Trichlorido[(meth­yl{2-[meth­yl(2-pyridyl­meth­yl)amino]eth­yl}amino)acetonitrile]iron(III) methanol hemisolvate

Anne Nielsen; Christine J McKenzie; Andrew D Bond

doi:10.1107/S160053680904375X

. 2009 Oct 28;65(Pt 11):m1437. doi: 10.1107/S160053680904375X

Trichlorido[(methyl{2-[methyl(2-pyridylmethyl)amino]ethyl}amino)acetonitrile]iron(III) methanol hemisolvate

Anne Nielsen ^a, Christine J McKenzie ^a, Andrew D Bond ^a,^*

PMCID: PMC2971013 PMID: 21578169

Abstract

The title compound, [FeCl₃(C₁₂H₁₈N₄)]·0.5CH₃OH, contains an Fe^III ion in a distorted octahedral coordination environment. The neutral N,N′,N′′-tridentate ligand adopts a fac coordination mode, and chloride ligands lie trans to each of the three coordinated N atoms. In the crystal, the complexes form columns extending parallel to the approximate local threefold axes of the FeN₃Cl₃ octahedra, and the columns are arranged so that the uncoordinated nitrile groups align in an antiparallel manner and the pyridyl rings form offset face-to-face arrangements [interplanar separations = 2.95 (1) and 3.11 (1) Å; centroid–centroid distances = 5.31 (1) and 4.92 (1) Å]. The methanol solvent molecule is disordered about a twofold rotation axis.

Related literature

For structures of similar Fe^III complexes, see: Cowdell et al. (2004 ▶); Sundaravel et al. (2008 ▶); Velusamy et al. (2005 ▶).

Experimental

Crystal data

[FeCl₃(C₁₂H₁₈N₄)]·0.5CH₄O
M _r = 396.53
Monoclinic,
a = 34.243 (2) Å
b = 7.1331 (5) Å
c = 15.4835 (11) Å
β = 116.733 (3)°
V = 3377.8 (4) Å³
Z = 8
Mo Kα radiation
μ = 1.37 mm⁻¹
T = 180 K
0.18 × 0.10 × 0.10 mm

Data collection

Bruker–Nonius X8 APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.744, T _max = 0.875
38084 measured reflections
2937 independent reflections
2033 reflections with I > 2σ(I)
R _int = 0.066

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.105
S = 1.07
2937 reflections
196 parameters
H-atom parameters constrained
Δρ_max = 0.48 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680904375X/hb5138sup1.cif

e-65-m1437-sup1.cif^{(20.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680904375X/hb5138Isup2.hkl

e-65-m1437-Isup2.hkl^{(144.2KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Fe1—N1	2.186 (3)
Fe1—N2	2.235 (3)
Fe1—N3	2.330 (3)
Fe1—Cl1	2.2873 (11)
Fe1—Cl2	2.2908 (11)
Fe1—Cl3	2.3284 (11)

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Acknowledgments

We are grateful to the Danish Natural Sciences Research Council and the Carlsberg Foundation for provision of the X-ray equipment.

supplementary crystallographic information

Comment

The ligand N,N'-dimethyl-N-(2-pyridylmethyl)ethylendiamine- N'-acetonitrile was prepared as a by-product during synthesis of N,N'-dimethyl-N-(2-pyridylmethyl)ethylendiamine- N'-acetic acid, as a result of contamination of the reagent bromoacetic acid with bromoacetonitrile.

Experimental

The ligand synthesis was undertaken in three steps:

(i) Picolinal (2.50 ml, 24 mmol) and N,N'-dimethylethylenediamine (2.22 ml, 24 mmol) in dry diethylether (20 ml) were stirred overnight under CaCl₂ protection. The solvent was removed under reduced pressure to leave 1,3-dimethyl-2-(2-pyridylmethyl)imidazolidine as a thin yellow oil (3.9 g, yield 92%).

(ii) NaBH₃CN (1.3925 g, 22 mmol) and CF₃COOH (3.365 ml, 44 mmol) were added in small portions [CAUTION: possible formation of HCN!] to 1,3-dimethyl-2-(2-pyridylmethyl)imidazolidine (3.8944 g, 22 mmol) in methanol (80 ml) and the reaction mixture was stirred overnight under CaCl₂ protection. NaOH (85 ml of a 4 M aqueous solution) was added. The reaction mixture was stirred overnight and extracted with CHCl₂ (3 × 20 ml), then the organic phase was dried over Na₂SO₄ and filtered. The filtrate was evaporated in vacuo to leave N,N'-dimethyl-N-(2-pyridylmethyl)ethylenediamine as a thin yellow oil (3.2 g, yield 81%).

(iii) A mixture of N,N'-dimethyl-N-(2-pyridylmethyl)ethylenediamine (3.1602 g, 18 mmol), bromoacetic acid (2.4499 g, 18 mmol) and triethylamine (2.444 ml, 18 mmol) in absolute ethanol (10 ml) was heated overnight under reflux and N₂. The solvent was removed under reduced pressure, then the residue was re-dissolved in water, adjusted to pH 8 with conc. NaOH and washed with CH₂Cl₂ (3 × 15 ml). The aqueous phase was adjusted to pH 4 with conc. HCl then evaporated in vacuo to leave a mixture of N,N'-dimethyl-N-(2-pyridylmethyl)ethylendiamine- N'-acetonitrile (L) and N,N'-dimethyl-N-(2-pyridylmethyl)ethylendiamine- N'-acetic acid as a brown oil (6.0 g, yield 139% due to impurities of triethylammonium bromide).

The title compound was then prepared as follows:

Anhydrous FeCl₃ (15.8 mg, 0.097 mmol) was added to the mixed ligand product from above (23.3 mg, 0.098 mmol) in methanol (1.75 ml), and a few yellow blocks of (I) were deposited overnight.