Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105028167/ln1183sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270105028167/ln1183Isup2.hkl |
CCDC reference: 288619
Compound (I) was synthesized as follows. A mixture of 2-picolylamine (1-pyridine-2-ylmethanamine; 2.4 mmol) and FeCl2·4H2O (0.7 mmol) in 1-butanol (120 ml) was left standing with partial reflux under an N2 atmosphere at ~355 K for 5 d. A minute quantity of yellow crystals was found in the round flask just below the surface of the reaction liquid, and these were shown to contain a 1:1 cis and trans mixture of (I). Exposed to the air, the crystals deteriorate within hours.
The searches of the CSD were carried out as follows. The search for MN4L2 fragments with any transition metal (M) coordinated to four N atoms and to any two other atoms (L), with M–ligand bond type `ANY', resulted in 11769 hits, while a search for crystal structures with Z' ≥ 2 with reported coordinates resulted in 21665 hits. Combining the two sets led to 605 hits. Only two of these show both the cis and trans isomers in the unit cell, namely refcodes CAWPOF (Mather et al., 1983), discussed above, and UCAHUB (Kozmin et al., 2001), (propylene-1,2-diamine-N,N')dichlorodinitroplatinum(IV). The latter is disordered, and both sites in the asymmetric part of the unit cell have been modelled with a superposition of cis and trans isomers. Therefore, this crystal structure cannot be considered an unambiguous case of cis/trans co-crystallization.
The CSD was also searched for FeII–N4L2 complexes for which the cis and trans isomers are found in different crystals (L is any non-cyclic ligand atom). Among these 338 crystal structures, there are three pairs of cis and transisomers. RUHLUB and RUHMAI (Guilard et al., 1997) refer to the trans and cis isomers of the complex dichloro(1,4,8,11-tetraazacyclotetradecane)iron(III), respectively. These were obtained in the same synthesis, but the trans isomer crystallizes with a tetrachloroiron(III) anion, while the cis isomer has a chloride counterion. FEVKAS and FEVMIC (Meyer et al., 1999) refer to the trans and cis isomers of the complex diazido(1,4,8,11-tetra-azacyclotetradecane)iron(III), respectively. The trans isomer crystallizes with a hexafluorophosphate and the cis isomer with a perchlorate anion. Both compounds were obtained from the same reaction mixture but at different temperatures, 323 and 291 K, respectively. FADVUC and FADWAJ (Zhu et al., 2002), discussed above, refer to compounds with the same chemical sum formulae, with trans and cis coordination geometry, but with ligands differing in the position of the methyl group on the phenyl rings. Finally, we are aware of the analogous example of dithiocyanatobis[4 − p(or m)-methylphenyl-3,5-bis(pyridin-2-yl)-1,2,4- triazole]iron(II), which displays a CdII–O4L2 coordination geometry (Soldatov et al., 2001).
H atoms were located geometrically and treated as riding, with C—H distances in the range 0.95–0.99 Å and N—H distances of 0.92 Å, and with Uiso(H) = 1.2Ueq(C,N). [Please check added text and correct as necessary.]
Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2000); software used to prepare material for publication: PLATON (Spek, 2003).
[FeCl2(C6H8N2)2] | F(000) = 1408 |
Mr = 343.04 | Dx = 1.591 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 2031 reflections |
a = 26.626 (2) Å | θ = 2.6–27.9° |
b = 6.6818 (5) Å | µ = 1.42 mm−1 |
c = 16.8821 (13) Å | T = 150 K |
β = 107.565 (1)° | Irregular prism, yellow |
V = 2863.5 (4) Å3 | 0.35 × 0.25 × 0.18 mm |
Z = 8 |
Siemens SMART 1K CCD area-detector diffractometer | 3276 independent reflections |
Radiation source: normal-focus sealed tube | 2676 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.025 |
ω scans | θmax = 28.1°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −33→34 |
Tmin = 0.671, Tmax = 0.775 | k = −8→8 |
14985 measured reflections | l = −22→21 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.063 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0302P)2 + 2.1803P] where P = (Fo2 + 2Fc2)/3 |
3276 reflections | (Δ/σ)max = 0.001 |
174 parameters | Δρmax = 0.39 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
[FeCl2(C6H8N2)2] | V = 2863.5 (4) Å3 |
Mr = 343.04 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 26.626 (2) Å | µ = 1.42 mm−1 |
b = 6.6818 (5) Å | T = 150 K |
c = 16.8821 (13) Å | 0.35 × 0.25 × 0.18 mm |
β = 107.565 (1)° |
Siemens SMART 1K CCD area-detector diffractometer | 3276 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2676 reflections with I > 2σ(I) |
Tmin = 0.671, Tmax = 0.775 | Rint = 0.025 |
14985 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.063 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.39 e Å−3 |
3276 reflections | Δρmin = −0.23 e Å−3 |
174 parameters |
Experimental. Comment on transmission values: The program SADABS (v2.06) outputs the ratio of minimum to maximum apparent transmission (0.86590). We have set T(max) to the expected value, i.e. exp(-r_min*mu) and we calculate T(min) from the minimum to maximum apparent transmission given by SADABS. |
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. |
x | y | z | Uiso*/Ueq | ||
Fe1 | 0.2500 | 0.7500 | 0.0000 | 0.01732 (9) | |
Cl1 | 0.312318 (16) | 1.01509 (6) | 0.07476 (2) | 0.02246 (10) | |
N1 | 0.31203 (5) | 0.5213 (2) | 0.03628 (8) | 0.0204 (3) | |
H1A | 0.3406 | 0.5726 | 0.0766 | 0.024* | |
H1B | 0.2997 | 0.4129 | 0.0584 | 0.024* | |
C1 | 0.18185 (7) | 0.8894 (3) | 0.10330 (10) | 0.0199 (3) | |
N2 | 0.21563 (5) | 0.7419 (2) | 0.10159 (8) | 0.0194 (3) | |
C2 | 0.15885 (7) | 0.9035 (3) | 0.16724 (11) | 0.0243 (4) | |
H2 | 0.1347 | 1.0082 | 0.1671 | 0.029* | |
C3 | 0.17136 (7) | 0.7647 (3) | 0.23059 (11) | 0.0264 (4) | |
H3 | 0.1561 | 0.7731 | 0.2746 | 0.032* | |
C4 | 0.20654 (7) | 0.6129 (3) | 0.22916 (11) | 0.0282 (4) | |
H4 | 0.2162 | 0.5161 | 0.2723 | 0.034* | |
C5 | 0.22709 (7) | 0.6062 (3) | 0.16351 (11) | 0.0255 (4) | |
H5 | 0.2506 | 0.5004 | 0.1618 | 0.031* | |
C6 | 0.32876 (7) | 0.4556 (3) | −0.03536 (11) | 0.0240 (4) | |
H6A | 0.3099 | 0.3307 | −0.0582 | 0.029* | |
H6B | 0.3669 | 0.4254 | −0.0162 | 0.029* | |
Fe2 | 0.5000 | 0.19638 (5) | 0.2500 | 0.01782 (9) | |
Cl2 | 0.436406 (17) | 0.44402 (6) | 0.16968 (3) | 0.02504 (11) | |
N3 | 0.44029 (6) | −0.0442 (2) | 0.20511 (9) | 0.0216 (3) | |
H3A | 0.4108 | 0.0094 | 0.1675 | 0.026* | |
H3B | 0.4537 | −0.1399 | 0.1780 | 0.026* | |
N4 | 0.53275 (6) | 0.1473 (2) | 0.14522 (9) | 0.0204 (3) | |
C7 | 0.59057 (7) | −0.0476 (3) | 0.09209 (11) | 0.0269 (4) | |
H7 | 0.6141 | −0.1575 | 0.0991 | 0.032* | |
C8 | 0.58075 (7) | 0.0711 (3) | 0.02259 (11) | 0.0287 (4) | |
H8 | 0.5973 | 0.0451 | −0.0189 | 0.034* | |
C9 | 0.54614 (8) | 0.2294 (3) | 0.01458 (11) | 0.0303 (4) | |
H9 | 0.5383 | 0.3139 | −0.0328 | 0.036* | |
C10 | 0.52328 (8) | 0.2623 (3) | 0.07659 (11) | 0.0275 (4) | |
H10 | 0.4996 | 0.3717 | 0.0707 | 0.033* | |
C11 | 0.56592 (7) | −0.0067 (3) | 0.15230 (10) | 0.0216 (4) | |
C12 | 0.57514 (8) | −0.1402 (3) | 0.22693 (11) | 0.0293 (4) | |
H12A | 0.5547 | −0.2652 | 0.2104 | 0.035* | |
H12B | 0.6129 | −0.1763 | 0.2473 | 0.035* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.01793 (18) | 0.01892 (18) | 0.01616 (17) | 0.00234 (13) | 0.00671 (13) | 0.00080 (13) |
Cl1 | 0.0219 (2) | 0.0240 (2) | 0.0218 (2) | −0.00264 (16) | 0.00713 (17) | −0.00366 (16) |
N1 | 0.0209 (7) | 0.0225 (8) | 0.0191 (7) | 0.0016 (6) | 0.0080 (6) | 0.0011 (6) |
C1 | 0.0196 (8) | 0.0209 (9) | 0.0190 (8) | −0.0029 (7) | 0.0056 (7) | −0.0032 (7) |
N2 | 0.0186 (7) | 0.0227 (7) | 0.0167 (7) | 0.0004 (6) | 0.0049 (6) | 0.0005 (6) |
C2 | 0.0251 (9) | 0.0253 (10) | 0.0247 (9) | −0.0022 (8) | 0.0111 (7) | −0.0053 (7) |
C3 | 0.0269 (10) | 0.0352 (11) | 0.0187 (8) | −0.0071 (8) | 0.0095 (7) | −0.0044 (7) |
C4 | 0.0270 (10) | 0.0370 (11) | 0.0200 (9) | 0.0005 (8) | 0.0063 (7) | 0.0074 (8) |
C5 | 0.0221 (9) | 0.0318 (10) | 0.0223 (8) | 0.0041 (8) | 0.0059 (7) | 0.0044 (8) |
C6 | 0.0296 (10) | 0.0201 (9) | 0.0257 (9) | 0.0046 (7) | 0.0138 (8) | 0.0001 (7) |
Fe2 | 0.02003 (19) | 0.01700 (18) | 0.01772 (17) | 0.000 | 0.00764 (14) | 0.000 |
Cl2 | 0.0243 (2) | 0.0237 (2) | 0.0262 (2) | 0.00658 (17) | 0.00630 (17) | 0.00133 (17) |
N3 | 0.0233 (8) | 0.0232 (8) | 0.0190 (7) | −0.0010 (6) | 0.0074 (6) | −0.0034 (6) |
N4 | 0.0213 (7) | 0.0206 (7) | 0.0202 (7) | 0.0023 (6) | 0.0078 (6) | 0.0014 (6) |
C7 | 0.0288 (10) | 0.0271 (10) | 0.0266 (9) | 0.0063 (8) | 0.0111 (8) | −0.0033 (8) |
C8 | 0.0301 (10) | 0.0371 (11) | 0.0225 (9) | −0.0008 (8) | 0.0133 (8) | −0.0032 (8) |
C9 | 0.0347 (11) | 0.0354 (11) | 0.0230 (9) | 0.0032 (8) | 0.0120 (8) | 0.0085 (8) |
C10 | 0.0306 (10) | 0.0289 (10) | 0.0252 (9) | 0.0089 (8) | 0.0119 (8) | 0.0078 (8) |
C11 | 0.0238 (9) | 0.0211 (9) | 0.0203 (8) | −0.0002 (7) | 0.0073 (7) | −0.0013 (7) |
C12 | 0.0403 (11) | 0.0247 (10) | 0.0264 (9) | 0.0115 (8) | 0.0154 (8) | 0.0048 (8) |
Fe1—N1 | 2.1969 (14) | C6—C1i | 1.508 (2) |
Fe1—N2 | 2.1746 (13) | C6—H6A | 0.9900 |
Fe2—N3 | 2.2267 (14) | C6—H6B | 0.9900 |
Fe2—N4 | 2.2198 (14) | Fe2—N4ii | 2.2198 (14) |
Fe1—N2i | 2.1746 (13) | Fe2—N3ii | 2.2267 (14) |
Fe1—N1i | 2.1969 (14) | Fe2—Cl2ii | 2.4613 (5) |
Fe1—Cl1 | 2.4939 (4) | N3—C12ii | 1.477 (2) |
Fe1—Cl1i | 2.4939 (4) | N3—H3A | 0.9200 |
Fe2—Cl2 | 2.4613 (5) | N3—H3B | 0.9200 |
N1—C6 | 1.476 (2) | N4—C11 | 1.338 (2) |
N1—H1A | 0.9200 | N4—C10 | 1.350 (2) |
N1—H1B | 0.9200 | C7—C8 | 1.375 (3) |
C1—N2 | 1.340 (2) | C7—C11 | 1.393 (2) |
C1—C2 | 1.396 (2) | C7—H7 | 0.9500 |
C1—C6i | 1.508 (2) | C8—C9 | 1.382 (3) |
N2—C5 | 1.347 (2) | C8—H8 | 0.9500 |
C2—C3 | 1.378 (3) | C9—C10 | 1.378 (3) |
C2—H2 | 0.9500 | C9—H9 | 0.9500 |
C3—C4 | 1.386 (3) | C10—H10 | 0.9500 |
C3—H3 | 0.9500 | C11—C12 | 1.502 (2) |
C4—C5 | 1.377 (2) | C12—N3ii | 1.477 (2) |
C4—H4 | 0.9500 | C12—H12A | 0.9900 |
C5—H5 | 0.9500 | C12—H12B | 0.9900 |
N1—Fe1—N1i | 180.00 (7) | N3—Fe2—N3ii | 87.58 (8) |
N1—Fe1—Cl1 | 91.35 (4) | N3—Fe2—Cl2ii | 167.06 (4) |
N1i—Fe1—Cl1 | 88.65 (4) | N3—Fe2—Cl2 | 89.77 (4) |
N2—Fe1—N1 | 102.87 (5) | N4ii—Fe2—N3 | 75.68 (5) |
N2i—Fe1—N1 | 77.13 (5) | N4—Fe2—N3 | 91.94 (5) |
N2—Fe1—N1i | 77.13 (5) | N4ii—Fe2—N3ii | 91.94 (5) |
N2i—Fe1—N1i | 102.87 (5) | N4—Fe2—N3ii | 75.68 (5) |
N2—Fe1—Cl1 | 89.57 (4) | N4ii—Fe2—N4 | 162.99 (8) |
N2i—Fe1—Cl1 | 90.43 (4) | N4ii—Fe2—Cl2ii | 91.76 (4) |
N2—Fe1—Cl1i | 90.43 (4) | N4—Fe2—Cl2ii | 99.68 (4) |
N2i—Fe1—Cl1i | 89.57 (4) | N3ii—Fe2—Cl2ii | 89.77 (4) |
N2—Fe1—N2i | 180.00 (6) | N4ii—Fe2—Cl2 | 99.68 (4) |
N1—Fe1—Cl1i | 88.65 (4) | N4—Fe2—Cl2 | 91.76 (4) |
N1i—Fe1—Cl1i | 91.35 (4) | N3ii—Fe2—Cl2 | 167.06 (4) |
Cl1—Fe1—Cl1i | 180.000 (17) | Cl2ii—Fe2—Cl2 | 95.51 (2) |
C6—N1—Fe1 | 111.47 (10) | C12ii—N3—Fe2 | 112.74 (10) |
C6—N1—H1A | 109.3 | C12ii—N3—H3A | 109.0 |
Fe1—N1—H1A | 109.3 | Fe2—N3—H3A | 109.0 |
C6—N1—H1B | 109.3 | C12ii—N3—H3B | 109.0 |
Fe1—N1—H1B | 109.3 | Fe2—N3—H3B | 109.0 |
H1A—N1—H1B | 108.0 | H3A—N3—H3B | 107.8 |
N2—C1—C2 | 121.36 (16) | C11—N4—C10 | 117.53 (14) |
N2—C1—C6i | 117.50 (14) | C11—N4—Fe2 | 116.76 (11) |
C2—C1—C6i | 121.10 (15) | C10—N4—Fe2 | 125.69 (12) |
C1—N2—C5 | 118.32 (14) | C8—C7—C11 | 119.96 (17) |
C1—N2—Fe1 | 116.34 (11) | C8—C7—H7 | 120.0 |
C5—N2—Fe1 | 125.30 (12) | C11—C7—H7 | 120.0 |
C3—C2—C1 | 119.66 (17) | C7—C8—C9 | 118.33 (16) |
C3—C2—H2 | 120.2 | C7—C8—H8 | 120.8 |
C1—C2—H2 | 120.2 | C9—C8—H8 | 120.8 |
C2—C3—C4 | 119.03 (16) | C10—C9—C8 | 118.84 (17) |
C2—C3—H3 | 120.5 | C10—C9—H9 | 120.6 |
C4—C3—H3 | 120.5 | C8—C9—H9 | 120.6 |
C5—C4—C3 | 118.22 (17) | N4—C10—C9 | 123.37 (17) |
C5—C4—H4 | 120.9 | N4—C10—H10 | 118.3 |
C3—C4—H4 | 120.9 | C9—C10—H10 | 118.3 |
N2—C5—C4 | 123.40 (17) | N4—C11—C7 | 121.97 (16) |
N2—C5—H5 | 118.3 | N4—C11—C12 | 117.89 (14) |
C4—C5—H5 | 118.3 | C7—C11—C12 | 120.12 (16) |
N1—C6—C1i | 112.64 (14) | N3ii—C12—C11 | 112.36 (14) |
N1—C6—H6A | 109.1 | N3ii—C12—H12A | 109.1 |
C1i—C6—H6A | 109.1 | C11—C12—H12A | 109.1 |
N1—C6—H6B | 109.1 | N3ii—C12—H12B | 109.1 |
C1i—C6—H6B | 109.1 | C11—C12—H12B | 109.1 |
H6A—C6—H6B | 107.8 | H12A—C12—H12B | 107.9 |
N2—Fe1—N1—C6 | 161.43 (11) | N4—Fe2—N3—C12ii | 151.49 (12) |
N2i—Fe1—N1—C6 | −18.57 (11) | Cl2ii—Fe2—N3—C12ii | −2.4 (3) |
Cl1—Fe1—N1—C6 | −108.69 (11) | Cl2—Fe2—N3—C12ii | −116.75 (12) |
Cl1i—Fe1—N1—C6 | 71.31 (11) | N3—Fe2—N4—C11 | −79.96 (13) |
C2—C1—N2—C5 | 0.0 (2) | N3ii—Fe2—N4—C11 | 7.05 (12) |
C6i—C1—N2—C5 | 177.58 (15) | Cl2ii—Fe2—N4—C11 | 94.31 (12) |
C2—C1—N2—Fe1 | −177.67 (13) | Cl2—Fe2—N4—C11 | −169.79 (12) |
C6i—C1—N2—Fe1 | 0.0 (2) | N3—Fe2—N4—C10 | 102.10 (15) |
N1—Fe1—N2—C1 | 169.60 (12) | N3ii—Fe2—N4—C10 | −170.89 (16) |
N1i—Fe1—N2—C1 | −10.40 (12) | Cl2ii—Fe2—N4—C10 | −83.62 (15) |
Cl1—Fe1—N2—C1 | 78.32 (12) | Cl2—Fe2—N4—C10 | 12.27 (15) |
Cl1i—Fe1—N2—C1 | −101.68 (12) | C11—C7—C8—C9 | −0.1 (3) |
N1—Fe1—N2—C5 | −7.83 (15) | C7—C8—C9—C10 | 0.5 (3) |
N1i—Fe1—N2—C5 | 172.17 (15) | C11—N4—C10—C9 | −0.3 (3) |
Cl1—Fe1—N2—C5 | −99.12 (14) | Fe2—N4—C10—C9 | 177.59 (15) |
Cl1i—Fe1—N2—C5 | 80.88 (14) | C8—C9—C10—N4 | −0.2 (3) |
N2—C1—C2—C3 | 0.7 (3) | C10—N4—C11—C7 | 0.7 (3) |
C6i—C1—C2—C3 | −176.84 (17) | Fe2—N4—C11—C7 | −177.43 (13) |
C1—C2—C3—C4 | −0.3 (3) | C10—N4—C11—C12 | −177.76 (16) |
C2—C3—C4—C5 | −0.7 (3) | Fe2—N4—C11—C12 | 4.1 (2) |
C1—N2—C5—C4 | −1.1 (3) | C8—C7—C11—N4 | −0.5 (3) |
Fe1—N2—C5—C4 | 176.33 (14) | C8—C7—C11—C12 | 177.95 (18) |
C3—C4—C5—N2 | 1.5 (3) | N4—C11—C12—N3ii | −18.8 (2) |
Fe1—N1—C6—C1i | 24.19 (18) | C7—C11—C12—N3ii | 162.71 (16) |
N4ii—Fe2—N3—C12ii | −16.70 (12) |
Symmetry codes: (i) −x+1/2, −y+3/2, −z; (ii) −x+1, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···Cl2 | 0.92 | 2.70 | 3.4358 (15) | 137 |
N1—H1B···Cl1iii | 0.92 | 2.68 | 3.4440 (15) | 141 |
N3—H3A···Cl1iii | 0.92 | 2.62 | 3.4762 (15) | 156 |
N3—H3B···Cl2iii | 0.92 | 2.81 | 3.4678 (15) | 129 |
Symmetry code: (iii) x, y−1, z. |
Experimental details
Crystal data | |
Chemical formula | [FeCl2(C6H8N2)2] |
Mr | 343.04 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 150 |
a, b, c (Å) | 26.626 (2), 6.6818 (5), 16.8821 (13) |
β (°) | 107.565 (1) |
V (Å3) | 2863.5 (4) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.42 |
Crystal size (mm) | 0.35 × 0.25 × 0.18 |
Data collection | |
Diffractometer | Siemens SMART 1K CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.671, 0.775 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14985, 3276, 2676 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.662 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.063, 1.04 |
No. of reflections | 3276 |
No. of parameters | 174 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.39, −0.23 |
Computer programs: SMART (Bruker, 1999), SAINT (Bruker, 2001), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 2000), PLATON (Spek, 2003).
Fe1—N1 | 2.1969 (14) | Fe2—N4 | 2.2198 (14) |
Fe1—N2 | 2.1746 (13) | Fe1—Cl1 | 2.4939 (4) |
Fe2—N3 | 2.2267 (14) | Fe2—Cl2 | 2.4613 (5) |
N1—Fe1—N1i | 180.00 (7) | N3—Fe2—N3ii | 87.58 (8) |
N1—Fe1—Cl1 | 91.35 (4) | N3—Fe2—Cl2ii | 167.06 (4) |
N1i—Fe1—Cl1 | 88.65 (4) | N3—Fe2—Cl2 | 89.77 (4) |
N2—Fe1—N1 | 102.87 (5) | N4—Fe2—N3 | 91.94 (5) |
N2i—Fe1—N1 | 77.13 (5) | N4—Fe2—N3ii | 75.68 (5) |
N2—Fe1—Cl1 | 89.57 (4) | N4ii—Fe2—N4 | 162.99 (8) |
N2i—Fe1—Cl1 | 90.43 (4) | N4—Fe2—Cl2ii | 99.68 (4) |
N2—Fe1—N2i | 180.00 (6) | N4—Fe2—Cl2 | 91.76 (4) |
Cl1—Fe1—Cl1i | 180.000 (17) | Cl2ii—Fe2—Cl2 | 95.51 (2) |
Symmetry codes: (i) −x+1/2, −y+3/2, −z; (ii) −x+1, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···Cl2 | 0.92 | 2.70 | 3.4358 (15) | 137 |
N1—H1B···Cl1iii | 0.92 | 2.68 | 3.4440 (15) | 141 |
N3—H3A···Cl1iii | 0.92 | 2.62 | 3.4762 (15) | 156 |
N3—H3B···Cl2iii | 0.92 | 2.81 | 3.4678 (15) | 129 |
Symmetry code: (iii) x, y−1, z. |
Subscribe to Acta Crystallographica Section C: Structural Chemistry
The full text of this article is available to subscribers to the journal.
- Information on subscribing
- Sample issue
- Purchase subscription
- Reduced-price subscriptions
- If you have already subscribed, you may need to register
Preparation of the methanol, ethanol, 1-propanol, 2-propanol, tert-butanol and allyl-alcohol solvates of [tris(2-picolylamine)iron(II)]dichloride from the corresponding alcohol solutions is straightforward (Hostettler et al., 2004). An attempt to synthesize the 1-butanol solvate, however, resulted in co-crystals of the cis and trans isomers of the title compound, (I), dichloro-bis(2-picolylamine)iron(II) (Fig. 1).
The cis-configured molecule has a twofold symmetry axis, while the trans isomer is located on an inversion centre. The Fe—N bond distances indicate that both Fe atoms are in a high-spin state. Nonetheless, chemically comparable Fe–ligand bond lengths differ slightly between the two isomers (Table 1). The Fe—NH2 bonds lengthen by 0.030 (2) Å on going from the trans to the cis isomer. This change is almost compensated for by a corresponding decrease of the Fe—Cl bond length by 0.033 (1) Å. A larger difference of 0.045 (2) Å is found for the Fe—N(py) bonds, with the distances in the cis isomer being longer.
The only other FeN4L2 compounds for which at least an approximate comparison can be made are bis{trans-isothiocyanato[4-methylphenyl-3,5 -bis(pyridin-2-yl)-1,2,4-triazole]}iron(II) and bis{cis-isothiocyanato[3-methylphenyl-3,5-bis(pyridin-2-yl)-1,2,4- triazole]}iron(II) [Cambridge Structural Database (CSD; Allen, 2002) refcodes FADVUC and FADWAJ; Zhu et al., 2002). In this case, the trans and cis isomers actually differ in the substitution of the peripheral phenyl rings, but the variation in the coordination geometry shows an effect similar to that observed in (I), the Fe—NCS distances in the trans isomer being longer by 0.063 (3) Å than those in the cis isomer. This difference is compensated for by a decrease in the Fe—N(triazole) bond length of 0.056 (3) Å. In contrast with (I), the Fe—N(py) distances are almost the same in these two isomers. The structural cis/trans influence has been studied in detail elsewhere (Pidcock et al., 1966; Coe & Glenwright, 2000; Gupta et al., 2000).
In the trans isomer of (I), symmetry dictates an N(py)—Fe—N(py) angle of 180°, but in the cis form the corresponding angle is smaller by about 17°. The dihedral angles between the two pyridine rings are 0 and 72.9 (1)° in the trans and cis isomers, respectively, and 50° on average in the tris(picolylamine)iron(II) series of solvates (Hostettler et al., 2004). The trend in conformational angles correlates with the observed lengthening of the Fe—N(py) distances from the trans to the cis isomer of (I) (Table 1), while the average Fe—N(py) trans distance in the high-spin tris(picolylamine)iron(II) complexes is intermediate, at 2.21 Å (Chernyshov et al., 2003; Hostettler et al., 2004).
The crystal structure of (I) may be considered as being built from layers of cis isomers alternating with layers of trans isomers along the (100) direction. Alternatively, the structure may be viewed in terms of layers parallel to the (101) planes. In these layers, cis and trans isomers are connected through N—H···Cl hydrogen bonds, which form a two-dimensional network of `tiles' in the shape of eight-membered rings, four around each Fe atom (Fig. 2). The hydrogen-bonded layers are stacked through π–π interactions, with typical centroid-to-centroid distances of 3.619 (1) Å (Fig. 3, Table 2).
As discussed in the Experimental section, searches in the CSD (version 5.25, November 2003 update with 298097 entries) for other co-crystals of cis- and trans-MN4L2 complexes have revealed only one other example with an ordered crystal structure, namely dichlorobis(2-methyl-1,3-propanediamine)cobalt(III) chloride methanol solvate. The trans isomer is located on an inversion centre, whereas the cis isomer lies in a general position (CSD refcode CAWPOF; Mather et al., 1983; M is any transition metal ion, N is any type of nitrogen ligand, and L is a halogen, O, S, N or P atom).
The rare occurrence of the cis/trans co-crystallization phenomenon may be understood intuitively. Firstly, the two isomers are expected to have different energies and also, most probably, different synthesis conditions, and are therefore not necessarily present simultaneously during synthesis and subsequent crystallization. Secondly, co-crystallization must be more favourable in thermodynamic and/or kinetic terms than crystallization of the individual isomers.