Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827011203209X/wq3016sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827011203209X/wq3016Isup2.hkl |
CCDC reference: 813790
For related literature, see: Bousseksou et al. (2011); Garcia et al. (2005); Guionneau et al. (2001); Halcrow (2011); Halder et al. (2002); Li et al. (2010); Li, Tao, Sun, Sato, Huang & Zheng (2008); Li, Yang, Tao, Sato, Huang & Zheng (2008); Matouzenko et al. (1997); Sunatsuki et al. (2003); Thompson et al. (2004); Yu & Li (2011).
The synthesis of dpqa was carried out according to the literature method of Li and co-workers (Li, Tao et al., 2008; Li, Yang et al., 2008). For the synthesis of the mononuclear complex, FeSO4.7H2O (0.1 mmol) and KSCN (0.2 mmol) were dissolved in methanol (5 ml), then ascorbic acid (5 mg) was added to the solution to avoid oxidation of the FeII ion. The solution was filtered to remove the K2SO4 precipitate, and an ethanol solution (10 ml) containing dpqa (0.1 mmol) and ascorbic acid (5 mg) was added to the filtrate immediately with stirring under a nitrogen atmosphere. The product precipitated as a powder, which was filtered off. The powder (30 mg) was dissolved in dimethylformamide (1 ml) and the solution was layered with ethanol to give yellow block-like single crystals of (I) in 40% yield. Elemental analysis, calculated: H 3.93, C 56.25, N 16.40%; experimental: H 4.12, C 55.91, N 16.94%.
Magnetic susceptibility measurements were carried out at a sweeping rate of 1 K min-1 in the temperature range 2–300 K with a magnetic field of 5000 Oe on a Quantum Design MPMS XL-7 magnetometer. Magnetic measurements under pressure were performed using an EasyLab Mcell 10 hydrostatic pressure cell, which is specially designed for the MPMS set up; it is made of hardened beryllium bronze with silicon oil as the pressure-transmitting medium. The applied pressure was measured using the pressure dependence of the superconducting transition temperature of a built-in pressure sensor made of high-purity tin. The magnetic data were calibrated with the sample holder and the diamagnetic contributions.
All H atoms were placed geometrically, with C—H = 0.93 (aromatic) or 0.96 Å (CH2), and refined using a riding-atom model, with Uiso(H) = 1.2Ueq(C).
Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL97 (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).
[Fe(NCS)2(C22H20N4)] | F(000) = 1056 |
Mr = 512.45 | Dx = 1.391 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 12.2292 (7) Å | Cell parameters from 3037 reflections |
b = 11.8350 (6) Å | θ = 2.4–26° |
c = 16.9729 (8) Å | µ = 0.81 mm−1 |
β = 95.293 (5)° | T = 293 K |
V = 2446.1 (2) Å3 | Block, yellow |
Z = 4 | 0.20 × 0.20 × 0.15 mm |
Oxford Gemini S Ultra diffractometer | 4800 independent reflections |
Radiation source: fine-focus sealed tube | 2639 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.053 |
Detector resolution: 0 pixels mm-1 | θmax = 26.0°, θmin = 2.4° |
ω scans | h = −15→15 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | k = 0→14 |
Tmin = 0.854, Tmax = 0.887 | l = 0→20 |
13672 measured reflections |
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)] = 0.044 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.089 | H-atom parameters constrained |
S = 0.81 | w = 1/[σ2(Fo2) + (0.0378P)2] where P = (Fo2 + 2Fc2)/3 |
4800 reflections | (Δ/σ)max = 0.001 |
298 parameters | Δρmax = 0.58 e Å−3 |
0 restraints | Δρmin = −0.49 e Å−3 |
[Fe(NCS)2(C22H20N4)] | V = 2446.1 (2) Å3 |
Mr = 512.45 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 12.2292 (7) Å | µ = 0.81 mm−1 |
b = 11.8350 (6) Å | T = 293 K |
c = 16.9729 (8) Å | 0.20 × 0.20 × 0.15 mm |
β = 95.293 (5)° |
Oxford Gemini S Ultra diffractometer | 4800 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | 2639 reflections with I > 2σ(I) |
Tmin = 0.854, Tmax = 0.887 | Rint = 0.053 |
13672 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.089 | H-atom parameters constrained |
S = 0.81 | Δρmax = 0.58 e Å−3 |
4800 reflections | Δρmin = −0.49 e Å−3 |
298 parameters |
Experimental. Absorption correction: CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.32.4 (release 27-04-2006 CrysAlis171 .NET) (compiled Apr 27 2007,17:53:11) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Fe1 | 0.31811 (4) | 0.21437 (3) | 0.20448 (2) | 0.03164 (13) | |
S1 | 0.28869 (11) | 0.54945 (8) | 0.04784 (6) | 0.0808 (4) | |
S2 | 0.69487 (8) | 0.22201 (9) | 0.13886 (8) | 0.0853 (4) | |
N1 | 0.37006 (18) | 0.2848 (2) | 0.32153 (13) | 0.0325 (6) | |
N2 | 0.1554 (2) | 0.1902 (2) | 0.24318 (15) | 0.0376 (6) | |
N3 | 0.26757 (19) | 0.06478 (19) | 0.12561 (14) | 0.0327 (6) | |
N4 | 0.3445 (2) | 0.06441 (19) | 0.28405 (14) | 0.0352 (6) | |
N5 | 0.2817 (2) | 0.3654 (2) | 0.14927 (16) | 0.0488 (8) | |
N6 | 0.4794 (2) | 0.2056 (2) | 0.17454 (14) | 0.0421 (7) | |
C1 | 0.3563 (2) | 0.3912 (2) | 0.34453 (17) | 0.0342 (7) | |
H1 | 0.3230 | 0.4420 | 0.3080 | 0.041* | |
C2 | 0.3889 (2) | 0.4295 (3) | 0.41929 (18) | 0.0395 (8) | |
H2 | 0.3787 | 0.5047 | 0.4327 | 0.047* | |
C3 | 0.4366 (3) | 0.3553 (3) | 0.47376 (18) | 0.0460 (9) | |
H3 | 0.4590 | 0.3790 | 0.5249 | 0.055* | |
C4 | 0.4509 (3) | 0.2439 (3) | 0.45142 (18) | 0.0472 (9) | |
H4 | 0.4822 | 0.1915 | 0.4877 | 0.057* | |
C5 | 0.4182 (2) | 0.2119 (3) | 0.37461 (17) | 0.0367 (7) | |
C6 | 0.4348 (3) | 0.0949 (2) | 0.34394 (18) | 0.0455 (9) | |
H6A | 0.5042 | 0.0912 | 0.3206 | 0.055* | |
H6B | 0.4375 | 0.0414 | 0.3874 | 0.055* | |
C7 | 0.0662 (3) | 0.2517 (3) | 0.2193 (2) | 0.0517 (9) | |
H7 | 0.0758 | 0.3144 | 0.1876 | 0.062* | |
C8 | −0.0365 (3) | 0.2289 (4) | 0.2380 (3) | 0.0748 (13) | |
H8 | −0.0955 | 0.2747 | 0.2202 | 0.090* | |
C9 | −0.0509 (3) | 0.1360 (4) | 0.2843 (3) | 0.0867 (15) | |
H9 | −0.1205 | 0.1168 | 0.2978 | 0.104* | |
C10 | 0.0397 (4) | 0.0709 (3) | 0.3107 (2) | 0.0696 (12) | |
H10 | 0.0317 | 0.0081 | 0.3427 | 0.084* | |
C11 | 0.1422 (3) | 0.1009 (3) | 0.2889 (2) | 0.0439 (9) | |
C12 | 0.2436 (3) | 0.0372 (3) | 0.32149 (19) | 0.0494 (9) | |
H12A | 0.2564 | 0.0527 | 0.3777 | 0.059* | |
H12B | 0.2294 | −0.0432 | 0.3154 | 0.059* | |
C13 | 0.2017 (2) | 0.0631 (2) | 0.05474 (17) | 0.0325 (7) | |
C14 | 0.1658 (3) | 0.1660 (3) | 0.02004 (18) | 0.0420 (8) | |
H14 | 0.1841 | 0.2339 | 0.0455 | 0.050* | |
C15 | 0.1039 (3) | 0.1660 (3) | −0.05136 (19) | 0.0514 (9) | |
H15 | 0.0802 | 0.2342 | −0.0741 | 0.062* | |
C16 | 0.0757 (3) | 0.0649 (3) | −0.0905 (2) | 0.0549 (10) | |
H16 | 0.0341 | 0.0664 | −0.1392 | 0.066* | |
C17 | 0.1083 (3) | −0.0345 (3) | −0.05804 (19) | 0.0499 (9) | |
H17 | 0.0881 | −0.1013 | −0.0843 | 0.060* | |
C18 | 0.1733 (3) | −0.0390 (3) | 0.01574 (19) | 0.0394 (8) | |
C19 | 0.2102 (3) | −0.1395 (3) | 0.0512 (2) | 0.0495 (9) | |
H19 | 0.1908 | −0.2083 | 0.0274 | 0.059* | |
C20 | 0.2746 (3) | −0.1368 (3) | 0.1209 (2) | 0.0461 (9) | |
H20 | 0.3011 | −0.2036 | 0.1444 | 0.055* | |
C21 | 0.3009 (3) | −0.0330 (2) | 0.15699 (18) | 0.0366 (8) | |
C22 | 0.3763 (3) | −0.0276 (2) | 0.23231 (18) | 0.0427 (8) | |
H22A | 0.3738 | −0.0990 | 0.2601 | 0.051* | |
H22B | 0.4511 | −0.0157 | 0.2195 | 0.051* | |
C23 | 0.2845 (3) | 0.4418 (3) | 0.10731 (19) | 0.0426 (9) | |
C24 | 0.5695 (3) | 0.2129 (3) | 0.16036 (17) | 0.0374 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.0344 (3) | 0.0287 (2) | 0.0320 (2) | 0.0016 (2) | 0.00382 (18) | 0.0041 (2) |
S1 | 0.1323 (11) | 0.0437 (6) | 0.0643 (7) | −0.0029 (6) | −0.0019 (7) | 0.0195 (5) |
S2 | 0.0386 (6) | 0.0876 (8) | 0.1339 (10) | −0.0208 (6) | 0.0301 (6) | −0.0701 (8) |
N1 | 0.0354 (15) | 0.0307 (14) | 0.0322 (13) | 0.0058 (13) | 0.0079 (11) | 0.0050 (13) |
N2 | 0.0334 (16) | 0.0371 (16) | 0.0422 (16) | 0.0040 (13) | 0.0031 (12) | −0.0078 (13) |
N3 | 0.0315 (15) | 0.0289 (14) | 0.0387 (15) | 0.0006 (12) | 0.0085 (12) | 0.0012 (12) |
N4 | 0.0404 (16) | 0.0300 (14) | 0.0360 (15) | 0.0074 (13) | 0.0089 (13) | 0.0022 (12) |
N5 | 0.070 (2) | 0.0332 (16) | 0.0413 (17) | −0.0007 (15) | −0.0034 (15) | 0.0072 (14) |
N6 | 0.0398 (17) | 0.0501 (17) | 0.0366 (15) | −0.0088 (16) | 0.0052 (13) | −0.0073 (13) |
C1 | 0.0326 (19) | 0.0363 (19) | 0.0341 (18) | −0.0011 (15) | 0.0049 (14) | 0.0054 (15) |
C2 | 0.045 (2) | 0.0382 (19) | 0.0368 (19) | −0.0037 (16) | 0.0119 (16) | −0.0019 (16) |
C3 | 0.054 (2) | 0.054 (2) | 0.0300 (18) | −0.0023 (19) | 0.0057 (16) | −0.0028 (17) |
C4 | 0.055 (2) | 0.054 (2) | 0.0307 (18) | 0.0086 (18) | −0.0032 (16) | 0.0065 (16) |
C5 | 0.0375 (19) | 0.0395 (18) | 0.0334 (17) | 0.0091 (17) | 0.0044 (14) | 0.0044 (16) |
C6 | 0.058 (2) | 0.045 (2) | 0.0331 (19) | 0.0173 (18) | 0.0008 (17) | 0.0036 (16) |
C7 | 0.041 (2) | 0.061 (2) | 0.052 (2) | 0.0121 (19) | −0.0034 (17) | −0.0120 (18) |
C8 | 0.036 (2) | 0.096 (4) | 0.091 (3) | 0.005 (3) | 0.001 (2) | −0.026 (3) |
C9 | 0.039 (3) | 0.104 (4) | 0.121 (4) | −0.025 (3) | 0.026 (3) | −0.046 (3) |
C10 | 0.070 (3) | 0.056 (3) | 0.087 (3) | −0.023 (2) | 0.031 (3) | −0.021 (2) |
C11 | 0.043 (2) | 0.036 (2) | 0.055 (2) | −0.0096 (17) | 0.0162 (18) | −0.0173 (17) |
C12 | 0.064 (3) | 0.037 (2) | 0.051 (2) | −0.0049 (19) | 0.0227 (19) | 0.0061 (17) |
C13 | 0.0261 (17) | 0.0329 (18) | 0.0398 (19) | −0.0028 (15) | 0.0097 (15) | −0.0017 (15) |
C14 | 0.045 (2) | 0.0420 (19) | 0.039 (2) | 0.0023 (17) | 0.0037 (16) | 0.0008 (17) |
C15 | 0.054 (2) | 0.058 (2) | 0.041 (2) | −0.0004 (19) | −0.0020 (18) | 0.0013 (18) |
C16 | 0.049 (2) | 0.076 (3) | 0.039 (2) | 0.001 (2) | 0.0007 (18) | −0.006 (2) |
C17 | 0.044 (2) | 0.064 (3) | 0.043 (2) | −0.010 (2) | 0.0100 (18) | −0.024 (2) |
C18 | 0.037 (2) | 0.0360 (19) | 0.047 (2) | −0.0031 (17) | 0.0149 (16) | −0.0078 (17) |
C19 | 0.055 (2) | 0.039 (2) | 0.058 (2) | −0.0133 (19) | 0.0220 (19) | −0.0189 (18) |
C20 | 0.057 (2) | 0.0271 (19) | 0.057 (2) | 0.0029 (17) | 0.0157 (19) | −0.0033 (17) |
C21 | 0.044 (2) | 0.0308 (19) | 0.0372 (19) | 0.0010 (16) | 0.0158 (16) | 0.0012 (15) |
C22 | 0.057 (2) | 0.0274 (18) | 0.044 (2) | 0.0084 (17) | 0.0098 (17) | 0.0048 (15) |
C23 | 0.052 (2) | 0.0333 (19) | 0.040 (2) | 0.0014 (17) | −0.0058 (17) | −0.0044 (16) |
C24 | 0.042 (2) | 0.0367 (18) | 0.0336 (17) | −0.0091 (19) | 0.0031 (15) | −0.0140 (15) |
Fe1—N5 | 2.048 (3) | C7—C8 | 1.352 (5) |
Fe1—N6 | 2.084 (3) | C7—H7 | 0.9300 |
Fe1—N2 | 2.171 (3) | C8—C9 | 1.372 (6) |
Fe1—N1 | 2.194 (2) | C8—H8 | 0.9300 |
Fe1—N4 | 2.236 (2) | C9—C10 | 1.390 (5) |
Fe1—N3 | 2.271 (2) | C9—H9 | 0.9300 |
S1—C23 | 1.629 (3) | C10—C11 | 1.386 (5) |
S2—C24 | 1.612 (3) | C10—H10 | 0.9300 |
N1—C1 | 1.334 (3) | C11—C12 | 1.513 (4) |
N1—C5 | 1.343 (3) | C12—H12A | 0.9700 |
N2—C11 | 1.329 (4) | C12—H12B | 0.9700 |
N2—C7 | 1.342 (4) | C13—C14 | 1.405 (4) |
N3—C21 | 1.322 (3) | C13—C18 | 1.406 (4) |
N3—C13 | 1.385 (3) | C14—C15 | 1.369 (4) |
N4—C22 | 1.474 (4) | C14—H14 | 0.9300 |
N4—C12 | 1.475 (4) | C15—C16 | 1.395 (4) |
N4—C6 | 1.475 (4) | C15—H15 | 0.9300 |
N5—C23 | 1.153 (4) | C16—C17 | 1.344 (4) |
N6—C24 | 1.153 (3) | C16—H16 | 0.9300 |
C1—C2 | 1.372 (4) | C17—C18 | 1.421 (4) |
C1—H1 | 0.9300 | C17—H17 | 0.9300 |
C2—C3 | 1.367 (4) | C18—C19 | 1.389 (4) |
C2—H2 | 0.9300 | C19—C20 | 1.361 (4) |
C3—C4 | 1.387 (4) | C19—H19 | 0.9300 |
C3—H3 | 0.9300 | C20—C21 | 1.397 (4) |
C4—C5 | 1.381 (4) | C20—H20 | 0.9300 |
C4—H4 | 0.9300 | C21—C22 | 1.507 (4) |
C5—C6 | 1.499 (4) | C22—H22A | 0.9700 |
C6—H6A | 0.9700 | C22—H22B | 0.9700 |
C6—H6B | 0.9700 | ||
N5—Fe1—N6 | 95.90 (11) | C8—C7—H7 | 117.7 |
N5—Fe1—N2 | 94.97 (11) | C7—C8—C9 | 117.8 (4) |
N6—Fe1—N2 | 168.96 (10) | C7—C8—H8 | 121.1 |
N5—Fe1—N1 | 96.63 (9) | C9—C8—H8 | 121.1 |
N6—Fe1—N1 | 92.19 (9) | C8—C9—C10 | 119.2 (4) |
N2—Fe1—N1 | 88.45 (9) | C8—C9—H9 | 120.4 |
N5—Fe1—N4 | 169.26 (10) | C10—C9—H9 | 120.4 |
N6—Fe1—N4 | 91.17 (10) | C11—C10—C9 | 119.0 (4) |
N2—Fe1—N4 | 78.35 (9) | C11—C10—H10 | 120.5 |
N1—Fe1—N4 | 74.97 (9) | C9—C10—H10 | 120.5 |
N5—Fe1—N3 | 112.02 (10) | N2—C11—C10 | 121.4 (3) |
N6—Fe1—N3 | 91.70 (9) | N2—C11—C12 | 118.0 (3) |
N2—Fe1—N3 | 82.44 (8) | C10—C11—C12 | 120.4 (3) |
N1—Fe1—N3 | 150.51 (9) | N4—C12—C11 | 115.1 (3) |
N4—Fe1—N3 | 75.73 (9) | N4—C12—H12A | 108.5 |
C1—N1—C5 | 118.0 (3) | C11—C12—H12A | 108.5 |
C1—N1—Fe1 | 126.14 (19) | N4—C12—H12B | 108.5 |
C5—N1—Fe1 | 115.84 (19) | C11—C12—H12B | 108.5 |
C11—N2—C7 | 117.9 (3) | H12A—C12—H12B | 107.5 |
C11—N2—Fe1 | 116.4 (2) | N3—C13—C14 | 119.1 (3) |
C7—N2—Fe1 | 125.4 (2) | N3—C13—C18 | 121.3 (3) |
C21—N3—C13 | 118.0 (3) | C14—C13—C18 | 119.6 (3) |
C21—N3—Fe1 | 112.8 (2) | C15—C14—C13 | 119.8 (3) |
C13—N3—Fe1 | 128.93 (19) | C15—C14—H14 | 120.1 |
C22—N4—C12 | 111.8 (2) | C13—C14—H14 | 120.1 |
C22—N4—C6 | 111.7 (2) | C14—C15—C16 | 120.9 (3) |
C12—N4—C6 | 111.1 (2) | C14—C15—H15 | 119.5 |
C22—N4—Fe1 | 104.96 (17) | C16—C15—H15 | 119.5 |
C12—N4—Fe1 | 110.72 (18) | C17—C16—C15 | 120.3 (3) |
C6—N4—Fe1 | 106.22 (17) | C17—C16—H16 | 119.9 |
C23—N5—Fe1 | 161.6 (3) | C15—C16—H16 | 119.9 |
C24—N6—Fe1 | 172.5 (3) | C16—C17—C18 | 121.0 (3) |
N1—C1—C2 | 123.3 (3) | C16—C17—H17 | 119.5 |
N1—C1—H1 | 118.4 | C18—C17—H17 | 119.5 |
C2—C1—H1 | 118.4 | C19—C18—C13 | 118.4 (3) |
C3—C2—C1 | 118.9 (3) | C19—C18—C17 | 123.2 (3) |
C3—C2—H2 | 120.6 | C13—C18—C17 | 118.4 (3) |
C1—C2—H2 | 120.6 | C20—C19—C18 | 119.7 (3) |
C2—C3—C4 | 118.9 (3) | C20—C19—H19 | 120.1 |
C2—C3—H3 | 120.6 | C18—C19—H19 | 120.1 |
C4—C3—H3 | 120.6 | C19—C20—C21 | 119.5 (3) |
C5—C4—C3 | 119.1 (3) | C19—C20—H20 | 120.2 |
C5—C4—H4 | 120.5 | C21—C20—H20 | 120.2 |
C3—C4—H4 | 120.5 | N3—C21—C20 | 122.9 (3) |
N1—C5—C4 | 121.9 (3) | N3—C21—C22 | 116.5 (3) |
N1—C5—C6 | 115.2 (3) | C20—C21—C22 | 120.4 (3) |
C4—C5—C6 | 123.0 (3) | N4—C22—C21 | 111.2 (3) |
N4—C6—C5 | 110.4 (2) | N4—C22—H22A | 109.4 |
N4—C6—H6A | 109.6 | C21—C22—H22A | 109.4 |
C5—C6—H6A | 109.6 | N4—C22—H22B | 109.4 |
N4—C6—H6B | 109.6 | C21—C22—H22B | 109.4 |
C5—C6—H6B | 109.6 | H22A—C22—H22B | 108.0 |
H6A—C6—H6B | 108.1 | N5—C23—S1 | 179.8 (4) |
N2—C7—C8 | 124.6 (4) | N6—C24—S2 | 178.8 (3) |
N2—C7—H7 | 117.7 | ||
N5—Fe1—N1—C1 | 11.3 (2) | Fe1—N1—C5—C4 | −177.4 (2) |
N6—Fe1—N1—C1 | 107.5 (2) | C1—N1—C5—C6 | −177.8 (3) |
N2—Fe1—N1—C1 | −83.5 (2) | Fe1—N1—C5—C6 | 3.4 (3) |
N4—Fe1—N1—C1 | −161.8 (2) | C3—C4—C5—N1 | −1.8 (5) |
N3—Fe1—N1—C1 | −155.1 (2) | C3—C4—C5—C6 | 177.2 (3) |
N5—Fe1—N1—C5 | −170.0 (2) | C22—N4—C6—C5 | 158.8 (2) |
N6—Fe1—N1—C5 | −73.8 (2) | C12—N4—C6—C5 | −75.5 (3) |
N2—Fe1—N1—C5 | 95.2 (2) | Fe1—N4—C6—C5 | 44.9 (3) |
N4—Fe1—N1—C5 | 16.82 (19) | N1—C5—C6—N4 | −33.6 (4) |
N3—Fe1—N1—C5 | 23.5 (3) | C4—C5—C6—N4 | 147.3 (3) |
N5—Fe1—N2—C11 | −175.3 (2) | C11—N2—C7—C8 | −0.4 (5) |
N6—Fe1—N2—C11 | 14.7 (6) | Fe1—N2—C7—C8 | 173.4 (3) |
N1—Fe1—N2—C11 | −78.8 (2) | N2—C7—C8—C9 | −0.4 (6) |
N4—Fe1—N2—C11 | −3.8 (2) | C7—C8—C9—C10 | 1.0 (6) |
N3—Fe1—N2—C11 | 73.1 (2) | C8—C9—C10—C11 | −0.7 (6) |
N5—Fe1—N2—C7 | 10.8 (2) | C7—N2—C11—C10 | 0.7 (4) |
N6—Fe1—N2—C7 | −159.2 (4) | Fe1—N2—C11—C10 | −173.7 (2) |
N1—Fe1—N2—C7 | 107.3 (2) | C7—N2—C11—C12 | −175.0 (3) |
N4—Fe1—N2—C7 | −177.7 (2) | Fe1—N2—C11—C12 | 10.7 (3) |
N3—Fe1—N2—C7 | −100.8 (2) | C9—C10—C11—N2 | −0.1 (5) |
N5—Fe1—N3—C21 | 173.2 (2) | C9—C10—C11—C12 | 175.5 (3) |
N6—Fe1—N3—C21 | 76.2 (2) | C22—N4—C12—C11 | −106.9 (3) |
N2—Fe1—N3—C21 | −94.4 (2) | C6—N4—C12—C11 | 127.5 (3) |
N1—Fe1—N3—C21 | −21.3 (3) | Fe1—N4—C12—C11 | 9.7 (3) |
N4—Fe1—N3—C21 | −14.6 (2) | N2—C11—C12—N4 | −13.9 (4) |
N5—Fe1—N3—C13 | −12.2 (3) | C10—C11—C12—N4 | 170.4 (3) |
N6—Fe1—N3—C13 | −109.3 (2) | C21—N3—C13—C14 | −179.6 (3) |
N2—Fe1—N3—C13 | 80.1 (2) | Fe1—N3—C13—C14 | 6.0 (4) |
N1—Fe1—N3—C13 | 153.3 (2) | C21—N3—C13—C18 | −1.8 (4) |
N4—Fe1—N3—C13 | 160.0 (3) | Fe1—N3—C13—C18 | −176.1 (2) |
N5—Fe1—N4—C22 | 169.6 (5) | N3—C13—C14—C15 | 177.7 (3) |
N6—Fe1—N4—C22 | −59.2 (2) | C18—C13—C14—C15 | −0.2 (5) |
N2—Fe1—N4—C22 | 117.3 (2) | C13—C14—C15—C16 | 0.0 (5) |
N1—Fe1—N4—C22 | −151.1 (2) | C14—C15—C16—C17 | 0.6 (5) |
N3—Fe1—N4—C22 | 32.27 (19) | C15—C16—C17—C18 | −1.0 (5) |
N5—Fe1—N4—C12 | 48.7 (6) | N3—C13—C18—C19 | 1.9 (4) |
N6—Fe1—N4—C12 | 180.0 (2) | C14—C13—C18—C19 | 179.8 (3) |
N2—Fe1—N4—C12 | −3.54 (19) | N3—C13—C18—C17 | −178.0 (3) |
N1—Fe1—N4—C12 | 88.0 (2) | C14—C13—C18—C17 | −0.2 (4) |
N3—Fe1—N4—C12 | −88.6 (2) | C16—C17—C18—C19 | −179.2 (3) |
N5—Fe1—N4—C6 | −72.0 (6) | C16—C17—C18—C13 | 0.7 (5) |
N6—Fe1—N4—C6 | 59.28 (19) | C13—C18—C19—C20 | −1.8 (5) |
N2—Fe1—N4—C6 | −124.22 (19) | C17—C18—C19—C20 | 178.2 (3) |
N1—Fe1—N4—C6 | −32.68 (18) | C18—C19—C20—C21 | 1.5 (5) |
N3—Fe1—N4—C6 | 150.7 (2) | C13—N3—C21—C20 | 1.5 (4) |
N6—Fe1—N5—C23 | 21.5 (8) | Fe1—N3—C21—C20 | 176.7 (2) |
N2—Fe1—N5—C23 | −156.6 (8) | C13—N3—C21—C22 | 177.5 (3) |
N1—Fe1—N5—C23 | 114.4 (8) | Fe1—N3—C21—C22 | −7.3 (3) |
N4—Fe1—N5—C23 | 152.4 (7) | C19—C20—C21—N3 | −1.4 (5) |
N3—Fe1—N5—C23 | −72.8 (8) | C19—C20—C21—C22 | −177.2 (3) |
C5—N1—C1—C2 | 0.1 (4) | C12—N4—C22—C21 | 73.2 (3) |
Fe1—N1—C1—C2 | 178.7 (2) | C6—N4—C22—C21 | −161.5 (2) |
N1—C1—C2—C3 | −0.9 (5) | Fe1—N4—C22—C21 | −46.9 (3) |
C1—C2—C3—C4 | 0.3 (5) | N3—C21—C22—N4 | 38.0 (4) |
C2—C3—C4—C5 | 1.0 (5) | C20—C21—C22—N4 | −145.9 (3) |
C1—N1—C5—C4 | 1.3 (4) |
Experimental details
Crystal data | |
Chemical formula | [Fe(NCS)2(C22H20N4)] |
Mr | 512.45 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 12.2292 (7), 11.8350 (6), 16.9729 (8) |
β (°) | 95.293 (5) |
V (Å3) | 2446.1 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.81 |
Crystal size (mm) | 0.20 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Oxford Gemini S Ultra diffractometer |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.854, 0.887 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13672, 4800, 2639 |
Rint | 0.053 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.089, 0.81 |
No. of reflections | 4800 |
No. of parameters | 298 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.58, −0.49 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999), publCIF (Westrip, 2010).
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Many studies have been carried out on FeII compounds with the typical form of an FeN6 coordination octahedron, which might present fascinating spin-crossover (SCO) properties and specific lattice interactions (Thompson et al., 2004; Yu & Li, 2011; Halcrow, 2011; Bousseksou et al., 2011). Among these efforts, the various noncovalent interactions between different FeII units in the solid state have also been verified as an efficient method for achieving an abrupt spin transition with significant bistability, for example by changing crystallization counteranions or solvents (Halder et al., 2002; Sunatsuki et al., 2003). Recently, the effect of noncovalent interactions, including hydrogen bonding and π–π interactions, on SCO behaviour in two mononuclear Fe systems containing the tripodal ligand tris(pyridin-2-ylmethyl)amine (tpa; see scheme) has been reported (Li et al., 2010). This ligand possesses many advantages as a terminal ligand coordinated to metal atoms, namely its stability, strong coordination ability and multiple opportunities for π–π interactions. Considering the important role of π–π interactions in affecting SCO behaviour, and in order to investigate systematically the relationship between SCO behaviour and noncovalent (π–π) interactions, the new tripodal ligand bis(pyridin-2-ylmethyl)(quinolin-2-ylmethyl)amine (dpqa), which possesses the possibility of stronger π–π interactions, has been introduced to construct new mononuclear iron(II) compounds with the typical FeN6 coordination octahedron (Li, Tao et al., 2008; Li, Yang et al., 2008). Herein, a new mononuclear iron(II) complex using this ligand, [Fe(NCS)2(dpqa)], (I), has been synthesized and structurally characterized. In this structure, a rigid FeN6 coordination octahedron for the FeII atom and much stronger π–π interactions are exhibited.
Compound (I) crystallizes in the monoclinic space group P21/c. Its asymmetric unit contains one complete C1-symmetric [Fe(NCS)2(dpqa)] molecule, as shown in Figs. 1 and 2. The neutral unit contains a tetradentate tripodal dpqa ligand, one FeII cation and two NCS- anions, where only a cis configuration of the NCS- groups is stable due to the geometric constraints of the tripodal ligand. The FeII centre is coordinated by six N atoms, four from the dpqa ligand and two from the NCS- groups. The equatorial plane of the coordination octahedron of the FeII cation is formed by two NCS- groups (N5 and N6), one pyridine N atom (N2) and aliphatic atom N4, while the axial positions are occupied by the pyridine ring associated with atom N1 and by the quinoline ring, with a dihedral angle of 16.19 (1)°. The average Fe—N bond length is 2.167 (3) Å, with a range of 2.050 (3)–2.273 (2) Å, corresponding to typical HS-FeII—N bond lengths (HS is high spin; [Reference for typical values?]). Here, the slightly longer Fe—N bond lengths [Fe—N3 = 2.273 (2) Å and Fe—N4 = 2.238 (2) Å] in the HS-FeII state are mostly caused by the steric strain originating from the substituted quinoline ring (Matouzenko et al., 1997); much shorter Fe—NNCS bonds have also been observed in other SCO compounds containing Fe—NNCS [Reference?]. At low temperature, the Σ parameter (Guionneau et al., 2001), which is used to quantify angular deviation from an ideal FeN6 coordination octahedron, is 84.7° for (I), implying high-spin states. The adjacent neutral units are further interconnected by strong πbenzene–πbenzene [3.806 (1) Å] interactions and intricate S···H—C interactions [S2···H2—C2 = 2.948 (2) Å and S2···H22—C22 = 2.898 (2) Å] to form the three-dimensional supramolecular structure, shown in Figs. 2 and 3. However, no S···S interactions are observed. Thermal stability and powder X-ray diffraction experiments were also carried out to validate the structure of the (I), shown in Figs. 5 and 6, respectively.
The magnetic properties of (I) were studied in the temperature range 2–300 K using a SQUID magnetometer, and a plot of χMT versus T under ambient air pressure is shown in Fig. 4. At 300 K, the χMT value for (I) is 3.35 cm3 mol-1 K, showing the HS state of the FeII cations. On cooling, the χMT values remain nearly constant down to 70 K. Below this temperature, χMT begins to decrease slowly and finally attains a value of 2.63 cm3 mol-1 K at 2 K. Thus, the temperature-dependent decrease of χMT in the low-temperature region indicates the presence of zero-field splitting of the HS-FeII ground state (Garcia et al., 2005). The variable-temperature magnetic properties of (I) thus indicate that there is no SCO behaviour observable in the temperature range 2–300 K. [Rephrasing OK?]
It is well known that the application of hydrostatic pressure can be an approach that effectively triggers and/or modifies the behaviour of SCO compounds. Therefore, the magnetic properties of (I) under hydrostatic pressure up to 10 kbar (1 bar = 100 000 Pa) were also investigated in the temperature range 2–300 K in order to observe a possible pressure-induced spin transition of the HS-FeII state, but still no noticeable change was observed. All of the FeII cations remain in the HS state throughout the observed temperature range.
Compared with the crystal structure and spin transition behaviour of [Fe(NCS)2(tpa)] (Li et al., 2010), in (I) the tripodal dpqa ligand plays a vital role in affecting a change in the HS state. In other mononuclear iron compounds, such as [Fe(NCS)2(tpa)], the Fe—N(aliphatic) bond is usually longer than the Fe—N(pyridine) distances. However, in (I) the Fe—N(quinoline) bond is longer than the others, which might be caused by steric repulsion between the thiocyanate ligand and atom H14 of the quinoline ring. Thus, a long Fe—N bond would stablize the HS iron state, but not the low-spin states that exhibit shorter Fe—N bond lenghths. Therefore, the arm of the substituted quinoline ring not only facilitates the formation of π–π interactions but also tends to decrease the ligand field and elongate the Fe—N bond due to the supervenient steric hindrance. As a result, the rigid FeN6 octahedron of the FeII cations and the dense structure type of (I) are stabilized over the complete temperature range, which could well explain the absence of a spin transition of the HS-FeII state either under hydrostatic pressure or thermal changes.
In summary, we have synthesized a new compound, (I), and structurally characterized it by X-ray crystallography. The crystal structure of (I) is stabilized by π–π supramolecular interactions and thus favours a highly co-operative SCO behaviour. No change in the spin state of (I) could be observed. Even the typical FeN6 coordination octahedron necessary for SCO behaviour is present, and it is not affected by any kind of external perturbation (temperature or pressure). The steric hindrance originating from the substituted quinolinate ring of dpqa and the supervenient stiffness of the FeN6 octahedron, compared with the corresponding observations in tpa, must play an important role in elongating the Fe—N bonds, decreasing the intensity of the ligand field and stabilizing the HS state of the FeII cations under any external stimulus. [Rephrasing OK?]