Diaqua­bis[malonato(1–)-κ²O,O′]cobalt(II)

The title complex, [Co(C₃H₃O₄)₂(H₂O)₂], is isostructural with its iron, zinc and magnesium analogues. The mol­ecule has inversion symmetry. The mol­ecules are linked together via O—H...O hydrogen bonds, leading to a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 292 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.031
• wR factor = 0.077
• Data-to-parameter ratio = 13.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       3.08

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

The title complex, [Co(Hmal)₂(H₂O)₂] (H₂mal is malonic acid), (I), is isostructural with its iron(II) (Ravi et al., 1982), zinc (Sinha & Ojha, 1980) and magnesium (Briggman & Oskarsson, 1978) analogues. A compound with the same formula as (I) and a similar unit cell was reported by Walter-Levy et al. (1973), but no atomic coordinates were established.

The complete molecule of (I) is generated by inversion symmetry (Fig. 1), resulting in a slightly distorted Co^IIO₆ octahedron arising from two bidentate HMal ligands and two water molecules (Table 1). The fact that the Co1—O3 bond is significantly shorter than the Co1—O2 bond might be rationalized in terms of the formal negative charge shared between atoms O3 and O4, resulting in a stronger electrostatic attraction between atoms Co1 and O3 than between atoms Co1 and O2.

The molecules of (I) are linked together via O—H···O hydrogen bonds, leading to a three-dimensional network (Fig. 2, Table 2).

S2. Experimental

Solid cobalt basic carbonate (1.11 mmol, 0.593 g) was added to an aqueous solution (20 ml) of malonic acid (5.0 mmol, 0.520 g) under continuous stirring until a pink solution resulted. The solution was filtered and left at room temperature. After slow evaporation of the solvent over a period of a week, large pink crystals of (I) were formed (40% yield, based on Co). Analysis, found: C 23.98, H 3.42%; calculated for C₆H₁₀CoO₁₀: C 23.91, H 3.32%.

S3. Refinement

Bruker H atoms bonded to C and carboxylate O atoms were located in idealized positions (C—H = 0.97, O—H = 0.82 Å) and refined as riding, with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(carboxylate O). The water H atoms were found in a difference Fourier map and were refined with restraints on the O—H distance [0.811(s.u.?)–0.815(s.u.?) Å].

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.

Figures

	Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level. Atoms with the suffix a are generated by the symmetry operation (−x, 1 − y, 1 − z).
	Fig. 2. The crystal packing in (I), viewed down the a axis of the unit cell, showing hydrogen bonds as dashed lines. [Symmetry codes: (h) 1 − x, 1/2 + y, 1/2 − z; (j) x, 1/2 + y, 1/2 + z.]

Diaquabis[malonato(1-)-κ²O,O']cobalt(II)

Crystal data

[Co(C3H3O4)2(H2O)2]	F(000) = 306
Mr = 301.07	Dx = 1.857 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2256 reflections
a = 4.9331 (16) Å	θ = 2.8–28.0°
b = 11.276 (4) Å	µ = 1.64 mm^−1
c = 9.682 (3) Å	T = 292 K
β = 90.018 (1)°	Block, pink
V = 538.6 (3) Å^3	0.30 × 0.20 × 0.10 mm
Z = 2

Data collection

Bruker SMART APEX CCD area-detector diffractometer	1170 independent reflections
Radiation source: fine-focus sealed Siemens Mo tube	1070 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.061
ω scans	θmax = 27.0°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −6→6
Tmin = 0.639, Tmax = 0.853	k = −10→14
3190 measured reflections	l = −12→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.077	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0457P)^2 + 0.0555P] where P = (Fo^2 + 2Fc^2)/3
1170 reflections	(Δ/σ)max < 0.001
88 parameters	Δρmax = 0.32 e Å^−3
3 restraints	Δρmin = −0.40 e Å^−3

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
Co1	0.0000	0.5000	0.5000	0.02544 (15)
O1	0.3183 (3)	0.84282 (11)	0.43588 (14)	0.0445 (4)
H1	0.4132	0.8190	0.3722	0.067*
O2	0.1923 (2)	0.65524 (10)	0.43735 (12)	0.0314 (3)
O3	0.2381 (2)	0.39473 (10)	0.37745 (13)	0.0321 (3)
O4	0.3494 (3)	0.24680 (11)	0.24153 (15)	0.0448 (4)
O5	0.2791 (3)	0.48460 (11)	0.66041 (16)	0.0328 (3)
C1	0.1738 (3)	0.75504 (14)	0.48429 (16)	0.0265 (3)
C3	0.2095 (3)	0.29053 (14)	0.33622 (16)	0.0256 (3)
C2	0.0045 (4)	0.20592 (15)	0.39938 (19)	0.0354 (4)
H2A	−0.1133	0.1794	0.3253	0.042*
H2B	0.1039	0.1369	0.4311	0.042*
H5A	0.317 (4)	0.4173 (10)	0.683 (2)	0.051 (7)*
H5B	0.416 (3)	0.5251 (16)	0.655 (2)	0.040 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0259 (2)	0.0202 (2)	0.0302 (2)	−0.00018 (10)	0.01361 (14)	−0.00208 (10)
O1	0.0541 (8)	0.0289 (7)	0.0505 (8)	−0.0104 (5)	0.0338 (7)	−0.0025 (6)
O2	0.0327 (6)	0.0250 (6)	0.0366 (7)	−0.0023 (5)	0.0177 (5)	−0.0002 (5)
O3	0.0291 (6)	0.0256 (6)	0.0417 (7)	−0.0024 (4)	0.0185 (5)	−0.0080 (5)
O4	0.0488 (8)	0.0346 (7)	0.0511 (8)	−0.0083 (6)	0.0341 (6)	−0.0137 (6)
O5	0.0304 (7)	0.0291 (7)	0.0388 (8)	−0.0022 (5)	0.0070 (6)	0.0033 (5)
C1	0.0255 (8)	0.0273 (8)	0.0268 (8)	−0.0022 (6)	0.0079 (6)	0.0023 (6)
C3	0.0230 (7)	0.0279 (8)	0.0259 (8)	0.0005 (6)	0.0098 (6)	−0.0020 (6)
C2	0.0387 (10)	0.0291 (9)	0.0384 (9)	−0.0079 (7)	0.0198 (8)	−0.0065 (7)

Geometric parameters (Å, º)

Co1—O3^i	2.0488 (11)	C3—O3	1.249 (2)
Co1—O3	2.0488 (11)	C3—O4	1.2492 (19)
Co1—O2	2.0815 (12)	O5—H5A	0.811 (9)
Co1—O2^i	2.0815 (12)	O5—H5B	0.815 (9)
Co1—O5^i	2.0825 (15)	C1—C2^i	1.496 (2)
Co1—O5	2.0825 (15)	C3—C2	1.519 (2)
C1—O1	1.3067 (19)	C2—C1^i	1.496 (2)
O1—H1	0.8200	C2—H2A	0.9700
C1—O2	1.2170 (19)	C2—H2B	0.9700
O3^i—Co1—O3	179.998 (1)	C3—O3—Co1	131.71 (10)
O3^i—Co1—O2	86.73 (5)	Co1—O5—H5A	115.6 (16)
O3—Co1—O2	93.27 (5)	Co1—O5—H5B	117.0 (15)
O3^i—Co1—O2^i	93.27 (5)	H5A—O5—H5B	110.6 (15)
O3—Co1—O2^i	86.73 (5)	O2—C1—O1	121.70 (15)
O2—Co1—O2^i	180.0	O2—C1—C2^i	126.70 (14)
O3^i—Co1—O5^i	90.26 (6)	O1—C1—C2^i	111.60 (14)
O3—Co1—O5^i	89.74 (6)	O3—C3—O4	122.92 (14)
O2—Co1—O5^i	90.80 (5)	O3—C3—C2	122.52 (13)
O2^i—Co1—O5^i	89.20 (5)	O4—C3—C2	114.56 (14)
O3^i—Co1—O5	89.74 (6)	C1^i—C2—C3	120.67 (14)
O3—Co1—O5	90.26 (6)	C1^i—C2—H2A	107.2
O2—Co1—O5	89.21 (5)	C3—C2—H2A	107.2
O2^i—Co1—O5	90.79 (5)	C1^i—C2—H2B	107.2
O5^i—Co1—O5	180.0	C3—C2—H2B	107.2
C1—O1—H1	109.5	H2A—C2—H2B	106.8
C1—O2—Co1	129.38 (11)

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4^ii	0.82	1.80	2.6099 (17)	168
O5—H5A···O4^iii	0.81 (1)	1.94 (1)	2.747 (2)	172 (2)
O5—H5B···O3^iv	0.82 (1)	1.96 (1)	2.767 (2)	171 (2)

Symmetry codes: (ii) −x+1, y+1/2, −z+1/2; (iii) x, −y+1/2, z+1/2; (iv) −x+1, −y+1, −z+1.