyatake ^c, E Zangrando ^d

PMCID: PMC4719858 PMID: 26870449

Abstract

The title compound, [Cu₂(C₁₄H₁₈N₂OS₂)₂], is a binuclear copper(II) complex of an oxybenzylidenedithiocarbazate ligand. The ligand coordinates in a tridentate manner through N-, S- and O-donor atoms. Each O atom also bridges to a second Cu^II ion to form the binuclear species. It has a central Cu₂O₂ rhomboid moiety and a metal-to-metal separation of 2.9923 (6) Å. In the crystal, the binuclear complexes stack along the a axis with all the hexyl chains located side-by-side, forming a hydrophobic region. The complexes are linked via C—H⋯N hydrogen bonds, forming chains along the c-axis direction. One Cu^II atom has the S atom of a symmetry-related complex located approximately in the apical position at 2.9740 (11) Å. This weak interaction links the chains to form slabs parallel to the ac plane.

Keywords: crystal structure, Schiff base, binuclear copper(II) complex, dithiocarbazate ligand

Related literature

For details of the bioactivities of metal complexes of bidentate Schiff bases of S-methyl or S-benzyl dithiocarbazate ligands, see: Chan et al. (2008 ▸); How et al. (2008 ▸); Ali et al. (2002 ▸); Chew et al. (2004 ▸). For square-planar metal complexes of dithiocarbazate ligands coordinating in a bidentate manner, see: Tarafder et al. (2008 ▸); Howlader et al. (2015 ▸); Begum et al. (2015 ▸). For Cu—N and Cu—S bond lengths in mononuclear bis-chelated species, see: Zangrando, Begum et al. (2015 ▸); Zangrando, Islam et al. (2015 ▸). For copper(II) complexes of similar ligands, see: Ali, Tan et al. (2012 ▸); Ali, Mirza et al. (2012 ▸). graphic file with name e-71-0m249-scheme1.jpg

Experimental

Crystal data

[Cu₂(C₁₄H₁₈N₂OS₂)₂]
M _r = 715.93
Monoclinic,
a = 7.2792 (4) Å
b = 37.7252 (16) Å
c = 11.3443 (5) Å
β = 94.701 (2)°
V = 3104.8 (3) Å³
Z = 4
Mo Kα radiation
μ = 1.67 mm⁻¹
T = 173 K
0.36 × 0.34 × 0.03 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▸) T _min = 0.723, T _max = 0.951
12702 measured reflections
5278 independent reflections
5114 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.027
wR(F ²) = 0.066
S = 1.06
5278 reflections
361 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.60 e Å⁻³
Δρ_min = −0.29 e Å⁻³
Absolute structure: Flack x determined using 2223 quotients [(I ⁺)−(I ⁻)]/[(I ⁺)+(I ⁻)] (Parsons et al., 2013 ▸)
Absolute structure parameter: 0.006 (6)

Data collection: RAPID-AUTO (Rigaku, 2001 ▸); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: CrystalStructure (Rigaku, 2010 ▸); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989015022914/su5246sup1.cif

e-71-0m249-sup1.cif^{(204.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015022914/su5246Isup2.hkl

e-71-0m249-Isup2.hkl^{(420KB, hkl)}

Click here for additional data file.^{(37.2KB, tif)}

. DOI: 10.1107/S2056989015022914/su5246fig1.tif

A view of the molecular structure of the title complex, with atom labelling. The displacement ellipsoids are drawn at the 50% probability level.

Click here for additional data file.^{(1.2MB, tif)}

c i x y z . DOI: 10.1107/S2056989015022914/su5246fig2.tif

A view along the c axis of the crystal packing of the title complex. Dotted lines indicated the Cu2—S2ⁱ distances of 2.9740 (11) Å [symmetry code: (i) x − Inline graphic , −y + , z + ], and H atoms have been omitted for clarity.

CCDC reference: 1439650

Additional supporting information: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C19—H19⋯N2ⁱ	0.95	2.52	3.457 (5)	167

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

MSB and MBHH are grateful to the Department of Chemistry, Rajshahi University, for the provision of laboratory facilities. MCS acknowledges the Department of Applied Chemistry, Toyama University, for providing funds for single-crystal X-ray analyses.

supplementary crystallographic information

S1. Comments

Metal complexes of bidentate Schiff bases of S-methyl or S-benzyl dithiocarbazates have received considerable attention for their possible bioactivities (Chan et al., 2008; How et al., 2008; Ali et al., 2002; Chew et al., 2004). In square planar metal complexes reported so far dithiocarbazato ligands coordinate in a bidentate manner through the N,S donors leading to bischelated species with a trans (Howlader et al., 2015) or cis (Begum et al., 2015) configuration. The presence of an oxobenzylidene moiety is expected to induce the ligand to coordinate to the metal through the N,S,O donors. Continuing our studies on S-containing Schiff bases (Howlader et al., 2015; Begum et al., 2015), we report herein on the crystal structure of an unexpected binuclear copper(II) complex of the ligand S-hexyl-β-N-(2-hydroxybenzylidene)dithiocarbazate.

In the title compound, Fig. 1, the presence of the oxobenzylidene moiety in the Schiff base ligand has induced it to coordinate to the metal through the N, S, and O donor atoms, with formation of five- and six-membered chelate rings. Each oxygen atom bridges to a second copper(II) ion to form a binuclear species having a central Cu₂O₂ rhomboid moiety. The bridging angles Cu1—O1—Cu2 and Cu1—O2—Cu2 of 99.23 (12) and 99.69 (12) °, respectively, lead to a metal-metal separation of 2.9923 (6) Å. The Cu—N bond distances of 1.919 (4) and 1.931 (4) Å, and the Cu—S bond distances of 2.2171 (10) and 2.2352 (11) Å, appear slightly shorter by ca. 0.02-0.04 Å than those observed in mononuclear bischelated species (Zangrando, Begum, et al., 2015; Zangrando, Islam, et al., 2015; Tarafder et al., 2008). This feature can be ascribed to the double deprotonated ligand in the present case. With exception of the alkyl chains the two chelating ligands have almost coplanar atoms and their mean plane forms a dihedral angle of 34.45 (9)°. It is worth noting that the alkyl chain C23—C28 presents all methylene groups in an anti conformation, while the other chain presents a torsion angle C10—C11—C12—C13 of 62.1 (6)°, likely induced by packing requirements. To the best of our knowledge the present complex represents a unique example of a binuclear species with similar tridentate S,N,O ligands derived from S-alkyldithiocarbazate, although copper complexes of similar ligands have been reported (Ali, Tan et al., 2012; Ali, Mirza et al., 2012).

In the crystal, the binuclear complexes stack along the a axis with all the hexyl chains located side-by-side forming a hydrophobic region. The complexes are linked via C—H···N hydrogen bonds forming chains along the c axis direction (Table 1). Atom Cu2 has the sulfur atom, S2ⁱ [code: (i) x - 1/2, -y + 3/2, z+ 1/2], of a symmetry-related complex located approximately in the apical position at 2.9740 (11) Å (Fig. 2). This weak interaction links the chains to form slabs parallel to the ac plane.

S2. Synthesis and crystallization

A solution of Cu(CH₃COO)₂.H₂O (0.11 g, 0.5 mmol, 15 ml methanol) was added to a solution of the S-hexyl-β-N-(2-hydroxybenzylidene)dithiocarbazate (1.0 mmol, 10 ml methanol). The resulting mixture was stirred at room temperature for 5 h. A dark reddish brown precipitate was formed, filtered off, washed with methanol and dried in vacuo over anhydrous CaCl₂. Dark reddish brown single crystals suitable for X-ray diffraction were obtained by slow evaporation from a mixture of dichloromethane and acetonitrile (3:1); m.p. 443 K.

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were fixed geometrically (C—H = 0.95 - 0.99 Å) and refined as riding with U_iso(H) = 1.2U_eq(C).