catena-Poly[[diaqua­cadmium(II)]-μ-(methyl morpholino dichloro­methylene­diphospho­nato)-κ3 O,O′:O′′-[tetra­aqua­cadmium(II)]-μ-(methyl morpholino dichloro­methyl­enediphospho­nato)-κ3 O:O′,O′′]

Jonna Jokiniemi; Jouko Vepsäläinen; Markku Ahlgrén

doi:10.1107/S160053680901527X

. 2009 Apr 30;65(Pt 5):m600–m601. doi: 10.1107/S160053680901527X

catena-Poly[[diaquacadmium(II)]-μ-(methyl morpholino dichloromethylenediphosphonato)-κ³ O,O′:O′′-[tetraaquacadmium(II)]-μ-(methyl morpholino dichloromethylenediphosphonato)-κ³ O:O′,O′′]

Jonna Jokiniemi ^a,^*, Jouko Vepsäläinen ^b, Markku Ahlgrén ^a

PMCID: PMC2977635 PMID: 21583821

Abstract

The asymmetric unit of the title compound, [Cd(C₆H₁₁Cl₂NO₆P₂)(H₂O)₃]_n, contains two octahedrally coordinated Cd atoms located in special positions, one on a twofold rotation axis and the other on a centre of symmetry. The metal atoms are connected by methyl morpholino dichloromethylenediphosphonate ligands into chains in the c-axis direction. These chains are further connected by O—H⋯O hydrogen bonds into a layer-like construction along (100).

Related literature

For applications of metal complexes of bisphosphonates, see: Clearfield (1998 ▶); Clearfield et al. (2001 ▶); Fu et al. (2007 ▶). For cadmium bisphosphonate complexes, see: Ying & Mao (2006 ▶); Man et al. (2006 ▶). For metal complexes of bisphosphonate ester derivatives, see: Jokiniemi et al. (2007 ▶, 2008 ▶). For Mg, Zn and Cd complexes of the symmetrical diethyl ester derivative of (dichloromethylene)bisphosphonate, see: Kontturi et al. (2002 ▶, 2005a ▶,b ▶).

Experimental

Crystal data

[Cd(C₆H₁₁Cl₂NO₆P₂)(H₂O)₃]
M _r = 492.45
Monoclinic,
a = 26.2488 (8) Å
b = 7.6578 (3) Å
c = 17.5445 (7) Å
β = 116.002 (3)°
V = 3169.6 (2) Å³
Z = 8
Mo Kα radiation
μ = 1.96 mm⁻¹
T = 120 K
0.30 × 0.25 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (XPREP in SHELXTL; Sheldrick, 2008 ▶) T _min = 0.565, T _max = 0.676
21828 measured reflections
4053 independent reflections
3370 reflections with I > 2σ(I)
R _int = 0.038

Refinement

R[F ² > 2σ(F ²)] = 0.027
wR(F ²) = 0.068
S = 1.06
4053 reflections
195 parameters
H-atom parameters constrained
Δρ_max = 1.04 e Å⁻³
Δρ_min = −1.12 e Å⁻³

Data collection: COLLECT (Nonius, 1997 ▶); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2005 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680901527X/er2063sup1.cif

e-65-0m600-sup1.cif^{(21.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680901527X/er2063Isup2.hkl

e-65-0m600-Isup2.hkl^{(194.7KB, hkl)}

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

Table 1. Selected geometric parameters (Å, °).

Cd1—O11	2.2256 (17)
Cd1—O21	2.3173 (16)
Cd1—O1	2.3409 (17)
Cd2—O12	2.1884 (17)
Cd2—O3	2.2795 (16)
Cd2—O2	2.3486 (16)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O2ⁱ	0.84	2.06	2.849 (2)	156
O1—H1B⋯O22ⁱⁱ	0.88	2.12	2.990 (2)	170
O2—H2A⋯O21ⁱⁱⁱ	0.86	2.04	2.844 (2)	155
O2—H2B⋯O22	0.86	1.84	2.662 (2)	159
O3—H3A⋯O22	0.83	2.03	2.773 (2)	149
O3—H3B⋯O13^iv	0.90	1.87	2.745 (2)	163

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

supplementary crystallographic information

Comment

Metal complexes with bisphosphonic acids have interesting structures with various coordination architectures, and properties that offer practical applications in catalysis, ion-exchange and sorption (Clearfield et al., 2001, Clearfield, 1998, Fu et al., 2007). In our recent investigations, we studied the complexing properties of amide ester derivatives of (dichloromethylene)bisphosphonate, Cl₂MBP (Jokiniemi et al., 2007, 2008). Introduction of these ester substituents to phosphorus groups can result in novel structures of metal bishosphonates and lead to interesting functionalities. We now present the crystal structure of the Cd(II) complex of the P-morpholinyl-P'-methyl ester derivative of Cl₂MBP obtained by gel crystallization.

The title compound is isomorphous with the earlier reported Mg complexes of (dichloromethylene)bisphosphonic acid methyl esters of piperidinyl and morpholinyl derivatives (Jokiniemi et al., 2007, 2008). The title compound is polymeric, consisting of chains in the direction of the c-axis. There are two crystallographically independent six-coordinated Cd²⁺ cations in the asymmetric unit, located in special positions: Cd1 on the twofold rotation axis and Cd2 on the centre of symmetry (Fig. 1). Two symmetrically related L₁ ligands, L₁ = (Cl₂CP2O₅MeNC₄H₈O), around the Cd1 atom form six-membered chelate rings. The L₁ ligand is further connected to Cd2 through one O atom, and thus acts as a triatomic bridge between the adjacent Cd atoms. The fourth phosphonate O atom remains non-coordinated but is involved in hydrogen bonding. The remaining coordination sites around the Cd1 atoms are occupied by aqua ligands in cis position; the geometry is a significantly distorted octahedron having Cd1–O bond distances 2.226 (2)–2.341 (2) Å (Table 1). The three trans angles are O11–Cd1–O11A 166.14 (9), O21–Cd1–O1A 174.23 (5) and O21A–Cd1–O1 174.23 (5)°. The Cd2 atom has a distorted octahedral geometry, and the binding sites around the metal atom are occupied by two phosphonate O atoms in axial positions and four aqua ligands having Cd2–O bond lengths 2.188 (2)–2.349 (2) Å. The three trans bond angles are 180°, while the cis bond angles around the Cd2 atom range from 82.50 (6) to 97.50 (6)°. In addition to isomorphous Mg complexes of monomethyl ester of morpholinyl and piperidinyl derivatives of Cl₂MBP (Jokiniemi et al., 2007 and 2008), the same kind of chain construction is found in Mg, Zn and Cd complexes of the symmetrical diethyl ester derivative of Cl₂MBP (Kontturi et al., 2002, 2005a and 2005b).

The polymeric chains are connected, in a layer-like structure parallel to the (100) plane, by hydrogen bonds [O···O 2.745 (2)–2.990 (2) Å, 149–170°, Table 2]. The morpholinyl rings and chlorine atoms of the L₁ ligands point out from the layers (Fig. 2), which are held together solely by weak Van der Waals interactions, with an interlayer distance of 11.7959 Å.

Experimental

(H₂N[(CH₂)₂]₂O)₂CH₃PO₃CCl₂PO₂NC₄H₈O (19.8 mg, 0.039 mmol) and Cd(NO₃)₂×4H₂O (12.1 mg, 0.039 mmol) were dissolved separately in water (0.45 ml), the solutions were mixed, and tetramethoxysilane (TMOS 0.1 ml) was added. The two-phase system was shaken until homogeneous. After gel formation, a precipitant, acetone (1.0 ml), was added above the gel to induce crystallization. After about three weeks, large, colourless plank-shaped crystals suitable for X-ray analysis formed at the gel-liquid boundary. Anal. Found: C, 14.63; H, 3.48; N, 2.84; Cd, 22.83%. Calc. for C₆H₁₇Cl₂CdNO₉P₂: C, 14.74; H, 3.48; N, 2.86; Cd, 22.45%. Main IR absorptions (KBr pellet, cm^-1): 3432 (s), 2961 (m), 2926 (m), 2854 (m), 1627 (m), 1204 (versus), 1145 (m), 1101 (versus), 1072 (s), 1056 (s), 981 (s), 869 (m), 843 (m). ³¹P CP/MAS NMR: δ_P 8.4 and 4.3 p.p.m.. TGA (25–900 °C under a synthetic air): 30–110 °C 12.6% (calculated 11.0% for the loss of three aqua ligands). The second step (190–900 °C) is attributed to the release of organic groups, chlorine atoms and a methylene carbon atom. The observed total weight loss is 47.0% (calculated 45.1% if the final product is assumed to be Cd(PO₃)₂).