Oxonium (dihydrogen 1-amino­ethane-1,1-diyldiphospho­nato-κ2 N,O)[hydrogen (1-amino-1-phosphono­ethyl)phospho­nato-κ2 N,O]palladium(II) trihydrate

Anatolij Dudko; Vladimir Bon; Alexandra Kozachkova; Natalia Tsaryk; Vasily Pekhnyo

doi:10.1107/S1600536810000930

. 2010 Jan 16;66(Pt 2):m170–m171. doi: 10.1107/S1600536810000930

Oxonium (dihydrogen 1-aminoethane-1,1-diyldiphosphonato-κ² N,O)[hydrogen (1-amino-1-phosphonoethyl)phosphonato-κ² N,O]palladium(II) trihydrate

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

PMCID: PMC2979892 PMID: 21579644

Abstract

The title compound, (H₃O)[Pd(C₂H₇NO₆P₂)(C₂H₈NO₆P₂)]·3H₂O, was synthesized by the reaction of [Pd(H₂O)₄](NO₃)₂ with 1-aminoethane-1,1-diyldiphosphonic acid in aqueous solution. The asymmetric unit contains one molecule of the complex existing as an anion, an oxonium counter-ion and three solvent water molecules. The Pd^II ion occupies a position on a pseudo-twofold axis, which is not realized crystallographically. The slightly distorted square-planar coordination environment of the Pd^II ion consists of the O atoms from two phosphonic acid groups and two N atoms of the amino groups in cis positions. The crystal structure displays N—H⋯O and O—H⋯O hydrogen bonding, which creates a wide three-dimensional network.

Related literature

For general background and the medical use of organic diphosphonic acids, see: Matczak-Jon & Videnova-Adrabinska (2005 ▶); Curic et al. (1996 ▶); Szabo et al. (2002 ▶). For related structures, see: Shkol’nikova et al. (1991 ▶).

Experimental

Crystal data

(H₃O)[Pd(C₂H₇NO₆P₂)(C₂H₈NO₆P₂)]·3H₂O
M _r = 586.53
Orthorhombic,
a = 9.9412 (2) Å
b = 9.0941 (2) Å
c = 19.9004 (3) Å
V = 1799.12 (6) Å³
Z = 4
Mo Kα radiation
μ = 1.47 mm⁻¹
T = 100 K
0.48 × 0.29 × 0.14 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.536, T _max = 0.823
53680 measured reflections
5568 independent reflections
5545 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.015
wR(F ²) = 0.041
S = 1.09
5568 reflections
301 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.80 e Å⁻³
Δρ_min = −0.61 e Å⁻³
Absolute structure: racemic twin (Flack, 1983 ▶), 2697 Friedel pairs
Flack parameter: 0.362 (11)

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, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810000930/hg2625sup1.cif

e-66-0m170-sup1.cif^{(23KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810000930/hg2625Isup2.hkl

e-66-0m170-Isup2.hkl^{(272.6KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11N⋯O1ⁱ	0.83 (2)	2.28 (2)	3.0527 (16)	154 (2)
N1—H12N⋯O16	0.77 (2)	2.38 (2)	3.0647 (18)	149 (2)
N2—H21N⋯O7ⁱ	0.86 (2)	2.01 (2)	2.8245 (17)	159 (2)
N2—H22N⋯O10	0.80 (2)	2.53 (2)	2.9844 (17)	117.7 (19)
O2—H2O⋯O6ⁱⁱ	0.77 (2)	1.79 (2)	2.5582 (15)	174 (3)
O4—H4O⋯O11ⁱⁱⁱ	0.73 (3)	1.94 (3)	2.6593 (16)	170 (3)
O13—H133⋯O5	1.06 (2)	1.40 (3)	2.4558 (16)	174 (2)
O8—H8O⋯O15	0.81 (2)	1.76 (2)	2.5607 (17)	173 (3)
O10—H10O⋯O16^iv	0.83 (3)	1.80 (3)	2.6298 (17)	172 (3)
O12—H12O⋯O14	0.79 (2)	1.71 (2)	2.4608 (16)	159 (3)
O13—H131⋯O3^v	0.80 (3)	1.79 (3)	2.5728 (16)	165 (2)
O13—H132⋯O9^vi	0.89 (2)	1.62 (2)	2.5044 (16)	174 (2)
O14—H141⋯O3^vii	0.79 (2)	1.96 (2)	2.7220 (16)	162 (2)
O14—H142⋯O11^viii	0.80 (3)	1.90 (3)	2.6911 (17)	171 (3)
O15—H151⋯O4^ix	0.82 (3)	2.18 (3)	2.9904 (18)	169 (3)
O15—H152⋯O6^iv	0.79 (2)	1.97 (2)	2.7504 (17)	176 (3)
O16—H161⋯O14^ix	0.76 (3)	2.19 (3)	2.8534 (16)	147 (3)
O16—H162⋯O8^x	0.87 (3)	2.48 (3)	3.0109 (17)	120 (2)
O16—H162⋯O2	0.87 (3)	2.62 (3)	3.1809 (16)	123 (2)

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

supplementary crystallographic information

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 perspective antitumor preparation (Curic et al., 1996).

The title compound crystallized in non-centrosymmetric space group Pca2₁ with Flack parameter equal 0.362 (11), which indicate the presence of racemic twin in the structure (Flack, 1983). The asymmetric unit of title compound contains one formula unit, which exists as a complex anion and oxonium cation, which are bonding together via strong H-bond (Fig.1, Table 1). The Pd atom occupies a position on the pseudo twofold axis and shows slightly distorted square-planar coordination environment, which consists of O atoms from two phosphonic groups and two N atoms of amino group, located in cis position. The crystal structure displays N—H···O and O—H···O hydrogen bonding, which creates a three-dimensional network (Table 1, Fig.2). Hydrogen bonds often play a dominant role in crystal engineering (Matczak-Jon & Videnova-Adrabinska, 2005) because they combine the desirable attributes of specificity, strength and directionality.

Experimental

Aqueous solution of AgNO₃ (0,4076 g, 0,24 mmol) was added to the solution of PdCl₂ (0,063 g, 0,6 mmol) in 12 ml of hydrochloric acid. The solution was stirred at 3–4 °C and protected from light for 30 min. The AgCl precipitated and was filtered off. The dark red solution turned yellow and than 1-aminoethane-1,1-diyldiphosphonic acid (0,2459 g, 0,12 mmol) was added in one portion. The solution was stirred for 1 h at 3–4 °C and left staying overnight at room temperature. The solvent was removed under reduced pressure leaving a pale yellow solid, which was washed twice with methanol and diethyl ether and dried under vacuum. Suitable single crystals of title compound were produced by slow evaporation of a water solution at room temperature. A pale yellow rectangular crystal was used for data collection.