metal-organic compounds
Diaquabis(dihydrogen 3-azaniumyl-1-hydroxypropylidene-1,1-diphosphonato-κ2O,O′)cobalt(II)
aInstitute of General and Inorganic Chemistry, NAS Ukraine, Kyiv, prosp. Palladina 32/34, 03680, Ukraine
*Correspondence e-mail: complex@ionc.kiev.ua
The 3H10NO7P2)2(H2O)2], contains one half-molecule of the complex. The CoII atom is located on an inversion centre and displays a distorted octahedral coordination geometry defined by four O atoms of two 3-azaniumyl-1-hydroxypropylidene-1,1-bisphosphonato ligands in the equatorial plane and two water molecules located in axial positions. The ligand molecules, which exist in a zwitterionic state, form two six-membered chelate rings with chair conformations. In the crystal, molecules are interlinked by O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional supramolecular structure.
of title compound, [Co(CRelated literature
For general background to organic diphosphonic acids and their applications, see: Matczak-Jon & Videnova-Adrabinska (2005). For applications of bisphosphonate metal complexes in medicine, see: Matkovskaya et al. (2001). For a related structure, see: Bon et al. (2010). For bond-length data, see: Allen et al. (2004).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2010); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
https://doi.org/10.1107/S1600536811045120/ez2263sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811045120/ez2263Isup2.hkl
Light pink crystals of the title compound were obtained from a mixture of Co(NO3)2.6H2O (0,25 mmol; 0,0728 g) and 3-aminohydroxypropilidene-1,1-diphosphonic acid (0,5 mmol; 0,1175 g) in 20 ml H2O. The combined solution was allowed to slowly evaporate. After 30 days, suitable crystals for X-ray data collection were obtained.
All non-H atoms were refined with anisotropic displacement parameters. H atoms bonded to O and N atoms were located in a difference Fourier map. Their positions were refined freely whereas displacement parameters were fixed to Uiso(H) = 1.5Ueq(N,O).The H1n atom of the amino group was refined with a distance restraint (N—H= 0.91 Å). Other H atoms bonded to C were positioned geometrically and refined using a riding model with C—H = 0.99 Å for CH2 with Uiso(H) = 1.2Ueq(C).
In recent years the design and synthesis of novel metal-organic coordination compounds based on gem-diphosphonic acids has attracted much interest due to their structural diversity and possible applications in many areas (Matczak-Jon & Videnova-Adrabinska, 2005). Particular attention has been paid to 3-amino-1-hydroxypropane-1,1-diyl)bis(phosphonic acid) (pamidronic acid) due to its biological activity and as a result of its usage as a drug to prevent calcification and inhibit bone resorption, etc. (Matkovskaya et al., 2001).
The molecular structure of title complex is shown in Fig. 1; as illustrated the molecule of the complex forms discrete monomeric units. The
contains one-half of the formula unit [Co(C3H10NO7P2)2(H2O)2], with the Co atom lying on an inversion center.The CoII ion is coordinated in a slightly distorted octahedral geometry which consists of six oxygen atoms, two from water molecules located in the axial positions and four from the two phosphonate groups of two different ligands, which exist in zwitterionic form, creating two six-membered [O, O] chelate rings. The Co—O bond lengths and the O—Co—O angles have expected values (Allen et al., 2004) and conform well to the previously reported related structure (Bon et al., 2010). In the packing, O—H···O and N—H···O hydrogen-bonds exist between the water molecules, phosphonate, hydroxyl O atoms and nitrogen atoms of the amino group (Fig. 2, Table 1). Thus, the molecules are interlinked by these hydrogen bonds to create a three-dimensional structure which partially influences and stabilizes the configuration of the molecule.
For general background to organic diphosphonic acids and their applications, see: Matczak-Jon & Videnova-Adrabinska (2005). For applications of bisphosphonate metal complexes in medicine, see: Matkovskaya et al. (2001). For a related structure, see: Bon et al. (2010). For bond-length data, see: Allen et al. (2004).
Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2010); software used to prepare material for publication: publCIF (Westrip, 2010).Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. Crystal packing of the title compound viewed down the a axis, showing the three-dimensional chain structure. Hydrogen bonds are shown as dashed lines. |
[Co(C3H10NO7P2)2(H2O)2] | F(000) = 578 |
Mr = 563.08 | Dx = 2.172 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3543 reflections |
a = 7.3292 (2) Å | θ = 2.7–30.6° |
b = 10.8172 (3) Å | µ = 1.46 mm−1 |
c = 12.6403 (3) Å | T = 100 K |
β = 120.801 (1)° | Block, pink |
V = 860.79 (4) Å3 | 0.50 × 0.25 × 0.15 mm |
Z = 2 |
Bruker APEXII CCD diffractometer | 2613 independent reflections |
Radiation source: fine-focus sealed tube | 2273 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
φ and ω scans | θmax = 30.6°, θmin = 2.7° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −10→9 |
Tmin = 0.528, Tmax = 0.811 | k = −12→15 |
6688 measured reflections | l = −18→12 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.080 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0452P)2 + 0.4224P] where P = (Fo2 + 2Fc2)/3 |
2613 reflections | (Δ/σ)max = 0.003 |
157 parameters | Δρmax = 0.70 e Å−3 |
1 restraint | Δρmin = −0.41 e Å−3 |
[Co(C3H10NO7P2)2(H2O)2] | V = 860.79 (4) Å3 |
Mr = 563.08 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.3292 (2) Å | µ = 1.46 mm−1 |
b = 10.8172 (3) Å | T = 100 K |
c = 12.6403 (3) Å | 0.50 × 0.25 × 0.15 mm |
β = 120.801 (1)° |
Bruker APEXII CCD diffractometer | 2613 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 2273 reflections with I > 2σ(I) |
Tmin = 0.528, Tmax = 0.811 | Rint = 0.020 |
6688 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 1 restraint |
wR(F2) = 0.080 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.70 e Å−3 |
2613 reflections | Δρmin = −0.41 e Å−3 |
157 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Co1 | 0.0000 | 0.5000 | 0.0000 | 0.01045 (9) | |
P1 | 0.25936 (6) | 0.70145 (4) | −0.05843 (4) | 0.00902 (10) | |
P2 | −0.12574 (6) | 0.58120 (4) | −0.28208 (4) | 0.00964 (10) | |
O1 | 0.1630 (2) | 0.72770 (13) | −0.29229 (12) | 0.0156 (3) | |
H1O | 0.127 (4) | 0.802 (3) | −0.289 (2) | 0.023* | |
O2 | 0.25165 (18) | 0.60515 (12) | 0.02492 (11) | 0.0124 (2) | |
O3 | 0.1139 (2) | 0.81197 (12) | −0.07370 (12) | 0.0145 (3) | |
H3O | 0.154 (4) | 0.874 (3) | −0.079 (2) | 0.022* | |
O4 | 0.48210 (18) | 0.74524 (13) | −0.01964 (11) | 0.0137 (3) | |
O5 | −0.1323 (2) | 0.49001 (12) | −0.19349 (11) | 0.0143 (3) | |
O6 | −0.2632 (2) | 0.69798 (12) | −0.29892 (12) | 0.0151 (3) | |
H6O | −0.334 (4) | 0.712 (2) | −0.365 (2) | 0.023* | |
O7 | −0.1968 (2) | 0.52889 (12) | −0.40857 (11) | 0.0137 (3) | |
O8 | 0.1663 (2) | 0.33228 (13) | 0.02254 (13) | 0.0158 (3) | |
H81 | 0.270 (4) | 0.320 (2) | 0.007 (2) | 0.024* | |
H82 | 0.082 (4) | 0.283 (2) | −0.014 (2) | 0.024* | |
N1 | 0.4212 (3) | 0.38826 (17) | −0.30480 (17) | 0.0192 (3) | |
H2N | 0.356 (4) | 0.323 (3) | −0.297 (2) | 0.029* | |
H3N | 0.553 (5) | 0.394 (2) | −0.237 (3) | 0.029* | |
H1N | 0.439 (4) | 0.383 (3) | −0.3675 (19) | 0.029* | |
C1 | 0.1504 (2) | 0.63551 (16) | −0.21320 (15) | 0.0108 (3) | |
C2 | 0.2914 (3) | 0.52507 (17) | −0.20331 (16) | 0.0140 (3) | |
H2A | 0.4370 | 0.5391 | −0.1330 | 0.017* | |
H2B | 0.2357 | 0.4493 | −0.1858 | 0.017* | |
C3 | 0.3018 (3) | 0.50443 (17) | −0.31959 (18) | 0.0164 (4) | |
H3A | 0.1565 | 0.4980 | −0.3922 | 0.020* | |
H3B | 0.3743 | 0.5750 | −0.3325 | 0.020* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Co1 | 0.01100 (15) | 0.00938 (17) | 0.00988 (16) | −0.00047 (11) | 0.00457 (12) | 0.00097 (12) |
P1 | 0.00920 (18) | 0.0085 (2) | 0.00885 (19) | −0.00167 (14) | 0.00423 (15) | −0.00129 (15) |
P2 | 0.01040 (19) | 0.0090 (2) | 0.00774 (18) | −0.00077 (14) | 0.00333 (15) | −0.00018 (15) |
O1 | 0.0225 (6) | 0.0115 (6) | 0.0157 (6) | 0.0003 (5) | 0.0118 (5) | 0.0027 (5) |
O2 | 0.0120 (5) | 0.0124 (6) | 0.0107 (5) | −0.0017 (4) | 0.0042 (4) | 0.0020 (5) |
O3 | 0.0171 (6) | 0.0076 (6) | 0.0190 (6) | −0.0005 (5) | 0.0094 (5) | −0.0013 (5) |
O4 | 0.0110 (5) | 0.0168 (7) | 0.0133 (6) | −0.0049 (4) | 0.0063 (5) | −0.0040 (5) |
O5 | 0.0163 (6) | 0.0141 (6) | 0.0103 (6) | −0.0043 (5) | 0.0052 (5) | 0.0014 (5) |
O6 | 0.0148 (6) | 0.0147 (6) | 0.0109 (6) | 0.0051 (5) | 0.0031 (5) | 0.0004 (5) |
O7 | 0.0162 (6) | 0.0125 (6) | 0.0092 (5) | −0.0015 (5) | 0.0041 (5) | −0.0030 (5) |
O8 | 0.0139 (6) | 0.0134 (6) | 0.0210 (6) | −0.0007 (5) | 0.0096 (5) | −0.0009 (5) |
N1 | 0.0186 (7) | 0.0182 (8) | 0.0237 (8) | −0.0020 (6) | 0.0129 (7) | −0.0071 (7) |
C1 | 0.0114 (7) | 0.0099 (8) | 0.0103 (7) | −0.0005 (6) | 0.0050 (6) | 0.0001 (6) |
C2 | 0.0155 (7) | 0.0125 (8) | 0.0125 (7) | 0.0038 (6) | 0.0061 (6) | −0.0007 (7) |
C3 | 0.0181 (8) | 0.0156 (9) | 0.0180 (9) | 0.0017 (6) | 0.0111 (7) | −0.0008 (7) |
Co1—O2i | 2.0494 (12) | O1—H1O | 0.85 (3) |
Co1—O2 | 2.0494 (12) | O3—H3O | 0.76 (3) |
Co1—O8i | 2.1221 (14) | O6—H6O | 0.74 (3) |
Co1—O8 | 2.1221 (14) | O8—H81 | 0.89 (3) |
Co1—O5i | 2.1225 (13) | O8—H82 | 0.77 (3) |
Co1—O5 | 2.1225 (13) | N1—C3 | 1.487 (3) |
P1—O2 | 1.5031 (13) | N1—H2N | 0.88 (3) |
P1—O4 | 1.5199 (12) | N1—H3N | 0.91 (3) |
P1—O3 | 1.5469 (14) | N1—H1N | 0.870 (17) |
P1—C1 | 1.8367 (17) | C1—C2 | 1.542 (2) |
P2—O5 | 1.5115 (13) | C2—C3 | 1.527 (3) |
P2—O7 | 1.5149 (13) | C2—H2A | 0.9900 |
P2—O6 | 1.5609 (14) | C2—H2B | 0.9900 |
P2—C1 | 1.8422 (16) | C3—H3A | 0.9900 |
O1—C1 | 1.448 (2) | C3—H3B | 0.9900 |
O2i—Co1—O2 | 180.0 | P2—O5—Co1 | 130.65 (7) |
O2i—Co1—O8i | 92.52 (5) | P2—O6—H6O | 111 (2) |
O2—Co1—O8i | 87.48 (5) | Co1—O8—H81 | 126.4 (17) |
O2i—Co1—O8 | 87.48 (5) | Co1—O8—H82 | 107 (2) |
O2—Co1—O8 | 92.52 (5) | H81—O8—H82 | 107 (2) |
O8i—Co1—O8 | 180.0 | C3—N1—H2N | 111.7 (18) |
O2i—Co1—O5i | 92.85 (5) | C3—N1—H3N | 109.5 (17) |
O2—Co1—O5i | 87.15 (5) | H2N—N1—H3N | 109 (2) |
O8i—Co1—O5i | 90.19 (5) | C3—N1—H1N | 107.2 (19) |
O8—Co1—O5i | 89.81 (5) | H2N—N1—H1N | 113 (2) |
O2i—Co1—O5 | 87.15 (5) | H3N—N1—H1N | 106 (2) |
O2—Co1—O5 | 92.85 (5) | O1—C1—C2 | 108.19 (14) |
O8i—Co1—O5 | 89.81 (5) | O1—C1—P1 | 108.73 (11) |
O8—Co1—O5 | 90.19 (5) | C2—C1—P1 | 107.85 (11) |
O5i—Co1—O5 | 180.00 (7) | O1—C1—P2 | 109.67 (11) |
O2—P1—O4 | 114.17 (7) | C2—C1—P2 | 108.63 (12) |
O2—P1—O3 | 110.62 (8) | P1—C1—P2 | 113.62 (9) |
O4—P1—O3 | 110.93 (8) | C3—C2—C1 | 113.39 (14) |
O2—P1—C1 | 109.00 (8) | C3—C2—H2A | 108.9 |
O4—P1—C1 | 105.91 (8) | C1—C2—H2A | 108.9 |
O3—P1—C1 | 105.73 (8) | C3—C2—H2B | 108.9 |
O5—P2—O7 | 114.46 (8) | C1—C2—H2B | 108.9 |
O5—P2—O6 | 111.46 (8) | H2A—C2—H2B | 107.7 |
O7—P2—O6 | 108.02 (7) | N1—C3—C2 | 108.60 (15) |
O5—P2—C1 | 107.58 (7) | N1—C3—H3A | 110.0 |
O7—P2—C1 | 108.58 (8) | C2—C3—H3A | 110.0 |
O6—P2—C1 | 106.40 (8) | N1—C3—H3B | 110.0 |
C1—O1—H1O | 119.0 (17) | C2—C3—H3B | 110.0 |
P1—O2—Co1 | 129.11 (7) | H3A—C3—H3B | 108.4 |
P1—O3—H3O | 115 (2) | ||
O4—P1—O2—Co1 | −170.27 (9) | O4—P1—C1—C2 | 61.76 (13) |
O3—P1—O2—Co1 | 63.77 (11) | O3—P1—C1—C2 | 179.55 (12) |
C1—P1—O2—Co1 | −52.07 (12) | O2—P1—C1—P2 | 58.97 (11) |
O8i—Co1—O2—P1 | −55.98 (10) | O4—P1—C1—P2 | −177.76 (9) |
O8—Co1—O2—P1 | 124.02 (10) | O3—P1—C1—P2 | −59.97 (11) |
O5i—Co1—O2—P1 | −146.30 (11) | O5—P2—C1—O1 | −177.36 (11) |
O5—Co1—O2—P1 | 33.70 (11) | O7—P2—C1—O1 | 58.25 (13) |
O7—P2—O5—Co1 | 166.92 (9) | O6—P2—C1—O1 | −57.80 (13) |
O6—P2—O5—Co1 | −70.11 (12) | O5—P2—C1—C2 | 64.58 (13) |
C1—P2—O5—Co1 | 46.17 (13) | O7—P2—C1—C2 | −59.81 (13) |
O2i—Co1—O5—P2 | 148.83 (11) | O6—P2—C1—C2 | −175.86 (11) |
O2—Co1—O5—P2 | −31.17 (11) | O5—P2—C1—P1 | −55.46 (11) |
O8i—Co1—O5—P2 | 56.30 (11) | O7—P2—C1—P1 | −179.85 (8) |
O8—Co1—O5—P2 | −123.70 (11) | O6—P2—C1—P1 | 64.10 (11) |
O2—P1—C1—O1 | −178.61 (10) | O1—C1—C2—C3 | −31.88 (19) |
O4—P1—C1—O1 | −55.34 (13) | P1—C1—C2—C3 | −149.34 (13) |
O3—P1—C1—O1 | 62.45 (12) | P2—C1—C2—C3 | 87.10 (16) |
O2—P1—C1—C2 | −61.51 (13) | C1—C2—C3—N1 | −173.76 (14) |
Symmetry code: (i) −x, −y+1, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···O5ii | 0.85 (3) | 2.05 (3) | 2.845 (2) | 155 (2) |
O3—H3O···O7ii | 0.76 (3) | 1.72 (3) | 2.4627 (19) | 167 (3) |
O6—H6O···O4iii | 0.74 (3) | 1.78 (3) | 2.5124 (18) | 175 (3) |
O8—H81···O4iv | 0.89 (3) | 1.88 (3) | 2.7277 (18) | 160 (2) |
O8—H82···O1v | 0.77 (3) | 2.25 (3) | 2.8953 (19) | 142 (3) |
N1—H2N···O6v | 0.88 (3) | 2.15 (3) | 2.975 (2) | 156 (2) |
N1—H3N···O2iv | 0.91 (3) | 2.30 (3) | 3.096 (2) | 146 (2) |
N1—H3N···O5vi | 0.91 (3) | 2.32 (3) | 3.030 (2) | 134 (2) |
N1—H1N···O4vii | 0.87 (2) | 2.33 (2) | 3.071 (2) | 143 (2) |
Symmetry codes: (ii) −x, y+1/2, −z−1/2; (iii) x−1, −y+3/2, z−1/2; (iv) −x+1, −y+1, −z; (v) −x, y−1/2, −z−1/2; (vi) x+1, y, z; (vii) −x+1, y−1/2, −z−1/2. |
Experimental details
Crystal data | |
Chemical formula | [Co(C3H10NO7P2)2(H2O)2] |
Mr | 563.08 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 7.3292 (2), 10.8172 (3), 12.6403 (3) |
β (°) | 120.801 (1) |
V (Å3) | 860.79 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.46 |
Crystal size (mm) | 0.50 × 0.25 × 0.15 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.528, 0.811 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6688, 2613, 2273 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.715 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.080, 1.04 |
No. of reflections | 2613 |
No. of parameters | 157 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.70, −0.41 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2010), publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···O5i | 0.85 (3) | 2.05 (3) | 2.845 (2) | 155 (2) |
O3—H3O···O7i | 0.76 (3) | 1.72 (3) | 2.4627 (19) | 167 (3) |
O6—H6O···O4ii | 0.74 (3) | 1.78 (3) | 2.5124 (18) | 175 (3) |
O8—H81···O4iii | 0.89 (3) | 1.88 (3) | 2.7277 (18) | 160 (2) |
O8—H82···O1iv | 0.77 (3) | 2.25 (3) | 2.8953 (19) | 142 (3) |
N1—H2N···O6iv | 0.88 (3) | 2.15 (3) | 2.975 (2) | 156 (2) |
N1—H3N···O2iii | 0.91 (3) | 2.30 (3) | 3.096 (2) | 146 (2) |
N1—H3N···O5v | 0.91 (3) | 2.32 (3) | 3.030 (2) | 134 (2) |
N1—H1N···O4vi | 0.870 (17) | 2.33 (2) | 3.071 (2) | 143 (2) |
Symmetry codes: (i) −x, y+1/2, −z−1/2; (ii) x−1, −y+3/2, z−1/2; (iii) −x+1, −y+1, −z; (iv) −x, y−1/2, −z−1/2; (v) x+1, y, z; (vi) −x+1, y−1/2, −z−1/2. |
Acknowledgements
The authors gratefully acknowledge the support of this work by the Ukrainian National Academy of Sciences.
References
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In recent years the design and synthesis of novel metal-organic coordination compounds based on gem-diphosphonic acids has attracted much interest due to their structural diversity and possible applications in many areas (Matczak-Jon & Videnova-Adrabinska, 2005). Particular attention has been paid to 3-amino-1-hydroxypropane-1,1-diyl)bis(phosphonic acid) (pamidronic acid) due to its biological activity and as a result of its usage as a drug to prevent calcification and inhibit bone resorption, etc. (Matkovskaya et al., 2001).
The molecular structure of title complex is shown in Fig. 1; as illustrated the molecule of the complex forms discrete monomeric units. The asymmetric unit contains one-half of the formula unit [Co(C3H10NO7P2)2(H2O)2], with the Co atom lying on an inversion center.
The CoII ion is coordinated in a slightly distorted octahedral geometry which consists of six oxygen atoms, two from water molecules located in the axial positions and four from the two phosphonate groups of two different ligands, which exist in zwitterionic form, creating two six-membered [O, O] chelate rings. The Co—O bond lengths and the O—Co—O angles have expected values (Allen et al., 2004) and conform well to the previously reported related structure (Bon et al., 2010). In the packing, O—H···O and N—H···O hydrogen-bonds exist between the water molecules, phosphonate, hydroxyl O atoms and nitrogen atoms of the amino group (Fig. 2, Table 1). Thus, the molecules are interlinked by these hydrogen bonds to create a three-dimensional structure which partially influences and stabilizes the configuration of the molecule.