Poly[[diaqua-μ3-citrato-praseodymium(III)] monohydrate]

Li-Jun Han; Yuan-Fu Deng; Seik Weng Ng

doi:10.1107/S1600536811023804

. 2011 Jun 25;67(Pt 7):m981. doi: 10.1107/S1600536811023804

Poly[[diaqua-μ₃-citrato-praseodymium(III)] monohydrate]

Li-Jun Han ^a, Yuan-Fu Deng ^a, Seik Weng Ng ^b,^*

PMCID: PMC3152053 PMID: 21836955

Abstract

In the coordination polymer, {[Pr(C₆H₅O₇)(H₂O)₂]·H₂O}_n, seven of the nine coordination sites of the monocapped square-antiprismatic geometry are occupied by three O atoms of the same citrate trianion (an O atom of the hydroxy unit and the formally single-bond O atoms from two carboxyl units). Two other coordination sites are occupied by the O atoms of a chelating carboxyl unit of another citrate; one of these atoms is additionally involved in bridging. The seventh coordination site is occupied by the O atom of the formally double-bond O atom of a neighboring citrate. The remaining two coordination sites are occupied by water molecules. The citrate functions in a μ₃-bridging mode, connecting the metal atoms into a ribbon structure parallel to [010]. The structure is consolidated into a three-dimensional network by O—H⋯O hydrogen bonds.

Related literature

For isotypic [Eu(C₆H₅O₇)(H₂O)₂]·H₂O, see: Tang et al. (2011 ▶).

Experimental

Crystal data

[Pr(C₆H₅O₇)(H₂O)₂]·H₂O
M _r = 384.06
Monoclinic,
a = 6.2645 (3) Å
b = 9.7356 (7) Å
c = 17.0425 (10) Å
β = 91.0672 (18)°
V = 1039.22 (11) Å³
Z = 4
Mo Kα radiation
μ = 4.74 mm⁻¹
T = 293 K
0.30 × 0.15 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.331, T _max = 0.649
9596 measured reflections
2366 independent reflections
2182 reflections with I > 2σ(I)
R _int = 0.038

Refinement

R[F ² > 2σ(F ²)] = 0.026
wR(F ²) = 0.050
S = 1.18
2366 reflections
175 parameters
10 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.76 e Å⁻³
Δρ_min = −0.81 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811023804/si2362sup1.cif

e-67-0m981-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811023804/si2362Isup2.hkl

e-67-0m981-Isup2.hkl^{(116.3KB, 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
O7—H7⋯O2ⁱ	0.83 (1)	1.72 (1)	2.536 (3)	167 (4)
O1w—H11⋯O2ⁱⁱ	0.84 (1)	1.84 (1)	2.666 (3)	169 (4)
O1w—H12⋯O3ⁱⁱⁱ	0.84 (1)	1.89 (2)	2.692 (3)	159 (3)
O2w—H21⋯O1w^iv	0.84 (1)	2.09 (2)	2.854 (4)	151 (4)
O2w—H22⋯O3w	0.84 (1)	1.89 (1)	2.718 (4)	168 (4)
O3w—H31⋯O6^v	0.84 (1)	2.05 (2)	2.856 (4)	160 (6)

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

Acknowledgments

We thank South China University of Technology and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

A recent report describes the synthesis of Eu(H₂O)₂(C₆H₅O₇)^.H₂O, a citrate(3-) based coordination polymer that exhibits useful luminescence; the ribbon motif propagates along the a-axis and adjacent chains are linked by O–H···O hydrogen bonds into a three-dimensional network. The presence of manganese dichloride is crucial to the synthesis (Tang et al., 2011). The present Pr analog (Scheme I) is isostructural, the two compounds crystallizing with matching cell dimensions. In the coordination polymer, Pr(H₂O)₂(C₆H₅O₇)^.H₂O (Fig. 1), seven of the nine coordination sites a mono-capped square-antiprismatic geometry (Fig. 2) are occupied by three O atoms of the same citrate trianion (an O atom of the hydroxy unit and the formally single-bond O atoms from two carboxyl units). Two other coordination sites are occupied by the O atoms of a chelating carboxyl unit of another citrate; one of these atoms is additionally involved in bridging. The seventh coordination site is occupied by the O atom of the formally double-bond O atom of a neighboring citrate. The remaining two coordination sites of the are occupied by water molecules. The citrate functions in a µ₃– bridging mode to connect the metal atoms into a ribbon structure. The structure is consolidated into a three-dimensional network by O–H···O hydrogen bonds (Table 1).

Experimental

Praseodymium oxide, Pr₆O₁₁ (0.341 g), was suspended in water (20 ml) and to the suspension was added manganese dichloride tetrahydrate (0.395 g, 2.0 mmol) and citric acid monohydrate (0.841 g, 4.0 mmol). The mixture was placed in a 25 ml, teflon-lined, stainless-steel Parr bomb. The bomb was heated at 393 K for 72 h. It was cooled to room temperature at 30 K an hour. Green crystals were isolated in 75% yield based on Pr₆O₁₁.