Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103008734/fg1690sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103008734/fg1690Isup2.hkl |
CCDC reference: 214372
All manipulations were carried out under nitrogen using a double manifold vacuum line, Schlenkware, and cannula techniques. Tetrahydrofuran (THF) and hexane were distilled over sodium/benzophenone and dichloromethane over CaH2. 4-Methylpiperidine (Aldrich) was freshly distilled over CaH2 under nitrogen prior to use. H2TPP was synthesized using published procedures (Barnett et al., 1975). [Fe(TPP)Cl] was prepared by metallation of H2TPP with anhydrous iron(II) chloride in refluxing dimethylformamide (Adler et al., 1970). Silver perchlorate (Aldrich) was used as received. To [Fe(TPP)Cl] (156.3 mg, 0.222 mmol) and silver perchlorate (99.8 mg, 0.481 mmol) in a 100 ml two-necked round-bottomed flask under nitrogen was added 30 ml of freshly distilled THF. The solution was allowed to stir for ~12 h at room temperature. The solvent was removed in vacuo and the red–brown solid redissolved in dichloromethane (ca 30 ml). The solution was cannula-filtered under nitrogen into a dry 100 ml two-necked round-bottomed flask containing 4-methylpiperidine (2.83 ml, 23.9 mmol). After swirling the solution for 10 min, the color changed from red–brown to deep red, consistent with reduction of the metal to the ferrous state (Castro et al., 1986). The solution was transferred in ~5 ml aliquots into Schlenk tubes and each aliquot layered with hexane; X-ray quality crystals were observed after 6 d. The deep-red crystals of (I) were collected by filtration and washed with 10° ethanol in hexane to remove colorless crystals of 4-methylpiperidine. Isolated yield: 28 mg, 15°. Analysis calculated for C56H54FeN6: C 77.59, H 6.28, N 9.69%; found: C 77.2, H 5.96, N 9.29%. AM1 geometry optimization calculations on Pip and 4-MePip were carried out with the default singlet-state parameters in HYPERCHEM 6.03 (Hypercube, 2000).
Molecule (I) crystallized as deep-red rhombs in the triclinic crystal system (space group P1). A difference Fourier calculation after refinement of all non-H atoms anisotropically located over 80° of the H atoms in the molecule, including the unique H atom appended to amine atom N3. This H atom (H3) was refined isotropically with H—N—C and H—N—Fe angle restraints (SHELXL97 DANG method; Sheldrick, 1997) and a distance restraint of 0.87 (2) Å (SHELXL97 DFIX method) to ensure chemically feasible values for these parameters (Byrn et al., 1991). All other H atoms were refined using the standard riding model of SHELXL97.
Data collection: CAD-4-PC Software (Enraf-Nonius, 1992); cell refinement: CAD-4-PC Software; data reduction: PROFIT (Streltsov & Zavodnik, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
[Fe(C6H12N)2(C50H30N4)] | Z = 1 |
Mr = 866.9 | F(000) = 458 |
Triclinic, P1 | Dx = 1.256 Mg m−3 |
a = 10.3189 (14) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 11.2427 (17) Å | Cell parameters from 25 reflections |
c = 11.8631 (15) Å | θ = 2–12° |
α = 93.077 (12)° | µ = 0.37 mm−1 |
β = 111.112 (11)° | T = 296 K |
γ = 113.483 (12)° | Rhomb, deep red |
V = 1145.8 (3) Å3 | 0.54 × 0.31 × 0.23 mm |
Enraf-Nonius CAD-4 diffractometer | θmax = 24.0°, θmin = 2.0° |
non–profiled ω/2θ scans | h = −2→11 |
4719 measured reflections | k = −12→12 |
3593 independent reflections | l = −13→13 |
3317 reflections with I > 2σ(I) | 3 standard reflections every 100 reflections |
Rint = 0.010 | intensity decay: 2% |
Refinement on F2 | 4 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.038 | w = 1/[σ2(Fo2) + (0.0561P)2 + 0.6693P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.107 | (Δ/σ)max = 0.001 |
S = 1.06 | Δρmax = 0.52 e Å−3 |
3593 reflections | Δρmin = −0.41 e Å−3 |
290 parameters |
[Fe(C6H12N)2(C50H30N4)] | γ = 113.483 (12)° |
Mr = 866.9 | V = 1145.8 (3) Å3 |
Triclinic, P1 | Z = 1 |
a = 10.3189 (14) Å | Mo Kα radiation |
b = 11.2427 (17) Å | µ = 0.37 mm−1 |
c = 11.8631 (15) Å | T = 296 K |
α = 93.077 (12)° | 0.54 × 0.31 × 0.23 mm |
β = 111.112 (11)° |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.010 |
4719 measured reflections | θmax = 24.0° |
3593 independent reflections | 3 standard reflections every 100 reflections |
3317 reflections with I > 2σ(I) | intensity decay: 2% |
R[F2 > 2σ(F2)] = 0.038 | 4 restraints |
wR(F2) = 0.107 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.52 e Å−3 |
3593 reflections | Δρmin = −0.41 e Å−3 |
290 parameters |
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. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) − 4.9758 (0.0055) x − 5.0976 (0.0044) y + 9.4729 (0.0031) z = 0.0608 (0.0014) * 0.0562 (0.0016) N1 * −0.0263 (0.0016) N2 * −0.0025 (0.0017) C1A * 0.0426 (0.0020) C2A * −0.0219 (0.0020) C3A * 0.0066 (0.0019) C4A * −0.0414 (0.0020) C1B * −0.0085 (0.0020) C2B * −0.0018 (0.0019) C3B * 0.0218 (0.0020) C4B * −0.0058 (0.0019) C1M * −0.0189 (0.0015) C2M −0.0608 (0.0014) Fe Rms deviation of fitted atoms = 0.0272 − 9.4244 (0.0049) x + 2.5503 (0.0122) y + 0.2042 (0.0133) z = 0.0809 (0.0067) Angle to previous plane (with approximate e.s.d.) = 69.63 (0.07) * −0.0047 (0.0017) C21 * 0.0013 (0.0018) C22 * 0.0027 (0.0020) C23 * −0.0032 (0.0020) C24 * −0.0003 (0.0021) C25 * 0.0043 (0.0019) C26 Rms deviation of fitted atoms = 0.0031 Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) − 4.9758 (0.0055) x − 5.0976 (0.0044) y + 9.4729 (0.0031) z = 0.0608 (0.0014) * 0.0562 (0.0016) N1 * −0.0263 (0.0016) N2 * −0.0025 (0.0017) C1A * 0.0426 (0.0020) C2A * −0.0219 (0.0020) C3A * 0.0066 (0.0019) C4A * −0.0414 (0.0020) C1B * −0.0085 (0.0020) C2B * −0.0018 (0.0019) C3B * 0.0218 (0.0020) C4B * −0.0058 (0.0019) C1M * −0.0189 (0.0015) C2M −0.0608 (0.0014) Fe Rms deviation of fitted atoms = 0.0272 3.4760 (0.0108) x − 9.1050 (0.0079) y − 5.8755 (0.0125) z = 0.0012 (0.0068) Angle to previous plane (with approximate e.s.d.) = 87.12 (0.06) * −0.0031 (0.0017) C11 * 0.0013 (0.0021) C12 * 0.0014 (0.0022) C13 * −0.0023 (0.0020) C14 * 0.0004 (0.0020) C15 * 0.0023 (0.0018) C16 Rms deviation of fitted atoms = 0.0020 |
x | y | z | Uiso*/Ueq | ||
Fe | 0 | 0 | 0 | 0.03121 (15) | |
N1 | 0.17121 (19) | 0.11410 (17) | 0.16368 (15) | 0.0345 (4) | |
N2 | 0.10706 (19) | −0.11295 (17) | −0.00090 (16) | 0.0342 (4) | |
N3 | 0.1210 (2) | 0.1200 (2) | −0.09392 (18) | 0.0449 (5) | |
C1A | 0.1888 (2) | 0.2289 (2) | 0.22855 (19) | 0.0371 (5) | |
C2A | 0.3067 (2) | 0.1041 (2) | 0.22802 (19) | 0.0367 (5) | |
C3A | 0.2505 (2) | −0.0935 (2) | 0.0854 (2) | 0.0370 (5) | |
C4A | 0.0540 (2) | −0.2275 (2) | −0.08696 (19) | 0.0366 (5) | |
C1B | 0.3362 (3) | 0.2902 (2) | 0.3348 (2) | 0.0462 (6) | |
H1B | 0.3747 | 0.3684 | 0.3929 | 0.055* | |
C2B | 0.4076 (3) | 0.2136 (2) | 0.3346 (2) | 0.0450 (5) | |
H2B | 0.5048 | 0.2286 | 0.3928 | 0.054* | |
C3B | 0.2866 (3) | −0.1965 (2) | 0.0510 (2) | 0.0450 (5) | |
H3B | 0.3768 | −0.2046 | 0.0937 | 0.054* | |
C4B | 0.1662 (3) | −0.2793 (2) | −0.0543 (2) | 0.0455 (5) | |
H4B | 0.1572 | −0.3556 | −0.0977 | 0.055* | |
C1M | 0.3456 (2) | 0.0084 (2) | 0.19183 (19) | 0.0363 (5) | |
C2M | −0.0851 (2) | −0.2843 (2) | −0.1932 (2) | 0.0375 (5) | |
C11 | 0.5046 (2) | 0.0203 (2) | 0.2674 (2) | 0.0371 (5) | |
C12 | 0.6248 (3) | 0.0872 (3) | 0.2340 (2) | 0.0584 (7) | |
H12 | 0.6062 | 0.1243 | 0.1651 | 0.07* | |
C13 | 0.7717 (3) | 0.1001 (3) | 0.3010 (3) | 0.0664 (8) | |
H13 | 0.8511 | 0.1456 | 0.2769 | 0.08* | |
C14 | 0.8015 (3) | 0.0469 (3) | 0.4017 (3) | 0.0588 (7) | |
H14 | 0.9009 | 0.0561 | 0.447 | 0.071* | |
C15 | 0.6846 (3) | −0.0201 (3) | 0.4358 (3) | 0.0598 (7) | |
H15 | 0.7042 | −0.057 | 0.5046 | 0.072* | |
C16 | 0.5366 (3) | −0.0336 (3) | 0.3688 (2) | 0.0495 (6) | |
H16 | 0.4576 | −0.0799 | 0.3931 | 0.059* | |
C21 | −0.1257 (2) | −0.4129 (2) | −0.2719 (2) | 0.0413 (5) | |
C22 | −0.1314 (3) | −0.4222 (3) | −0.3906 (2) | 0.0535 (6) | |
H22 | −0.1122 | −0.3474 | −0.4241 | 0.064* | |
C23 | −0.1658 (3) | −0.5432 (3) | −0.4599 (3) | 0.0674 (8) | |
H23 | −0.1696 | −0.5489 | −0.5396 | 0.081* | |
C24 | −0.1941 (3) | −0.6539 (3) | −0.4114 (3) | 0.0708 (9) | |
H24 | −0.2163 | −0.7345 | −0.4577 | 0.085* | |
C25 | −0.1896 (4) | −0.6455 (3) | −0.2952 (3) | 0.0710 (9) | |
H25 | −0.2091 | −0.7207 | −0.2622 | 0.085* | |
C26 | −0.1565 (3) | −0.5268 (2) | −0.2261 (3) | 0.0551 (6) | |
H26 | −0.1548 | −0.5231 | −0.147 | 0.066* | |
C31 | 0.0462 (3) | 0.1811 (4) | −0.1804 (3) | 0.0796 (10) | |
H31A | 0.0321 | 0.2457 | −0.1347 | 0.096* | |
H31B | −0.0564 | 0.113 | −0.2365 | 0.096* | |
C32 | 0.1291 (3) | 0.2505 (3) | −0.2575 (3) | 0.0725 (9) | |
H32A | 0.1188 | 0.1835 | −0.3196 | 0.087* | |
H32B | 0.0781 | 0.3011 | −0.3009 | 0.087* | |
C33 | 0.2973 (4) | 0.3420 (4) | −0.1845 (3) | 0.0824 (10) | |
H33 | 0.3004 | 0.4135 | −0.131 | 0.099* | |
C34 | 0.3725 (3) | 0.2756 (3) | −0.0991 (3) | 0.0709 (9) | |
H34A | 0.4746 | 0.3425 | −0.0408 | 0.085* | |
H34B | 0.3878 | 0.2137 | −0.1469 | 0.085* | |
C35 | 0.2882 (3) | 0.2012 (3) | −0.0267 (3) | 0.0649 (8) | |
H35A | 0.3337 | 0.1437 | 0.0081 | 0.078* | |
H35B | 0.3065 | 0.2653 | 0.0423 | 0.078* | |
C36 | 0.3830 (4) | 0.4109 (4) | −0.2591 (4) | 0.1014 (14) | |
H36A | 0.4887 | 0.4704 | −0.2043 | 0.152* | |
H36B | 0.3338 | 0.4605 | −0.3046 | 0.152* | |
H36C | 0.3811 | 0.3456 | −0.3161 | 0.152* | |
H3 | 0.106 (2) | 0.0394 (15) | −0.1464 (18) | 0.138 (16)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe | 0.0238 (2) | 0.0321 (2) | 0.0309 (2) | 0.01183 (17) | 0.00527 (17) | 0.00501 (17) |
N1 | 0.0271 (9) | 0.0346 (9) | 0.0344 (9) | 0.0126 (7) | 0.0067 (7) | 0.0061 (7) |
N2 | 0.0265 (9) | 0.0363 (9) | 0.0331 (9) | 0.0132 (7) | 0.0067 (7) | 0.0053 (7) |
N3 | 0.0312 (10) | 0.0503 (11) | 0.0459 (11) | 0.0163 (9) | 0.0096 (8) | 0.0172 (9) |
C1A | 0.0316 (11) | 0.0353 (11) | 0.0343 (11) | 0.0118 (9) | 0.0071 (9) | 0.0041 (9) |
C2A | 0.0272 (10) | 0.0385 (11) | 0.0350 (11) | 0.0125 (9) | 0.0056 (9) | 0.0080 (9) |
C3A | 0.0280 (11) | 0.0428 (12) | 0.0373 (11) | 0.0169 (9) | 0.0095 (9) | 0.0095 (9) |
C4A | 0.0335 (11) | 0.0373 (11) | 0.0368 (11) | 0.0162 (9) | 0.0123 (9) | 0.0072 (9) |
C1B | 0.0379 (12) | 0.0393 (12) | 0.0415 (13) | 0.0133 (10) | 0.0017 (10) | −0.0031 (10) |
C2B | 0.0305 (11) | 0.0456 (13) | 0.0407 (12) | 0.0144 (10) | −0.0004 (9) | 0.0026 (10) |
C3B | 0.0352 (12) | 0.0536 (14) | 0.0456 (13) | 0.0266 (11) | 0.0093 (10) | 0.0068 (11) |
C4B | 0.0428 (13) | 0.0466 (13) | 0.0462 (13) | 0.0258 (11) | 0.0123 (11) | 0.0034 (10) |
C1M | 0.0263 (10) | 0.0407 (11) | 0.0364 (11) | 0.0140 (9) | 0.0083 (9) | 0.0108 (9) |
C2M | 0.0348 (11) | 0.0343 (11) | 0.0373 (11) | 0.0133 (9) | 0.0115 (9) | 0.0051 (9) |
C11 | 0.0271 (11) | 0.0391 (11) | 0.0378 (11) | 0.0140 (9) | 0.0073 (9) | 0.0049 (9) |
C12 | 0.0373 (13) | 0.0772 (18) | 0.0534 (15) | 0.0203 (13) | 0.0158 (12) | 0.0276 (14) |
C13 | 0.0321 (13) | 0.087 (2) | 0.0690 (18) | 0.0178 (14) | 0.0203 (13) | 0.0150 (16) |
C14 | 0.0333 (13) | 0.0716 (17) | 0.0576 (16) | 0.0284 (13) | 0.0009 (12) | −0.0017 (13) |
C15 | 0.0512 (16) | 0.0682 (17) | 0.0507 (15) | 0.0319 (14) | 0.0050 (12) | 0.0188 (13) |
C16 | 0.0359 (12) | 0.0573 (15) | 0.0471 (14) | 0.0175 (11) | 0.0118 (11) | 0.0167 (11) |
C21 | 0.0308 (11) | 0.0395 (12) | 0.0430 (12) | 0.0147 (9) | 0.0066 (9) | 0.0013 (10) |
C22 | 0.0489 (14) | 0.0504 (14) | 0.0466 (14) | 0.0165 (12) | 0.0125 (11) | −0.0001 (11) |
C23 | 0.0532 (16) | 0.078 (2) | 0.0534 (16) | 0.0267 (15) | 0.0108 (13) | −0.0152 (15) |
C24 | 0.0530 (16) | 0.0525 (17) | 0.081 (2) | 0.0295 (14) | −0.0015 (15) | −0.0184 (15) |
C25 | 0.0656 (19) | 0.0426 (15) | 0.081 (2) | 0.0244 (14) | 0.0066 (16) | 0.0040 (14) |
C26 | 0.0542 (15) | 0.0429 (14) | 0.0568 (15) | 0.0200 (12) | 0.0138 (12) | 0.0078 (11) |
C31 | 0.0444 (16) | 0.107 (3) | 0.086 (2) | 0.0314 (17) | 0.0225 (15) | 0.060 (2) |
C32 | 0.0524 (17) | 0.095 (2) | 0.0716 (19) | 0.0337 (16) | 0.0230 (15) | 0.0476 (18) |
C33 | 0.0595 (19) | 0.089 (2) | 0.093 (2) | 0.0232 (17) | 0.0334 (18) | 0.050 (2) |
C34 | 0.0386 (14) | 0.087 (2) | 0.078 (2) | 0.0203 (14) | 0.0203 (14) | 0.0389 (17) |
C35 | 0.0360 (14) | 0.0771 (19) | 0.0609 (17) | 0.0128 (13) | 0.0104 (12) | 0.0296 (15) |
C36 | 0.072 (2) | 0.123 (3) | 0.108 (3) | 0.031 (2) | 0.045 (2) | 0.073 (3) |
Fe—N2i | 1.9895 (17) | C13—H13 | 0.93 |
Fe—N2 | 1.9895 (17) | C14—C15 | 1.359 (4) |
Fe—N1 | 1.9981 (17) | C14—H14 | 0.93 |
Fe—N1i | 1.9981 (17) | C15—C16 | 1.384 (4) |
Fe—N3i | 2.1074 (19) | C15—H15 | 0.93 |
Fe—N3 | 2.1074 (19) | C16—H16 | 0.93 |
N1—C1A | 1.378 (3) | C21—C26 | 1.383 (3) |
N1—C2A | 1.384 (3) | C21—C22 | 1.385 (3) |
N2—C4A | 1.377 (3) | C22—C23 | 1.392 (4) |
N2—C3A | 1.384 (3) | C22—H22 | 0.93 |
N3—C31 | 1.431 (3) | C23—C24 | 1.369 (5) |
N3—C35 | 1.457 (3) | C23—H23 | 0.93 |
N3—H3 | 0.996 (14) | C24—C25 | 1.360 (5) |
C1A—C2Mi | 1.395 (3) | C24—H24 | 0.93 |
C1A—C1B | 1.438 (3) | C25—C26 | 1.373 (4) |
C2A—C1M | 1.386 (3) | C25—H25 | 0.93 |
C2A—C2B | 1.436 (3) | C26—H26 | 0.93 |
C3A—C1M | 1.388 (3) | C31—C32 | 1.512 (4) |
C3A—C3B | 1.430 (3) | C31—H31A | 0.97 |
C4A—C2M | 1.392 (3) | C31—H31B | 0.97 |
C4A—C4B | 1.438 (3) | C32—C33 | 1.490 (4) |
C1B—C2B | 1.339 (3) | C32—H32A | 0.97 |
C1B—H1B | 0.93 | C32—H32B | 0.97 |
C2B—H2B | 0.93 | C33—C34 | 1.472 (4) |
C3B—C4B | 1.344 (3) | C33—C36 | 1.501 (4) |
C3B—H3B | 0.93 | C33—H33 | 0.98 |
C4B—H4B | 0.93 | C34—C35 | 1.494 (4) |
C1M—C11 | 1.506 (3) | C34—H34A | 0.97 |
C2M—C1Ai | 1.395 (3) | C34—H34B | 0.97 |
C2M—C21 | 1.492 (3) | C35—H35A | 0.97 |
C11—C16 | 1.370 (3) | C35—H35B | 0.97 |
C11—C12 | 1.379 (3) | C36—H36A | 0.96 |
C12—C13 | 1.377 (4) | C36—H36B | 0.96 |
C12—H12 | 0.93 | C36—H36C | 0.96 |
C13—C14 | 1.356 (4) | ||
N2i—Fe—N2 | 180 | C12—C13—H13 | 119.7 |
N2i—Fe—N1 | 89.98 (7) | C13—C14—C15 | 119.3 (2) |
N2—Fe—N1 | 90.02 (7) | C13—C14—H14 | 120.3 |
N2i—Fe—N1i | 90.02 (7) | C15—C14—H14 | 120.3 |
N2—Fe—N1i | 89.98 (7) | C14—C15—C16 | 120.5 (2) |
N1—Fe—N1i | 180 | C14—C15—H15 | 119.8 |
N2i—Fe—N3i | 88.80 (7) | C16—C15—H15 | 119.8 |
N2—Fe—N3i | 91.20 (7) | C11—C16—C15 | 121.0 (2) |
N1—Fe—N3i | 89.41 (7) | C11—C16—H16 | 119.5 |
N1i—Fe—N3i | 90.59 (7) | C15—C16—H16 | 119.5 |
N2i—Fe—N3 | 91.20 (7) | C26—C21—C22 | 118.0 (2) |
N2—Fe—N3 | 88.80 (7) | C26—C21—C2M | 120.1 (2) |
N1—Fe—N3 | 90.59 (7) | C22—C21—C2M | 121.9 (2) |
N1i—Fe—N3 | 89.41 (7) | C21—C22—C23 | 120.2 (3) |
N3i—Fe—N3 | 180 | C21—C22—H22 | 119.9 |
C1A—N1—C2A | 105.22 (16) | C23—C22—H22 | 119.9 |
C1A—N1—Fe | 127.24 (14) | C24—C23—C22 | 120.4 (3) |
C2A—N1—Fe | 127.09 (14) | C24—C23—H23 | 119.8 |
C4A—N2—C3A | 105.20 (17) | C22—C23—H23 | 119.8 |
C4A—N2—Fe | 127.46 (14) | C25—C24—C23 | 119.6 (3) |
C3A—N2—Fe | 127.34 (14) | C25—C24—H24 | 120.2 |
C31—N3—C35 | 113.6 (2) | C23—C24—H24 | 120.2 |
C31—N3—Fe | 118.69 (16) | C24—C25—C26 | 120.6 (3) |
C35—N3—Fe | 118.09 (15) | C24—C25—H25 | 119.7 |
C31—N3—H3 | 104.5 (12) | C26—C25—H25 | 119.7 |
C35—N3—H3 | 106.4 (12) | C25—C26—C21 | 121.2 (3) |
Fe—N3—H3 | 90.6 (11) | C25—C26—H26 | 119.4 |
N1—C1A—C2Mi | 125.64 (19) | C21—C26—H26 | 119.4 |
N1—C1A—C1B | 110.21 (19) | N3—C31—C32 | 116.3 (2) |
C2Mi—C1A—C1B | 124.0 (2) | N3—C31—H31A | 108.2 |
N1—C2A—C1M | 125.68 (19) | C32—C31—H31A | 108.2 |
N1—C2A—C2B | 109.93 (19) | N3—C31—H31B | 108.2 |
C1M—C2A—C2B | 124.25 (19) | C32—C31—H31B | 108.2 |
N2—C3A—C1M | 125.68 (19) | H31A—C31—H31B | 107.4 |
N2—C3A—C3B | 110.11 (19) | C33—C32—C31 | 114.2 (3) |
C1M—C3A—C3B | 124.2 (2) | C33—C32—H32A | 108.7 |
N2—C4A—C2M | 125.77 (19) | C31—C32—H32A | 108.7 |
N2—C4A—C4B | 110.23 (18) | C33—C32—H32B | 108.7 |
C2M—C4A—C4B | 124.0 (2) | C31—C32—H32B | 108.7 |
C2B—C1B—C1A | 107.2 (2) | H32A—C32—H32B | 107.6 |
C2B—C1B—H1B | 126.4 | C34—C33—C32 | 110.2 (3) |
C1A—C1B—H1B | 126.4 | C34—C33—C36 | 114.6 (3) |
C1B—C2B—C2A | 107.45 (19) | C32—C33—C36 | 115.3 (3) |
C1B—C2B—H2B | 126.3 | C34—C33—H33 | 105.2 |
C2A—C2B—H2B | 126.3 | C32—C33—H33 | 105.2 |
C4B—C3B—C3A | 107.46 (19) | C36—C33—H33 | 105.2 |
C4B—C3B—H3B | 126.3 | C33—C34—C35 | 116.4 (3) |
C3A—C3B—H3B | 126.3 | C33—C34—H34A | 108.2 |
C3B—C4B—C4A | 107.0 (2) | C35—C34—H34A | 108.2 |
C3B—C4B—H4B | 126.5 | C33—C34—H34B | 108.2 |
C4A—C4B—H4B | 126.5 | C35—C34—H34B | 108.2 |
C2A—C1M—C3A | 124.01 (19) | H34A—C34—H34B | 107.3 |
C2A—C1M—C11 | 118.34 (19) | N3—C35—C34 | 116.7 (2) |
C3A—C1M—C11 | 117.52 (19) | N3—C35—H35A | 108.1 |
C4A—C2M—C1Ai | 123.7 (2) | C34—C35—H35A | 108.1 |
C4A—C2M—C21 | 117.66 (19) | N3—C35—H35B | 108.1 |
C1Ai—C2M—C21 | 118.63 (19) | C34—C35—H35B | 108.1 |
C16—C11—C12 | 117.6 (2) | H35A—C35—H35B | 107.3 |
C16—C11—C1M | 122.9 (2) | C33—C36—H36A | 109.5 |
C12—C11—C1M | 119.5 (2) | C33—C36—H36B | 109.5 |
C13—C12—C11 | 121.1 (2) | H36A—C36—H36B | 109.5 |
C13—C12—H12 | 119.4 | C33—C36—H36C | 109.5 |
C11—C12—H12 | 119.4 | H36A—C36—H36C | 109.5 |
C14—C13—C12 | 120.5 (2) | H36B—C36—H36C | 109.5 |
C14—C13—H13 | 119.7 | ||
N2i—Fe—N1—C1A | −4.63 (18) | N2—C4A—C4B—C3B | 0.0 (3) |
N2—Fe—N1—C1A | 175.37 (18) | C2M—C4A—C4B—C3B | 177.9 (2) |
N3i—Fe—N1—C1A | −93.43 (18) | N1—C2A—C1M—C3A | −1.3 (4) |
N3—Fe—N1—C1A | 86.57 (18) | C2B—C2A—C1M—C3A | −176.7 (2) |
N2i—Fe—N1—C2A | −175.76 (17) | N1—C2A—C1M—C11 | 174.40 (19) |
N2—Fe—N1—C2A | 4.24 (17) | C2B—C2A—C1M—C11 | −1.0 (3) |
N3i—Fe—N1—C2A | 95.44 (17) | N2—C3A—C1M—C2A | 1.7 (4) |
N3—Fe—N1—C2A | −84.56 (17) | C3B—C3A—C1M—C2A | −176.6 (2) |
N1—Fe—N2—C4A | 175.68 (18) | N2—C3A—C1M—C11 | −174.03 (19) |
N1i—Fe—N2—C4A | −4.32 (18) | C3B—C3A—C1M—C11 | 7.7 (3) |
N3i—Fe—N2—C4A | 86.27 (18) | N2—C4A—C2M—C1Ai | 1.8 (4) |
N3—Fe—N2—C4A | −93.73 (18) | C4B—C4A—C2M—C1Ai | −175.8 (2) |
N1—Fe—N2—C3A | −3.90 (17) | N2—C4A—C2M—C21 | −177.0 (2) |
N1i—Fe—N2—C3A | 176.10 (17) | C4B—C4A—C2M—C21 | 5.4 (3) |
N3i—Fe—N2—C3A | −93.31 (18) | C2A—C1M—C11—C16 | 87.9 (3) |
N3—Fe—N2—C3A | 86.69 (18) | C3A—C1M—C11—C16 | −96.1 (3) |
N2i—Fe—N3—C31 | −32.8 (2) | C2A—C1M—C11—C12 | −92.6 (3) |
N2—Fe—N3—C31 | 147.2 (2) | C3A—C1M—C11—C12 | 83.4 (3) |
N1—Fe—N3—C31 | −122.8 (2) | C16—C11—C12—C13 | −0.5 (4) |
N1i—Fe—N3—C31 | 57.2 (2) | C1M—C11—C12—C13 | 180.0 (3) |
N2i—Fe—N3—C35 | 111.2 (2) | C11—C12—C13—C14 | 0.0 (5) |
N2—Fe—N3—C35 | −68.8 (2) | C12—C13—C14—C15 | 0.3 (5) |
N1—Fe—N3—C35 | 21.2 (2) | C13—C14—C15—C16 | −0.2 (4) |
N1i—Fe—N3—C35 | −158.8 (2) | C12—C11—C16—C15 | 0.6 (4) |
C2A—N1—C1A—C2Mi | 175.4 (2) | C1M—C11—C16—C15 | −179.9 (2) |
Fe—N1—C1A—C2Mi | 2.8 (3) | C14—C15—C16—C11 | −0.2 (4) |
C2A—N1—C1A—C1B | −0.5 (2) | C4A—C2M—C21—C26 | 65.8 (3) |
Fe—N1—C1A—C1B | −173.16 (15) | C1Ai—C2M—C21—C26 | −113.1 (3) |
C1A—N1—C2A—C1M | −175.3 (2) | C4A—C2M—C21—C22 | −113.1 (3) |
Fe—N1—C2A—C1M | −2.6 (3) | C1Ai—C2M—C21—C22 | 68.0 (3) |
C1A—N1—C2A—C2B | 0.7 (2) | C26—C21—C22—C23 | −0.6 (4) |
Fe—N1—C2A—C2B | 173.39 (15) | C2M—C21—C22—C23 | 178.3 (2) |
C4A—N2—C3A—C1M | −177.8 (2) | C21—C22—C23—C24 | −0.1 (4) |
Fe—N2—C3A—C1M | 1.8 (3) | C22—C23—C24—C25 | 0.5 (4) |
C4A—N2—C3A—C3B | 0.7 (2) | C23—C24—C25—C26 | −0.2 (5) |
Fe—N2—C3A—C3B | −179.68 (15) | C24—C25—C26—C21 | −0.5 (4) |
C3A—N2—C4A—C2M | −178.3 (2) | C22—C21—C26—C25 | 0.9 (4) |
Fe—N2—C4A—C2M | 2.1 (3) | C2M—C21—C26—C25 | −178.0 (2) |
C3A—N2—C4A—C4B | −0.4 (2) | C35—N3—C31—C32 | 42.4 (4) |
Fe—N2—C4A—C4B | 179.94 (15) | Fe—N3—C31—C32 | −172.0 (2) |
N1—C1A—C1B—C2B | 0.1 (3) | N3—C31—C32—C33 | −48.2 (5) |
C2Mi—C1A—C1B—C2B | −175.9 (2) | C31—C32—C33—C34 | 47.6 (5) |
C1A—C1B—C2B—C2A | 0.4 (3) | C31—C32—C33—C36 | 179.2 (3) |
N1—C2A—C2B—C1B | −0.7 (3) | C32—C33—C34—C35 | −45.6 (5) |
C1M—C2A—C2B—C1B | 175.3 (2) | C36—C33—C34—C35 | −177.7 (3) |
N2—C3A—C3B—C4B | −0.7 (3) | C31—N3—C35—C34 | −39.6 (4) |
C1M—C3A—C3B—C4B | 177.8 (2) | Fe—N3—C35—C34 | 174.6 (2) |
C3A—C3B—C4B—C4A | 0.4 (3) | C33—C34—C35—N3 | 43.0 (5) |
Symmetry code: (i) −x, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | [Fe(C6H12N)2(C50H30N4)] |
Mr | 866.9 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 10.3189 (14), 11.2427 (17), 11.8631 (15) |
α, β, γ (°) | 93.077 (12), 111.112 (11), 113.483 (12) |
V (Å3) | 1145.8 (3) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.37 |
Crystal size (mm) | 0.54 × 0.31 × 0.23 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4719, 3593, 3317 |
Rint | 0.010 |
θmax (°) | 24.0 |
(sin θ/λ)max (Å−1) | 0.572 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.107, 1.06 |
No. of reflections | 3593 |
No. of parameters | 290 |
No. of restraints | 4 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.52, −0.41 |
Computer programs: CAD-4-PC Software (Enraf-Nonius, 1992), CAD-4-PC Software, PROFIT (Streltsov & Zavodnik, 1989), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
Fe—N2 | 1.9895 (17) | N3—C31 | 1.431 (3) |
Fe—N1 | 1.9981 (17) | N3—C35 | 1.457 (3) |
Fe—N3 | 2.1074 (19) | ||
N2—Fe—N1 | 90.02 (7) | C31—N3—C35 | 113.6 (2) |
N2—Fe—N3i | 91.20 (7) | C31—N3—Fe | 118.69 (16) |
N1—Fe—N3i | 89.41 (7) | C35—N3—Fe | 118.09 (15) |
N3—Fe—N1—C1A | 86.57 (18) | N1—Fe—N3—C31 | −122.8 (2) |
N3—Fe—N1—C2A | −84.56 (17) | N2—Fe—N3—C35 | −68.8 (2) |
N3—Fe—N2—C4A | −93.73 (18) | N1—Fe—N3—C35 | 21.2 (2) |
N3—Fe—N2—C3A | 86.69 (18) | Fe—N3—C31—C32 | −172.0 (2) |
N2—Fe—N3—C31 | 147.2 (2) | Fe—N3—C35—C34 | 174.6 (2) |
Symmetry code: (i) −x, −y, −z. |
We have been investigating the structures, conformations, and electronic properties of bis(alkylamine) derivatives of low-spin iron(II) porphyrinates (Munro et al., 1999) as part of an effort to understand the unusual coordination chemistry displayed by plant cytochrome f, in which one of the axial ligands is the N-terminal amino group of the protein (Martinez et al., 1996). One of the objectives of the present investigation was to synthesize and structurally characterize a non-planar bis(amine) derivative of a ferrous porphyrin for two reasons: (i) the heme group in cytochrome f is non-planar and (ii) it is now widely recognized that non-planar conformations of porphyrins (Shelnutt, 2000) modulate the electronic structure (Barkigia et al., 1999) of the heme iron and thus the reactivity of the metal center in heme proteins.
We previously used molecular mechanics (MM) simulations (Munro et al., 1999) to show that [Fe(TPP)(Pip)2], (II), could adopt three low-energy conformations: (i) a centrosymmetric structure with a planar porphyrin core conformation that matched the X-ray structure reported by Hoard's group in 1971 (Radonovich et al., 1972), (ii) a non-centrosymmetric structure with a planar porphyrin core conformation, and (iii) a non-planar conformation in which a staggered relative orientation of the axial piperidine ligands leads to a marked S4-ruffled porphyrin core conformation. The S4-ruffled conformation of (II) was predicted to be lowest in energy by ~6.7 kJ mol−1. Since there are relatively few crystallographically characterized iron(II) derivatives of tetraphenyl- and octaethylporphyrin that have non-planar porphyrin core conformations (Scheidt, 2000), and our MM simulations suggested that a non-planar conformation for (II) was in fact preferred on steric grounds, our strategy in this study was to build up some additional steric bulk on the axial ligands in the hope that crystal-packing constraints might favor crystallization of (I) in a non-centrosymmetric space group, or indeed at a general position in a centrosymmetric space group. Without crystallographically required inversion symmetry, the structure of (I) would, on conformational energy grounds, likely have an S4-ruffled porphyrin core conformation. Unfortunately, as we show in this paper, a single 4-methyl substituent on the piperidine ring in the case of (I) is not sufficiently bulky to change the centrosymmetric crystal packing that was previously observed for (II). There are, however, crystallographic indicators that suggest an increase in molecular strain attends packing of the more bulky axial ligands of (I) in the triclinic lattice. Compound (I), in fact, experiences significant axial (ax) compression that leads to a rather short unique Fe—Nax distance, a phenomenon that has probably been frequently overlooked as a significant cause of coordination group structural variance in model heme systems.
The reaction of a ferric porphyrin with an excess of a primary or secondary amine in a non-aqueous solvent results in one-electron reduction of the metal to the FeII state by a mechanism which involves initial deprotonation of the metal-bound N—H group by excess ligand in solution (Del Gaudio & La Mar, 1978; Castro et al., 1986). We previously made use of this redox process to synthesize and structurally characterize several [Fe(TPP)L2] derivatives, where L = butylamine, benzylamine, and 2-phenylethylamine (Munro et al., 1999). In the present study, excess 4-MePip was reacted with a labile FeIII complex, namely [Fe(TPP)(OClO3)], to ensure facile substitution of the anion by the secondary amine and thus complete reduction to the ferrous state. Reduction of the complex was confirmed by the dark-red color of the solution after the addition of the amine and the electronic spectrum of (I) under nitrogen, which was consistent with that reported for (II) (Del Gaudio & La Mar, 1978).
The X-ray crystal structure of (I) is shown in Fig. 1. The centrosymmetric structure exhibits an approximately planar porphyrin core conformation. The FeII state is confirmed by the absence of a counter anion (ClO4) in the lattice and the fact that H3 was cleanly located in a difference Fourier map. Importantly, this H atom refined well isotropically and its presence confirms that 4-MePip coordinates as the neutral amine. The axial 4-MePip ligands adopt a chair conformation and the mean planes taken through each 4-MePip ring are exactly eclipsed due to the crystallographically imposed symmetry. This is shown more clearly in Fig. 2, which is a view of the structure perpendicular to the N1—Fe—N2 plane. The Fe—NTPP distances differ by slightly more than 3σ [Fe—N1 = 1.998 (2) Å and Fe—N2 = 1.990 (2) Å]. We surmise that this in-plane coordination group asymmetry reflects the fact that the dihedral angles between each symmetry-unique porphyrin N atom and the closest 4-MePip α-carbon are non-equivalent [N1—Fe—N3—C35 = 21.2 (2)° and N2i—Fe—N3—C31 = 32.8 (2)°; symmetry code: (i) −x, −y, −z]. Evidently, the smaller repulsive steric interaction between N2i and C31 allows for a slightly shorter Fe—NTPP coordination distance than is the case for N1. Interestingly, although not statistically significant, the average Fe—NTPP distance for (I) [1.994 (6) Å] is slightly shorter than that reported by Hoard for the bis(piperidine) analogue (II) [2.004 (4) Å]. Average values for all other chemically unique bonds and angles of (I) are summarized in Fig. 3; these are in good agreement with those reported for (II) (Radonovich et al., 1972) and even better agreement with those of the toluene solvate [Fe(TPP)(Pip)2]·C7H8 (Byrn et al., 1991). The perpendicular displacements of each porphyrin core atom from the 24-atom mean plane of the macrocycle are also shown in Fig. 3. Since none of the displacements exceed 0.06 Å, the porphyrin conformation is essentially flat. Moreover, there is no real pattern or symmetry (e.g. D2 d-saddle or S4-ruffle distortion) evident from the atomic displacements shown in Fig. 3.
The unique axial coordination distance to the 4-MePip ligands, Fe—Nax, measures 2.107 (2) Å in compound (I) and is considerably shorter than that reported for (II) [2.127 (3) Å]. The statistically significant difference between the axial coordination distances (> 6σ) observed for (I) and (II) is noteworthy. AM1 geometry optimizations (Dewar & Thiel, 1977) and calculations of the charge distributions for the free ligands Pip and 4-MePip show that the nitrogen donors are equivalent both geometrically and electronically (charge = −0.298 e) in these two compounds. If the electronic structures of the axial ligand donor atoms are the same, then the shorter axial coordination distance for (I) can only be attributed to crystal-packing constraints, particularly since the metal ions are located at the same (special) positions in the unit cell in both cases (space group P1). In the case of (I), crystal packing (non-bonded contacts with the 4-Me groups of the axial ligands) would have to favor compression of the molecule along its principal axis to bring about the observed ~0.02 Å foreshortening of the Fe—Nax bonds. Interestingly, although the structure of [Fe(TPP)(Pip)2]·C7H8 is also centrosymmetric (space group P1), it displays a somewhat different crystal packing symmetry to both (I) and (II) and, importantly, an even shorter Fe—Nax bond distance of 2.092 Å (Byrn et al., 1991).
The packing symmetry and interactions for (I) are shown more clearly in Fig. 4, which depicts a stereoview of the unit cell. Since the FeII ions are located on special positions, there is a full molecule positioned at each corner of the unit cell that projects into the neighboring unit cells. The crystal symmetry and occupancy of the asymmetric unit requires that the porphyrin rings are tilted equivalently with respect to each of the unit cell axes such that the molecular packing places the molecule at [111] in close van der Waals contact with the molecule at [001] and those at the two flanking positions [101] and [011]. The crystal packing clearly demonstrates that, for example, the upper axial 4-MePip ligand of the molecule located at the cell origin [000] fits into a rather tight pocket created by the molecule at [110] and [001]. This is shown more clearly in the space-filling plot of Fig. 5. Although none of the intermolecular contacts is less than the sum of the van der Waals radii of the interacting atoms, there are several key contacts with the H atoms of the 4-MePip methyl group that are fully consistent with steric interactions being responsible for compression of the axial Fe—N distances in (I). Some of the more noteworthy contacts (Å) to pyrrole ring atoms include the following: C36···H1B(-x + 1, −y + 1, −z) 3.64, H36A···C1B(-x + 1, −y + 1, −z) 3.39, H36A···H1B(-x + 1, −y + 1, −z) 3.31, H36B···C1B(-x + 1, −y + 1, −z) 3.60, H36B···H1B(-x + 1, −y + 1, −z) 3.42 and H36C···H1B(-x + 1, −y + 1, −z) 3.61. There are also several contacts (Å) with neighboring phenyl groups that add to the steric congestion around the 4-MePip methyl group: C36···H22(-x, −y, −z − 1) 3.61, C36···H23(-x, −y, −z − 1) 3.51, H36B···C22(-x, −y, −z − 1) 3.36, H36B···H22(-x, −y, −z − 1) 3.02, H36B···C23(-x, −y, −z − 1) 3.12, H36B···H23(-x, −y, −z − 1) 2.56 and H36C···H22(-x, −y, −z − 1) 3.33.
Finally, inspection of the crystal packing for [Fe(TPP)(Pip)2]·C7H8 (Byrn et al., 1991) shows that the equatorial H atom at the 4-position of the axial Pip ligand points directly between the o- and m-H atoms of one of the phenyl groups of the neighboring porphyrin. Two short H···H contacts of 2.31 and 2.35 Å, respectively, are thus observed which may account for the marked compression of the Fe—Nax bonds in this compound. Collectively, the structural evidence strongly supports the notion that the Fe—Nax bond distances are critically dependent on the nature of the crystal packing in these ferrous porphyrin derivatives.