Bis{2-meth­oxy-6-[(4-methyl­phen­yl)iminiometh­yl]phenolato-κ2 O 1,O 2}tris­(nitrato-κ2 O,O′)methano­lsamarium(III)

Hang-Ming Guo

doi:10.1107/S1600536811000407

. 2011 Jan 15;67(Pt 2):m184–m185. doi: 10.1107/S1600536811000407

Bis{2-methoxy-6-[(4-methylphenyl)iminiomethyl]phenolato-κ² O ¹,O ²}tris(nitrato-κ² O,O′)methanolsamarium(III)

Hang-Ming Guo ^a,^*

PMCID: PMC3051746 PMID: 21522856

Abstract

The asymmetric unit of the title compound, [Sm(NO₃)₃(C₁₅H₁₅NO₂)₂(CH₃OH)], contains two Schiff base 2-methoxy-6-[(4-methylphenyl)iminiomethyl]phenolate (HL) ligands, three nitrate ions and one methanol molecule that binds to the nine-coordinate samarium(III) ion via its O atoms. The HL ligands chelate with a strong Sm—O(deprotonated phenolic) bond and a weak Sm—O(methoxy) contact. The latter can be interpreted as the apices of the bicapped square-antiprismatic Sm^IIIO₉ polyhedron. The Schiff base ligands are in a zwitterionic state with the phenolic H atom transferred to the imine N atom. O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds lend stability to the structure. One O atom of one nitrate group is equally disordered over two positions.

Related literature

For the syntheses of rare earth complexes with Schiff bases derived from o-vanillin and adamantaneamine, see: Burrows & Bailar (1966 ▶); Li et al. (2008 ▶); Xian et al. (2008 ▶); Zhao et al. (2005 ▶); Liu et al. (2009 ▶, 2010 ▶). For their applications, see: Leadbeater & Marco (2002 ▶); Quici et al. (2004 ▶).

Experimental

Crystal data

[Sm(NO₃)₃(C₁₅H₁₅NO₂)₂(CH₄O)]
M _r = 850.99
Triclinic,
a = 7.8547 (10) Å
b = 14.6893 (19) Å
c = 16.590 (2) Å
α = 73.402 (8)°
β = 85.738 (7)°
γ = 79.230 (7)°
V = 1801.6 (4) Å³
Z = 2
Mo Kα radiation
μ = 1.70 mm⁻¹
T = 296 K
0.26 × 0.11 × 0.08 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.797, T _max = 0.870
25616 measured reflections
6337 independent reflections
5512 reflections with I > 2σ(I)
R _int = 0.043

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.123
S = 1.05
6337 reflections
474 parameters
H-atom parameters constrained
Δρ_max = 0.91 e Å⁻³
Δρ_min = −0.73 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); 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: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811000407/bv2165sup1.cif

e-67-0m184-sup1.cif^{(35.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811000407/bv2165Isup2.hkl

e-67-0m184-Isup2.hkl^{(310.2KB, 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
O14—H14B⋯O10ⁱ	0.82	2.04	2.859 (6)	174
O14—H14B⋯O8ⁱ	0.82	2.53	3.121 (6)	130
O14—H14B⋯N4ⁱ	0.82	2.60	3.367 (6)	157
N1—H1A⋯O1	0.86	1.96	2.637 (5)	135
N1—H1A⋯O6	0.86	2.65	3.449 (7)	154
N2—H2A⋯O3	0.86	2.02	2.678 (5)	132
N2—H2A⋯O11	0.86	2.52	3.311 (5)	153

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

Schiff base complexes utilizing ligands obtained from substituted o-vanillin have been attracted considerable attention in past decades due to the intriguing biological activities of o-vanillin (Zhao et al., 2005) and its convenience in Schiff base syntheses (Burrows & Bailar, 1966). Interested in this field, we have been engaged in a major effort directed toward the development of syntheses of new analogous Schiff bases derived from o-vanillin and their rare metal complexes. In a few of articles we have reported our partial research results (Zhao et al., 2005; Xian et al. 2008; Li et al. 2008; Liu et al., 2009). Herein, we describe a new Sm^III complex.

The structure of the title complex is shown in Fig.1. In this complex, the O5 atom in a nitrate anion is disordered over two sites (assigned in a 50: 50 ratio). The Sm^III is nine-coordinated by O atoms, six of which come from three nitrate ions, one from methanol and two from the Schiff base ligands (HL). The HL ligands coordinate to the Sm^III ion using oxygen atoms from deprotonated phenolic hydroxyl groups. Interestingly, the Schiff base ligands are in a zwitterionic state with the phenolic H transferred to the imine N. The bonds between Sm^III and O atoms from phenoxy groups are 2.486 (3) and 2.428 (3), which are shorter than those between Sm^III and O atoms of methoxyl groups (2.806 (4) Å and 2.957 (4) Å for Sm—O2 and Sm—O4). The nitrate anions coordinate to the Sm^III via O atoms with distances ranging from 2.59 (2) to 2.743 (5), which are intermediate between the Sm—O(phenolic) and the Sm—O (methoxy) bond lengths. The Sm—O(methoxyl) bond length is only slightly longer than that for Sm—O(phenolic), and these values are similar to those reported for related complexes (Liu et al., 2010).

The hydrogen bonds and π–π weak non-covalent interactions lend stability to the structure. The hydrogen bonds are listed in Table 2 and the stacking plot of this compound is shown in Fig. 2. Different lines are interlocked with benzene rings of Schiff base using π–π stacking. As indicated above, in the HL ligands, the proton of the phenolic hydroxyl group has been transferred to the N-imine atom, and is involved in an intramolecular hydrogen bond (Table 2).

Experimental

Reagents and solvents used were of commercially available quality and used without further purification. The Schiff base ligand 2-[(4-methylphenyl)iminomethyl]-6-methoxy-phenol was prepared by condensation of o-vanillin and p-methylaniline with a high yield and which was purified by recrystallization in ethanol. The compound (1) was obtained by adding Sm(NO₃)₃ (1 mmol, dissolved in methanol) to N-salicylidene-p-toluidine (2 mmol) in methanol solution. The solution was stirred at room temperature for 8 h to obtain a purplish red solution. At last, the deposit was filtered out and the solution was kept for evaporating. Red crystals were formed after several days.