Poly[di-μ-aqua-di­aqua-di-μ₆-malonato-cobalt(II)dipotassium(I)]

In the title complex, [CoK₂(C₃H₂O₄)₂(H₂O)₄]_n, the Co atom is located on a position with site symmetry 2/m, the K atom and one water mol­ecule are located on a mirror plane, and the malonate and one water mol­ecule are located on a twofold rotation axis. The K^I atom is seven-coordinated by four carboxyl­ate O atoms from four malonate ligands and by three water O atoms, forming a distorted polyhedron. The Co^II atom is in an almost octa­hedral environment formed by four carboxyl­ate O atoms from two malonate ligands and two water O atoms. The structure consists of layers parallel to (20) built up from edge-sharing KO₇ and CoO₆ polyhedra, which are connected by O—H⋯O hydrogen bonding including water mol­ecules into a three-dimensional network.

Related literature

For related structures, see: Baggio et al. (2003); Li et al. (2004); Zhao et al. (2007); Wang (2006).

Experimental

Crystal data

• [CoK₂(C₃H₂O₄)₂(H₂O)₄]

• M_r = 413.28

• Monoclinic, C 2/m

• a = 9.462 (2) Å

• b = 11.014 (3) Å

• c = 7.740 (2) Å

• β = 115.65 (2)°

• V = 727.1 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 1.81 mm⁻¹

• T = 293 K

• 0.15 × 0.13 × 0.10 mm

Data collection

• Enraf–Nonius CAD-4 diffractometer

• 1825 measured reflections

• 835 independent reflections

• 813 reflections with I > 2σ(I)

• R_int = 0.022

• Standard reflections: 2; every 120 minutes intensity decay: none

Refinement

• R[F² > 2σ(F²)] = 0.022

• wR(F²) = 0.057

• S = 1.15

• 835 reflections

• 63 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.33 e Å⁻³

• Δρ_min = −0.30 e Å⁻³

Table 1
Selected bond lengths (Å)

Co1—O2	2.0584 (11)
Co1—O1	2.1347 (18)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—HW1⋯O3^iv	0.81 (2)	1.91 (2)	2.7077 (17)	167 (2)
O4—HW2⋯O3^i	0.80 (3)	2.03 (3)	2.8372 (18)	176 (3)
Symmetry codes: (i) -x, -y, -z; (iv) .

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

The structure of the title compound is represented in Fig. 1. The Co^II cations are in a near perfect octahedral geometry with all trans-octahedral angles being 180° and the K ions are all in seven coordinated environment. In the quasi-regular octahedral environment of the six-coordinated Co^II cation, basal coordination positions are occupied by four oxygen atoms from two malonate ligands with Co—O distances of 2.0584 (11)Å and the O—Co—O angles in the range [86.32 (5)–93.68 (5) °]. These values agree with those found in literature (Baggio et al., 2003; Li et al.). The apical coordination position are occupied by oxygen atoms from water mlecules with bond length [Co—O 2.1347 (18) Å] and an angle value of 180.00 (11) which agree with the values observed for [Co(malonate)(H₂O]^2- cobalt complex (Zhao et al., 2007). The potassium cation has an O7 donor set made up by four µ₂-bridging malonate oxygen atoms and one µ₂-bridging water oxygen atoms and two water coordinated molecules. The K cations share four oxygen atoms bridges from malonate groups and two oxygen atoms from water molecule with Co cations. There are hydrogen bonds between water molecules and carbonyl groups of the malonate anions. The cations Co^II and K^I are arranged in the following sequence: Co—K—K—Co. The metal atoms are found at linear positions [K—Co—K, 180.00 (0)°] as shown in Fig. 2. The Co—K distance is 3.5726 (13) Å. Two K atoms are found to be very close together, having a distance of 4.2086 (14) Å, which is a short metal–metal distance for these types of complexes. The insertion of two polyhedra of KO₇ between two polyhedra of CoO₆ results in long Co–Co distances. These two types of geometries form zigzag layers parallel to the ac-plane and alternating with malonate groups along the b axis. The water oxygen atoms provide bridges between K cations. The different polyhedra are still bound to each other through edge-sharing with a compact layer structure defining narrow crossed channels.

Related literature

For related structures, see : Baggio et al. (2003); Li et al. (2004); Zhao et al. (2007); Wang (2006).

S2. Experimental

In a round bottomed flask, cobalt acetate tetrahydrate (0.4982 g, 2 mmol) dissoveld in a mixture of water and methanol (10 ml, 1:1) was introduced. Imidazole (0.2720 g, 4 mmol) dissolved in 10 ml of the same mixture was added. The solution turn pink. After 10 mn of stirring, 10 ml of a mixture of methanol and water (10 ml, 1:1) containing malonic acid (0.2081 g, 2 mmol) and KOH (0.2240 g, 4 mmol) was added to the pink solution. After 2 h under stirring, the suspension was filtered off and the precipitate was washed with water and diethyl ether before dring under P₂O₅. The compound was recrystallized in a mixture of water and dimethylformamide (1/1). After one week, suitable pink crystals for X-ray analyses was obtained. Yield: 72%. m.p. 228±1°C. Anal. Calc. For [C₆H₁₂O₁₂K₂Co]_n (%):C, 17.44; H, 2.93. Found: C, 17.44; H, 2.93. Selected IR data (cm^-1, KBr pellet): 3216, 1637, 1600, 1582, 1197, 764.

S3. Refinement

The H atoms of the water molecules were located in a Fourier difference map and freely refined. H atoms of the CH₂ groups were geometrically placed and refined with a riding model with U_iso(H) = 1.2 U_eq(C).

Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. An ORTEP view of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are plotted at the 50% probability level. Broken lines indicate hydrogen bonds.
	Fig. 2. Projection of the structure onto the c axis showing the polyhedra layers connected by the organics molecules.

Poly[di-µ-aqua-diaqua-di-µ₆-malonato-cobalt(II)dipotassium]

Crystal data

[CoK2(C3H2O4)2(H2O)4]	F(000) = 418
Mr = 413.28	Dx = 1.888 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 25 reflections
a = 9.462 (2) Å	θ = 11–15°
b = 11.014 (3) Å	µ = 1.81 mm^−1
c = 7.740 (2) Å	T = 293 K
β = 115.65 (2)°	Prism, pink
V = 727.1 (3) Å^3	0.15 × 0.13 × 0.10 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.022
Radiation source: fine-focus sealed tube	θmax = 27.0°, θmin = 2.9°
Graphite monochromator	h = −12→12
ω scans	k = −1→14
1825 measured reflections	l = −9→9
835 independent reflections	2 standard reflections every 120 min
813 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.022	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.057	w = 1/[σ^2(Fo^2) + (0.0236P)^2 + 0.6549P] where P = (Fo^2 + 2Fc^2)/3
S = 1.15	(Δ/σ)max < 0.001
835 reflections	Δρmax = 0.33 e Å^−3
63 parameters	Δρmin = −0.30 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.045 (2)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Co1	0.0000	0.0000	0.0000	0.01988 (16)
K1	−0.27538 (6)	0.0000	−0.49356 (7)	0.03100 (18)
O1	0.0747 (2)	0.0000	−0.2237 (3)	0.0308 (4)
O2	0.15473 (12)	0.13440 (10)	0.15312 (16)	0.0290 (3)
O3	0.24932 (14)	0.31676 (10)	0.26017 (17)	0.0334 (3)
O4	−0.5000	−0.16509 (19)	−0.5000	0.0479 (5)
C1	0.14331 (17)	0.24844 (13)	0.1464 (2)	0.0234 (3)
C2	0.0000	0.3130 (2)	0.0000	0.0519 (8)
H1	−0.0371	0.3657	0.0720	0.062*	0.50
H2	0.0371	0.3657	−0.0720	0.062*	0.50
HW1	0.134 (2)	0.055 (2)	−0.217 (3)	0.054 (7)*
HW2	−0.431 (3)	−0.211 (2)	−0.435 (4)	0.066 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0200 (2)	0.0129 (2)	0.0208 (2)	0.000	0.00322 (16)	0.000
K1	0.0360 (3)	0.0267 (3)	0.0248 (3)	0.000	0.0079 (2)	0.000
O1	0.0357 (9)	0.0200 (7)	0.0416 (10)	0.000	0.0215 (8)	0.000
O2	0.0261 (5)	0.0169 (5)	0.0309 (6)	−0.0021 (4)	0.0001 (4)	0.0004 (4)
O3	0.0328 (6)	0.0228 (6)	0.0330 (6)	−0.0090 (4)	0.0034 (5)	−0.0032 (5)
O4	0.0287 (9)	0.0348 (10)	0.0599 (13)	0.000	0.0000 (9)	0.000
C1	0.0253 (7)	0.0185 (7)	0.0233 (7)	−0.0039 (6)	0.0076 (6)	−0.0002 (5)
C2	0.0451 (15)	0.0169 (11)	0.0555 (17)	0.000	−0.0141 (13)	0.000

Geometric parameters (Å, º)

Co1—O2^i	2.0584 (11)	K1—O1^vii	3.4628 (19)
Co1—O2	2.0584 (11)	K1—K1^iv	4.2086 (14)
Co1—O2^ii	2.0584 (11)	K1—HW2	2.89 (3)
Co1—O2^iii	2.0584 (11)	O1—K1^vii	3.4628 (19)
Co1—O1	2.1347 (18)	O1—HW1	0.81 (2)
Co1—O1^i	2.1347 (18)	O2—C1	1.2598 (18)
Co1—K1^i	3.5726 (13)	O2—K1^i	2.7987 (13)
Co1—K1	3.5726 (13)	O3—C1	1.2582 (18)
K1—O4	2.7811 (15)	O3—K1^viii	2.8541 (14)
K1—O4^iv	2.7811 (15)	O4—K1^iv	2.7810 (15)
K1—O2^iii	2.7987 (13)	O4—HW2	0.80 (3)
K1—O2^i	2.7987 (13)	C1—C2	1.5157 (19)
K1—O3^v	2.8541 (14)	C2—C1^iii	1.5157 (19)
K1—O3^vi	2.8541 (14)	C2—H1	0.9700
K1—O1	3.057 (2)	C2—H2	0.9700
O2^i—Co1—O2	180.00 (11)	O3^v—K1—O1^vii	49.62 (3)
O2^i—Co1—O2^ii	88.03 (6)	O3^vi—K1—O1^vii	49.62 (3)
O2—Co1—O2^ii	91.97 (6)	O1—K1—O1^vii	72.74 (6)
O2^i—Co1—O2^iii	91.97 (6)	O4—K1—Co1	102.54 (2)
O2—Co1—O2^iii	88.03 (6)	O4^iv—K1—Co1	102.54 (2)
O2^ii—Co1—O2^iii	180.0	O2^iii—K1—Co1	35.11 (2)
O2^i—Co1—O1	86.32 (5)	O2^i—K1—Co1	35.11 (2)
O2—Co1—O1	93.68 (5)	O3^v—K1—Co1	118.77 (3)
O2^ii—Co1—O1	93.68 (5)	O3^vi—K1—Co1	118.77 (3)
O2^iii—Co1—O1	86.32 (5)	O1—K1—Co1	36.53 (4)
O2^i—Co1—O1^i	93.68 (5)	O1^vii—K1—Co1	109.27 (4)
O2—Co1—O1^i	86.32 (5)	O4—K1—K1^iv	40.83 (3)
O2^ii—Co1—O1^i	86.32 (5)	O4^iv—K1—K1^iv	40.83 (3)
O2^iii—Co1—O1^i	93.68 (5)	O2^iii—K1—K1^iv	91.05 (3)
O1—Co1—O1^i	180.00 (8)	O2^i—K1—K1^iv	91.05 (3)
O2^i—Co1—K1^i	128.56 (3)	O3^v—K1—K1^iv	110.98 (3)
O2—Co1—K1^i	51.44 (3)	O3^vi—K1—K1^iv	110.98 (3)
O2^ii—Co1—K1^i	51.44 (3)	O1—K1—K1^iv	143.21 (4)
O2^iii—Co1—K1^i	128.56 (3)	O1^vii—K1—K1^iv	144.05 (4)
O1—Co1—K1^i	121.53 (5)	Co1—K1—K1^iv	106.68 (3)
O1^i—Co1—K1^i	58.47 (5)	O4—K1—HW2	16.2 (5)
O2^i—Co1—K1	51.44 (3)	O4^iv—K1—HW2	95.2 (5)
O2—Co1—K1	128.56 (3)	O2^iii—K1—HW2	107.8 (5)
O2^ii—Co1—K1	128.56 (3)	O2^i—K1—HW2	57.0 (5)
O2^iii—Co1—K1	51.44 (3)	O3^v—K1—HW2	74.4 (6)
O1—Co1—K1	58.47 (5)	O3^vi—K1—HW2	150.2 (5)
O1^i—Co1—K1	121.53 (5)	O1—K1—HW2	111.6 (5)
K1^i—Co1—K1	180.0	O1^vii—K1—HW2	123.8 (6)
O4—K1—O4^iv	81.66 (7)	Co1—K1—HW2	91.0 (5)
O4—K1—O2^iii	111.08 (4)	K1^iv—K1—HW2	54.9 (5)
O4^iv—K1—O2^iii	70.62 (3)	Co1—O1—K1	85.00 (6)
O4—K1—O2^i	70.62 (3)	Co1—O1—K1^vii	167.75 (8)
O4^iv—K1—O2^i	111.08 (4)	K1—O1—K1^vii	107.26 (6)
O2^iii—K1—O2^i	63.86 (5)	Co1—O1—HW1	114.1 (18)
O4—K1—O3^v	78.97 (4)	K1—O1—HW1	124.1 (16)
O4^iv—K1—O3^v	137.16 (4)	K1^vii—O1—HW1	59.3 (17)
O2^iii—K1—O3^v	152.22 (4)	C1—O2—Co1	131.78 (10)
O2^i—K1—O3^v	97.86 (4)	C1—O2—K1^i	123.99 (10)
O4—K1—O3^vi	137.16 (4)	Co1—O2—K1^i	93.45 (4)
O4^iv—K1—O3^vi	78.97 (4)	C1—O3—K1^viii	128.27 (10)
O2^iii—K1—O3^vi	97.86 (4)	K1—O4—K1^iv	98.34 (7)
O2^i—K1—O3^vi	152.22 (4)	K1—O4—HW2	89.5 (19)
O3^v—K1—O3^vi	90.00 (5)	K1^iv—O4—HW2	146 (2)
O4—K1—O1	127.30 (3)	O3—C1—O2	122.62 (14)
O4^iv—K1—O1	127.30 (3)	O3—C1—C2	115.27 (15)
O2^iii—K1—O1	58.47 (4)	O2—C1—C2	122.11 (15)
O2^i—K1—O1	58.47 (4)	C1^iii—C2—C1	124.1 (2)
O3^v—K1—O1	94.50 (4)	C1^iii—C2—H1	106.3
O3^vi—K1—O1	94.50 (4)	C1—C2—H1	106.3
O4—K1—O1^vii	127.77 (3)	C1^iii—C2—H2	106.3
O4^iv—K1—O1^vii	127.77 (3)	C1—C2—H2	106.3
O2^iii—K1—O1^vii	118.90 (4)	H1—C2—H2	106.4
O2^i—K1—O1^vii	118.90 (4)

Symmetry codes: (i) −x, −y, −z; (ii) x, −y, z; (iii) −x, y, −z; (iv) −x−1, −y, −z−1; (v) x−1/2, y−1/2, z−1; (vi) x−1/2, −y+1/2, z−1; (vii) −x, −y, −z−1; (viii) x+1/2, y+1/2, z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—HW1···O3^ix	0.81 (2)	1.91 (2)	2.7077 (17)	167 (2)
O4—HW2···O3^i	0.80 (3)	2.03 (3)	2.8372 (18)	176 (3)

Symmetry codes: (i) −x, −y, −z; (ix) −x+1/2, −y+1/2, −z.