6-Ethyl-5,7-di­methyl-6H-1,4-diazepine-2,3-dicarbo­nitrile

In the title compound, C₁₁H₁₂N₄, the diazepine ring exhibits a boat conformation, where the displacements of the C atoms attached to the nitrile groups and the C atom attached to the ethyl group are 0.591 (1), 0.585 (1) and 0.845 (1) Å from the base of the boat.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.043
• wR factor = 0.111
• Data-to-parameter ratio = 17.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_371  Alert C Long   C(sp2)-C(sp1) Bond  C(2)   -   C(10)  =       1.44 Ang.

PLAT_371  Alert C Long   C(sp2)-C(sp1) Bond  C(3)   -   C(12)  =       1.45 Ang.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

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S1. Comment

The present work is a continuation of our investigations of chemical properties of diaminomaleonitrile (Sidorov et al., 1999; Nesterov et al., 2001). We sythesized 6-ethyl-5,7-dimethyl-6H-1,4-diazepine-2,3-dicarbonitrile, (I), and investigated its structure (Fig. 1). Although such 1,4-diazepine derivatives have been known for a long time (Begland et al., 1974; Ohtsuka, 1976) their structures have not yet been sufficiently investigated. In the Cambridge Structural Database (CSD; Allen, 2002), we found only two examples (Donzello et al., 1999; Mague & Eduok, 2000). Such compounds can be used as starting materails in the synthesis of bi- and triheterocyclic systems (Essaber et al., 1998). 5,7-Diphenyl-1,4-diazepine have been used as dicyano monomeric precursor for the synthesis of a new class of porphyrazine macrocycles (Donzello et al., 1999). According to literature data (Begland et al., 1974), such compounds can be readily oxidized to the corresponding dihydrodiazepines.

The geometric parameters in the investigated compound are very similar to those found in 5,7-dimethyl-6H-1,4-diazepine-2,3-dicarbonitrile and 5,7-diphenyl-6H-1,4-diazepine-2,3-dicarbonitrile (Mague et al., 2000; Donzello et al., 1999). The diazepine ring in (I) exhibits a boat conformation. The displacements of atoms C2, C3 and C6 from the mean N1/N4/C5/C7 plane are 0.591 (1), 0.585 (1) and 0.845 (1) Å, respectively. The dihedral angles between the N1/N4/C5/C7 mean plane and the C5/C6/C7 and N1/C2/C3/N4 planes are 60.2 (1) and 32.0 (1)°, respectively. The ethyl substituent in (I) has an equatorial orientation, as can be seen in Fig. 1.

The bond lengths in diazepine ring have values intermediate between single- and double-bond values (Allen et al., 1987). This indicates that π-conjugation exists in the fragment of molecule, that includes those bonds, despite the fact that the diazepine ring is not planar.

S2. Experimental

The title compound, (I), was obtained according to the following procedure, which is different from the literature method of Begland et al. (1974): diaminomaleonitrile (1.08 g, 0.010 mol) and 3-ethyl-2,4-pentanedione (1.34 ml, 0.010 mol) were heated to boiling in ethanol solution (20 ml) in the presence of a catalytic amount of acetic acid. The precipitate which formed was separated and recrystallized from ethanol (30 ml) [m.p. 461 K; yield 1.58 g (79%)]. Crystals were obtained by isothermal evaporation from an ethanol solution.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: SHELXTL (Sheldrick, 1994); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. A view of compound (I), showing the atom numbering used. The non-H atoms are shown with displacement ellipsoids drawn at the 50% probability level.

(I)

Crystal data

C11H12N4	F(000) = 424
Mr = 200.25	Dx = 1.208 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.4160 (15) Å	Cell parameters from 24 reflections
b = 13.344 (3) Å	θ = 10–11°
c = 11.141 (2) Å	µ = 0.08 mm^−1
β = 92.90 (3)°	T = 295 K
V = 1101.1 (4) Å^3	Prism, colorless
Z = 4	0.40 × 0.30 × 0.20 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.031
Radiation source: fine-focus sealed tube	θmax = 27.0°, θmin = 2.4°
Graphite monochromator	h = 0→9
θ/2θ scans	k = 0→17
2560 measured reflections	l = −14→14
2381 independent reflections	3 standard reflections every 97 reflections
1380 reflections with I > 2σ(I)	intensity decay: 3%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.111	H-atom parameters constrained
S = 1.18	w = 1/[σ^2(Fo^2) + (0.045P)^2] where = (Fo^2 + 2Fc^2)/3
2381 reflections	(Δ/σ)max < 0.001
139 parameters	Δρmax = 0.13 e Å^−3
0 restraints	Δρmin = −0.12 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. All H atoms were placed in geometrically calculated positions and refined using a riding model.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.10731 (19)	0.18980 (10)	0.38935 (11)	0.0464 (4)
N4	0.12346 (19)	0.07830 (10)	0.62176 (12)	0.0440 (4)
N11	0.3273 (3)	0.01951 (14)	0.22649 (16)	0.0760 (6)
N13	0.3415 (2)	−0.12728 (12)	0.52073 (16)	0.0663 (5)
C2	0.2007 (2)	0.10241 (12)	0.41329 (14)	0.0434 (4)
C3	0.2074 (2)	0.05144 (12)	0.51989 (15)	0.0415 (4)
C5	0.1093 (2)	0.17159 (12)	0.65030 (14)	0.0431 (4)
C6	0.2114 (2)	0.25156 (12)	0.58571 (13)	0.0420 (4)
H6A	0.3284	0.2233	0.5663	0.050*
C7	0.0961 (2)	0.25762 (12)	0.47089 (14)	0.0433 (4)
C8	−0.0404 (3)	0.33896 (13)	0.45013 (17)	0.0605 (5)
H8A	−0.1029	0.3293	0.3734	0.091*
H8B	0.0194	0.4028	0.4514	0.091*
H8C	−0.1254	0.3370	0.5123	0.091*
C9	−0.0172 (3)	0.19930 (14)	0.74478 (16)	0.0586 (5)
H9A	−0.0670	0.1396	0.7779	0.088*
H9B	−0.1130	0.2399	0.7099	0.088*
H9C	0.0469	0.2363	0.8073	0.088*
C10	0.2695 (3)	0.05489 (13)	0.30876 (16)	0.0528 (5)
C12	0.2809 (2)	−0.04902 (14)	0.52091 (15)	0.0481 (4)
C14	0.2470 (3)	0.34919 (13)	0.65255 (17)	0.0548 (5)
H14A	0.3016	0.3348	0.7316	0.066*
H14B	0.1333	0.3832	0.6631	0.066*
C15	0.3710 (3)	0.41741 (15)	0.58535 (19)	0.0757 (7)
H15A	0.3936	0.4775	0.6310	0.114*
H15D	0.3146	0.4343	0.5085	0.114*
H15B	0.4831	0.3836	0.5740	0.114*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0512 (9)	0.0451 (8)	0.0427 (8)	−0.0064 (7)	0.0018 (6)	0.0015 (7)
N4	0.0452 (8)	0.0434 (8)	0.0437 (8)	−0.0031 (7)	0.0063 (6)	0.0022 (6)
N11	0.0906 (14)	0.0739 (12)	0.0658 (11)	−0.0107 (10)	0.0271 (10)	−0.0185 (9)
N13	0.0662 (11)	0.0535 (10)	0.0793 (12)	0.0081 (9)	0.0056 (9)	0.0026 (9)
C2	0.0427 (10)	0.0452 (9)	0.0425 (9)	−0.0082 (8)	0.0041 (8)	−0.0045 (8)
C3	0.0368 (9)	0.0396 (9)	0.0481 (9)	−0.0049 (7)	0.0025 (7)	−0.0019 (8)
C5	0.0440 (10)	0.0459 (10)	0.0392 (9)	−0.0031 (8)	0.0004 (7)	0.0006 (8)
C6	0.0415 (9)	0.0424 (9)	0.0425 (9)	−0.0052 (8)	0.0047 (7)	−0.0018 (7)
C7	0.0470 (10)	0.0396 (9)	0.0435 (9)	−0.0081 (8)	0.0056 (8)	0.0035 (8)
C8	0.0658 (13)	0.0502 (11)	0.0648 (12)	0.0068 (9)	−0.0033 (10)	0.0009 (9)
C9	0.0674 (12)	0.0544 (11)	0.0557 (10)	−0.0057 (10)	0.0199 (10)	−0.0052 (9)
C10	0.0594 (12)	0.0485 (10)	0.0510 (11)	−0.0098 (9)	0.0098 (9)	−0.0066 (9)
C12	0.0431 (10)	0.0483 (11)	0.0533 (11)	−0.0029 (9)	0.0056 (8)	−0.0014 (8)
C14	0.0585 (12)	0.0528 (11)	0.0532 (11)	−0.0129 (9)	0.0036 (9)	−0.0064 (8)
C15	0.0849 (16)	0.0634 (13)	0.0794 (14)	−0.0327 (12)	0.0095 (12)	−0.0093 (11)

Geometric parameters (Å, º)

N1—C7	1.288 (2)	C7—C8	1.494 (2)
N1—C2	1.376 (2)	C8—H8A	0.9600
N4—C5	1.290 (2)	C8—H8B	0.9600
N4—C3	1.370 (2)	C8—H8C	0.9600
N11—C10	1.134 (2)	C9—H9A	0.9600
N13—C12	1.137 (2)	C9—H9B	0.9600
C2—C3	1.367 (2)	C9—H9C	0.9600
C2—C10	1.442 (2)	C14—C15	1.518 (3)
C3—C12	1.447 (2)	C14—H14A	0.9700
C5—C9	1.492 (3)	C14—H14B	0.9700
C5—C6	1.511 (2)	C15—H15A	0.9600
C6—C7	1.504 (2)	C15—H15D	0.9600
C6—C14	1.517 (2)	C15—H15B	0.9600
C6—H6A	0.9800
C7—N1—C2	120.58 (14)	C7—C8—H8C	109.5
C5—N4—C3	120.18 (14)	H8A—C8—H8C	109.5
C3—C2—N1	125.88 (15)	H8B—C8—H8C	109.5
C3—C2—C10	118.95 (16)	C5—C9—H9A	109.5
N1—C2—C10	114.30 (15)	C5—C9—H9B	109.5
C2—C3—N4	126.26 (15)	H9A—C9—H9B	109.5
C2—C3—C12	117.70 (15)	C5—C9—H9C	109.5
N4—C3—C12	115.02 (14)	H9A—C9—H9C	109.5
N4—C5—C9	118.35 (15)	H9B—C9—H9C	109.5
N4—C5—C6	120.99 (15)	N11—C10—C2	178.08 (19)
C9—C5—C6	120.59 (14)	N13—C12—C3	178.72 (19)
C7—C6—C5	99.57 (12)	C6—C14—C15	111.57 (15)
C7—C6—C14	116.65 (15)	C6—C14—H14A	109.3
C5—C6—C14	116.84 (13)	C15—C14—H14A	109.3
C7—C6—H6A	107.7	C6—C14—H14B	109.3
C5—C6—H6A	107.7	C15—C14—H14B	109.3
C14—C6—H6A	107.7	H14A—C14—H14B	108.0
N1—C7—C8	117.94 (16)	C14—C15—H15A	109.5
N1—C7—C6	120.52 (15)	C14—C15—H15D	109.5
C8—C7—C6	121.48 (15)	H15A—C15—H15D	109.5
C7—C8—H8A	109.5	C14—C15—H15B	109.5
C7—C8—H8B	109.5	H15A—C15—H15B	109.5
H8A—C8—H8B	109.5	H15D—C15—H15B	109.5
C7—N1—C2—C3	36.5 (2)	C9—C5—C6—C7	−100.26 (17)
C7—N1—C2—C10	−154.38 (15)	N4—C5—C6—C14	−156.72 (16)
N1—C2—C3—N4	−0.3 (3)	C9—C5—C6—C14	26.3 (2)
C10—C2—C3—N4	−168.93 (15)	C2—N1—C7—C8	−166.01 (15)
N1—C2—C3—C12	167.48 (15)	C2—N1—C7—C6	11.1 (2)
C10—C2—C3—C12	−1.2 (2)	C5—C6—C7—N1	−76.88 (17)
C5—N4—C3—C2	−36.1 (2)	C14—C6—C7—N1	156.47 (15)
C5—N4—C3—C12	155.79 (16)	C5—C6—C7—C8	100.15 (17)
C3—N4—C5—C9	166.41 (15)	C14—C6—C7—C8	−26.5 (2)
C3—N4—C5—C6	−10.7 (2)	C7—C6—C14—C15	−70.0 (2)
N4—C5—C6—C7	76.76 (18)	C5—C6—C14—C15	172.46 (16)