Dipotassium diaqua­bis(methyl­enedi­phospho­nato-κ2 O,O′)cobaltate(II)

HG Visser; JA Venter; KA Van der Merwe

doi:10.1107/S160053680905106X

. 2010 Jan 16;66(Pt 2):m159. doi: 10.1107/S160053680905106X

Dipotassium diaquabis(methylenediphosphonato-κ² O,O′)cobaltate(II)

HG Visser ^a,^*, JA Venter ^a, KA Van der Merwe ^a

PMCID: PMC2979685 PMID: 21579634

Abstract

In the title complex, K₂[Co(CH₄O₆P₂)₂(H₂O)₂], the asymmetric unit contains two K⁺ cations and two half-anions in which the Co atoms lie on inversion centers. The Co^II ions assume an octahedral CoO₆ coordination geometry. In the crystal, a three-dimensional network is formed through O—H⋯O hydrogen-bond interactions as well as intermolecular interactions between the K⁺ cations and neighbouring O atoms.

Related literature

For related structures, see: DeLaMatter et al. (1973 ▶); Jurisson et al. (1983 ▶); Barthelet et al. (2002 ▶); Stahl et al. (2006 ▶); Van der Merwe et al. (2009 ▶).

Experimental

Crystal data

K₂[Co(CH₄O₆P₂)₂(H₂O)₂]
M _r = 521.13
Triclinic,
a = 6.4523 (3) Å
b = 8.7056 (3) Å
c = 13.1930 (5) Å
α = 91.334 (2)°
β = 93.304 (2)°
γ = 93.333 (2)°
V = 738.32 (5) Å³
Z = 2
Mo Kα radiation
μ = 2.23 mm⁻¹
T = 100 K
0.28 × 0.17 × 0.17 mm

Data collection

Bruker X8 APEXII 4K Kappa CCD diffractometer
Absorption correction: multi-scan SADABS (Bruker, 2004 ▶) T _min = 0.635, T _max = 0.690
13474 measured reflections
3645 independent reflections
3194 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.1096
S = 1.23
3645 reflections
235parameters
14 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.04 e Å⁻³
Δρ_min = −0.61 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680905106X/ds2013sup1.cif

e-66-0m159-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680905106X/ds2013Isup2.hkl

e-66-0m159-Isup2.hkl^{(178.7KB, hkl)}

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

Table 1. Selected bond lengths (Å).

O1—Co1	2.052 (3)
O2—Co1	2.132 (2)
O3—Co1	2.127 (3)
O8—Co2	2.081 (3)
O9—Co2	2.117 (2)
O10—Co2	2.064 (3)

Open in a new tab

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3A⋯O14ⁱ	0.85 (2)	1.83 (2)	2.680 (4)	175 (4)
O3—H3B⋯O6ⁱⁱ	0.86 (2)	1.89 (2)	2.737 (4)	172 (4)
O4—H4⋯O9ⁱⁱⁱ	0.84 (2)	1.81 (2)	2.632 (4)	166 (5)
O7—H7⋯O6^iv	0.85 (2)	1.72 (2)	2.570 (4)	177 (5)
O8—H8A⋯O5^v	0.85 (2)	1.84 (2)	2.678 (4)	170 (4)
O8—H8B⋯O11^vi	0.85 (2)	1.84 (2)	2.687 (4)	176 (5)
O12—H12⋯O11^vii	0.85 (1)	1.72 (1)	2.561 (4)	175 (5)
O13—H13⋯O2ⁱ	0.84 (2)	1.78 (2)	2.616 (4)	174 (5)

Open in a new tab

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

Acknowledgments

The research fund of the University of the Free State is gratefully acknowledged.

supplementary crystallographic information

Comment

We reported a similar structure recently with the only differences being the cation and the +2 oxidation state of the cobalt ion (Van der Merwe et al.<i/>, 2009).

The Co^III ion in the title complex, K[Co(C₂H₄O₆P)₂(H₂O)₂], is in a slightly distorted octahedral environment with O–Co–O bond angles varying from 83.75 (10) to 96.25 (10)°. All the bonding distance and angles fall within the normal range observed for complexes of this nature. The P-O distances are significantly different for P═O and P-OH type bonds and vary from 1.501 (3) to 1.580 (3) Å. This could possibly be an indication that the assignment of positional disorders for the respective Co^II complex previously was correct since these difference were not so prominent in the previous structure.

A three-dimensional network is provided by numerous hydrogen bonds and other weak interactions between the potassium ions and the oxygen atoms of the anionic species.

Experimental

CoCl₂.6H₂O (0,1696 g, 71 mmol) was dissolved in water (7 cm³) and heated to 70°C. Potassium bicarbonate was added to raise the pH to 5,5 after which methylene disphosphonate (0,25 g, 142 mmol), dissolved in water (5 cm³) was added dropwise. The final pH of the solution was adjusted to 1.50 to obtain the Co^II salt as described previously (Van der Merwe et al.<i/> 2009). Crystals of the Co^III salt, suitable for X-ray diffraction, was obtained from redissolving and adding H₂O₂ to the solution.