Poly[[tri-μ-aqua-do­deca­aqua­tris­(μ3-1-hy­droxy­ethyl­idene-1,1-di­phospho­nato)tricalcium(II)tripalladium(II)] penta­hydrate]

Irina P Kutsenko; Alexandra N Kozachkova; Natalia V Tsaryk; Vasily I Pekhnyo; Julia A Rusanova

doi:10.1107/S1600536814015189

. 2014 Jul 5;70(Pt 8):m291–m292. doi: 10.1107/S1600536814015189

Poly[[tri-μ-aqua-dodecaaquatris(μ₃-1-hydroxyethylidene-1,1-diphosphonato)tricalcium(II)tripalladium(II)] pentahydrate]

Irina P Kutsenko ^a,^*, Alexandra N Kozachkova ^a, Natalia V Tsaryk ^a, Vasily I Pekhnyo ^a, Julia A Rusanova ^b

PMCID: PMC4158508 PMID: 25249877

Abstract

The asymmetric unit of the title compound, {[CaPd{CH₃OHC(PO₃)₂}(H₂O)₅]·5/3H₂O}_n, consists of one half of the complex [Pd{CH₃OHC(PO₃)₂}]²⁻ anion (point group symmetry m..), one Ca²⁺ cation [site symmetry (.2.)] that is surrounded by three water molecules (one of which is on the same rotation axis) and by three disordered lattice water molecules. The anions form a trinuclear metallocycle around a crystallographic threefold rotation axis. The cations are related by a twofold rotation axis to form a [Ca₂(H₂O)₁₀]²⁺ dimer. The slightly distorted square-planar coordination environment of the Pd^II atoms in the complex anions is formed by O atoms of the bidentate chelating phosphonate groups of the 1-hydroxyethylidene-1,1-diphosphonate ligands. In the crystal, cations are bound to anions through —Ca—O—P—O— bonds, as well as through O—H⋯O hydrogen bonds, resulting in a three-dimensional polymer. The structure is completed by five disordered solvent molecules localized in cavities within the framework.

Keywords: crystal structure

Related literature

For background to diphosphonic acids see: Zhang et al. (2007 ▶); Szabo et al. (2002 ▶); Matczak-Jon & Videnova-Adrabinska (2005 ▶). For background to the antitumor activity of palladium(II) complexes, see: Juribašiċ et al. (2011 ▶); Curic et al. (1996 ▶); Abu-Surrah et al. (2008 ▶); Ruiz et al. (2005 ▶, 2006 ▶); Tušek-Božiċ et al. (2008 ▶). For the structures of related complexes, see: Babaryk et al. (2012 ▶); Hammerl et al. (2002 ▶); Müller (1972 ▶).

Experimental

Crystal data

[CaPd(C₂H₄O₇P₂)(H₂O)₅]·1.67H₂O
M _r = 468.58
Hexagonal,
a = 15.9731 (3) Å
c = 18.4149 (4) Å
V = 4068.91 (14) Å³
Z = 12
Mo Kα radiation
μ = 2.05 mm⁻¹
T = 296 K
0.39 × 0.07 × 0.06 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2009 ▶) T _min = 0.502, T _max = 0.887
37638 measured reflections
1774 independent reflections
1410 reflections with I > 2σ(I)
R _int = 0.082

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.071
S = 1.08
1774 reflections
116 parameters
28 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.56 e Å⁻³
Δρ_min = −0.57 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536814015189/br2239sup1.cif

e-70-0m291-sup1.cif^{(21.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814015189/br2239Isup2.hkl

e-70-0m291-Isup2.hkl^{(87.6KB, hkl)}

CCDC reference: 1010912

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H1⋯O1ⁱ	0.84 (1)	1.95 (2)	2.756 (3)	160 (4)
O5—H2⋯O5ⁱⁱ	0.79 (2)	2.07 (2)	2.799 (5)	155 (4)
O6—H3⋯O2ⁱⁱⁱ	0.82 (2)	1.87 (2)	2.685 (3)	170 (4)
O7—H4⋯O3ⁱ	0.82 (2)	2.07 (2)	2.865 (4)	166 (4)
O4A—H4A⋯O8	0.82	1.99	2.731 (16)	150

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

supplementary crystallographic information

S1. Comment

During the last decade, there has been a growing interest in the study of organic diphosphonic acids owing to their potentially very powerful chelating properties used in metal extractions and are tested by the pharmaceutical industry for use as efficient drugs preventing calcification and inhibiting bone resorption (Matczak-Jon & Videnova-Adrabinska, 2005). Diphosphonic acids and their metal complexes are used in the treatment of Pagets disease, osteoporosis and tumoral osteolysis (Szabo et al., 2002). Also in the last years, there has been a surge of interest in palladium complexes as a prospective antitumor preparation (Abu-Surrah et al., 2008, Curic et al., 1996).

The title compound crystallized in centric space group P6/mcc. The square-planar environment of palladium atoms in the complex anion [Pd₃{CH₃OHC(PO₃)₂}₃]^6-is formed by coordination of the oxygen atoms of the chelating phosphonic groups of the ligand. By crystallographic threefold rotation axis it completed to trinuclear species with equilateral triangle geometry (Fig.1). Palladium atoms slightly deviate from the oxygen mean-planes towards the triangle center by 0.12 Å. The range of Pd – O bond distances of 2,006 (2) – 2,010 (2)Å as well cis O–Pd–O angles ranging from 85.78 (9)° to 92.91 (13)° are in a good agreement with literature values (Babaryk et al., 2012 and references therein). CH₃ and OH groups of the HEDP are statistically disordered over two positions with equal occupation numbers.

As it shown on Fig. 2, each Ca atom of the complex binuclear cation is surrounded by eight oxygen atoms (six from water molecules, comprising two bridging ones, and two from phosphonic groups of the trinuclear clusters) in the form of a slightly distorted, bi-capped trigonal prism. (Hammerl et al., 2002). The Ca – O bond distances were observed within the range of 2,416 (3) – 2,538 (3)Å. Calcium coordinated by eight water molecules is well known in the literature, and the distances of the bridging and nonbridging oxygen atoms found here agree well with the previously reported values (Müller et al., 1972). Each binuclear cation linked to four trinuclear anions of adjacent layers through -Ca-O-P-O- bonds (Fig. 3) as well thought O-H···O hydrogen bonds. Moreover, each trinuclear anion is linked to six binuclear cations. In the crystal packing cations and anions stacked along the c axis into columns where layer of cations alternates with layer of anions. Resulting layered 3d polymer structure (Fig.4) completed by five disordered solvent water molecules which are located in cavities. The Ca – O and P-O bond distances (2.507 (2)Å and 1.498 (2)Å respectively) as well as D···A distances ranging from 2.756 (3)Å to 2.865 (4)Å are in a good agreement with literature values. Oxygen atom of one of the water solvent molecules O8 is statistically disordered over two positions and linked to cation thought CH₃-C-OH···O8 hydrogen bonds with D···A distance about 2.731 (16) Å. Another one water molecule oxygen atom O9 is situated at the origin (0, 0, 0) with 1/12 multiplicity. Remaining 3 oxygen atoms O10 of the water molecules are disordered around 6-fold rotation axis with centre of symmetry over 12 positions with an occupation number of 1/4. Considering this reasonable H-atom positions of the disordered solvent water molecules were not established

S2. Experimental

A solution of AgNO₃ (0.3398 g, 2.0 mmol) in H₂O (5 ml) was added to a solution of PdCl₂ (0.0885 g, 0.5 mmol) in hydrochloric acid (0.1M, 10 ml) and the resulting solution stirred at 276 K for 30 min under protection from light until AgCl was precipitated and filtered off. Hydroxyethylidenediphosphonic acid (0.112 g, 0.5 mmol) and CaCO₃ (0.05 g, 0.5 mmol) were added to filtrate. The resulting solution was stirred for 1 h at 276 - 277 K and left staying overnight at room temperature. The solvent was removed from resulting reaction mixture under reduced pressure leaving an yellow solid, which was washed twice with methanol and diethyl ether and dried under vacuum. Yellow rectangular crystals of the title compound suitable for crystallographic study were produced by slow evaporation of a water solution at room temperature.