The first two crystal structures of enamines derived from 1-
n-alkyl-3-methyl-5-pyrazolones, namely 1-(
n-hexyl)-3-methyl-4-[1-(phenylamino)propylidene]-2-pyrazolin-5-one, C
19H
27N
3O, (I), and
N,
N'-bis{1-[1-(
n-hexyl)-3-methyl-5-oxo-2-pyrazolin-4-ylidene]ethyl}hexane-1,6-diamine, C
30H
52N
6O
2, (II), are reported. The molecule of (II) lies about an inversion centre. Both (I) and (II) are stabilized by intramolecular N-H
O hydrogen bonding. This confirms previous results based on spectroscopic evidence alone.
Supporting information
CCDC references: 251342; 251343
4-Acetyl-1-(n-hexyl)-3-methylpyrazol-5-ol and 1-(n-hexyl)-3-methyl-4-propionylpyrazol-5-ol were prepared using the usual methods of Jensen (1959) and Belmar et al. (1997). Each reaction was carried out using a magnetic stirrer in a flask provided with a Dean Stark Something missing? to separate the water produced during the reaction. Acylpyrazolone and the corresponding amine were dissolved in toluene and heated to reflux. The solution was then washed with brine until a neutral pH was achieved and then dried over Na2SO4. After filtration, the solution was concentrated in a rotary evaporator to obtain the crude product of enamines. For the preparation of (I), 1-(n-hexyl)-3-methyl-4-propionylpyrazol-5-ol (1.00 g, 4.2 mmol) and aniline (0.4 ml, 4.2 mmol) in toluene (10 ml) were heated to reflux for 8 h. The crude product of (I) was crystallized from a heptane solution (yield 0.79 g, 60%; m.p. 367 K). Elemental analysis, calculated: C 72.81, H 8.68, N 13.41%; found: C 72.70, H 8.70, N 13.50%. For the preparation of (II), 4-acetyl-1-(n-hexyl)-3-methylpyrazol-5-ol (3.00 g, 13.4 mmol) and 1,6-diaminohexane (0.93 g, 8.0 mmol) in toluene (20 ml) were heated to reflux for 10 h. The crude product of (II) was crystallized from a hexane-ethyl acetate mixture (Ratio?) (yield 1.42 g, 40%; m.p. 389 K). Elemental analysis, calculated: C 68.14, H 9.91, N 15.89%; found: C 68.00, H 10.00, N 16.20%.
Even though all H atoms were clearly seen in difference Fourier maps (in particular those involved in intramolecular N—H···O bonds), for simplicity they were placed in their theoretical positions (C—H = 0.93–0.97 and N—H = 0.86 Å) and allowed to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C,N) [or 1.5Ueq(C) for methyl groups]. The latter were allowed to rotate as well. Full use of the CCDC package was made for searching in the Cambridge Structural Database (Allen, 2002).
For both compounds, data collection: SMART (Bruker, 2001); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1994); software used to prepare material for publication: SHELXTL/PC.
(I) 1-(n-hexyl)-3-methyl-4-(1-phenylaminopropylidene)-2-pyrazolin-5-one
top
Crystal data top
C19H27N3O | Z = 2 |
Mr = 313.44 | F(000) = 340 |
Triclinic, P1 | Dx = 1.158 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 9.0221 (14) Å | Cell parameters from 2388 reflections |
b = 9.1427 (14) Å | θ = 4.5–50.1° |
c = 11.9077 (18) Å | µ = 0.07 mm−1 |
α = 85.111 (2)° | T = 300 K |
β = 68.812 (2)° | Prisms, yellow |
γ = 78.911 (2)° | 0.32 × 0.14 × 0.12 mm |
V = 898.6 (2) Å3 | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 2155 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.020 |
Graphite monochromator | θmax = 25.0°, θmin = 1.8° |
ϕ and ω scans | h = −10→10 |
5601 measured reflections | k = −10→10 |
3132 independent reflections | l = −14→14 |
Refinement top
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.158 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0865P)2] where P = (Fo2 + 2Fc2)/3 |
3132 reflections | (Δ/σ)max = 0.004 |
211 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
Crystal data top
C19H27N3O | γ = 78.911 (2)° |
Mr = 313.44 | V = 898.6 (2) Å3 |
Triclinic, P1 | Z = 2 |
a = 9.0221 (14) Å | Mo Kα radiation |
b = 9.1427 (14) Å | µ = 0.07 mm−1 |
c = 11.9077 (18) Å | T = 300 K |
α = 85.111 (2)° | 0.32 × 0.14 × 0.12 mm |
β = 68.812 (2)° | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 2155 reflections with I > 2σ(I) |
5601 measured reflections | Rint = 0.020 |
3132 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.158 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.25 e Å−3 |
3132 reflections | Δρmin = −0.28 e Å−3 |
211 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.33453 (18) | 0.88340 (16) | 0.28489 (13) | 0.0709 (4) | |
N1 | 0.20236 (19) | 1.12682 (18) | 0.28119 (15) | 0.0631 (5) | |
N2 | 0.11541 (18) | 1.24112 (18) | 0.36057 (16) | 0.0641 (5) | |
N3 | 0.31692 (18) | 0.80665 (16) | 0.51385 (14) | 0.0571 (4) | |
H3N | 0.3499 | 0.7887 | 0.4382 | 0.068* | |
C1 | 0.2555 (2) | 1.0027 (2) | 0.33617 (18) | 0.0561 (5) | |
C2 | 0.1989 (2) | 1.03999 (19) | 0.46136 (17) | 0.0502 (5) | |
C3 | 0.1115 (2) | 1.1902 (2) | 0.46784 (18) | 0.0557 (5) | |
C4 | 0.0217 (3) | 1.2879 (2) | 0.5722 (2) | 0.0735 (6) | |
H4A | −0.0248 | 1.3814 | 0.5454 | 0.110* | |
H4B | 0.0940 | 1.3047 | 0.6104 | 0.110* | |
H4C | −0.0626 | 1.2409 | 0.6287 | 0.110* | |
C5 | 0.2296 (2) | 0.94039 (19) | 0.54886 (16) | 0.0496 (5) | |
C6 | 0.1784 (2) | 0.9790 (2) | 0.67776 (17) | 0.0580 (5) | |
H6A | 0.1634 | 0.8892 | 0.7272 | 0.070* | |
H6B | 0.0758 | 1.0467 | 0.7007 | 0.070* | |
C7 | 0.3026 (3) | 1.0515 (2) | 0.7010 (2) | 0.0765 (7) | |
H7A | 0.2678 | 1.0719 | 0.7853 | 0.115* | |
H7B | 0.3135 | 1.1431 | 0.6553 | 0.115* | |
H7C | 0.4047 | 0.9854 | 0.6771 | 0.115* | |
C8 | 0.3616 (2) | 0.68928 (19) | 0.58946 (16) | 0.0515 (5) | |
C9 | 0.2538 (2) | 0.5986 (2) | 0.65451 (18) | 0.0618 (5) | |
H9A | 0.1500 | 0.6150 | 0.6521 | 0.074* | |
C10 | 0.3010 (3) | 0.4830 (2) | 0.72332 (19) | 0.0701 (6) | |
H10A | 0.2284 | 0.4215 | 0.7677 | 0.084* | |
C11 | 0.4541 (3) | 0.4578 (2) | 0.72692 (19) | 0.0701 (6) | |
H11A | 0.4853 | 0.3796 | 0.7734 | 0.084* | |
C12 | 0.5602 (3) | 0.5480 (2) | 0.6620 (2) | 0.0734 (6) | |
H12A | 0.6643 | 0.5306 | 0.6638 | 0.088* | |
C13 | 0.5143 (2) | 0.6649 (2) | 0.59368 (19) | 0.0639 (6) | |
H13A | 0.5868 | 0.7270 | 0.5505 | 0.077* | |
C14 | 0.2228 (3) | 1.1460 (3) | 0.15446 (19) | 0.0770 (7) | |
H14A | 0.1190 | 1.1876 | 0.1476 | 0.092* | |
H14B | 0.2583 | 1.0490 | 0.1173 | 0.092* | |
C15 | 0.3426 (3) | 1.2461 (3) | 0.0859 (2) | 0.0824 (7) | |
H15A | 0.3467 | 1.2560 | 0.0032 | 0.099* | |
H15B | 0.3046 | 1.3444 | 0.1209 | 0.099* | |
C16 | 0.5102 (3) | 1.1905 (2) | 0.0865 (2) | 0.0753 (6) | |
H16A | 0.5436 | 1.0883 | 0.0593 | 0.090* | |
H16B | 0.5075 | 1.1900 | 0.1686 | 0.090* | |
C17 | 0.6347 (3) | 1.2811 (3) | 0.0084 (2) | 0.0798 (7) | |
H17A | 0.6440 | 1.2747 | −0.0748 | 0.096* | |
H17B | 0.5972 | 1.3848 | 0.0312 | 0.096* | |
C18 | 0.7992 (3) | 1.2321 (3) | 0.0173 (2) | 0.0925 (8) | |
H18A | 0.7889 | 1.2358 | 0.1010 | 0.111* | |
H18B | 0.8374 | 1.1290 | −0.0072 | 0.111* | |
C19 | 0.9231 (3) | 1.3219 (4) | −0.0564 (3) | 0.1162 (10) | |
H19A | 1.0230 | 1.2846 | −0.0439 | 0.174* | |
H19B | 0.8872 | 1.4242 | −0.0328 | 0.174* | |
H19C | 0.9389 | 1.3148 | −0.1401 | 0.174* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0852 (10) | 0.0624 (9) | 0.0647 (9) | −0.0039 (8) | −0.0312 (8) | 0.0031 (7) |
N1 | 0.0625 (10) | 0.0637 (11) | 0.0643 (11) | −0.0100 (8) | −0.0283 (8) | 0.0178 (9) |
N2 | 0.0543 (10) | 0.0604 (10) | 0.0764 (12) | −0.0104 (8) | −0.0261 (9) | 0.0211 (9) |
N3 | 0.0646 (10) | 0.0498 (9) | 0.0557 (10) | −0.0031 (8) | −0.0251 (8) | 0.0073 (7) |
C1 | 0.0533 (11) | 0.0548 (12) | 0.0657 (13) | −0.0146 (9) | −0.0280 (10) | 0.0134 (10) |
C2 | 0.0445 (10) | 0.0480 (10) | 0.0615 (12) | −0.0123 (8) | −0.0234 (8) | 0.0121 (8) |
C3 | 0.0449 (10) | 0.0532 (11) | 0.0699 (13) | −0.0134 (9) | −0.0224 (9) | 0.0149 (10) |
C4 | 0.0718 (14) | 0.0540 (12) | 0.0889 (16) | −0.0023 (10) | −0.0279 (12) | 0.0084 (11) |
C5 | 0.0427 (10) | 0.0471 (10) | 0.0605 (12) | −0.0129 (8) | −0.0196 (8) | 0.0090 (8) |
C6 | 0.0591 (12) | 0.0498 (11) | 0.0608 (13) | −0.0069 (9) | −0.0198 (10) | 0.0100 (9) |
C7 | 0.0900 (16) | 0.0735 (14) | 0.0780 (15) | −0.0166 (12) | −0.0435 (13) | 0.0016 (12) |
C8 | 0.0566 (11) | 0.0442 (10) | 0.0540 (11) | −0.0041 (8) | −0.0235 (9) | 0.0042 (8) |
C9 | 0.0595 (12) | 0.0577 (12) | 0.0709 (13) | −0.0121 (10) | −0.0271 (10) | 0.0078 (10) |
C10 | 0.0855 (16) | 0.0537 (12) | 0.0679 (14) | −0.0167 (11) | −0.0244 (12) | 0.0152 (10) |
C11 | 0.0896 (17) | 0.0537 (12) | 0.0615 (13) | 0.0075 (11) | −0.0320 (12) | 0.0061 (10) |
C12 | 0.0636 (13) | 0.0782 (15) | 0.0785 (15) | 0.0054 (12) | −0.0354 (12) | 0.0045 (12) |
C13 | 0.0536 (12) | 0.0637 (13) | 0.0735 (14) | −0.0095 (10) | −0.0242 (10) | 0.0106 (10) |
C14 | 0.0746 (14) | 0.0952 (17) | 0.0686 (15) | −0.0194 (13) | −0.0374 (12) | 0.0248 (12) |
C15 | 0.0816 (16) | 0.0932 (17) | 0.0718 (15) | −0.0159 (13) | −0.0328 (12) | 0.0295 (13) |
C16 | 0.0785 (15) | 0.0766 (15) | 0.0712 (15) | −0.0143 (12) | −0.0285 (12) | 0.0079 (12) |
C17 | 0.0848 (16) | 0.0916 (16) | 0.0627 (14) | −0.0204 (13) | −0.0255 (12) | 0.0096 (12) |
C18 | 0.0914 (18) | 0.1036 (19) | 0.0853 (18) | −0.0243 (16) | −0.0325 (15) | 0.0056 (15) |
C19 | 0.097 (2) | 0.149 (3) | 0.102 (2) | −0.045 (2) | −0.0274 (17) | 0.0189 (19) |
Geometric parameters (Å, º) top
O1—C1 | 1.253 (2) | C10—C11 | 1.372 (3) |
N1—C1 | 1.355 (2) | C10—H10A | 0.9300 |
N1—N2 | 1.385 (2) | C11—C12 | 1.361 (3) |
N1—C14 | 1.452 (3) | C11—H11A | 0.9300 |
N2—C3 | 1.312 (2) | C12—C13 | 1.378 (3) |
N3—C5 | 1.330 (2) | C12—H12A | 0.9300 |
N3—C8 | 1.434 (2) | C13—H13A | 0.9300 |
N3—H3N | 0.8600 | C14—C15 | 1.512 (3) |
C1—C2 | 1.438 (3) | C14—H14A | 0.9700 |
C2—C5 | 1.394 (2) | C14—H14B | 0.9700 |
C2—C3 | 1.439 (2) | C15—C16 | 1.501 (3) |
C3—C4 | 1.477 (3) | C15—H15A | 0.9700 |
C4—H4A | 0.9600 | C15—H15B | 0.9700 |
C4—H4B | 0.9600 | C16—C17 | 1.512 (3) |
C4—H4C | 0.9600 | C16—H16A | 0.9700 |
C5—C6 | 1.487 (3) | C16—H16B | 0.9700 |
C6—C7 | 1.521 (3) | C17—C18 | 1.504 (3) |
C6—H6A | 0.9700 | C17—H17A | 0.9700 |
C6—H6B | 0.9700 | C17—H17B | 0.9700 |
C7—H7A | 0.9600 | C18—C19 | 1.488 (3) |
C7—H7B | 0.9600 | C18—H18A | 0.9700 |
C7—H7C | 0.9600 | C18—H18B | 0.9700 |
C8—C13 | 1.372 (3) | C19—H19A | 0.9600 |
C8—C9 | 1.375 (2) | C19—H19B | 0.9600 |
C9—C10 | 1.379 (3) | C19—H19C | 0.9600 |
C9—H9A | 0.9300 | | |
| | | |
C1—N1—N2 | 112.89 (16) | C12—C11—C10 | 119.61 (18) |
C1—N1—C14 | 127.03 (19) | C12—C11—H11A | 120.2 |
N2—N1—C14 | 120.04 (16) | C10—C11—H11A | 120.2 |
C3—N2—N1 | 106.42 (15) | C11—C12—C13 | 120.49 (19) |
C5—N3—C8 | 126.59 (16) | C11—C12—H12A | 119.8 |
C5—N3—H3N | 116.7 | C13—C12—H12A | 119.8 |
C8—N3—H3N | 116.7 | C8—C13—C12 | 119.86 (18) |
O1—C1—N1 | 125.42 (19) | C8—C13—H13A | 120.1 |
O1—C1—C2 | 129.71 (17) | C12—C13—H13A | 120.1 |
N1—C1—C2 | 104.86 (17) | N1—C14—C15 | 113.81 (18) |
C5—C2—C1 | 122.63 (16) | N1—C14—H14A | 108.8 |
C5—C2—C3 | 132.34 (18) | C15—C14—H14A | 108.8 |
C1—C2—C3 | 105.03 (15) | N1—C14—H14B | 108.8 |
N2—C3—C2 | 110.79 (18) | C15—C14—H14B | 108.8 |
N2—C3—C4 | 118.51 (18) | H14A—C14—H14B | 107.7 |
C2—C3—C4 | 130.70 (18) | C16—C15—C14 | 113.80 (18) |
C3—C4—H4A | 109.5 | C16—C15—H15A | 108.8 |
C3—C4—H4B | 109.5 | C14—C15—H15A | 108.8 |
H4A—C4—H4B | 109.5 | C16—C15—H15B | 108.8 |
C3—C4—H4C | 109.5 | C14—C15—H15B | 108.8 |
H4A—C4—H4C | 109.5 | H15A—C15—H15B | 107.7 |
H4B—C4—H4C | 109.5 | C15—C16—C17 | 114.42 (18) |
N3—C5—C2 | 118.10 (17) | C15—C16—H16A | 108.7 |
N3—C5—C6 | 118.36 (15) | C17—C16—H16A | 108.7 |
C2—C5—C6 | 123.43 (16) | C15—C16—H16B | 108.7 |
C5—C6—C7 | 111.51 (15) | C17—C16—H16B | 108.7 |
C5—C6—H6A | 109.3 | H16A—C16—H16B | 107.6 |
C7—C6—H6A | 109.3 | C18—C17—C16 | 114.03 (19) |
C5—C6—H6B | 109.3 | C18—C17—H17A | 108.7 |
C7—C6—H6B | 109.3 | C16—C17—H17A | 108.7 |
H6A—C6—H6B | 108.0 | C18—C17—H17B | 108.7 |
C6—C7—H7A | 109.5 | C16—C17—H17B | 108.7 |
C6—C7—H7B | 109.5 | H17A—C17—H17B | 107.6 |
H7A—C7—H7B | 109.5 | C19—C18—C17 | 115.1 (2) |
C6—C7—H7C | 109.5 | C19—C18—H18A | 108.5 |
H7A—C7—H7C | 109.5 | C17—C18—H18A | 108.5 |
H7B—C7—H7C | 109.5 | C19—C18—H18B | 108.5 |
C13—C8—C9 | 120.04 (17) | C17—C18—H18B | 108.5 |
C13—C8—N3 | 119.64 (17) | H18A—C18—H18B | 107.5 |
C9—C8—N3 | 120.29 (16) | C18—C19—H19A | 109.5 |
C8—C9—C10 | 119.42 (19) | C18—C19—H19B | 109.5 |
C8—C9—H9A | 120.3 | H19A—C19—H19B | 109.5 |
C10—C9—H9A | 120.3 | C18—C19—H19C | 109.5 |
C11—C10—C9 | 120.6 (2) | H19A—C19—H19C | 109.5 |
C11—C10—H10A | 119.7 | H19B—C19—H19C | 109.5 |
C9—C10—H10A | 119.7 | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3N···O1 | 0.86 | 1.99 | 2.712 (2) | 141 |
(II)
N,
N'-bis{1-[1-(n-hexyl)-3-methyl-5-oxo-2-pyrazolin-4-ylidene]ethyl}hexane- 1,6-diamine
top
Crystal data top
C30H52N6O2 | Z = 1 |
Mr = 528.78 | F(000) = 290 |
Triclinic, P1 | Dx = 1.141 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.0168 (13) Å | Cell parameters from 1755 reflections |
b = 9.5029 (15) Å | θ = 5.0–47.1° |
c = 10.7032 (17) Å | µ = 0.07 mm−1 |
α = 71.357 (2)° | T = 293 K |
β = 86.811 (2)° | Prisms, yellow |
γ = 85.112 (3)° | 0.28 × 0.16 × 0.10 mm |
V = 769.5 (2) Å3 | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 1477 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.056 |
Graphite monochromator | θmax = 25.0°, θmin = 2.0° |
ϕ and ω scans | h = −9→9 |
5582 measured reflections | k = −11→11 |
2689 independent reflections | l = −12→12 |
Refinement top
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)] = 0.048 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.152 | H-atom parameters constrained |
S = 0.93 | w = 1/[σ2(Fo2) + (0.0659P)2] where P = (Fo2 + 2Fc2)/3 |
2689 reflections | (Δ/σ)max = 0.007 |
174 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
Crystal data top
C30H52N6O2 | γ = 85.112 (3)° |
Mr = 528.78 | V = 769.5 (2) Å3 |
Triclinic, P1 | Z = 1 |
a = 8.0168 (13) Å | Mo Kα radiation |
b = 9.5029 (15) Å | µ = 0.07 mm−1 |
c = 10.7032 (17) Å | T = 293 K |
α = 71.357 (2)° | 0.28 × 0.16 × 0.10 mm |
β = 86.811 (2)° | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 1477 reflections with I > 2σ(I) |
5582 measured reflections | Rint = 0.056 |
2689 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.152 | H-atom parameters constrained |
S = 0.93 | Δρmax = 0.25 e Å−3 |
2689 reflections | Δρmin = −0.27 e Å−3 |
174 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.2199 (2) | 0.0708 (2) | 0.27772 (17) | 0.0680 (6) | |
N1 | 0.1036 (3) | −0.1523 (2) | 0.3047 (2) | 0.0535 (6) | |
N2 | 0.0615 (2) | −0.2787 (2) | 0.4054 (2) | 0.0549 (6) | |
N3 | 0.2937 (2) | 0.0847 (2) | 0.5155 (2) | 0.0535 (6) | |
H3N | 0.2875 | 0.1202 | 0.4311 | 0.064* | |
C1 | 0.1729 (3) | −0.0519 (3) | 0.3489 (2) | 0.0496 (6) | |
C2 | 0.1765 (3) | −0.1196 (3) | 0.4894 (2) | 0.0447 (6) | |
C3 | 0.1037 (3) | −0.2591 (3) | 0.5151 (2) | 0.0475 (6) | |
C4 | 0.0703 (4) | −0.3769 (3) | 0.6427 (3) | 0.0687 (8) | |
H4A | 0.0229 | −0.4584 | 0.6260 | 0.103* | |
H4B | −0.0068 | −0.3365 | 0.6964 | 0.103* | |
H4C | 0.1734 | −0.4118 | 0.6879 | 0.103* | |
C5 | 0.2395 (3) | −0.0484 (3) | 0.5709 (2) | 0.0475 (6) | |
C6 | 0.2512 (4) | −0.1164 (3) | 0.7164 (2) | 0.0673 (8) | |
H6A | 0.2966 | −0.0479 | 0.7524 | 0.101* | |
H6B | 0.3229 | −0.2065 | 0.7360 | 0.101* | |
H6C | 0.1416 | −0.1388 | 0.7548 | 0.101* | |
C7 | 0.3632 (3) | 0.1790 (3) | 0.5803 (3) | 0.0579 (7) | |
H7A | 0.4655 | 0.1296 | 0.6231 | 0.069* | |
H7B | 0.2842 | 0.1938 | 0.6477 | 0.069* | |
C8 | 0.4003 (3) | 0.3272 (3) | 0.4837 (3) | 0.0612 (8) | |
H8A | 0.2967 | 0.3784 | 0.4447 | 0.073* | |
H8B | 0.4737 | 0.3116 | 0.4134 | 0.073* | |
C9 | 0.4823 (3) | 0.4246 (2) | 0.5468 (3) | 0.0576 (7) | |
H9A | 0.4100 | 0.4375 | 0.6186 | 0.069* | |
H9B | 0.5869 | 0.3737 | 0.5842 | 0.069* | |
C10 | 0.0750 (3) | −0.1397 (3) | 0.1691 (3) | 0.0654 (8) | |
H10A | 0.0879 | −0.0377 | 0.1142 | 0.078* | |
H10B | −0.0394 | −0.1618 | 0.1623 | 0.078* | |
C11 | 0.1929 (4) | −0.2426 (3) | 0.1171 (3) | 0.0703 (8) | |
H11A | 0.1897 | −0.3429 | 0.1781 | 0.084* | |
H11B | 0.1529 | −0.2431 | 0.0334 | 0.084* | |
C12 | 0.3716 (4) | −0.2011 (3) | 0.0977 (3) | 0.0671 (8) | |
H12A | 0.4087 | −0.1921 | 0.1793 | 0.081* | |
H12B | 0.3763 | −0.1044 | 0.0308 | 0.081* | |
C13 | 0.4907 (3) | −0.3114 (3) | 0.0569 (3) | 0.0694 (8) | |
H13A | 0.4828 | −0.4086 | 0.1226 | 0.083* | |
H13B | 0.4547 | −0.3182 | −0.0259 | 0.083* | |
C14 | 0.6687 (4) | −0.2757 (4) | 0.0408 (3) | 0.0848 (10) | |
H14A | 0.7066 | −0.2745 | 0.1249 | 0.102* | |
H14B | 0.6758 | −0.1762 | −0.0212 | 0.102* | |
C15 | 0.7860 (4) | −0.3816 (4) | −0.0071 (3) | 0.0920 (11) | |
H15A | 0.8979 | −0.3504 | −0.0149 | 0.138* | |
H15B | 0.7518 | −0.3818 | −0.0916 | 0.138* | |
H15C | 0.7828 | −0.4802 | 0.0547 | 0.138* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0953 (15) | 0.0570 (12) | 0.0530 (12) | −0.0228 (11) | −0.0011 (10) | −0.0151 (10) |
N1 | 0.0629 (14) | 0.0567 (14) | 0.0472 (13) | −0.0125 (11) | −0.0026 (10) | −0.0230 (12) |
N2 | 0.0559 (14) | 0.0554 (14) | 0.0605 (15) | −0.0110 (11) | 0.0026 (11) | −0.0274 (12) |
N3 | 0.0593 (14) | 0.0543 (14) | 0.0541 (14) | −0.0115 (11) | −0.0045 (10) | −0.0248 (12) |
C1 | 0.0520 (16) | 0.0481 (16) | 0.0531 (17) | −0.0080 (13) | 0.0005 (12) | −0.0213 (14) |
C2 | 0.0473 (15) | 0.0441 (15) | 0.0464 (15) | −0.0040 (12) | −0.0004 (11) | −0.0192 (12) |
C3 | 0.0467 (15) | 0.0428 (15) | 0.0544 (17) | −0.0036 (12) | 0.0047 (12) | −0.0183 (13) |
C4 | 0.082 (2) | 0.0574 (18) | 0.069 (2) | −0.0165 (15) | 0.0057 (16) | −0.0212 (16) |
C5 | 0.0454 (15) | 0.0481 (16) | 0.0519 (16) | −0.0002 (12) | −0.0010 (12) | −0.0208 (13) |
C6 | 0.086 (2) | 0.0651 (19) | 0.0568 (18) | −0.0072 (16) | −0.0075 (15) | −0.0258 (15) |
C7 | 0.0577 (17) | 0.0606 (18) | 0.0685 (19) | −0.0121 (14) | −0.0026 (13) | −0.0366 (16) |
C8 | 0.0580 (17) | 0.0572 (17) | 0.078 (2) | −0.0076 (14) | −0.0072 (14) | −0.0326 (16) |
C9 | 0.0525 (16) | 0.0560 (16) | 0.074 (2) | −0.0076 (14) | −0.0059 (14) | −0.0330 (14) |
C10 | 0.0650 (18) | 0.088 (2) | 0.0553 (18) | −0.0113 (16) | −0.0072 (14) | −0.0367 (16) |
C11 | 0.081 (2) | 0.080 (2) | 0.0641 (19) | −0.0147 (17) | −0.0014 (15) | −0.0406 (17) |
C12 | 0.079 (2) | 0.0671 (19) | 0.0619 (19) | −0.0147 (16) | 0.0031 (15) | −0.0279 (16) |
C13 | 0.078 (2) | 0.073 (2) | 0.0649 (19) | −0.0134 (17) | 0.0001 (15) | −0.0309 (16) |
C14 | 0.081 (2) | 0.091 (2) | 0.093 (2) | −0.0233 (19) | 0.0142 (18) | −0.041 (2) |
C15 | 0.077 (2) | 0.099 (3) | 0.106 (3) | −0.003 (2) | 0.0066 (19) | −0.042 (2) |
Geometric parameters (Å, º) top
O1—C1 | 1.248 (3) | C8—H8A | 0.9700 |
N1—C1 | 1.360 (3) | C8—H8B | 0.9700 |
N1—N2 | 1.385 (3) | C9—C9i | 1.502 (5) |
N1—C10 | 1.447 (3) | C9—H9A | 0.9700 |
N2—C3 | 1.312 (3) | C9—H9B | 0.9700 |
N3—C5 | 1.313 (3) | C10—C11 | 1.514 (3) |
N3—C7 | 1.456 (3) | C10—H10A | 0.9700 |
N3—H3N | 0.8600 | C10—H10B | 0.9700 |
C1—C2 | 1.435 (3) | C11—C12 | 1.503 (4) |
C2—C5 | 1.399 (3) | C11—H11A | 0.9700 |
C2—C3 | 1.433 (3) | C11—H11B | 0.9700 |
C3—C4 | 1.492 (3) | C12—C13 | 1.509 (4) |
C4—H4A | 0.9600 | C12—H12A | 0.9700 |
C4—H4B | 0.9600 | C12—H12B | 0.9700 |
C4—H4C | 0.9600 | C13—C14 | 1.483 (4) |
C5—C6 | 1.488 (3) | C13—H13A | 0.9700 |
C6—H6A | 0.9600 | C13—H13B | 0.9700 |
C6—H6B | 0.9600 | C14—C15 | 1.509 (4) |
C6—H6C | 0.9600 | C14—H14A | 0.9700 |
C7—C8 | 1.499 (3) | C14—H14B | 0.9700 |
C7—H7A | 0.9700 | C15—H15A | 0.9600 |
C7—H7B | 0.9700 | C15—H15B | 0.9600 |
C8—C9 | 1.516 (3) | C15—H15C | 0.9600 |
| | | |
C1—N1—N2 | 112.98 (19) | C9i—C9—C8 | 114.0 (3) |
C1—N1—C10 | 127.1 (2) | C9i—C9—H9A | 108.8 |
N2—N1—C10 | 119.9 (2) | C8—C9—H9A | 108.8 |
C3—N2—N1 | 105.94 (19) | C9i—C9—H9B | 108.8 |
C5—N3—C7 | 127.6 (2) | C8—C9—H9B | 108.8 |
C5—N3—H3N | 116.2 | H9A—C9—H9B | 107.7 |
C7—N3—H3N | 116.2 | N1—C10—C11 | 113.3 (2) |
O1—C1—N1 | 125.2 (2) | N1—C10—H10A | 108.9 |
O1—C1—C2 | 130.2 (2) | C11—C10—H10A | 108.9 |
N1—C1—C2 | 104.7 (2) | N1—C10—H10B | 108.9 |
C5—C2—C3 | 133.3 (2) | C11—C10—H10B | 108.9 |
C5—C2—C1 | 121.7 (2) | H10A—C10—H10B | 107.7 |
C3—C2—C1 | 105.1 (2) | C12—C11—C10 | 114.3 (2) |
N2—C3—C2 | 111.3 (2) | C12—C11—H11A | 108.7 |
N2—C3—C4 | 118.6 (2) | C10—C11—H11A | 108.7 |
C2—C3—C4 | 130.1 (2) | C12—C11—H11B | 108.7 |
C3—C4—H4A | 109.5 | C10—C11—H11B | 108.7 |
C3—C4—H4B | 109.5 | H11A—C11—H11B | 107.6 |
H4A—C4—H4B | 109.5 | C11—C12—C13 | 113.9 (2) |
C3—C4—H4C | 109.5 | C11—C12—H12A | 108.8 |
H4A—C4—H4C | 109.5 | C13—C12—H12A | 108.8 |
H4B—C4—H4C | 109.5 | C11—C12—H12B | 108.8 |
N3—C5—C2 | 118.2 (2) | C13—C12—H12B | 108.8 |
N3—C5—C6 | 118.3 (2) | H12A—C12—H12B | 107.7 |
C2—C5—C6 | 123.5 (2) | C14—C13—C12 | 115.1 (2) |
C5—C6—H6A | 109.5 | C14—C13—H13A | 108.5 |
C5—C6—H6B | 109.5 | C12—C13—H13A | 108.5 |
H6A—C6—H6B | 109.5 | C14—C13—H13B | 108.5 |
C5—C6—H6C | 109.5 | C12—C13—H13B | 108.5 |
H6A—C6—H6C | 109.5 | H13A—C13—H13B | 107.5 |
H6B—C6—H6C | 109.5 | C13—C14—C15 | 114.9 (3) |
N3—C7—C8 | 111.4 (2) | C13—C14—H14A | 108.5 |
N3—C7—H7A | 109.4 | C15—C14—H14A | 108.5 |
C8—C7—H7A | 109.4 | C13—C14—H14B | 108.5 |
N3—C7—H7B | 109.4 | C15—C14—H14B | 108.5 |
C8—C7—H7B | 109.4 | H14A—C14—H14B | 107.5 |
H7A—C7—H7B | 108.0 | C14—C15—H15A | 109.5 |
C7—C8—C9 | 112.6 (2) | C14—C15—H15B | 109.5 |
C7—C8—H8A | 109.1 | H15A—C15—H15B | 109.5 |
C9—C8—H8A | 109.1 | C14—C15—H15C | 109.5 |
C7—C8—H8B | 109.1 | H15A—C15—H15C | 109.5 |
C9—C8—H8B | 109.1 | H15B—C15—H15C | 109.5 |
H8A—C8—H8B | 107.8 | | |
Symmetry code: (i) −x+1, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3N···O1 | 0.86 | 1.96 | 2.691 (3) | 142 |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C19H27N3O | C30H52N6O2 |
Mr | 313.44 | 528.78 |
Crystal system, space group | Triclinic, P1 | Triclinic, P1 |
Temperature (K) | 300 | 293 |
a, b, c (Å) | 9.0221 (14), 9.1427 (14), 11.9077 (18) | 8.0168 (13), 9.5029 (15), 10.7032 (17) |
α, β, γ (°) | 85.111 (2), 68.812 (2), 78.911 (2) | 71.357 (2), 86.811 (2), 85.112 (3) |
V (Å3) | 898.6 (2) | 769.5 (2) |
Z | 2 | 1 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.07 | 0.07 |
Crystal size (mm) | 0.32 × 0.14 × 0.12 | 0.28 × 0.16 × 0.10 |
|
Data collection |
Diffractometer | Bruker SMART CCD area-detector diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5601, 3132, 2155 | 5582, 2689, 1477 |
Rint | 0.020 | 0.056 |
(sin θ/λ)max (Å−1) | 0.595 | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.158, 1.07 | 0.048, 0.152, 0.93 |
No. of reflections | 3132 | 2689 |
No. of parameters | 211 | 174 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.28 | 0.25, −0.27 |
Selected bond lengths (Å) for (I) topO1—C1 | 1.253 (2) | N3—C8 | 1.434 (2) |
N1—C1 | 1.355 (2) | C1—C2 | 1.438 (3) |
N1—N2 | 1.385 (2) | C2—C5 | 1.394 (2) |
N1—C14 | 1.452 (3) | C2—C3 | 1.439 (2) |
N2—C3 | 1.312 (2) | C3—C4 | 1.477 (3) |
N3—C5 | 1.330 (2) | | |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3N···O1 | 0.86 | 1.99 | 2.712 (2) | 141 |
Selected bond lengths (Å) for (II) topO1—C1 | 1.248 (3) | N3—C5 | 1.313 (3) |
N1—C1 | 1.360 (3) | N3—C7 | 1.456 (3) |
N1—N2 | 1.385 (3) | C1—C2 | 1.435 (3) |
N1—C10 | 1.447 (3) | C2—C5 | 1.399 (3) |
N2—C3 | 1.312 (3) | C2—C3 | 1.433 (3) |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3N···O1 | 0.86 | 1.96 | 2.691 (3) | 142 |
Pyrazolones constitute an important group of organic compounds (Wiley & Wiley, 1964; Elguero, 1984; Elguero, 1996; Elnagdi et al., 1985), for both theoretical and practical reasons (Kuznetsov et al., 2001). Their application fields include analgesics and antiinflammatory drugs (Kees et al., 1996; Gürzov et al., 2000), dyes (Venkataraman, 1952), chelating extractants for several ions (Petinari et al., 1999, 2000), etc.
In addition, these compounds exhibit prototropic tautomerism, a subject that has attracted much attention (Elguero et al., 1976; Wolfgang & Reiner, 1981; Nivorozhkin et al., 1985; Uraev et al., 1989, 2000; Gilchrist, 2001). In solution, the situation may become quite complex to analyse, since several equilibria among the different possible tautomers may be established. Such equilibria depend on the structure of the compound, its concentration, the nature of the solvent and the temperature (Kurkovskaya et al., 1973). Further difficulties arise from inherent limitations in the spectroscopic techniques used in the study of these equilibria. In spite of this, 1H, 13C and 15N NMR spectroscopies are still very powerful tools to undertake these studies in solution and thus are the most frequently used. Only in those cases where single crystals can be obtained does X-ray diffraction allow the unambiguous establishment of the structure of the tautomeric form (see, for example, O'Connell et al., 1985; Uzoukwu et al., 1993; Akama et al., 1995; Holzer et al., 2003).
Pyrazolones have been obtained by the same synthetic procedure, a condensation between an acylacetate and a hydrazine, for more than a century (Knorr, 1884; Varvouris et al., 2001). In spite of the many advantages of 1-alkylpyrazolone derivatives (viz. their greater solubility), most literature reports deal with 1-phenylpyrazolones or N-1 unsubstituted pyrazolones, and only recently has research aimed at synthesizing 1-alkylpyrazolones and derivatives been undertaken (Bartulin et al., 1992, 1994; Belmar et al., 1997, 1999), paying particular attention to the study of the tautomerism involved. These efforts finally led to the obtention of the title enamines, (I) and (II), derived from 4-acyl-1-(n-hexyl)-3-methyl-5-pyrazolones (Belmar et al., 2004). \sch
The fact that several tautomers can be envisaged for (I) and (II) left open the question of whether there was one single tautomer or a mixture of them in the solid state. Both situations have been shown to occur in related compounds (Foces-Foces et al., 2000). Based upon 1H, 13C and 15N NMR measurements, it was concluded at the time that, in solution (CDCl3), (I) and (II) exist mainly as enamines stabilized by an intramolecular hydrogen bond (case D in Scheme 2). In addition, IR measurements had also suggested that the same tautomeric species was present in the solid state, though unfortunately no single crystals could be obtained to support this hypothesis further. Furthermore, to our knowledge and to date, not a single-crystal structure of enamines derived from alkylpyrazolones has been reported, in contrast with their 1-aryl homologues, of which a few are known (see, for example, Singh et al., 1995; Malhotra et al., 1997; Wang et al., 2003; Jiang et al., 2004). In this paper, we present the first examples of two such structures, (I) and (II). Scheme 2 here.
Figs. 1 and 2 show molecular diagrams of the two structures, and Tables 1 and 3 give selected bond lengths. From the analysis of the values therein, it can be concluded that C1═O1 and C2═C5 are well defined double bonds, and that the shortest bond in the heterocycle (and therefore, the one with enhanced double-bond character) is N2═C3. All these features point to the enamine character of both compounds. In addition, both structures share an intramolecular medium-strength hydrogen bond (N3—H3N···O1; Tables 2 and 4), all of which fully confirms the hypothesis previously raised on spectroscopic grounds alone.
The analogies between the two compounds go even further. The group of 17 atoms determined by the heterocyclic ring, the alkyl substituent at N1 and the C atoms bound to atoms C3, C5 and N3 present exactly the same conformation in both structures, with a least-squares fit (SHELXTL/PC; Sheldrick, 1994) of both moieties giving a mean deviation of 0.08 (1) Å (Fig. 3). Regarding their differences, the largest one arises from the sustituents at N3, a phenyl group in (I) and an alkyl C6H12 chain in (II).
In fact, the alkyl chain lies on a symmetry centre in (II), thus defining a dimeric unit, in contrast with the monomeric character of (I). But even here, there is a striking similarity to be found. In (I), the terminal phenyl groups related by the symmetry operation (1 − x, 1 − y, 1 − z) appear connected by a π–π bond, with an interplanar distance of 3.60 (1) Å, a centre-to-centre distance of 3.78 (1) Å and a slippage angle of 17.7 (1)° (Fig. 1; for details, see Janiak, 2000). This second-order interaction also has the effect of defining some sort of dimer in (I), which thus becomes a structural unit fully comparable with that in (II): both are centrosymmetric, and present the terminal alkyl chains in a position trans to each other, at right angles to the line connecting their bases [angles of the lateral chains to the N1···N1' line are 90.2 (2)° in (I) and 92.9 (2)° in (II)].
Both `dimers', however, have different shapes, which also promote different packing interactions. In (I), the two almost-perpendicular aromatic rings [dihedral angle 80.1 (2)°] develop π–π interactions with their respective centrosymmetric counterparts, the first with that at (1/2,1/2,1/2) (the above-mentioned interaction between the phenyl groups which define the `elementary dimers'), and the second with that at (0,0,1/2), connecting the aromatic system composed of the heterocyclic ring plus C1═O1 and C2═C5 with its (-x, −y, 1 − z) image, 3.50 (3) Å apart and with 4.20 (3) Å between centres, linking the former units together (Fig. 4). Structure (II) instead lacks any particular intermolecular contacts shorter than the usual van der Waals interactions. In spite of these dissimilar interactions, in both structures the terminal alkyl groups arrange in space in a similar way, as centrosymmetric pairs parallel to one another and at a nearest C···C distance of ca 4.20 Å.