N,N-Bis(cyano­meth­yl)nitrous amide

In the title compound, C₄H₄N₄O, both H atoms bonded to one methyl­ene C atom are involved in C—H...N hydrogen-bonding inter­actions; one of the inter­actions results in dimers of the title mol­ecule lying about inversion centers in R₂²(12) motifs and the other forms chains of mol­ecules lying along the c axis.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.050
• wR factor = 0.162
• Data-to-parameter ratio = 17.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C1     --  C2      ..       5.64 su
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          3

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

At present, much attention in the field of ferroelectric materials is focused on developing ferroelectric organic or inorganic compounds (Haertling et al., 1999; Homes et al., 2001). It has been reported that N,N-bis(cyanomethyl)nitramide crystallizes in space group (C 2) at room temperature (Adolf et al., 1996), a noncentrosymmetric space group is required for ferroelectric behavior. Its ferroelectric property still needs to be further confirmed by many experiments, such as dielectric measurements and DSC to varify the permittivity anomaly, phase transition, etc. For this reason, we have synthesized the title compound to investigate its physical properties. The dielectric constant of the title compound as a function of temperature indicates that the permittivity is basically temperature-independent (dielectric constant = 3.2 to 5.6), suggesting that this compound should not be a real ferroelectric or there may be no distinct phase transition within the measured temperature range. Similarly, below the melting point (308 K) of the compound, the dielectric constant as a function of temperature also goes smoothly, and there is no dielectric anomaly observed. Herein, we report the synthesis and crystal structure of the title compound.

The bond distances and bond angles in the title compound agree very well with the corresponding distances and angles reported for a closely related compound (Kaida et al., 1990); both cyanic groups are linear (Fig. 1). It is interesting to note that both H-atoms bonded to only one methylene carbon (C3) are involved in hydrogen bonding interactions of the type C—H···N, C3—H3B···N2 hydrogen bonds result in dimers of the title molecule lying about inversion centers in R₂²(12) motifs in graph set notation (Bernstein et al., 1994) while C3—H3C···N1 interactions result in chains of molecules lying along the c-axis (Tab. 1, Fig. 2). Dipole–dipole and van der Waals interactions are effective in the molecular packing.

Related literature

For background to ferroelectric compounds, see: Haertling et al. (1999); Homes et al. (2001). For related structures, see: Adolf et al. (1996); Kaida et al. (1990). For graph-set notation, see: Bernstein et al. (1994).

S2. Experimental

A solution of sodium nitrite (2.3 g, 33 mmoles) in water (10 ml) was added at 291–293 K to a solution of 2,2'-azanediyldiacetonitrile hydrochloride (1.7 g, 28 mmoles) in water (30 ml). The mixture was heated for 1.5 h at 313–323 K and allowed to stand for 12 h at 293 K. The title compound as nitroso derivative, was extracted with ether, the ether solution was evaporated. Single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of an ethyl acetate solution of the title compound.

S3. Refinement

H atoms were positioned geometrically and refined using a riding model, with C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. Perspective drawing of the title compound with displacement ellipsoids drawn at the 30% probability level.
	Fig. 2. The crystal packing of the title compound viewed along the a-axis showing H-bondings interactions; the H atoms not involved in H-bonds have been ommitted for clarity.

N,N-Bis(cyanomethyl)nitrous amide

Crystal data

C4H4N4O	F(000) = 256
Mr = 124.11	Dx = 1.341 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1409 reflections
a = 6.5622 (13) Å	θ = 2.3–27.5°
b = 8.9765 (18) Å	µ = 0.10 mm^−1
c = 11.008 (4) Å	T = 293 K
β = 108.55 (3)°	Prism, colorless
V = 614.7 (3) Å^3	0.20 × 0.20 × 0.20 mm
Z = 4

Data collection

Rigaku Mercury2 diffractometer	1408 independent reflections
Radiation source: fine-focus sealed tube	1094 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.059
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 3.0°
CCD_Profile_fitting scans	h = −8→8
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −11→11
Tmin = 0.742, Tmax = 1.000	l = −14→14
6154 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.050	H-atom parameters constrained
wR(F^2) = 0.162	w = 1/[σ^2(Fo^2) + (0.1P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1408 reflections	Δρmax = 0.20 e Å^−3
83 parameters	Δρmin = −0.20 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.15 (2)

Special details

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

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.

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

	x	y	z	Uiso*/Ueq
O1	0.1721 (2)	−0.00421 (14)	0.24979 (14)	0.0738 (5)
N1	0.1213 (3)	0.3227 (2)	0.03826 (14)	0.0730 (6)
N2	0.6354 (3)	0.36079 (17)	0.61699 (14)	0.0593 (5)
N3	0.3553 (2)	0.02971 (15)	0.31634 (14)	0.0537 (5)
N4	0.38510 (18)	0.17474 (12)	0.33544 (10)	0.0345 (4)
C2	0.6201 (2)	0.29919 (17)	0.52436 (14)	0.0411 (4)
C1	0.6039 (2)	0.22069 (18)	0.40327 (13)	0.0419 (4)
H1A	0.6543	0.2860	0.3487	0.050*
H1B	0.6962	0.1336	0.4222	0.050*
C4	0.1609 (2)	0.30241 (19)	0.14509 (15)	0.0439 (4)
C3	0.2111 (2)	0.28025 (16)	0.28328 (13)	0.0405 (4)
H3B	0.2504	0.3752	0.3264	0.049*
H3C	0.0835	0.2446	0.3006	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0564 (9)	0.0523 (9)	0.0991 (11)	−0.0192 (6)	0.0056 (7)	−0.0124 (6)
N1	0.0569 (11)	0.1157 (16)	0.0448 (9)	0.0196 (9)	0.0140 (7)	0.0171 (8)
N2	0.0655 (11)	0.0593 (10)	0.0484 (8)	−0.0107 (8)	0.0113 (7)	−0.0105 (7)
N3	0.0509 (9)	0.0336 (8)	0.0697 (10)	−0.0029 (6)	0.0094 (7)	−0.0008 (6)
N4	0.0342 (7)	0.0298 (7)	0.0356 (7)	0.0010 (5)	0.0056 (5)	0.0001 (4)
C2	0.0369 (8)	0.0392 (8)	0.0407 (8)	−0.0047 (6)	0.0032 (6)	0.0029 (6)
C1	0.0357 (9)	0.0485 (9)	0.0387 (8)	−0.0044 (7)	0.0076 (6)	−0.0030 (6)
C4	0.0339 (8)	0.0545 (9)	0.0390 (9)	0.0035 (7)	0.0058 (6)	0.0048 (6)
C3	0.0449 (9)	0.0372 (8)	0.0352 (8)	0.0099 (6)	0.0067 (6)	−0.0017 (6)

Geometric parameters (Å, º)

O1—N3	1.2305 (18)	C2—C1	1.481 (2)
N1—C4	1.135 (2)	C1—H1A	0.9700
N2—C2	1.136 (2)	C1—H1B	0.9700
N3—N4	1.3233 (18)	C4—C3	1.464 (2)
N4—C1	1.4516 (18)	C3—H3B	0.9700
N4—C3	1.4539 (17)	C3—H3C	0.9700
O1—N3—N4	113.89 (13)	C2—C1—H1B	109.2
N3—N4—C1	115.67 (12)	H1A—C1—H1B	107.9
N3—N4—C3	121.36 (12)	N1—C4—C3	178.53 (19)
C1—N4—C3	122.83 (12)	N4—C3—C4	112.80 (12)
N2—C2—C1	178.83 (17)	N4—C3—H3B	109.0
N4—C1—C2	111.97 (13)	C4—C3—H3B	109.0
N4—C1—H1A	109.2	N4—C3—H3C	109.0
C2—C1—H1A	109.2	C4—C3—H3C	109.0
N4—C1—H1B	109.2	H3B—C3—H3C	107.8

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3B···N2^i	0.97	2.50	3.450 (2)	165
C3—H3C···N1^ii	0.97	2.62	3.183 (2)	117

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, −y+1/2, z+1/2.