Aqua­chloridobis(diphenyl­glyoximato-κ2 N,N′)cobalt(III) dihydrate

Parthasarathy Meera; Madhavan Amutha Selvi; Arunachalam Dayalan

doi:10.1107/S1600536811014280

. 2011 Apr 22;67(Pt 5):m626–m627. doi: 10.1107/S1600536811014280

Aquachloridobis(diphenylglyoximato-κ² N,N′)cobalt(III) dihydrate

Parthasarathy Meera ^a, Madhavan Amutha Selvi ^a, Arunachalam Dayalan ^a,^*

PMCID: PMC3089102 PMID: 21754336

Abstract

The asymmetric unit of the title complex, [Co(C₁₄H₁₁N₂O₂)₂Cl(H₂O)]·2H₂O or [Co(dpgH)₂Cl(H₂O)]·2H₂O, where dpgH⁻ is diphenyl glyoximate, consists of one-half of a [Co(dpgH)₂Cl(H₂O)] complex and one solvent water molecule. The complex is completed through inversion symmetry, with the Co^III atom situated at the centre of symmetry. The coordination geometry around the Co^III atom is distorted octahedral with the four N atoms of the two dpgH⁻ ligands forming an approximate square plane with N—Co—N bite angles of 81.13 (14) and 98.87 (14)°. The Cl⁻ ligand and the water molecule are disordered in a 1:1 ratio and are in the axial positions, almost perpendicular to the plane of the glyoximate ligands [O—Co—Cl = 175.3 (10)°]. The two glyoximate ligands are linked by strong intramolecular O—H⋯O hydrogen bonds. In addition, O—H⋯O interactions involving the solvent water molecules and O—H⋯N hydrogen-bonding interactions are also observed. The solvent water molecule is disordered over five positions with different occupancies.

Related literature

For related complexes, see: Gupta et al. (2003 ▶); Randaccio (1999 ▶); Brown & Satyanarayana (1992 ▶); Gilaberte et al. (1988 ▶). For the nature of equatorial ligands, see: Varhelyi et al. (1999 ▶). For similar structures, see: Meera et al. (2009 ▶). For details of the synthesis, see: Toscano et al. (1983 ▶); Gupta et al. (2001 ▶). For spectroscopic studies related to the complex, see: Gupta et al. (2004 ▶); Lopez et al. (1992 ▶); Silverstein & Bassler (1984 ▶); Mandal & Gupta (2005 ▶).

Experimental

Crystal data

[Co(C₁₄H₁₁N₂O₂)₂Cl(H₂O)]·2H₂O
M _r = 626.92
Monoclinic,
a = 12.0709 (4) Å
b = 5.9689 (2) Å
c = 21.9224 (5) Å
β = 104.770 (1)°
V = 1527.32 (8) Å³
Z = 2
Mo Kα radiation
μ = 0.70 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1999 ▶) T _min = 0.761, T _max = 0.861
13610 measured reflections
2682 independent reflections
2431 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.199
S = 1.25
2682 reflections
215 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.92 e Å⁻³
Δρ_min = −0.53 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811014280/wm2477sup1.cif

e-67-0m626-sup1.cif^{(20.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811014280/wm2477Isup2.hkl

e-67-0m626-Isup2.hkl^{(131.7KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Co1—N2ⁱ	1.891 (3)
Co1—N1ⁱ	1.894 (3)
Co1—O3	1.95 (3)
Co1—Cl1	2.214 (11)

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Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯O1ⁱ	0.82	1.68	2.477 (4)	162
O2—H2A⋯N1ⁱ	0.82	2.40	2.999 (4)	130
O4A⋯O3ⁱⁱ			2.592 (4)

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

Acknowledgments

The authors are thankful to Rev. Dr B. Jeyaraj, S. J., Principal, Loyola College (Autonomous), Chennai 34, India, for providing the necessary facilities, the Head, SAIF, CDRI, Lucknow, India, for supplying elemental data, and the Head, SAIF, IIT Madras, Chennai 36, India, for recording NMR spectra and for X-ray data collection.

supplementary crystallographic information

Comment

The dioxime complexes of cobalt(III), known as cobaloximes, and their derivatives have been found to mimic vitamin-B₁₂ coenzyme. The studies on steric and electronic effects of cobaloximes helped in the successful design of novel derivatives with desired properties (Gupta et al., 2003; Randaccio, 1999; Brown & Satyanarayana, 1992; Gilaberte et al., 1988). Among the stereoisomeric benzildioximes (syn, amphi, anti), only the anti isomer shows chelation properties towards transition metal ions (Varhelyi et al., 1999).

In the structure of the title compound, [Co(C₁₄H₁₁N₂O₂)₂Cl(H₂O)]^.2H₂O, or [Co(dpgH)₂Cl(H₂O)]^.2H₂O, where dpgH^- = diphenyl glyoximate, two halves of the complex molecule are related through inversion symmetry with Co^III situated at the centre of symmetry. The coordination geometry around Co^III is a slightly distorted octahedron (Fig. 1) with the four N atoms of the dpgH^- ligand forming an approximate square plane. The bite angles N1—Co—N2 of the equatorial ligands are 81.13 (14) and 98.87 (14)°, respectively. The Cl^- ligand and the water molecule are in axial positions and are disordered in a 1:1 ratio. They are almost perpendicular to the plane containing the equatorial dpgH^- ligand (O3—Co1—Cl1 = 175.3 (10)°). The two glyoximate ligands are linked by strong intramolecular O—H···O hydrogen bonds. In addition, O1—H1···N2 hydrogen bonding interaction is also observed (Fig. 2). A similar interaction was observed for a related complex (Meera et al., 2009). The lattice water molecule (O4) is disordered over five positions with different occupancies. Although the H positions of the disordered water molecules could not be located, close O···O interactions suggest likewise an involvement in hydrogen bonding (Table 2).

Experimental

Cobalt(II) chloride hexahydrate was thoroughly ground and mixed with diphenylglyoxime in a 1:2 molar ratio in an aqueous solution of acetone. The reaction mixture was stirred for five hours at an elevated temperature (Toscano et al., 1983; Gupta et al., 2001). The resulting brown mass was filtered, washed with acetone, ether and dried in a desiccator. Brown coloured crystals appeared in two to three days on slow evaporation of the saturated solution of the complex in ethanol. Elemental analysis, obtained by analytical method, agreed well with the theoretical data expected for the formula of the complex, C₂₈H₂₈N₄O₇ClCo. Anal., % (calc., %): C 53.97 (53.58); H 4.94 (4.47); N 9.05 (8.93). The C═N stretching vibration of oxime in its complex was observed at 1385 cm^-1 and the intramolecular hydrogen bonded –OH around 3140 cm^-1. A moderate peak around 1090 cm^-1 may be assigned to the C=N—O stretching of the oxime. The band around 540 cm^-1 could be attributed to cobalt(III)-nitrogen stretching. The ¹H NMR spectrum of the complex in acetone-d₆ shows three different signals corresponding to the three different aromatic protons of the diphenylglyoximate (Gupta et al., 2004; Lopez et al., 1992). The H atoms in the second and the sixth position of the benzene ring of the diphenylglyoximate show a doublet at 7.2 p.p.m., while the third and fifth H atoms show a triplet at 7.4 p.p.m.. Similarly, the fourth one gives a triplet at 7.3 p.p.m..The oxime –OH protons resonate at 9.1 p.p.m.. A singlet around 8.5 p.p.m. represents the protons of the –OH group of the aqua ligand (Silverstein & Bassler, 1984; Mandal & Gupta, 2005).