Redetermination of [Gd(NO3)3(H2O)4]·2H2O

Ziyad A Taha; Abdulaziz Ajlouni; Ahmed K Hijazi; Fritz E Kühn; Eberhardt Herdtweck

doi:10.1107/S1600536812028000

. 2012 Jun 27;68(Pt 7):i56–i57. doi: 10.1107/S1600536812028000

Redetermination of [Gd(NO₃)₃(H₂O)₄]·2H₂O

Ziyad A Taha ^a,^*, Abdulaziz Ajlouni ^a, Ahmed K Hijazi ^b, Fritz E Kühn ^c, Eberhardt Herdtweck ^d,^*

PMCID: PMC3393141 PMID: 22807698

Abstract

The crystal structure of the title compound, tetraaquatris(nitrato-κ² O,O′)gadolinium(III) dihydrate, was redetermined from single-crystal X-ray data. In comparison with the first determination [Ma et al. (1991 ▶). Wuji Huaxue Xuebao, 7, 351–353], all H atoms could be located, accompanied with higher accuracy and precision. The Gd^III atom shows a ten-coordination with three nitrate ligands behaving in a bidentate manner and the other positions being occupied by four water molecules, forming a distorted bicapped square antiprism. Two nitrate ions coordinate to the metal atom with similar bond lengths while the third shows a more asymmetric bonding behaviour. An intricate network of O—H⋯O hydrogen bonds, including the lattice water molecules, stabilizes the crystal packing.

Related literature

For a previous determination of the title compound, see: Ma et al. (1991 ▶). Isotypic [RE(NO₃)₃(H₂O)₄]·2H₂O structures were described for RE = Nd by Rogers et al. (1983 ▶), for Tb by Moret et al. (1990 ▶), for Sm by Kawashima et al. (2000 ▶), for Eu by Stumpf & Bolte (2001 ▶), for Dy by Gao et al. (1990 ▶), and for La by Eriksson et al. (1980 ▶). [RE(NO₃)₃(H₂O)₄]·H₂O structures with one less water molecule were described for RE = Eu by Ribár et al. (1986 ▶), for Gd by Stockhause & Meyer (1997 ▶), and for Yb by Junk et al. (1999 ▶).

Experimental

Crystal data

[Gd(NO₃)₃(H₂O)₄]·2H₂O
M _r = 451.38
Triclinic,
a = 6.6996 (2) Å
b = 9.1145 (3) Å
c = 11.6207 (3) Å
α = 69.8257 (10)°
β = 88.9290 (11)°
γ = 69.2170 (11)°
V = 618.36 (3) Å³
Z = 2
Mo Kα radiation
μ = 5.45 mm⁻¹
T = 173 K
0.48 × 0.46 × 0.23 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.349, T _max = 0.745
19731 measured reflections
2256 independent reflections
2255 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.016
wR(F ²) = 0.041
S = 1.20
2256 reflections
221 parameters
All H-atom parameters refined
Δρ_max = 1.04 e Å⁻³
Δρ_min = −1.10 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812028000/wm2634sup1.cif

e-68-00i56-sup1.cif^{(24.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812028000/wm2634Isup2.hkl

e-68-00i56-Isup2.hkl^{(108.6KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Gd1—O1	2.528 (2)
Gd1—O2	2.494 (3)
Gd1—O4	2.578 (2)
Gd1—O5	2.518 (3)
Gd1—O7	2.552 (2)
Gd1—O8	2.754 (2)
Gd1—O10	2.398 (2)
Gd1—O11	2.389 (2)
Gd1—O12	2.392 (3)
Gd1—O13	2.364 (3)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O10—H1⋯O15ⁱ	0.76 (5)	1.97 (5)	2.720 (4)	171 (5)
O10—H2⋯O4ⁱⁱ	0.75 (4)	2.21 (4)	2.956 (3)	178 (6)
O11—H3⋯O14ⁱⁱⁱ	0.82 (4)	1.85 (4)	2.671 (3)	176 (5)
O11—H4⋯O7^iv	0.78 (5)	2.19 (5)	2.967 (4)	173 (5)
O12—H5⋯O4^v	0.77 (6)	2.50 (6)	3.185 (3)	149 (5)
O12—H5⋯O7^v	0.77 (6)	2.56 (6)	3.156 (4)	135 (5)
O12—H6⋯O8^vi	0.83 (5)	2.27 (5)	3.074 (3)	162 (4)
O12—H6⋯O9^vi	0.83 (5)	2.39 (5)	3.062 (4)	139 (4)
O13—H7⋯O15	0.90 (4)	1.84 (4)	2.721 (3)	169 (5)
O13—H8⋯O14	0.71 (4)	2.04 (4)	2.738 (4)	168 (5)
O14—H9⋯O9^iv	0.81 (5)	2.03 (5)	2.826 (4)	167 (4)
O14—H10⋯O3^v	0.76 (5)	2.45 (5)	3.008 (4)	132 (5)
O14—H10⋯O5^vii	0.76 (5)	2.31 (5)	2.888 (4)	134 (5)
O15—H11⋯O6ⁱⁱ	0.80 (6)	2.02 (6)	2.819 (4)	176 (6)
O15—H12⋯O3^viii	0.76 (6)	2.30 (6)	2.903 (4)	139 (5)

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

Acknowledgments

The authors are grateful to the Deanship of Scientific Research at Jordan University of Science and Technology for the financial support of this work (grant No. 48/2008).

supplementary crystallographic information

Comment

Single crystals of gadolinium nitrate hexahydrate, [Gd(NO₃)₃(H₂O)₄]^.2H₂O, were obtained and its structure was re-determined using single-crystal X-ray diffraction analysis.

As shown in Figure 1, the Gd^III atom is ten-coordinated, being bound to six nitrate-oxygen atoms, O1, O2, O4, O5, O7, and O8, and four water-oxygen atoms O10, O11, O12, and O13. The nitrate ions are coordinated to the central gadolinium atom in a bidentate mode and show clearly the changes in bond lengths and angles noted previously for the isotypic Eu(III) structure (Stumpf & Bolte, 2001). The distances between the Gd^III ion and the nitrate-O atoms (Gd—O) are in the range 2.494 (3)–2.754 (2) Å, with a mean value of 2.571 Å. The differences between the Gd^III atom and the two oxygen atoms of the same nitrate group are 0.034 Å and 0.060 Å for nitrate N1 and nitrate N2, respectively. Nitrate N1 and nitrate N2 groups appear to be more symmetrically bonded to the Gd^III atom because the third nitrate group N3 exhibits one Gd—O distance that is 0.202 Å longer than the other. This asymmetric bonding seem to be associated with a steric effect of the coordinating water molecules. There is simply not space enough for all the oxygen atoms around the Gd^III atom at the same distance. The Gd—O_water distances are in the range of 2.364 (3)–2.398 (2) Å with an average distance of 2.386 Å. Hence the water molecules are closer to the Gd^III atom than the nitrate groups by ca. 0.185 Å.

These results are comparable to that reported for other lanthanide complexes with bidentately coordinating nitrate groups. The coordination polyhedron around the Gd^III ion can be best described as a distorted bi-capped square antiprism (Fig. 1), as previously reported for other hydrated lanthanide(III) nitrate complexes (Ribár et al., 1986; Moret et al., 1990; Ma et al., 1991, Stockhause & Meyer, 1997; Kawashima et al., 2000; Stumpf & Bolte, 2001; Junk et al., 1999; Gao et al., 1990; Eriksson et al., 1980; Rogers et al., 1983). The structure contains additional two lattice water molecules, which are associated with the complex by a network of hydrogen bonds. All hydrogen atoms and except for O1 and O2 all oxygen atoms are involved in a complicated network of O—H···O hydrogen bonds, stabilizing the crystal packing (Table 1, Fig. 2). H5, H6 and H10 act as bifurcated bridging atoms. In contrast to the original work of Ma et al. (1991), we report much more precise results. All hydrogen atoms could be located in the difference Fourier maps and were allowed to refine freely. The final R1 value changed from 0.076 to 0.0158 and the overall e.s.d.'s for the positional parameters dropped from e.g. Gd1 x = 0.8016 (1) to 0.80352 (2). The same is valid for distances e.g. Gd1—O1 dropped from 2.558 (56) Å to 2.528 (2) Å and for the angels e.g. O1—Gd1—O2 dropped from 51.1 (22) to 50.56 (7).

Experimental

Single crystals of [Gd(NO₃)₃(H₂O)₄]^.2H₂O have been obtained accidentally during the synthesis of a Gd—N,N-bis(salicylicaldehyde)-o-phenylenediamine Schiff base complex. 1.0 mmol of the Schiff base were dissolved in 10 ml chloroform. To this solution was added in a drop-wise manner a 10 ml ethyl acetate solution of 2.0 mmol Gd(NO₃)₃^.6(H₂O). The reaction mixture was stirred for 2 h at room temperature. The yellow precipitate was filtered, washed several times with ethyl acetate and chloroform. Single crystals suitable for X-ray were obtained after a few days by the slow evaporation of the solvent in an open atmosphere.