Dibromidobis(1-ethyl-2,6-dimethyl­pyridinium-4-olate-κO)zinc(II)

M Thenmozhi; A Philominal; S Dhanuskodi; M N Ponnuswamy

doi:10.1107/S1600536810052190

. 2010 Dec 18;67(Pt 1):m103–m104. doi: 10.1107/S1600536810052190

Dibromidobis(1-ethyl-2,6-dimethylpyridinium-4-olate-κO)zinc(II)

M Thenmozhi ^a, A Philominal ^b, S Dhanuskodi ^b, M N Ponnuswamy ^a,^*

PMCID: PMC3050368 PMID: 21522518

Abstract

In the bioactive title compound, [ZnBr₂(C₉H₁₃NO)₂], the Zn^II atom is coordinated in a distorted tetrahedral arrangement by two Br⁻ anions and the O atoms of two zwitterionic organic ligands. The pyridinium rings are almost planar [maximum deviations = 0.004 (4) and 0.003 (4) Å]. The ethyl groups are approximately perpendicular to the corresponding pyridinium ring planes [N—C—C—C = 88.8 (4)° in each ligand]. The packing of the molecules is controlled by π–π interactions, with centroid–centroid distances of 3.625 (3) and 3.711 (2) Å, forming chains approximately parallel to (102). The crystal studied was non-merohedrally twinned (twin relationship between the domains 1 0 0, 0 1 0, −0.4672 −0.1864 −1 and batch scale factor of 7.39%).

Related literature

For general background to pyridinium compounds and their applications, see: Darensbourg et al. (2003 ▶); Dhanuskodi et al. (2006 ▶); Glavcheva et al. (2004 ▶); Lakshmanaperumal et al. (2002 ▶, 2004 ▶); Usman et al. (2000 ▶, 2001 ▶); Mootz & Wusson (1981 ▶). For their biological activity, see: Akkurt et al. (2005 ▶). For related structures, see: Thenmozhi et al. (2010 ▶); Mootz & Wusson (1981 ▶); Sundar et al. (2004 ▶). For the preparation of the ligand, see: Garratt (1963 ▶).

Experimental

Crystal data

[ZnBr₂(C₉H₁₃NO)₂]
M _r = 527.60
Triclinic,
a = 8.462 (1) Å
b = 8.518 (1) Å
c = 14.418 (3) Å
α = 93.131 (6)°
β = 97.871 (7)°
γ = 90.210 (8)°
V = 1027.9 (2) Å³
Z = 2
Mo Kα radiation
μ = 5.10 mm⁻¹
T = 293 K
0.12 × 0.11 × 0.11 mm

Data collection

Bruker Kappa APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ▶) T _min = 0.580, T _max = 0.604
16553 measured reflections
16553 independent reflections
13614 reflections with I > 2σ(I)

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.189
S = 1.06
16553 reflections
233 parameters
H-atom parameters constrained
Δρ_max = 1.20 e Å⁻³
Δρ_min = −0.95 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810052190/sj5050sup1.cif

e-67-0m103-sup1.cif^{(20.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810052190/sj5050Isup2.hkl

e-67-0m103-Isup2.hkl^{(809KB, hkl)}

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

Table 1. Selected bond lengths (Å).

O1—Zn1	1.957 (3)
O2—Zn1	1.976 (3)
Zn1—Br2	2.3501 (8)
Zn1—Br1	2.3635 (8)

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Acknowledgments

MT and AP thank the UGC for financial support in the form of a Research Fellowship in Science for Meritorious Students.

supplementary crystallographic information

Comment

Pyridinium derivatives are found to possess nonlinear optical properties (Lakshmanaperumal et al., 2002, 2004; Usman et al., 2000, 2001). When pyridinium cations are combined with metal halide anions, the refractive indices of the crystals could be tuned due to exchangeability of metal and halogen species within the anions (Glavcheva et al., 2004). Halide anions have been reported to improve the physicochemical stability of 1-ethyl-2, 6-dimethyl-4-(1H)- pyridinones (Dhanuskodi et al., 2006). Reactions of zinc halides with pyridines lead to a variety of complexes involving zinc centers and were shown to be catalytically active (Darensbourg et al., 2003). Pyridinium derivatives also exhibit antibacterial and antifungal activities (Akkurt et al., 2005). As a part of our interest in the bioactivity of pyridinium complexes, we report here the crystal structure of the title compound, Fig. 1.

The bromidozinc complex is similar to the related chlorido complex, bis(1-ethyl-2,6-dimethylpyridinium-4-oxide-κO)dichloridozinc(II) (Thenmozhi et al., 2010). The pyridinium rings are planar and oriented at an angle of 34.4 (2)° to one another. The Zn^II atom is coordinated in a distorted tetrahedral arrangement by two halide ions and two zwitterionic pyridinium oxide ligands. The pyridinium rings assume a substantial degree of quinoidal character, which is reflected in the variation of bond lengths (Sundar et al., 2004). The ethyl groups attached at N1 and N11 are approximately perpendicular to pyridinium ring, which can be observed from the torsion angles [C8-C7-N1-C2 = -88.5 (6)°; C18-C17-N11-C12 = 87.6 (5)°]. The methyl substituents at C2, C6, C12 and C16 are nearly coplanar with the corresponding pyridinium rings, which is evident from the torsion angles [C9-C2-N1-C6 = 178.0 (4)°; C10-C6-N1-C2 = -178.4 (4)°; C19-C12-N11-C16 = 179.9 (4)°; C20-C16-N11-C12 = -178.2 (4)°]. Due to protonation of N1 and N11 atoms of the pyridinium rings, the C2-N1-C6 and C12-N11-C16 angles [Table 1] are widened in comparison with the literature value (Mootz & Wusson, 1981). The sum of the bond angles around the protonated nitrogen atoms N1[359.8°] and N11[360.0°] of both the pyridinium rings is in accordance with sp² character.

The packing of the molecules is reinforced by π-π intermolecular interactions. [Cg1···Cg1(2-x, 1-y, -z) = 3.625 (3)Å; where Cg1 is the centroid of the (N1-C6) ring] and [Cg2···Cg2(1-x, 1-y, 1-z) = 3.711 (2)Å; where Cg2 is the centroid of the (N11-C16) ring]. The π–π interactions generate infinite continuous chains approximately parallel to (102), Fig.2.

Experimental

The complex was prepared by the reaction of ZnBr₂with 1-ethyl-2, 6-dimethyl -4(1H) pyridinone trihydrate (EDMP.3H₂O) in a 1:2 molar ratio in aqueous medium. The starting material EDMP.3H₂O had been prepared by the reported synthetic method (Garratt et al., 1963). The salts were further purified by the repeated recrystallization in triple distilled water. The solubility test of the salts were carried out by mass gravimetric method in the temperature range 30°-55°C and water is the suitable solvent for the growth of good quality crystals. Single crystals of (EDMP)₂ZnBr₂ were harvested after a typical growth period of 15 days from the saturated aqueous solution at 30°C by the slow evaporation of the solvent.