Tetra­kis(μ-5-bromo­nicotinato)-κ3 O,O′:O′;κ3 O:O,O′;κ4 O:O′-bis­[diaqua­(5-bromo­nicotinato-κ2 O,O′)neodymium(III)] dihydrate

Jing Huang; Jin Zhang; Hong-Ji Chen

doi:10.1107/S1600536811023798

. 2011 Jun 25;67(Pt 7):m974. doi: 10.1107/S1600536811023798

Tetrakis(μ-5-bromonicotinato)-κ³ O,O′:O′;κ³ O:O,O′;κ⁴ O:O′-bis[diaqua(5-bromonicotinato-κ² O,O′)neodymium(III)] dihydrate

Jing Huang ^a, Jin Zhang ^b, Hong-Ji Chen ^b,^*

PMCID: PMC3152138 PMID: 21836949

Abstract

In the title compound, [Nd₂(C₆H₃BrNO₂)₆(H₂O)₄]·2H₂O, the Nd^III ion is coordinated by nine O atoms from one chelating 5-bromonicotinate ligand, four bridging 5-bromonicotinate ligands and two water molecules, exhibiting a distorted three-capped triangular-prismatic geometry. Two Nd^III ions are bridged by four carboxylate groups in bi- and tridentate modes, forming a centrosymmetric dinuclear unit, with an Nd⋯Nd distance of 4.0021 (5) Å, and intramolecular π–π interactions between the pyridine rings [centroid–centroid distance = 3.960 (2) Å]. Intermolecular π–π interactions [centroid–centroid distances = 3.820 (2) and 3.804 (2) Å] and O—H⋯N and O—H⋯O hydrogen bonds connect the dinuclear molecules into a three-dimensional supramolecular network.

Related literature

For general background to lanthanide complexes with carboxylates, see: Ragunathan & Schneider (1996 ▶); Shibasaki & Yoshikawa (2002 ▶). For dimeric lanthanide carboxylates, see: Rupam et al. (2010 ▶); Song et al. (2004 ▶); Yang & Chen (2009 ▶).

Experimental

Crystal data

[Nd₂(C₆H₃BrNO₂)₆(H₂O)₄]·2H₂O
M _r = 1602.60
Monoclinic,
a = 11.5278 (13) Å
b = 16.6616 (18) Å
c = 12.2711 (13) Å
β = 102.478 (2)°
V = 2301.3 (4) Å³
Z = 2
Mo Kα radiation
μ = 7.52 mm⁻¹
T = 110 K
0.42 × 0.38 × 0.36 mm

Data collection

Bruker APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.059, T _max = 0.067
11552 measured reflections
4999 independent reflections
4295 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.022
wR(F ²) = 0.054
S = 1.07
4999 reflections
331 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.02 e Å⁻³
Δρ_min = −1.07 e Å⁻³

Data collection: SMART (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: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811023798/hy2440sup1.cif

e-67-0m974-sup1.cif^{(21.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811023798/hy2440Isup2.hkl

e-67-0m974-Isup2.hkl^{(244.9KB, 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—H71⋯N3ⁱ	0.84 (1)	1.94 (2)	2.769 (3)	165 (5)
O7—H72⋯O9ⁱⁱ	0.85 (3)	1.97 (2)	2.780 (3)	160 (4)
O8—H81⋯O9ⁱⁱ	0.85 (1)	1.87 (1)	2.699 (3)	164 (3)
O8—H82⋯N2ⁱⁱⁱ	0.85 (1)	1.88 (1)	2.735 (3)	175 (5)
O9—H91⋯N1	0.85 (3)	1.96 (3)	2.801 (3)	172 (4)
O9—H92⋯O4ⁱⁱⁱ	0.84 (1)	2.21 (2)	2.981 (3)	153 (4)
O9—H92⋯O8ⁱⁱⁱ	0.84 (1)	2.37 (4)	2.989 (3)	131 (4)

Open in a new tab

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

supplementary crystallographic information

Comment

Part of attentions has been paid to rational design and synthesis of lanthanide carboxylates due to their structural diversity and potential applications as catalysts (Ragunathan & Schneider, 1996; Shibasaki & Yoshikawa, 2002). Recent research results showed that olefin epoxidation reaction can be catalyzed by dimeric lanthanide carboxylates (Rupam et al., 2010). A few crystal structures of dimeric lanthanide carboxylates from 5-bromonicotinic acid (5-BrnicH) ligand, such as [La(5-Brnic)₃(H₂O)₂]₂.H₂O, [Gd(5-Brnic)₃(H₂O)₂]₂ (Rupam et al., 2010) and [Sm(5-Brnic)₃(H₂O)₂]₂.H₂O (Song et al., 2004), have been reported. As the research interest in the catalytic behavior of lanthanide compounds and the easy formation of dinuclear unit by using 5-BrnicH ligand (Yang & Chen, 2009), we synthesized a lanthanide carboxylate, the title compound. We report here its crystal structure.

The title compound is a dimeric lanthanide carboxylate that contains two Nd^III ions, six 5-Brnic ligands and four coordinated and two uncoordinated water molecules (Fig. 1). In the dimer, each Nd^III ion is nine-coordinated by nine O atoms, two of them from one (κ²O,O')-carboxylate group, two from two (κ²O:O')-carboxylate groups, three from two (κ³O,O':O')-carboxylate groups, and two from the coordinated water molecules. The coordination environment of the metal atom can be described as distorted three-capped triangular-prismatic. The two Nd^III ions are bridged by four carboxylate groups in bi- and tridentate modes, forming a centrosymmetric dinuclear unit, with a Nd···Nd distance of 4.0021 (5) Å and intramolecular π–π interactions between the pyridine rings [centroid–centroid distance = 3.960 (2) Å]. Intermolecular π–π interactions [centroid–centroid distances = 3.820 (2) and 3.804 (2) Å] and O—H···N and O—H···O hydrogen bonds (Table 1) connect the dinuclear molecules into a three-dimensional supramolecular network (Fig. 2).

In addition, the nine-coordinated Nd^III ion in the title compound exhibits higher coordination number than that in the dimers [Gd(5-Brnic)₃(H₂O)₂]₂ (Rupam et al., 2010) and [Sm(5-Brnic)₃(H₂O)₂]₂.H₂O (Song et al., 2004). As Nd^III ion has bigger ionic radius than that of Gd^III and Sm^III ions, we owe the increasing in coordination number to the principle of lanthanide contraction.

Experimental

A mixture of neodymium oxide (0.2 mmol, 0.067 g), 5-bromonicotinic acid (0.5 mmol, 0.101 g) and 10 ml water was sealed in a 15 ml Teflon-line autoclave and heated to 363 K for 72 h. The reaction solution was then cooled down to room temperature at a rate of 5 K per hour. Brown single crystals suitable for X-ray crystallography analysis were obtained (yield: 42%). Analysis, calculated for C₁₈H₁₅Br₃N₃NdO₉: C 26.38, H 1.89, N 5.24%; found: C 26.17, H 1.98, N 5.41%. IR (cm^-1, KBr): 3403 bm, 3051 m, 1618 vs, 1550 s, 1541 s, 1442 vs, 1400 vs, 1292 m, 1186 vw, 1130 w, 1026 w, 953 vw, 891 vw, 881 w, 789 m, 741 m, 687 m, 442 m.