Di­chloro­[N,N,N′,N′-tetrakis(2-pyridyl­methyl)­benzene-1,4-di­amine]­iron(II)

In the title complex, [FeCl₂(C₃₀H₂₈N₆)], the Fe atom is five-coordinated by two terminal chloride ligands and one end of the bis-tridentate ligand. The complexes display intermolecular C—H...π, π-stacking and C—H...X (X = N, Cl) interactions.

S1. Comment

N,N,N',N'-Tetrakis(2-pyridylmethyl)benzene-1,4-diamine (1,4-tpbd) is capable of forming both mono- and dinuclear complexes (Buchen et al., 1997; Hazell et al., 1998). As well, the coordination of the octahedral metal ions as connectors between the tridentate bis(2-pyridylmethyl)amine ends of two 1,4-tpbd ligands should make possible the formation of one-dimensional coordination polymers. The title complex, (I), was obtained in the course of our efforts to access an iron(II)-containing polymer. Such a polymeric complex may be particularly interesting due to similarity of the N₆ environment to well known mononuclear spin-crossover systems (Gütlich et al., 1994). The reaction of several iron(II) salts with 1,4-tpbd has lead to the precipitation of yellow powders which have shown a 1:1 ligand:metal stoichiometry by elemental analysis commensurable with either mononuclear or coordination polymeric structures (dinuclear could be excluded on this basis). The title compound was obtained as a yellow crystalline material from the reaction of iron(II) chloride with 1,4-tpbd and the structure reported here shows it to be monomeric. The cell parameters and space group are similar to the Zn analogue (Hazell et al., 1998), however the packing of the complexes in the two structures differs to some extent, and thus the two structures are not strictly isostructural. \sch

A search of the Cambridge Structural Database (update 5.19, April 2000; Allen & Kennard, 1993) reveals that it is only the third example of a pentacoordinated iron(II) with a N₃Cl₂ ligand set (Small et al., 1998; Britovsek et al., 1998; Hemmert et al., 1999). The geometry around the Fe atom (Table 1) is best described as being closer to square pyramidal (with Cl1 at the apex) than trigonal bipyramidal, although the geometry is more distorted from square pyramidal compared to the two other pentacoordinated iron(II) complexes with N₃Cl₂ coordination spheres. The sum of the C—N—C angles around the uncoordinated phenylenediamine nitrogen is 359.1 (9)°, and C16—N4 is only 1.386 (9) Å, indicating a π delocalization of this amine nitrogen atom lone pair with the aromatic system. In contrast, the corresponding values for the coordinated amine nitrogen atom are 335.8 (10) and 1.475 (8) Å, respectively.

The H-shaped complexes are interdigitated and display C—H···π interactions between a CH of a coordinated pyridyl ring of one complex and the benzene ring of another [closest contact: C4···C14^iv = 3.620 (9) Å, H4A···C14^iv = 2.69 Å, C4—H4A···C14^iv = 165°, symmetry code: (iv) x + 1, y, z]. This pyridyl ring also engages in π-stacking interactions with a coordinated pyridyl of this second complex [closest non-hydrogen interaction: C5···C12^iv = 3.34 (1) Å], which in turn engages in a π-stacking interaction with an uncoordinated pyridyl ring of a third complex [closest non-hydrogen interaction: C11···C24^v = 3.28 (1) Å, symmetry code: (v) x, y, z + 1]. There are also a number of close C—H···X intermolecular contacts between both aromatic and aliphatic H atoms and the uncoordinated pyridyl N atoms and the chloride ligands which connect the complexes (Table 2).

Related literature

For related literature, see: Allen & Kennard (1993); Britovsek et al. (1998); Buchen et al. (1997); Gütlich et al. (1994); Hazell et al. (1998); Hemmert et al. (1999); Small et al. (1998).

S2. Experimental

The title compound was prepared from the 1:1 reaction of anhydrous FeCl₂ and 1,4-tpbd in acetonitrile under an inert atmosphere (Hazell et al., 1998). Yellow single crystals suitable for X-ray crystallography were obtained directly from the reaction mixture.

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. Atom-numbering scheme for (I). Displacement ellipsoids are drawn at the 50% probability level.

Dichloro[N,N,N',N'-tetrakis(2-pyridylmethyl)benzene-1,4-diamine]iron(II)

Crystal data

[FeCl2(C30H28N6)]	F(000) = 620
Mr = 599.33	Dx = 1.457 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
a = 8.4470 (6) Å	Cell parameters from 11554 reflections
b = 12.9100 (12) Å	θ = 3.2–28.3°
c = 12.9850 (13) Å	µ = 0.78 mm^−1
β = 105.270 (6)°	T = 123 K
V = 1366.0 (2) Å^3	Irregular block, yellow
Z = 2	0.13 × 0.13 × 0.08 mm

Data collection

Nonius KappaCCD diffractometer	3608 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.110
Graphite monochromator	θmax = 28.3°, θmin = 3.2°
Detector resolution: 9 pixels mm^-1	h = −9→11
ϕ and ω scans	k = −12→17
11514 measured reflections	l = −17→17
5292 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.080	H-atom parameters constrained
wR(F^2) = 0.156	w = 1/[σ^2(Fo^2) + (0.0338P)^2 + 3.2934P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
5292 reflections	Δρmax = 1.03 e Å^−3
352 parameters	Δρmin = −0.66 e Å^−3
1 restraint	Absolute structure: Flack (1983), 1813 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.01 (3)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Fe1	0.40540 (11)	0.54750 (8)	0.43159 (7)	0.0200 (3)
Cl1	0.58024 (19)	0.53142 (16)	0.60247 (13)	0.0278 (5)
Cl2	0.2987 (2)	0.39034 (13)	0.35798 (15)	0.0277 (4)
N1	0.3807 (6)	0.7149 (4)	0.3814 (5)	0.0171 (12)
C1	0.5486 (7)	0.7511 (5)	0.3777 (6)	0.0204 (16)
H1A	0.5379	0.8125	0.3306	0.024*
H1B	0.6126	0.7716	0.4501	0.024*
C2	0.6369 (8)	0.6666 (5)	0.3365 (5)	0.0188 (15)
C3	0.7674 (8)	0.6892 (6)	0.2918 (6)	0.0283 (19)
H3A	0.7951	0.7590	0.2812	0.034*
C4	0.8546 (9)	0.6088 (7)	0.2637 (6)	0.0283 (19)
H4A	0.9445	0.6226	0.2345	0.034*
C5	0.8103 (9)	0.5079 (7)	0.2782 (6)	0.031 (2)
H5A	0.8681	0.4511	0.2588	0.038*
C6	0.6779 (8)	0.4916 (6)	0.3221 (5)	0.0236 (17)
H6A	0.6460	0.4226	0.3320	0.028*
N2	0.5948 (6)	0.5697 (4)	0.3507 (4)	0.0190 (14)
C7	0.3294 (8)	0.7655 (6)	0.4698 (6)	0.0230 (17)
H7A	0.2912	0.8368	0.4489	0.028*
H7B	0.4238	0.7696	0.5338	0.028*
C8	0.1926 (8)	0.7036 (5)	0.4951 (5)	0.0187 (15)
C9	0.0722 (8)	0.7490 (6)	0.5365 (6)	0.0272 (18)
H9A	0.0671	0.8220	0.5439	0.033*
C10	−0.0408 (9)	0.6843 (7)	0.5668 (6)	0.0308 (19)
H10A	−0.1228	0.7128	0.5963	0.037*
C11	−0.0318 (9)	0.5806 (7)	0.5536 (6)	0.034 (2)
H11A	−0.1076	0.5354	0.5734	0.041*
C12	0.0892 (7)	0.5416 (8)	0.5110 (5)	0.0283 (16)
H12A	0.0948	0.4689	0.5017	0.034*
N3	0.1985 (6)	0.6018 (4)	0.4822 (4)	0.0187 (13)
C13	0.2610 (7)	0.7263 (5)	0.2764 (5)	0.0162 (14)
C14	0.2437 (8)	0.6473 (5)	0.2013 (6)	0.0185 (15)
H14A	0.3061	0.5857	0.2200	0.022*
C15	0.1392 (8)	0.6559 (5)	0.1011 (6)	0.0199 (15)
H15A	0.1327	0.6014	0.0510	0.024*
C16	0.0399 (9)	0.7462 (5)	0.0715 (6)	0.0202 (16)
C17	0.0588 (9)	0.8243 (5)	0.1481 (6)	0.0235 (17)
H17A	−0.0053	0.8855	0.1315	0.028*
C18	0.1684 (8)	0.8148 (5)	0.2474 (6)	0.0220 (16)
H18A	0.1804	0.8704	0.2967	0.026*
N4	−0.0702 (7)	0.7538 (5)	−0.0284 (5)	0.0262 (15)
C19	−0.0808 (9)	0.6716 (6)	−0.1053 (6)	0.0290 (18)
H19A	−0.1759	0.6852	−0.1670	0.035*
H19B	−0.1020	0.6056	−0.0724	0.035*
C20	0.0722 (9)	0.6585 (6)	−0.1459 (6)	0.0252 (17)
C21	0.1731 (9)	0.7411 (6)	−0.1506 (6)	0.0323 (19)
H21A	0.1505	0.8077	−0.1270	0.039*
C22	0.3072 (10)	0.7255 (7)	−0.1902 (6)	0.037 (2)
H22A	0.3772	0.7817	−0.1954	0.044*
C23	0.3383 (10)	0.6290 (7)	−0.2217 (6)	0.039 (2)
H23A	0.4307	0.6164	−0.2486	0.047*
C24	0.2328 (10)	0.5495 (9)	−0.2136 (5)	0.0412 (19)
H24A	0.2551	0.4820	−0.2352	0.049*
N5	0.0991 (7)	0.5636 (5)	−0.1762 (5)	0.0327 (16)
C25	−0.1533 (9)	0.8509 (6)	−0.0635 (6)	0.0273 (18)
H25A	−0.1846	0.8522	−0.1425	0.033*
H25B	−0.0748	0.9082	−0.0385	0.033*
C26	−0.3064 (8)	0.8711 (6)	−0.0252 (5)	0.0227 (17)
C27	−0.3662 (9)	0.8030 (7)	0.0356 (6)	0.0312 (19)
H27A	−0.3125	0.7386	0.0557	0.037*
C28	−0.5053 (9)	0.8276 (7)	0.0680 (7)	0.037 (2)
H28A	−0.5493	0.7805	0.1094	0.044*
C29	−0.5775 (9)	0.9217 (7)	0.0387 (7)	0.036 (2)
H29A	−0.6706	0.9426	0.0615	0.043*
C30	−0.5126 (9)	0.9849 (6)	−0.0242 (6)	0.0317 (19)
H30A	−0.5669	1.0485	−0.0473	0.038*
N6	−0.3754 (7)	0.9623 (5)	−0.0555 (5)	0.0284 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.0167 (5)	0.0202 (5)	0.0235 (5)	0.0023 (5)	0.0059 (4)	0.0021 (5)
Cl1	0.0207 (8)	0.0401 (13)	0.0216 (9)	0.0080 (9)	0.0037 (7)	0.0032 (9)
Cl2	0.0295 (10)	0.0221 (10)	0.0276 (11)	−0.0037 (8)	0.0005 (8)	0.0008 (8)
N1	0.007 (2)	0.019 (3)	0.024 (3)	−0.006 (2)	0.002 (2)	−0.001 (3)
C1	0.012 (3)	0.021 (4)	0.026 (4)	−0.008 (3)	0.002 (3)	−0.001 (3)
C2	0.012 (3)	0.026 (4)	0.015 (4)	0.001 (3)	−0.003 (3)	0.008 (3)
C3	0.017 (4)	0.040 (5)	0.024 (4)	−0.007 (4)	−0.003 (3)	0.013 (4)
C4	0.014 (4)	0.046 (5)	0.025 (4)	0.005 (4)	0.006 (3)	0.005 (4)
C5	0.029 (4)	0.043 (5)	0.027 (4)	0.006 (4)	0.015 (4)	−0.001 (4)
C6	0.017 (4)	0.033 (4)	0.019 (4)	0.000 (3)	0.003 (3)	0.004 (3)
N2	0.017 (3)	0.020 (4)	0.019 (3)	0.002 (2)	0.004 (2)	0.001 (2)
C7	0.017 (3)	0.026 (4)	0.021 (4)	−0.002 (3)	−0.004 (3)	−0.006 (3)
C8	0.016 (3)	0.023 (4)	0.016 (4)	0.003 (3)	0.001 (3)	−0.002 (3)
C9	0.022 (4)	0.030 (5)	0.023 (4)	0.011 (3)	−0.006 (3)	−0.004 (3)
C10	0.014 (4)	0.051 (6)	0.025 (4)	0.006 (4)	0.000 (3)	−0.002 (4)
C11	0.017 (3)	0.062 (7)	0.020 (4)	0.001 (4)	0.001 (3)	0.003 (4)
C12	0.020 (3)	0.034 (4)	0.027 (4)	−0.003 (4)	−0.001 (3)	0.003 (4)
N3	0.012 (3)	0.028 (4)	0.016 (3)	0.000 (3)	0.002 (2)	−0.002 (3)
C13	0.011 (3)	0.020 (4)	0.016 (4)	−0.002 (3)	0.000 (3)	0.003 (3)
C14	0.012 (3)	0.015 (4)	0.029 (4)	−0.001 (3)	0.007 (3)	0.005 (3)
C15	0.017 (3)	0.022 (4)	0.022 (4)	0.001 (3)	0.008 (3)	0.000 (3)
C16	0.018 (3)	0.022 (4)	0.020 (4)	0.007 (3)	0.004 (3)	0.012 (3)
C17	0.026 (4)	0.021 (4)	0.024 (4)	0.003 (3)	0.007 (3)	−0.004 (3)
C18	0.023 (4)	0.016 (4)	0.024 (4)	−0.003 (3)	0.001 (3)	0.000 (3)
N4	0.024 (3)	0.030 (4)	0.021 (3)	0.000 (3)	−0.001 (3)	0.001 (3)
C19	0.026 (4)	0.040 (5)	0.015 (4)	0.001 (4)	−0.005 (3)	0.000 (4)
C20	0.021 (4)	0.031 (4)	0.018 (4)	0.006 (3)	−0.004 (3)	−0.001 (3)
C21	0.033 (4)	0.043 (5)	0.024 (4)	0.007 (4)	0.013 (4)	0.005 (4)
C22	0.039 (5)	0.041 (5)	0.031 (5)	−0.005 (4)	0.009 (4)	0.003 (4)
C23	0.028 (4)	0.065 (7)	0.024 (5)	0.012 (5)	0.008 (4)	0.004 (4)
C24	0.047 (5)	0.045 (5)	0.025 (4)	0.021 (6)	−0.001 (4)	0.006 (5)
N5	0.037 (3)	0.034 (4)	0.023 (3)	0.002 (3)	0.000 (3)	−0.003 (3)
C25	0.020 (4)	0.036 (5)	0.025 (4)	0.008 (4)	0.004 (3)	0.009 (4)
C26	0.010 (3)	0.036 (5)	0.018 (4)	0.004 (3)	−0.004 (3)	0.001 (3)
C27	0.026 (4)	0.039 (5)	0.027 (5)	0.003 (4)	0.003 (4)	0.011 (4)
C28	0.024 (4)	0.049 (6)	0.035 (5)	−0.013 (4)	0.003 (4)	0.006 (4)
C29	0.019 (4)	0.043 (5)	0.047 (5)	−0.004 (4)	0.011 (4)	−0.001 (4)
C30	0.022 (4)	0.029 (4)	0.039 (5)	0.012 (3)	−0.002 (4)	0.000 (4)
N6	0.017 (3)	0.029 (4)	0.034 (4)	0.001 (3)	−0.002 (3)	0.005 (3)

Geometric parameters (Å, º)

Fe1—N3	2.141 (5)	C13—C14	1.391 (9)
Fe1—N2	2.152 (5)	C14—C15	1.371 (9)
Fe1—N1	2.251 (6)	C15—C16	1.428 (9)
Fe1—Cl2	2.321 (2)	C16—N4	1.386 (9)
Fe1—Cl1	2.329 (2)	C16—C17	1.396 (9)
N1—C13	1.475 (8)	C17—C18	1.381 (9)
N1—C7	1.481 (9)	N4—C19	1.444 (10)
N1—C1	1.506 (8)	N4—C25	1.450 (9)
C1—C2	1.498 (9)	C19—C20	1.529 (10)
C2—N2	1.326 (8)	C20—N5	1.325 (10)
C2—C3	1.405 (9)	C20—C21	1.376 (11)
C3—C4	1.377 (11)	C21—C22	1.376 (11)
C4—C5	1.383 (10)	C22—C23	1.359 (12)
C5—C6	1.399 (10)	C23—C24	1.380 (13)
C6—N2	1.335 (8)	C24—N5	1.354 (9)
C7—C8	1.511 (9)	C25—C26	1.526 (10)
C8—N3	1.328 (8)	C26—N6	1.327 (9)
C8—C9	1.398 (9)	C26—C27	1.365 (10)
C9—C10	1.400 (11)	C27—C28	1.385 (11)
C10—C11	1.355 (11)	C28—C29	1.367 (11)
C11—C12	1.379 (10)	C29—C30	1.367 (11)
C12—N3	1.334 (9)	C30—N6	1.357 (9)
C13—C18	1.380 (9)
N3—Fe1—N2	151.4 (2)	C8—N3—C12	119.3 (6)
N3—Fe1—N1	75.7 (2)	C8—N3—Fe1	115.1 (4)
N2—Fe1—N1	75.8 (2)	C12—N3—Fe1	125.2 (5)
N3—Fe1—Cl2	98.8 (2)	C18—C13—C14	117.9 (6)
N2—Fe1—Cl2	100.0 (2)	C18—C13—N1	122.5 (6)
N1—Fe1—Cl2	136.3 (2)	C14—C13—N1	119.6 (6)
N3—Fe1—Cl1	95.8 (2)	C15—C14—C13	121.9 (6)
N2—Fe1—Cl1	96.3 (2)	C14—C15—C16	120.4 (7)
N1—Fe1—Cl1	110.4 (2)	N4—C16—C17	122.5 (6)
Cl2—Fe1—Cl1	113.24 (8)	N4—C16—C15	120.7 (6)
C13—N1—C7	113.7 (5)	C17—C16—C15	116.7 (7)
C13—N1—C1	111.2 (5)	C18—C17—C16	121.5 (6)
C7—N1—C1	110.9 (5)	C13—C18—C17	121.5 (6)
C13—N1—Fe1	110.6 (4)	C16—N4—C19	120.0 (6)
C7—N1—Fe1	102.9 (4)	C16—N4—C25	120.4 (6)
C1—N1—Fe1	107.0 (4)	C19—N4—C25	118.7 (6)
C2—C1—N1	110.3 (5)	N4—C19—C20	114.5 (6)
N2—C2—C3	121.5 (7)	N5—C20—C21	123.1 (7)
N2—C2—C1	117.4 (6)	N5—C20—C19	115.5 (7)
C3—C2—C1	120.9 (6)	C21—C20—C19	121.3 (7)
C4—C3—C2	119.0 (7)	C20—C21—C22	119.0 (8)
C3—C4—C5	119.5 (6)	C23—C22—C21	119.3 (8)
C4—C5—C6	118.1 (7)	C22—C23—C24	118.6 (8)
N2—C6—C5	122.4 (7)	N5—C24—C23	122.9 (9)
C2—N2—C6	119.5 (6)	C20—N5—C24	117.1 (8)
C2—N2—Fe1	117.0 (4)	N4—C25—C26	115.3 (6)
C6—N2—Fe1	123.2 (4)	N6—C26—C27	122.9 (6)
N1—C7—C8	109.4 (5)	N6—C26—C25	113.5 (6)
N3—C8—C9	121.2 (6)	C27—C26—C25	123.6 (7)
N3—C8—C7	116.0 (5)	C26—C27—C28	120.0 (8)
C9—C8—C7	122.6 (6)	C29—C28—C27	118.1 (8)
C8—C9—C10	118.5 (7)	C28—C29—C30	118.5 (7)
C11—C10—C9	119.3 (7)	N6—C30—C29	124.0 (7)
C10—C11—C12	118.9 (8)	C26—N6—C30	116.4 (6)
N3—C12—C11	122.8 (9)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···Cl1^i	0.95	2.76	3.556 (7)	142
C23—H23A···Cl1^ii	0.95	2.80	3.666 (8)	152
C25—H25A···Cl2^iii	0.99	2.75	3.730 (8)	169
C17—H17A···N5^iii	0.95	2.55	3.42 (1)	153

Symmetry codes: (i) x−1, y, z; (ii) x, y, z−1; (iii) −x, y+1/2, −z.