Aqua­bromidobis(dimethyl­glyoximato)cobalt(III)

Parthasarathy Meera; Madhavan Amutha Selvi; Pachaimuthu Jothi; Arunachalam Dayalan

doi:10.1107/S1600536811008877

. 2011 Mar 15;67(Pt 4):m442–m443. doi: 10.1107/S1600536811008877

Aquabromidobis(dimethylglyoximato)cobalt(III)

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

PMCID: PMC3099747 PMID: 21753964

Abstract

In the title complex, [CoBr(C₄H₇N₂O₂)₂(H₂O)], a crystallographic mirror plane bisects the molecule, perpendicular to the glyoximate ligands. The geometry around the cobalt(III) atom is approximately octahedral with the four glyoximate N atoms forming the square base. A bromide ion and the O atom of a water molecule occupy the remaining coordination sites. The N—Co—N bite angles are 82.18 (4) and 80.03 (16)°. The glyoximate moieties form strong intramolecular O—H⋯O hydrogen bonds. The coordinated water molecule forms an intermolecular O—H⋯O hydrogen bond with a glyoximate O atom, thereby generating supramolecular chains parallel to [010].

Related literature

For related complexes, see: Ohkubo & Fukuzumi (2005 ▶); Randall & Alberty (1970 ▶); Schrauzer (1968 ▶); Trommel et al. (2001 ▶). For similar structures, see: Bernstein et al. (1995 ▶); Mégnamisi-Bélombé et al. (1983 ▶); Meera et al. (2009 ▶); Ramesh et al. (2008 ▶). For the preparation of similar complexes, see: Vijayraghavan & Dayalan (1992 ▶). For spectroscopic studies related to the title complex, see: Folgando et al. (1986 ▶); Khan et al. (1997 ▶); Lopez et al. (1986 ▶).

Experimental

Crystal data

[CoBr(C₄H₇N₂O₂)₂(H₂O)]
M _r = 387.09
Monoclinic,
a = 7.5903 (3) Å
b = 8.8816 (4) Å
c = 10.5343 (5) Å
β = 96.137 (3)°
V = 706.09 (5) Å³
Z = 2
Mo Kα radiation
μ = 4.07 mm⁻¹
T = 293 K
0.15 × 0.10 × 0.10 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker 1999 ▶) T _min = 0.581, T _max = 0.687
7395 measured reflections
1480 independent reflections
1298 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.096
S = 1.22
1480 reflections
101 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.01 e Å⁻³
Δρ_min = −0.54 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus and XPREP (Bruker, 2004 ▶); 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/S1600536811008877/fj2399sup1.cif

e-67-0m442-sup1.cif^{(15.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811008877/fj2399Isup2.hkl

e-67-0m442-Isup2.hkl^{(73KB, 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
O2—H2⋯O1ⁱ	0.92 (1)	1.58 (1)	2.494 (3)	169 (4)
O3—H3⋯O1ⁱⁱ	0.85 (3)	1.79 (3)	2.616 (3)	167 (4)

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

Acknowledgments

The authors are thankful to Rev. Fr B. Jeyaraj, SJ, Principal, Loyola College (Autonomous), Chennai, India, for providing the necessary facilities, the Head, SAIF, CDRI, Lucknow, India, for supplying the elemental data and the SAIF, IIT Madras, Chennai, India, for recording the ¹HNMR spectra and for the X-ray data collection.

supplementary crystallographic information

Comment

A number of cobalt complexes have been proposed as model systems for vitamin-B₁₂(Trommel et al., 2001; Ohkubo & Fukuzumi, 2005). The most commonly mentioned model system is bis(dimethylglyoximato)cobalt(III) complexes on which Schrauzer has carried out a great amount of research.The common feature of the different models is that each possesses a strong equatorial ligand field (Schrauzer,1968). A variety of cobalt(III) complexes have been discovered possessing stable axial cobalt-carbon bonds. Simple alkyl cobaloximes, are thermally stable upto about 200°C and are therefore among the most stable organo metallic compounds known. Halide ions can coordinate to cobalt(III) as other common anionic ligands. Cobalt(III) complexes, being low spin, are conveniently studied in aqueous medium (Randall & Alberty, 1970). We report here the synthesis and X-ray crystal structure of the title compound.

The geometry around the cobalt(III) is approximately octahedral with the four glyoximate N atoms forming the square base;whereas, the coordinated bromide (Br1) and oxygen (O3) and the coordinated oxygen of water form the apex. The bite angles of the glyoximates with cobalt are N(1)#1-Co(1)—N(1) 82.18 (14)° and N(2)#1-Co(1)—N(2) 80.03 (03)°, respectively. Further N(1)#1-Co(1)—N(2)#1 178.29 (10)° confirms the distorted octahedral geometry of the molecule. The bond lengths Co(1)—N(1)#1, 1.883 (2) Å,Co(1)—N(2)#1, 1.911 (2) Å agree well with the previously reported structures (Meera et al., 2009, Ramesh et al., 2008) and the axial Co–Br distance d(Co1–Br1) = 2.3563 (6)Å agrees well with the reported structure of trans-aquabromobis[ethanedial dioximato(1-)-N,N']cobalt(III)(Mégnamisi-Bélombé et al., 1983). The glyoximate moieties are further bound by strong intraomecular O—H···O hydrogen bonds showing an S(6) ring motif (Bernstein et al., 1995). Thecoordinated water forms an intermolecular hydrogen bond O3—H3···O1ⁱⁱ[symmetry code (ii): -x + 1, y - 1/2, -z + 1] with the glyoximate oxygen atoms which links the inversion related title compound thus forming a ring motif of R₂²(10). Fused rings of R₂²(10) generates a supramolecular one dimensional chain extending parallel to [010] direction. The structure is further stabilized through van der waals interaction.

Experimental

Cobalt(II) bromide hexahydrate was thoroughly grinded and exposed to microwave for 30 s.The dehydrated cobalt(II) bromide was mixed with dimethylglyoxime in 1:2 molar ratio in acetone medium and allowed to stir for an hour (Vijayraghavan & Dayalan, 1992). The dibromo complex obtained was filtered dried and then it was refluxed with water for two hours. The resulting brown mass was filtered washed with ether and dried over desiccator. The elemental analysis data, obtained by analytical methods agree well with the theoretical data expected for the formula of the complex, C₈H₁₆N₄O₅BrCo proposed viz.,[Co(dmgH)₂(H₂O)Br]: Anal,% (cald,%): C, 25.12(24.8); H,4.82(4.13); N,14.50(14.47). The C=N stretching vibration of oxime in its complex was observed at 1580 cm^-1 and the intra molecular hydrogen bonded OH around 3100 cm^-1. A moderate peak around 1070 cm^-1 may be assigned to the C=N—O stretching of the oxime. The peak around 510 cm^-1 could be attributed to cobalt(III)-nitrogen stretching (Khan et al., 1997; Folgando et al., 1986). The ¹H NMR spectra of the complex in DMSO-d₆ shows a sharp intense singlet at 2.3 p.p.m. corresponding to methyl protons of the oxime.The oxime –OH resonates at 13.08 p.p.m..A singlet around 8.5 ppm represents the –OH of the aquo ligand (Lopez et al., 1986).