Bis(1-ammonio­ethane-1,1-diyl­diphos­phonato-κ2 O,O′)diaqua­cobalt(II) nona­hydrate

Vladimir V Bon; Anatolij V Dudko; Alexandra N Kozachkova; Vasily I Pekhnyo; Natalia V Tsaryk

doi:10.1107/S1600536810013681

. 2010 Apr 17;66(Pt 5):m537–m538. doi: 10.1107/S1600536810013681

Bis(1-ammonioethane-1,1-diyldiphosphonato-κ² O,O′)diaquacobalt(II) nonahydrate

Vladimir V Bon ^a, Anatolij V Dudko ^a, Alexandra N Kozachkova ^a, Vasily I Pekhnyo ^a, Natalia V Tsaryk ^a,^*

PMCID: PMC2979193 PMID: 21579029

Abstract

In the title compound, [Co(C₂H₈NO₆P₂)₂(H₂O)₂]·9H₂O, the Co^II atom has a slightly distorted octahedral coordination environment consisting of four deprotonated phosphonate O atoms of two independent 1-aminoethylidendiphosphonate anions and complemented by the O atoms of two water molecules in cis positions. The anions exists in the zwitterionic form (protonated amino group and two deprotonated phosphonate O atoms) and constitute two six-membered chelate rings. The crystal structure also contains nine partly disordered uncoordinated water molecules, which create an extensive three-dimensional network of strong O—H⋯O and N—H⋯O hydrogen bonds.

Related literature

For general background to organic diphosphonic acids, see: Matczak-Jon & Videnova-Adrabinska (2005 ▶). For applications of transition metal bisphosphonates, see: Eberhardt et al. (2005 ▶). For related structures, see: Xiang et al. (2007 ▶); Yin et al. (2005 ▶); Dudko et al. (2009 ▶).

Experimental

Crystal data

[Co(C₂H₈NO₆P₂)₂(H₂O)₂]·9H₂O
M _r = 665.17
Monoclinic,
a = 15.1925 (3) Å
b = 13.2046 (2) Å
c = 12.9688 (2) Å
β = 106.0866 (11)°
V = 2499.81 (7) Å³
Z = 4
Mo Kα radiation
μ = 1.04 mm⁻¹
T = 173 K
0.30 × 0.24 × 0.20 mm

Data collection

Bruker APEX-II CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.749, T _max = 0.820
51914 measured reflections
6273 independent reflections
5626 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.090
S = 1.12
6273 reflections
401 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.73 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810013681/wm2322sup1.cif

e-66-0m537-sup1.cif^{(25.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810013681/wm2322Isup2.hkl

e-66-0m537-Isup2.hkl^{(307.1KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Co1—O7	2.0697 (14)
Co1—O13	2.0747 (17)
Co1—O10	2.0771 (15)
Co1—O14	2.0837 (16)
Co1—O1	2.1007 (15)
Co1—O4	2.1201 (15)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11N⋯O17	0.86 (3)	2.00 (3)	2.836 (3)	165 (3)
N1—H12N⋯O7	0.81 (3)	1.98 (3)	2.785 (2)	175 (3)
N1—H13N⋯O15ⁱ	0.85 (3)	1.98 (3)	2.810 (2)	165 (3)
N2—H21N⋯O23A	0.91 (3)	1.94 (3)	2.808 (4)	159 (3)
N2—H22N⋯O4	0.90 (3)	2.05 (3)	2.944 (2)	173 (3)
N2—H23N⋯O16	0.90 (3)	1.90 (3)	2.783 (3)	164 (3)
O3—H3O⋯O6ⁱⁱ	0.66 (3)	1.92 (3)	2.570 (2)	169 (4)
O5—H5O⋯O2ⁱ	0.76 (3)	1.84 (3)	2.592 (2)	170 (3)
O8—H8O⋯O11ⁱⁱⁱ	0.70 (3)	1.81 (3)	2.508 (2)	169 (3)
O12—H12O⋯O9^iv	0.83 (3)	1.71 (3)	2.517 (2)	165 (3)
O13—H131⋯O6ⁱⁱ	0.79 (3)	1.92 (3)	2.691 (2)	166 (3)
O13—H132⋯O20A	0.77 (3)	1.92 (3)	2.671 (3)	165 (3)
O14—H141⋯O18A^v	0.82 (3)	1.91 (3)	2.697 (3)	163 (3)
O14—H142⋯O9^iv	0.74 (3)	1.95 (3)	2.688 (2)	172 (3)
O15—H151⋯O1	0.80 (3)	2.01 (3)	2.803 (2)	177 (3)
O15—H152⋯O14	0.66 (3)	2.50 (3)	2.946 (2)	127 (3)
O15—H152⋯O12^iv	0.66 (3)	2.54 (3)	3.049 (2)	136 (3)
O16—H161⋯O15ⁱ	0.85 (4)	1.94 (4)	2.788 (3)	176 (3)
O16—H162⋯O17ⁱ	0.89 (4)	1.97 (4)	2.844 (3)	170 (3)
O17—H171⋯O21^vi	0.75 (3)	2.14 (4)	2.795 (3)	147 (3)
O17—H172⋯O18A^vii	0.73 (4)	2.13 (4)	2.845 (3)	167 (4)
O19—H191⋯O13	0.84 (4)	2.27 (4)	3.063 (3)	158 (3)
O19—H192⋯O2^v	0.75 (4)	2.04 (4)	2.773 (3)	166 (4)
O21—H211⋯O19	0.80 (4)	2.05 (4)	2.815 (3)	162 (4)
O21—H212⋯O19^viii	1.00 (4)	1.93 (4)	2.914 (3)	169 (3)

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

supplementary crystallographic information

Comment

Organic diphosphonic acids are potentially very powerful chelating agents used in metal extractions and are tested by the pharmaceutical industry for use as efficient drugs preventing calcification and inhibiting bone resorption (Matczak-Jon et al., 2005). There is evidence that application of transition metal bisphosphonates can improve fixation of cementless metal implants by enhancing the extent of osseointegration (Eberhardt et al., 2005). In this respect, a detailed structure-correlated study of the individual properties and the complex-forming driving factors is desired in order to sufficiently understand bisphosphonate physiological activities.

Several structures of Co^II aminoethylidenediphosphonates have been reported previously (Xiang et al. 2007; Yin et al. 2005). The main difference between these structures and the title compound is the presence of two water molecules instead of a 1,10-phenanthroline ligand in the coordination environment of the transition metal ion (Xiang et al. 2007), leading also to a different symmetry.

The asymmetric unit of the title compound contains one molecule of the complex (Fig.1). Two 1-aminoethylidendiphosphonate anions chelate the central metal ion via two oxygen atoms from phosphonate groups forming six-membered non-planar metalla rings. Two water molecules complement the slightly distorted octahedral coordination environment of Co in cis-position. The Co—O bond lengths have expected values and conform with the previously reported related structures (Xiang et al., 2007). The values of the O—Co—O angles are in the range from 89.23 (7)° to 91.54 (5)°. The Co1—O1—P1—C1—P2—O4 and Co1—O7—P3—C3—P4—O10 metalla cycles have an envelope conformation with the C1 and C3 atoms out of plane by 0.850 (2) Å and 0.795 (2) Å, respectively. The dihedral angle between the planar fragments Co1—O1—P1—P2—O4 and Co1—O7—P3—P4—O10 is 84.20 (3)°. The coordinated ligand molecules exists in the zwitterionic form with a proton transfer from one of the phosphonic groups to the amino group which is representative for all 1-aminodiphosphonic acids. In addition, the amino group does also not participate in coordination (Dudko et al. 2009).

In the crystal structure of the title compound, nine solvent water molecules are present. Such an amount of solvent molecules could be explained by the presence of two coordinated water molecules in addition to the more hydrophilic phosphonate groups. As a result, a 3-D network of mostly strong O—H···O and N—H···O hydrogen bonds is observed in the structure (Fig. 2; Table 1). Several H-bonds can not be unambiguously derived from the model because some of the crystal lattice water molecules are disordered.

Experimental

Light pink crystals of the title compound were obtained from the mixture of 10 ml (10 ^-2 mol/l) water solution of Co(NO₃)₂ with 20 ml (10 ^-2 mol/l) solution of 1-aminoethylidendiphosphonic acid. The combined solution was stored in a dark place for slow evaporation. After 20 days of staying, suitable crystals for X-ray data collection were obtained.