The title compound (H
2L), C
27H
28N
4O
2, is an asymmetric binucleating ligand with well defined soft (N
3O-donor) and hard (NO
2-donor) sides. H
2L was designed as a ligand for the preparation of heterodinuclear mixed-valence
MIII/
M′
II complexes which are models for heterobimetallic active sites of enzymes, principally calcineurin. The molecular structure of H
2L shows a spatial pre-organization of the donor groups for coordination. This conformation is stabilized by bifurcated intra- and intermolecular O—H
N hydrogen bonds involving both phenol groups. The intermolecular hydrogen bonds link molecules of H
2L into chains running parallel to the crystallographic
c axis.
Supporting information
CCDC reference: 638312
H2L was synthesized from the precursor compound
3-[N,N-di(2-pyridylmethyl)aminomethyl]-5-methylsalicylaldehyde
(bpmamff), which was prepared as described by Uozumi et al. (1998) by
nucleophilic substitution of bis(2-pyridylmethyl)amine in
3-chloromethyl-5-methylsalicylaldehyde.
A methanolic solution (Volume?) of 2-aminophenol (0.32 g, 2.9 mmol) was
added dropwise to a stirred solution of bpmamff (1.0 g, 2.9 mmol) in
methanol–tetrahydrofuran (1:1) (Volume?) and the mixture was left to
react for 30 min. A strong orange colour appeared progressively due to the
formation of the Schiff base. Reduction of the imine was performed by the
addition, in portions, of NaBH4 (0.11 g, 2.9 mmol) in an ice bath. The pH of
the medium was then carefully adjusted to 6.0–7.0 with 4M HCl, and the
solvent was evaporated to half of its initial volume. The solution was then
filtered to eliminate any undesirable precipitate. After a few hours, crystals
of (I) suitable for X-ray determination were isolated by filtration, washed
with small amounts of cold methanol and diethyl ether, and dried in
vacuo (yield 0.56 g, 44%; m.p. 416 K). Analysis, found: C 73.56, H 6.33, N
12.55%; calculated for C27H28N4O2: C 73.61, H 6.41, N 12.72%.
The phenol hydroxyl H atoms were found from ΔF maps and were then
refined as part of rigid rotating groups, with O—H fixed at 0.82 Å and
Uiso(H) = 1.5Ueq(O). The amine H atom was found in a
ΔF map and thereafter refined freely with N—H restrained to 0.86 (1) Å. The remaining H atoms were added in their geometrically calculated
positions and refined with C—H = 0.93 Å (0.96 Å for methyl groups) and
Uiso(H) = 1.2Ueq(C), with the H atoms on C5 being treated as
an idealized methyl group equally disordered over two orientations separated
by a rotation of 60°. The slightly high displacement parameters observed for
atoms N42, C43, C44, C45 and C46 indicate possible disorder of this aromatic
ring, but the ΔF peaks near C45 and C46 are small, and no valid
disorder model could be developed. We therefore accepted the ordered model
with high U values.
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: SET4 in CAD-4 EXPRESS; data reduction: HELENA (Spek, 1996); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.
2-[
N,
N-Bis(2-pyridylmethyl)aminomethyl]-6-[
N-(2-hydroxyanilino)methyl]- 4-methylphenol
top
Crystal data top
C27H28N4O2 | F(000) = 936 |
Mr = 440.53 | Dx = 1.233 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 12.651 (1) Å | Cell parameters from 25 reflections |
b = 21.071 (5) Å | θ = 6.7–13.7° |
c = 9.262 (1) Å | µ = 0.08 mm−1 |
β = 106.09 (1)° | T = 293 K |
V = 2372.2 (7) Å3 | Irregular block, pale yellow |
Z = 4 | 0.46 × 0.30 × 0.23 mm |
Data collection top
Enraf–Nonius CAD-4 diffractometer | Rint = 0.039 |
Radiation source: fine-focus sealed tube | θmax = 25.1°, θmin = 1.7° |
Graphite monochromator | h = −15→0 |
ω/2θ scans | k = 0→25 |
4338 measured reflections | l = −10→11 |
4142 independent reflections | 3 standard reflections every 200 reflections |
2138 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.053 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.155 | w = 1/[σ2(Fo2) + (0.056P)2 + 0.792P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
4142 reflections | Δρmax = 0.23 e Å−3 |
305 parameters | Δρmin = −0.18 e Å−3 |
1 restraint | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0072 (11) |
Crystal data top
C27H28N4O2 | V = 2372.2 (7) Å3 |
Mr = 440.53 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 12.651 (1) Å | µ = 0.08 mm−1 |
b = 21.071 (5) Å | T = 293 K |
c = 9.262 (1) Å | 0.46 × 0.30 × 0.23 mm |
β = 106.09 (1)° | |
Data collection top
Enraf–Nonius CAD-4 diffractometer | Rint = 0.039 |
4338 measured reflections | 3 standard reflections every 200 reflections |
4142 independent reflections | intensity decay: 1% |
2138 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.053 | 1 restraint |
wR(F2) = 0.155 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.23 e Å−3 |
4142 reflections | Δρmin = −0.18 e Å−3 |
305 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
O1 | 0.68229 (18) | 0.12805 (9) | 0.7041 (3) | 0.0599 (6) | |
H1O | 0.7370 | 0.1234 | 0.6741 | 0.090* | |
O20 | 0.47861 (18) | 0.24240 (11) | 0.5095 (2) | 0.0643 (7) | |
H20O | 0.4700 | 0.2585 | 0.4264 | 0.096* | |
N1 | 0.4876 (2) | 0.18120 (13) | 0.7641 (3) | 0.0509 (7) | |
H1N | 0.5396 (17) | 0.1931 (13) | 0.728 (3) | 0.050 (9)* | |
N4 | 0.84061 (19) | 0.05914 (12) | 0.6194 (3) | 0.0485 (7) | |
N32 | 1.1004 (3) | 0.03344 (17) | 0.8827 (4) | 0.0802 (10) | |
N42 | 0.8029 (3) | 0.17139 (15) | 0.4450 (3) | 0.0786 (10) | |
C2 | 0.5232 (3) | 0.12487 (15) | 0.8595 (3) | 0.0553 (9) | |
H2A | 0.4649 | 0.1134 | 0.9040 | 0.066* | |
H2B | 0.5869 | 0.1365 | 0.9409 | 0.066* | |
C3 | 0.7420 (2) | 0.02186 (15) | 0.5442 (3) | 0.0506 (8) | |
H3A | 0.7644 | −0.0205 | 0.5241 | 0.061* | |
H3B | 0.7059 | 0.0415 | 0.4485 | 0.061* | |
C5 | 0.4781 (3) | −0.10945 (16) | 0.7337 (4) | 0.0635 (10) | |
H5A | 0.4261 | −0.1052 | 0.7914 | 0.076* | 0.50 |
H5B | 0.5336 | −0.1396 | 0.7814 | 0.076* | 0.50 |
H5C | 0.4408 | −0.1239 | 0.6343 | 0.076* | 0.50 |
H5D | 0.5076 | −0.1406 | 0.6800 | 0.076* | 0.50 |
H5E | 0.4000 | −0.1062 | 0.6900 | 0.076* | 0.50 |
H5F | 0.4929 | −0.1219 | 0.8371 | 0.076* | 0.50 |
C11 | 0.5522 (2) | 0.06693 (14) | 0.7822 (3) | 0.0448 (7) | |
C12 | 0.6327 (2) | 0.07022 (14) | 0.7071 (3) | 0.0450 (7) | |
C13 | 0.6613 (2) | 0.01699 (14) | 0.6364 (3) | 0.0432 (7) | |
C14 | 0.6101 (2) | −0.04015 (14) | 0.6476 (3) | 0.0466 (8) | |
H14 | 0.6296 | −0.0759 | 0.6019 | 0.056* | |
C15 | 0.5310 (2) | −0.04600 (14) | 0.7243 (3) | 0.0461 (8) | |
C16 | 0.5027 (2) | 0.00816 (15) | 0.7886 (3) | 0.0491 (8) | |
H16 | 0.4483 | 0.0054 | 0.8383 | 0.059* | |
C21 | 0.3899 (2) | 0.17803 (14) | 0.6457 (3) | 0.0464 (8) | |
C22 | 0.3845 (3) | 0.21213 (14) | 0.5142 (4) | 0.0491 (8) | |
C23 | 0.2884 (3) | 0.21430 (17) | 0.3998 (4) | 0.0674 (10) | |
H23 | 0.2860 | 0.2368 | 0.3126 | 0.081* | |
C24 | 0.1961 (3) | 0.18349 (19) | 0.4132 (5) | 0.0793 (12) | |
H24 | 0.1314 | 0.1851 | 0.3353 | 0.095* | |
C25 | 0.1997 (3) | 0.15053 (19) | 0.5411 (5) | 0.0778 (12) | |
H25 | 0.1367 | 0.1303 | 0.5508 | 0.093* | |
C26 | 0.2960 (3) | 0.14690 (16) | 0.6563 (4) | 0.0624 (9) | |
H26 | 0.2978 | 0.1233 | 0.7418 | 0.075* | |
C30 | 0.9078 (3) | 0.02456 (16) | 0.7502 (4) | 0.0624 (9) | |
H30A | 0.9355 | −0.0140 | 0.7162 | 0.075* | |
H30B | 0.8619 | 0.0124 | 0.8138 | 0.075* | |
C31 | 1.0032 (3) | 0.06306 (19) | 0.8409 (4) | 0.0625 (9) | |
C33 | 1.1866 (4) | 0.0661 (3) | 0.9666 (5) | 0.0963 (15) | |
H33 | 1.2546 | 0.0460 | 0.9959 | 0.116* | |
C34 | 1.1802 (5) | 0.1264 (3) | 1.0107 (5) | 0.1101 (18) | |
H34 | 1.2421 | 0.1467 | 1.0708 | 0.132* | |
C35 | 1.0820 (5) | 0.1573 (3) | 0.9664 (6) | 0.1223 (18) | |
H35 | 1.0758 | 0.1996 | 0.9921 | 0.147* | |
C36 | 0.9915 (4) | 0.1240 (2) | 0.8817 (5) | 0.0980 (14) | |
H36 | 0.9228 | 0.1433 | 0.8528 | 0.118* | |
C40 | 0.9037 (3) | 0.07305 (17) | 0.5122 (4) | 0.0631 (10) | |
H40A | 0.9115 | 0.0343 | 0.4594 | 0.076* | |
H40B | 0.9769 | 0.0870 | 0.5673 | 0.076* | |
C41 | 0.8518 (2) | 0.12308 (15) | 0.3990 (4) | 0.0515 (8) | |
C43 | 0.7592 (4) | 0.21651 (18) | 0.3444 (4) | 0.0839 (13) | |
H43 | 0.7233 | 0.2500 | 0.3763 | 0.101* | |
C44 | 0.7633 (4) | 0.2172 (2) | 0.2025 (5) | 0.0857 (13) | |
H44 | 0.7354 | 0.2510 | 0.1387 | 0.103* | |
C45 | 0.8102 (4) | 0.1662 (3) | 0.1551 (5) | 0.120 (2) | |
H45 | 0.8128 | 0.1640 | 0.0558 | 0.144* | |
C46 | 0.8540 (4) | 0.1176 (2) | 0.2534 (4) | 0.0937 (14) | |
H46 | 0.8843 | 0.0820 | 0.2209 | 0.112* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0582 (15) | 0.0454 (13) | 0.0839 (17) | −0.0073 (11) | 0.0330 (13) | −0.0076 (12) |
O20 | 0.0640 (15) | 0.0663 (16) | 0.0620 (15) | −0.0166 (13) | 0.0164 (12) | 0.0110 (13) |
N1 | 0.0566 (18) | 0.0493 (17) | 0.0515 (16) | −0.0032 (14) | 0.0228 (15) | −0.0017 (13) |
N4 | 0.0370 (14) | 0.0532 (17) | 0.0562 (16) | 0.0011 (12) | 0.0143 (12) | 0.0144 (13) |
N32 | 0.054 (2) | 0.106 (3) | 0.073 (2) | 0.004 (2) | 0.0055 (17) | 0.0227 (19) |
N42 | 0.116 (3) | 0.066 (2) | 0.0558 (18) | 0.029 (2) | 0.0274 (18) | 0.0058 (16) |
C2 | 0.067 (2) | 0.057 (2) | 0.0443 (18) | 0.0028 (18) | 0.0195 (16) | −0.0025 (16) |
C3 | 0.0479 (18) | 0.051 (2) | 0.0542 (19) | 0.0041 (15) | 0.0157 (15) | 0.0006 (16) |
C5 | 0.064 (2) | 0.058 (2) | 0.069 (2) | −0.0074 (18) | 0.0175 (18) | 0.0088 (18) |
C11 | 0.0478 (17) | 0.0488 (19) | 0.0374 (16) | −0.0009 (15) | 0.0109 (14) | 0.0007 (14) |
C12 | 0.0453 (17) | 0.0416 (19) | 0.0465 (18) | −0.0011 (15) | 0.0099 (15) | 0.0036 (14) |
C13 | 0.0393 (16) | 0.0444 (18) | 0.0438 (17) | −0.0001 (14) | 0.0083 (14) | 0.0002 (14) |
C14 | 0.0466 (18) | 0.0432 (18) | 0.0465 (18) | 0.0022 (15) | 0.0067 (15) | −0.0010 (15) |
C15 | 0.0430 (17) | 0.0474 (19) | 0.0437 (18) | −0.0014 (15) | 0.0049 (14) | 0.0078 (15) |
C16 | 0.0481 (18) | 0.061 (2) | 0.0399 (18) | 0.0017 (16) | 0.0154 (14) | 0.0089 (16) |
C21 | 0.0523 (19) | 0.0404 (18) | 0.0518 (19) | −0.0007 (15) | 0.0230 (17) | −0.0083 (15) |
C22 | 0.051 (2) | 0.0395 (18) | 0.058 (2) | −0.0013 (15) | 0.0166 (17) | −0.0009 (16) |
C23 | 0.071 (3) | 0.060 (2) | 0.067 (2) | −0.001 (2) | 0.011 (2) | 0.0083 (19) |
C24 | 0.056 (2) | 0.076 (3) | 0.098 (3) | −0.004 (2) | 0.008 (2) | −0.002 (2) |
C25 | 0.054 (2) | 0.073 (3) | 0.113 (3) | −0.016 (2) | 0.034 (2) | −0.011 (3) |
C26 | 0.062 (2) | 0.062 (2) | 0.072 (2) | −0.0066 (18) | 0.033 (2) | 0.0007 (18) |
C30 | 0.0482 (19) | 0.064 (2) | 0.074 (2) | 0.0049 (18) | 0.0151 (18) | 0.0206 (19) |
C31 | 0.054 (2) | 0.074 (3) | 0.059 (2) | 0.001 (2) | 0.0147 (18) | 0.0169 (19) |
C33 | 0.057 (3) | 0.149 (5) | 0.074 (3) | −0.010 (3) | 0.004 (2) | 0.028 (3) |
C34 | 0.099 (4) | 0.148 (5) | 0.077 (3) | −0.044 (4) | 0.015 (3) | −0.002 (4) |
C35 | 0.133 (5) | 0.107 (4) | 0.124 (4) | −0.026 (4) | 0.030 (4) | −0.031 (3) |
C36 | 0.078 (3) | 0.088 (3) | 0.124 (4) | −0.007 (3) | 0.022 (3) | −0.020 (3) |
C40 | 0.050 (2) | 0.069 (2) | 0.078 (2) | 0.0114 (18) | 0.0309 (18) | 0.0161 (19) |
C41 | 0.0492 (19) | 0.050 (2) | 0.062 (2) | 0.0010 (16) | 0.0270 (17) | 0.0074 (17) |
C43 | 0.129 (4) | 0.054 (2) | 0.066 (3) | 0.024 (2) | 0.024 (3) | 0.000 (2) |
C44 | 0.119 (4) | 0.073 (3) | 0.075 (3) | 0.017 (3) | 0.044 (3) | 0.025 (2) |
C45 | 0.155 (5) | 0.155 (5) | 0.071 (3) | 0.075 (4) | 0.063 (3) | 0.042 (3) |
C46 | 0.111 (3) | 0.108 (4) | 0.075 (3) | 0.053 (3) | 0.047 (3) | 0.007 (3) |
Geometric parameters (Å, º) top
O1—C12 | 1.374 (3) | C16—H16 | 0.9300 |
O1—H1O | 0.8200 | C21—C26 | 1.384 (4) |
O20—C22 | 1.362 (3) | C21—C22 | 1.399 (4) |
O20—H20O | 0.8200 | C22—C23 | 1.374 (4) |
N1—C21 | 1.408 (4) | C23—C24 | 1.371 (5) |
N1—C2 | 1.474 (4) | C23—H23 | 0.9300 |
N1—H1N | 0.86 (1) | C24—C25 | 1.363 (5) |
N4—C40 | 1.465 (4) | C24—H24 | 0.9300 |
N4—C30 | 1.466 (4) | C25—C26 | 1.382 (5) |
N4—C3 | 1.475 (4) | C25—H25 | 0.9300 |
N32—C31 | 1.337 (4) | C26—H26 | 0.9300 |
N32—C33 | 1.341 (5) | C30—C31 | 1.503 (5) |
N42—C41 | 1.322 (4) | C30—H30A | 0.9700 |
N42—C43 | 1.338 (4) | C30—H30B | 0.9700 |
C2—C11 | 1.511 (4) | C31—C36 | 1.357 (5) |
C2—H2A | 0.9700 | C33—C34 | 1.342 (7) |
C2—H2B | 0.9700 | C33—H33 | 0.9300 |
C3—C13 | 1.505 (4) | C34—C35 | 1.362 (7) |
C3—H3A | 0.9700 | C34—H34 | 0.9300 |
C3—H3B | 0.9700 | C35—C36 | 1.386 (6) |
C5—C15 | 1.509 (4) | C35—H35 | 0.9300 |
C5—H5A | 0.9600 | C36—H36 | 0.9300 |
C5—H5B | 0.9600 | C40—C41 | 1.504 (4) |
C5—H5C | 0.9600 | C40—H40A | 0.9700 |
C5—H5D | 0.9600 | C40—H40B | 0.9700 |
C5—H5E | 0.9600 | C41—C46 | 1.362 (5) |
C5—H5F | 0.9600 | C43—C44 | 1.330 (5) |
C11—C12 | 1.385 (4) | C43—H43 | 0.9300 |
C11—C16 | 1.396 (4) | C44—C45 | 1.358 (6) |
C12—C13 | 1.396 (4) | C44—H44 | 0.9300 |
C13—C14 | 1.384 (4) | C45—C46 | 1.379 (5) |
C14—C15 | 1.384 (4) | C45—H45 | 0.9300 |
C14—H14 | 0.9300 | C46—H46 | 0.9300 |
C15—C16 | 1.380 (4) | | |
| | | |
C12—O1—H1O | 109.5 | C26—C21—C22 | 118.0 (3) |
C22—O20—H20O | 109.5 | C26—C21—N1 | 123.5 (3) |
C21—N1—C2 | 119.0 (3) | C22—C21—N1 | 118.3 (3) |
C21—N1—H1N | 108 (2) | O20—C22—C23 | 123.6 (3) |
C2—N1—H1N | 109 (2) | O20—C22—C21 | 115.9 (3) |
C40—N4—C30 | 111.0 (2) | C23—C22—C21 | 120.5 (3) |
C40—N4—C3 | 109.6 (2) | C24—C23—C22 | 120.5 (4) |
C30—N4—C3 | 110.2 (2) | C24—C23—H23 | 119.7 |
C31—N32—C33 | 117.6 (4) | C22—C23—H23 | 119.7 |
C41—N42—C43 | 117.5 (3) | C25—C24—C23 | 119.7 (4) |
N1—C2—C11 | 116.1 (2) | C25—C24—H24 | 120.2 |
N1—C2—H2A | 108.3 | C23—C24—H24 | 120.2 |
C11—C2—H2A | 108.3 | C24—C25—C26 | 120.6 (3) |
N1—C2—H2B | 108.3 | C24—C25—H25 | 119.7 |
C11—C2—H2B | 108.3 | C26—C25—H25 | 119.7 |
H2A—C2—H2B | 107.4 | C25—C26—C21 | 120.6 (3) |
N4—C3—C13 | 112.7 (2) | C25—C26—H26 | 119.7 |
N4—C3—H3A | 109.0 | C21—C26—H26 | 119.7 |
C13—C3—H3A | 109.0 | N4—C30—C31 | 112.7 (3) |
N4—C3—H3B | 109.0 | N4—C30—H30A | 109.1 |
C13—C3—H3B | 109.0 | C31—C30—H30A | 109.1 |
H3A—C3—H3B | 107.8 | N4—C30—H30B | 109.1 |
C15—C5—H5A | 109.5 | C31—C30—H30B | 109.1 |
C15—C5—H5B | 109.5 | H30A—C30—H30B | 107.8 |
H5A—C5—H5B | 109.5 | N32—C31—C36 | 121.5 (4) |
C15—C5—H5C | 109.5 | N32—C31—C30 | 116.2 (4) |
H5A—C5—H5C | 109.5 | C36—C31—C30 | 122.2 (4) |
H5B—C5—H5C | 109.5 | N32—C33—C34 | 123.7 (5) |
C15—C5—H5D | 109.5 | N32—C33—H33 | 118.2 |
H5A—C5—H5D | 141.1 | C34—C33—H33 | 118.2 |
H5B—C5—H5D | 56.3 | C33—C34—C35 | 119.2 (5) |
H5C—C5—H5D | 56.3 | C33—C34—H34 | 120.4 |
C15—C5—H5E | 109.5 | C35—C34—H34 | 120.4 |
H5A—C5—H5E | 56.3 | C34—C35—C36 | 117.9 (6) |
H5B—C5—H5E | 141.1 | C34—C35—H35 | 121.0 |
H5C—C5—H5E | 56.3 | C36—C35—H35 | 121.0 |
H5D—C5—H5E | 109.5 | C31—C36—C35 | 120.0 (5) |
C15—C5—H5F | 109.5 | C31—C36—H36 | 120.0 |
H5A—C5—H5F | 56.3 | C35—C36—H36 | 120.0 |
H5B—C5—H5F | 56.3 | N4—C40—C41 | 113.4 (2) |
H5C—C5—H5F | 141.1 | N4—C40—H40A | 108.9 |
H5D—C5—H5F | 109.5 | C41—C40—H40A | 108.9 |
H5E—C5—H5F | 109.5 | N4—C40—H40B | 108.9 |
C12—C11—C16 | 117.8 (3) | C41—C40—H40B | 108.9 |
C12—C11—C2 | 120.4 (3) | H40A—C40—H40B | 107.7 |
C16—C11—C2 | 121.7 (3) | N42—C41—C46 | 121.6 (3) |
O1—C12—C11 | 117.2 (3) | N42—C41—C40 | 117.9 (3) |
O1—C12—C13 | 121.6 (3) | C46—C41—C40 | 120.5 (3) |
C11—C12—C13 | 121.2 (3) | C44—C43—N42 | 125.0 (4) |
C14—C13—C12 | 118.4 (3) | C44—C43—H43 | 117.5 |
C14—C13—C3 | 120.4 (3) | N42—C43—H43 | 117.5 |
C12—C13—C3 | 121.1 (3) | C43—C44—C45 | 116.8 (4) |
C15—C14—C13 | 122.4 (3) | C43—C44—H44 | 121.6 |
C15—C14—H14 | 118.8 | C45—C44—H44 | 121.6 |
C13—C14—H14 | 118.8 | C44—C45—C46 | 120.3 (4) |
C16—C15—C14 | 117.4 (3) | C44—C45—H45 | 119.8 |
C16—C15—C5 | 122.4 (3) | C46—C45—H45 | 119.8 |
C14—C15—C5 | 120.3 (3) | C41—C46—C45 | 118.5 (4) |
C15—C16—C11 | 122.8 (3) | C41—C46—H46 | 120.8 |
C15—C16—H16 | 118.6 | C45—C46—H46 | 120.8 |
C11—C16—H16 | 118.6 | | |
| | | |
C21—N1—C2—C11 | 63.9 (4) | C21—C22—C23—C24 | 0.5 (5) |
C40—N4—C3—C13 | −168.3 (2) | C22—C23—C24—C25 | 0.1 (6) |
C30—N4—C3—C13 | 69.2 (3) | C23—C24—C25—C26 | −1.2 (6) |
N1—C2—C11—C12 | 57.2 (4) | C24—C25—C26—C21 | 1.7 (6) |
N1—C2—C11—C16 | −125.3 (3) | C22—C21—C26—C25 | −1.1 (5) |
C16—C11—C12—O1 | −178.8 (3) | N1—C21—C26—C25 | 173.9 (3) |
C2—C11—C12—O1 | −1.2 (4) | C40—N4—C30—C31 | 64.4 (4) |
C16—C11—C12—C13 | 1.8 (4) | C3—N4—C30—C31 | −174.0 (3) |
C2—C11—C12—C13 | 179.4 (3) | C33—N32—C31—C36 | −0.1 (5) |
O1—C12—C13—C14 | 178.2 (3) | C33—N32—C31—C30 | −178.5 (3) |
C11—C12—C13—C14 | −2.4 (4) | N4—C30—C31—N32 | −134.2 (3) |
O1—C12—C13—C3 | −4.5 (4) | N4—C30—C31—C36 | 47.4 (5) |
C11—C12—C13—C3 | 174.9 (3) | C31—N32—C33—C34 | 0.3 (6) |
N4—C3—C13—C14 | −137.2 (3) | N32—C33—C34—C35 | −1.5 (8) |
N4—C3—C13—C12 | 45.5 (4) | C33—C34—C35—C36 | 2.4 (8) |
C12—C13—C14—C15 | 0.9 (4) | N32—C31—C36—C35 | 1.2 (7) |
C3—C13—C14—C15 | −176.4 (3) | C30—C31—C36—C35 | 179.5 (4) |
C13—C14—C15—C16 | 1.1 (4) | C34—C35—C36—C31 | −2.3 (8) |
C13—C14—C15—C5 | −179.8 (3) | C30—N4—C40—C41 | −164.0 (3) |
C14—C15—C16—C11 | −1.7 (4) | C3—N4—C40—C41 | 74.0 (4) |
C5—C15—C16—C11 | 179.2 (3) | C43—N42—C41—C46 | −2.7 (6) |
C12—C11—C16—C15 | 0.3 (4) | C43—N42—C41—C40 | 178.4 (3) |
C2—C11—C16—C15 | −177.2 (3) | N4—C40—C41—N42 | 37.6 (4) |
C2—N1—C21—C26 | 39.0 (4) | N4—C40—C41—C46 | −141.3 (4) |
C2—N1—C21—C22 | −146.0 (3) | C41—N42—C43—C44 | −1.5 (7) |
C26—C21—C22—O20 | 179.4 (3) | N42—C43—C44—C45 | 3.8 (7) |
N1—C21—C22—O20 | 4.2 (4) | C43—C44—C45—C46 | −2.0 (8) |
C26—C21—C22—C23 | 0.0 (4) | N42—C41—C46—C45 | 4.3 (7) |
N1—C21—C22—C23 | −175.3 (3) | C40—C41—C46—C45 | −176.8 (4) |
O20—C22—C23—C24 | −178.9 (3) | C44—C45—C46—C41 | −1.9 (8) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1 | 0.86 (1) | 2.32 (2) | 2.896 (3) | 124 (2) |
N1—H1N···O20 | 0.86 (1) | 2.22 (3) | 2.662 (3) | 113 (2) |
O1—H1O···N4 | 0.82 | 2.04 | 2.758 (3) | 145 |
O1—H1O···N42 | 0.82 | 2.68 | 3.309 (4) | 134 |
O20—H20O···N1i | 0.82 | 2.03 | 2.813 (3) | 160 |
Symmetry code: (i) x, −y+1/2, z−1/2. |
Experimental details
Crystal data |
Chemical formula | C27H28N4O2 |
Mr | 440.53 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 12.651 (1), 21.071 (5), 9.262 (1) |
β (°) | 106.09 (1) |
V (Å3) | 2372.2 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.46 × 0.30 × 0.23 |
|
Data collection |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4338, 4142, 2138 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.596 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.155, 1.02 |
No. of reflections | 4142 |
No. of parameters | 305 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.23, −0.18 |
Selected geometric parameters (Å, º) topO1—C12 | 1.374 (3) | N4—C40 | 1.465 (4) |
O20—C22 | 1.362 (3) | N4—C30 | 1.466 (4) |
N1—C21 | 1.408 (4) | N4—C3 | 1.475 (4) |
N1—C2 | 1.474 (4) | C2—C11 | 1.511 (4) |
| | | |
C21—N1—C2 | 119.0 (3) | C30—N4—C3 | 110.2 (2) |
C40—N4—C30 | 111.0 (2) | N1—C2—C11 | 116.1 (2) |
C40—N4—C3 | 109.6 (2) | N4—C3—C13 | 112.7 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1 | 0.86 (1) | 2.32 (2) | 2.896 (3) | 124 (2) |
N1—H1N···O20 | 0.86 (1) | 2.22 (3) | 2.662 (3) | 113 (2) |
O1—H1O···N4 | 0.82 | 2.04 | 2.758 (3) | 145 |
O1—H1O···N42 | 0.82 | 2.68 | 3.309 (4) | 134 |
O20—H20O···N1i | 0.82 | 2.03 | 2.813 (3) | 160 |
Symmetry code: (i) x, −y+1/2, z−1/2. |
Many enzymes contain bimetallic cores within their catalytic sites and can be classified as either homobinuclear [e.g. catechol oxidase, with its CuIICuII centre (Klabunde et al., 1998)] or heterobinuclear [e.g. kbPAP, with its FeIIIZnII centre (Sträter et al., 1995)] metalloenzymes, depending on the nature of the metals present. Recent X-ray crystallographic studies have indicated that, even for homobinuclear sites, the two metal centres usually reside in chemically different environments, an asymmetry that may also involve the coordination numbers and the geometry of the metal centres (Belle & Pierre, 2003). Calcineurin, a phosphatase found predominantly in neural tissues, constitutes an interesting example of total asymmetry in heterobinuclear sites: the metal, coordination number, donor and geometry all exhibit asymmetry. This enzyme contains an FeIIIZnII bimetallic core in its active centre, which comprises an octahedral FeIII nucleus coordinated by one O atom from Asp90, one N atom from His92, an O-bridging carboxylate from Asp118 and three water molecules. Three water molecules, one of them acting as an exogenous bridge, complete the Fe coordination sphere. On the other hand, the ZnII centre shows a distorted trigonal–bipyramidal geometry formed by three O atoms from Asp118, Asn150 and the bridging water molecule, and two N atoms from His199 and His281 (Kissinger et al., 1995).
In recent years, the study of models based on simple dinuclear metal complexes has become an important tool to gain insight into the biological functions of such bimetallic cores. In this context, the design of binucleating ligands capable of providing asymmetric dinuclear complexes is a subject of great interest. It is convenient to classify binucleating ligands by the bridging groups that are used for assembling the two metal ions in close proximity (Gavrilova & Bosnich, 2004). Our research group has long experience in the development of asymmetric binucleating ligands containing alkoxide (Rossi et al., 2005) and phenoxide (Mitić et al., 2006) bridging units, which have been used in the synthesis of numerous bimetallic complexes. Here, we report the structure of a new phenoxide-based binucleating hexadentate ligand, H2L, (I), which presents donor, geometry and coordination-number asymmetries, thereby constituting a versatile precursor to synthetic models for the active sites of asymmetric metalloenzymes, with a special focus on calcineurin. It should be emphasized that H2L possesses a softer N3O-donor side, defined by the tertiary amine, both pyridine rings and the bridging phenolate group, capable of accommodating divalent metal ions, and a harder NO2-donor side, comprising the secondary amine and the terminal and bridging phenol moieties, which binds preferentially to trivalent cations. This represents a convenient strategy for the attainment of mixed-valence heterobimetallic systems.
The structure of H2L is shown in Fig. 1, and selected bond lengths and angles are given in Table 1. The bond distances and angles for the aromatic and heteroaromatic rings are not significantly different from those found in similar compounds containing these groups (Example references?). An interesting trend in the three-dimensional arrangement of the molecule is that H2L shows a self-induced spatial pre-organization of the donor groups for coordination: with the exception of atom N32, all donor atoms point towards the bridging atom O1. The respective O20···O1 and N42···O1 distances are 3.622 (3) and 3.310 (4) Å, which are very similar to the values observed for a hydroxo-bridged FeIIIZnII complex [3.950 (8) and 3.354 (8) Å, respectively] of the asymmetric ligand 2-bis[{(2-pyridylmethyl)aminomethyl}-6-{(2-hydroxybenzyl)-(2-pyridylmethyl)}-aminomethyl]-4-methylphenol (Neves et al., 2006).
The molecular conformation is influenced by intra- and intermolecular hydrogen bonds involving both phenol groups (Table 2). Within each molecule, the N1—H1N donor interacts with the acceptors O1 [N···O = 2.896 (3) Å] and O20 [N···O = 2.662 (3) Å], although the latter only achieves a less favourable five-membered ring. The bridging phenol acts as an acceptor in the N1—H1N···O1 interaction, and as a donor in a second bifurcated hydrogen bond involving the interactions O1—H1O···N4 [moderate, O···N = 2.758 (3) Å] and O1—H1O···N42 [weak, O···N = 3.309 (4) Å]. It is interesting to note that the shorter component of this bifurcated hydrogen bond is associated with a narrower angle [N4—C3—C13 = 112.7 (2)°] compared with N1—C2—C11 [116.1 (2)°].
The title ligand has a direct linkage between the terminal phenolic ring and the secondary amine, allowing the formation of a more rigid five-membered chelate during the complexation process. The constriction induced in the complexes by going from a six-membered to a five-membered ring can give rise to modified spectroscopic and electrochemical properties. This was observed by Neves et al. (1992) for a mononuclear MnIII complex with the ligand N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-methylpyridy1)ethylenediamine. As far as we know, there is only one previous example in the literature of a phenoxide-bridging ligand with such a structural feature (Campbell et al., 1993).
Moderate intermolecular hydrogen bonds (Table 2) of the type O20—H20O···N1i [2.814 (3) Å; symmetry code: (i) x, 1/2 - y, z - 1/2] link the molecules of H2L into zigzag chains (Fig. 2) which run parallel to the crystallographic c axis.