Tris­(nitrato-κ2 O,O′)bis[4,4,5,5-tetra­methyl-2-(pyridin-2-yl-κN)imidazoline-1-oxyl 3-oxide-κO]holmium(III)

Dong-Jiao Li

doi:10.1107/S1600536812012445

. 2012 Apr 6;68(Pt 5):m550. doi: 10.1107/S1600536812012445

Tris(nitrato-κ² O,O′)bis[4,4,5,5-tetramethyl-2-(pyridin-2-yl-κN)imidazoline-1-oxyl 3-oxide-κO]holmium(III)

Dong-Jiao Li ^a,^*

PMCID: PMC3344306 PMID: 22590072

Abstract

In the title compound, [Ho(NO₃)₃(C₁₂H₁₆N₃O₂)₂], the Ho^III ion is ten-coordinated in a distorted bicapped square-antiprismatic environment by two N,O-bidentate nitronyl nitroxide radical ligands and three O,O′-bidentate nitrate anions. Complex molecules are connected by C—H⋯O hydrogen bonds into a three-dimensional network.

Related literature

For background on the use of rare earth complexes with nitroxide radicals in coordination chemistry, see: Sutter et al. (1998 ▶); Kahn et al. (2000 ▶); Lescop et al. (2000 ▶). For related complexes reported by our group, see: Li et al. (2005 ▶); Li, Gao & Liao (2004 ▶); Li, Wang & Liao (2004 ▶).

Experimental

Crystal data

[Ho(NO₃)₃(C₁₂H₁₆N₃O₂)₂]
M _r = 819.52
Monoclinic,
a = 12.2627 (10) Å
b = 11.1044 (8) Å
c = 23.2861 (17) Å
β = 98.391 (2)°
V = 3136.9 (4) Å³
Z = 4
Mo Kα radiation
μ = 2.60 mm⁻¹
T = 293 K
0.22 × 0.16 × 0.12 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.599, T _max = 0.746
17689 measured reflections
5530 independent reflections
4895 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.061
S = 1.25
5530 reflections
432 parameters
H-atom parameters constrained
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.87 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); 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: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812012445/is5078sup1.cif

e-68-0m550-sup1.cif^{(42.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812012445/is5078Isup2.hkl

e-68-0m550-Isup2.hkl^{(270.8KB, 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
C8—H8⋯O11ⁱ	0.93	2.42	3.053 (5)	126
C11—H11B⋯O13ⁱⁱ	0.96	2.54	3.460 (6)	161
C18—H18⋯O4ⁱⁱⁱ	0.93	2.56	3.450 (6)	160
C20—H20⋯O7^iv	0.93	2.37	3.193 (5)	147
C22—H22C⋯O13ⁱ	0.96	2.53	3.239 (6)	131
C24—H24B⋯O10^v	0.96	2.40	3.324 (6)	162

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

Acknowledgments

The author thanks the Chemical Institute of Linyi University for supporting this work.

supplementary crystallographic information

Comment

As a continuation of our work on the complexes adopting nitroxide radicals as the ligand, the title new Ho complex is reported. In this compound, the metal ion is ten-coordinated by two radicals and three nitrate anions (Fig. 1). The radical behaves as a bidentate chelating ligand through one oxygen of nitronyl nitroxide and one nitrogen of pyridyl, while the other oxygen of nitronyl nitroxide remains uncoordinated. The coordination sphere of the Ho atom is completed by the η²-coordination of three NO₃^- anions. The complexes are further connected by C—H···O hydrogen bonds (Table 1) into a three-dimensional framework, as shown in Fig. 2.

Experimental

The compound was synthesized by the following procedure. Ho(NO₃)₃.6H₂O (0.046 g, 0.2 mmol) and NIT2Py (0.047 g, 0.2 mmol) were dissolved in 10ml of anhydrous THF. The mixture was stirred at room temperature for four hours and then filtered. The dark brown filtrate was allowed to stand in the dark for one week. Dark brown crystals were obtained.