Diacridinium trans-diaqua­bis(pyrazine-2,3-dicarboxyl­ato)cobaltate(II) hexa­hydrate

Hossein Aghabozorg; Jafar Attar Gharamaleki; Mahdieh Parvizi; Zohreh Derikvand

doi:10.1107/S1600536809053628

. 2009 Dec 19;66(Pt 1):m83–m84. doi: 10.1107/S1600536809053628

Diacridinium trans-diaquabis(pyrazine-2,3-dicarboxylato)cobaltate(II) hexahydrate

Hossein Aghabozorg ^a,^*, Jafar Attar Gharamaleki ^b, Mahdieh Parvizi ^a, Zohreh Derikvand ^c

PMCID: PMC2980003 PMID: 21579976

Abstract

The title compound, (C₁₃H₁₀N)₂[Co(C₆H₂N₂O₄)₂(H₂O)₂]·6H₂O, consists of mononuclear trans-[Co(pz-2,3-dc)₂(H₂O)₂]²⁻ complex anions, (acrH)⁺ cations and uncoordinated water molecules (acr is acridine and pz-2,3-dcH₂ is pyrazine-2,3-dicarboxylic acid). The Co^II atom, which lies on a crystallographic center of symmetry, has a slightly distorted octahedral coordination environment, with two N and two O atoms from the (pz-2,3-dc)²⁻ ligands in the equatorial plane and with two water molecules in axial positions. In the crystal, the components are held together by two distinct N—H⋯O and C—H⋯O hydrogen bonds with R ₂ ²(8) graph-sets. The coordinated and uncoordinated water molecules are also involved in O—H⋯O hydrogen bonds, which lead to the formation of layers with R ₃ ³(12) graph-set motifs. Extensive π–π stacking interactions between parallel aromatic rings of the acridinium ions, with distances ranging from 3.533 (1) to 3.613 (1) Å, occur in the structure.

Related literature

For the crystal structure of pyrazine-2,3-dicarboxylic acid (pz-2,3-dcH₂), see: Takusagawa & Shimada (1973 ▶). For complexes of (pz-2,3-dcH₂) and manganese, copper, zinc, iron and cadmium, see: Zou et al. (1999 ▶); Konar et al. (2004 ▶); Li et al. (2003 ▶); Xu et al. (2008 ▶); Ma et al. (2006 ▶). For complexes of (pz-2,3-dcH₂) with main group metals such as calcium, magnesium and sodium, see: Ptasiewicz-Bak & Leciejewicz (1997a ▶,b ▶); Tombul et al. (2006 ▶). For related structures of Co^II complexes with py-2,6-dcH₂, see: Aghabozorg et al. (2007 ▶, 2009 ▶); Aghabozorg, Attar Gharamaleki et al. (2008 ▶). For a review article on proton-transfer agents and their metal complexes, see: Aghabozorg, Manteghi & Sheshmani (2008 ▶).

Experimental

Crystal data

(C₁₃H₁₀N)₂[Co(C₆H₂N₂O₄)₂(H₂O)₂]·6H₂O
M _r = 895.69
Triclinic,
a = 6.9434 (15) Å
b = 9.682 (2) Å
c = 15.660 (5) Å
α = 94.60 (2)°
β = 98.59 (2)°
γ = 110.656 (16)°
V = 963.9 (4) Å³
Z = 1
Mo Kα radiation
μ = 0.53 mm⁻¹
T = 120 K
0.35 × 0.10 × 0.10 mm

Data collection

Bruker SMART 1000 diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.828, T _max = 0.949
10681 measured reflections
5096 independent reflections
3880 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.101
S = 1.00
5096 reflections
277 parameters
H-atom parameters constrained
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.51 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1998 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809053628/om2301sup1.cif

e-66-00m83-sup1.cif^{(22.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809053628/om2301Isup2.hkl

e-66-00m83-Isup2.hkl^{(249.5KB, 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
O1W—H1WA⋯O3Wⁱ	0.87	1.81	2.684 (2)	174
O1W—H1WB⋯O4Wⁱⁱ	0.90	1.77	2.658 (2)	174
O2W—H2WA⋯O2	0.90	1.92	2.813 (2)	172
O2W—H2WB⋯O4ⁱⁱⁱ	0.88	1.90	2.776 (2)	177
O3W—H3WA⋯O1^iv	0.88	1.95	2.806 (2)	165
O3W—H3WB⋯O2W^iv	0.83	2.01	2.809 (2)	162
O4W—H4WA⋯O3	0.93	1.91	2.789 (2)	156
O4W—H4WB⋯N4ⁱⁱⁱ	0.96	1.92	2.848 (2)	163
N9—H9⋯O4	0.92	1.74	2.648 (2)	167
C11—H11⋯O3	0.95	2.50	3.365 (3)	151
C12—H12⋯O1^v	0.95	2.49	3.431 (3)	171
C16—H16⋯O2W^vi	0.95	2.46	3.395 (3)	169

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

supplementary crystallographic information

Comment

Takusagawa & Shimada (1973) first determined the structure of pyrazine-2,3-dicarboxlic acid by single-crystal X-ray analysis. Pyrazine-2,3-dicarboxylic acid, (pz-2,3-dcH₂), has proved to be well suited for the construction of multidimensional frameworks due to the presence of two adjacent carboxylate groups (O donor atoms) as substituents on the N-heterocyclic pyrazine ring (N donor atoms). A variety of metal-organic compounds of pyrazine-2,3-dicarboxylic acid have been characterized crystallographically. Among many reported compounds, complexes of transition metal ions, including manganese (Zou et al., 1999), copper (Konar et al.,2004), zinc (Li et al., 2003), iron (Xu et al., 2008) and cadmium (Ma et al., 2006), are extensively studied. Also, there are many reported compounds of (pz-2,3-dcH₂) with main group metals such as calcium (Ptasiewicz-Bak & Leciejewicz, 1997a), magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b) and sodium (Tombul et al., 2006) complexes. In this paper, we report the synthesis and crystal structure of the title compound.

The reaction of pyrazine-2,3-dicarboxlic acid, acridine and cobalt(II) nitrate, resulted in the formation of (acrH)₂[Co(py-2,3-dc)₂(H₂O)₂]. 6H₂O. This compound consists of an anionic complex, trans-[Co(pz-2,3-dc)₂(H₂O)₂]^2–, counter-ions, (acrH)⁺ and six uncoordinated water molecules. In the title compound, two carboxylic COOH protons have been transferred to non-coordinated pyridine rings of acridine. The central Co1 atom is six-coordinated by N1, O1, N1ⁱ and O1ⁱ atoms in the equatorial plane from two (pz-2,3-dc)^2– ligands and by two water molecules, O1W and O1Wⁱ, in the axial position [symmetry code (i), -x + 1,-y + 2, -z] (see Fig. 1). The water molecules are almost perpendicular to the plane of (pz-2,3-dc)^2– ligands, with O1W—Co1—N1, O1W—Co1—O1, O1Wⁱ—Co1—N1 and O1Wⁱ—Co1—O1 angles of 86.35 (6), 89.57 (6), 93.65 (6) and 90.43 (6)°, respectively.

The coordination environment around the Co^II may be considered as slightly distorted octahedral. The anionic complex lies on a crystallographic center of symmetry. The mean Co—N and Co—O bond distances are 2.1237 (15) and 2.0738 (14) Å, respectively, which are consistent with our previously reported data for Co^II complexes (Aghabozorg et al., 2009; Aghabozorg, Attar Gharamaleki et al., 2008; Aghabozorg, Manteghi, Sheshmani, 2008; Aghabozorg et al., 2007).

In the structure of the title compound, (acrH)⁺ cations and [Co(pz-2,3-dc)₂(H₂O)₂]^2– anions are linked together by two classical N9—H9···O4 and non-classical C11—H11···O3 hydrogen bonds by R₂²(8) graph-set motifs. Also, the coordinated and uncoordinated water molecules are involved in O—H···O hydrogen bonds with O···O distances of 2.658 (2) to 2.813 (2) Å, which lead to the formation of chains with R₃³(12) graph-set motifs (Fig. 2).

As can be seen from Fig. 3, in the crystal structure of (acrH)₂[Co(pz-2,3-dc)₂(H₂O)₂].6H₂O, the spaces between two layers of (acrH)⁺ cations (as counter-ions) are filled with layers of [Co(pz-2,3-dc)₂(H₂O)₂]^2– fragments and uncoordinated water molecules. Also an extensive π-π stacking interaction between aromatic rings of acridinium ions, (acrH)⁺, with centroid-centroid distances ranging from 3.533 (1) to 3.613 (1) Å are observed (Fig.4).

Experimental

The reaction of cobalt(II) nitrate hexahydrate (72 mg, 0.25 mmol), acridine, acr, (90 mg, 0.5 mmol) and pyrazine-2,3-dicarboxylic acid, pz-2,3-dcH₂, (84 mg, 0.5 mmol) in a 1:2:2 molar ratio in aqueous solution resulted in the formation of needle like, pale yellow, (acrH)₂[Co(pz-2,3-dc)₂(H₂O)₂]. 6H₂O crystals.