Tetra­methyl­ammonium (Z)-N′-cyano­carbamimidate

Butcher, R.J.; Purdy, A.P.

doi:10.1107/S2414314621010981

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 6| Part 11| November 2021| x211098

https://doi.org/10.1107/S2414314621010981

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Tetramethylammonium (Z)-N′-cyanocarbamimidate

Ray J. Butcher ^a ^* and Andrew P. Purdy ^b

^aDepartment of Chemistry, Howard University, 525 College Street NW, Washington DC 20059, USA, and ^bChemistry Division, Code 6123, Naval Research Laboratory, 4555 Overlook Av, SW, Washington DC 20375-5342, USA
^*Correspondence e-mail: rbutcher99@yahoo.com

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 12 October 2021; accepted 20 October 2021; online 4 November 2021)

In the structure of the tetramethyl ammonium salt of cyanourea, C₄H₁₂N⁺·C₂H₂N₃O⁻, the N—C and O—C bond distances in the cyano and keto groups are in the normal range for such a moieties at 1.1641 (18) and 1.2550 (16) Å. However, the bonds about the central C and N atoms are much shorter than would be expected for single bonds and indicate that there is considerable electron delocalization in the anion as was also found in the silver salt. The NH₂ group is coplanar with the central N₂CO core, in contrast with the nitrile group where the dihedral angle between the N—C—N and N₂CO planes is 36.5 (3)°. The packing of the cations and anions in the unit cell involves N—H⋯O hydrogen bonds between anions characterized by an R²₂(8) motif, as well as N—H⋯O hydrogen bonds between anions and C—H⋯O interactions between both cations and anions, forming an R³₃(14) pattern.

Keywords: crystal structure; cyanourea salt; tetramethylammonium salt.

CCDC reference: 2116890

Structure description

Cyanourea and its salts have been the subject of much interest including the use of its derivatives in the study of solid state reaction mechanisms (Lotsch & Schnick, 2004 ), as substituents in manipulating the conformation of calix[4]arenes (Ling et al., 2014 ), in the synthesis of amide-acid chloride adducts in organic synthesis (Harris, 1981 ), and in modulating the magnetic properties of Mn₆ clusters (Yang et al., 2009 ). In spite of this interest there has been very little structural characterization of this moiety and only structures of its ammonium (Lotsch & Schnick, 2004), silver (Britton, 1987 ), and potassium salts (Magomedova & Zvonkova, 1974 ) have been reported.

In the title compound, [C₄H₁₂N]⁺[C₂H₂N₃O]⁻, 1, the tetramethyl ammonium salt of cyanourea is reported and shown in Fig. 1. The N—C and O—C bond distances in the cyano and keto groups [1.1641 (18) and 1.2550 (16) Å,respective] are in the normal range for such a moieties and similar to the values found for the silver salt [1.149 (6) and 1.248 (5) Å, respectively]. However, the bonds about C5 and N3 are much shorter than would be expected for single bonds (Table 1) and indicate that there is considerable electron delocalization in the anion, as was also found in the silver salt. In 1, the NH₂ group is coplanar with the central N₂CO core [dihedral angle between NH₂ and N₂CO planes of only 0.54 (8)°] in contrast with the nitrile group where the dihedral angle between the N—C—N and N₂CO planes is 36.5 (3)°. These values are different to those found in the silver salt where the corresponding angles are 23 (6) and 4.5 (3)°.

Table 1
Selected geometric parameters (Å, °)

O1—C5	1.2550 (16)	N3—C5	1.3703 (17)
N2—C5	1.3464 (18)	N4—C6	1.1641 (18)
N3—C6	1.3155 (19)

C6—N3—C5	114.79 (12)	N2—C5—N3	114.95 (12)
O1—C5—N2	120.31 (12)	N4—C6—N3	174.73 (15)
O1—C5—N3	124.73 (13)

Figure 1
Diagram showing the [C₄H₁₂N]⁺ cation and [C₂H₂N₃O₃]⁻ anion linked by a C—H⋯O interaction (shown as a dashed line). Atomic displacement parameters are drawn at the 30% probability level.

The packing of the cations and anions in the unit cell involves N—H⋯O hydrogen bonds (Table 2) between anions characterized by an R₂²(8) motif as well as N—H⋯O hydrogen bonds between anions and C—H⋯O interactions between both cations and anions forming an R₃³(14) pattern as shown in Fig. 2.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1C⋯O1ⁱ	0.98	2.63	3.487 (2)	147
C2—H2A⋯O1ⁱ	0.98	2.57	3.447 (2)	149
C3—H3B⋯O1ⁱ	0.98	2.62	3.484 (2)	147
C3—H3C⋯O1	0.98	2.30	3.253 (2)	164
C4—H4A⋯N3ⁱⁱ	0.98	2.54	3.450 (2)	155
C4—H4C⋯N3ⁱⁱⁱ	0.98	2.59	3.536 (2)	162
N2—H2D⋯O1^iv	0.88	2.03	2.9084 (16)	174
N2—H2E⋯N4^v	0.88	2.18	3.0126 (19)	158
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (iii) ; (iv) ; (v) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Figure 2
Diagram showing the packing of the cations and anions in the unit cell, which involves N—H⋯O hydrogen bonds between anions characterized by an R₂²(8) motif as well as N—H⋯O hydrogen bonds between anions and C—H⋯O interactions between both cations and anions forming an R₃³(14) pattern (all interactions shown with dashed lines).

Synthesis and crystallization

An ion-exchange column packed with Dowex HCR-W2 resin was regenerated with 3M HCl and washed with water. A solution of 5.00 g of NaN(CN)₂ was run through the column and the product was neutralized with Me₄NOH until alkaline. The solution was roto-vapped to dryness, recrystallized from EtOH, washed with MeOH and recrystallized from EtOH again, and pumped to dryness to afford about 1 g of product. Apparently the dicyanamide was partially hydrolyzed to form cyanourea when in free acid form.

NMR of Me₄N⁺ H₂NC(O)NCN⁻ (D₂O) ¹H: δ3.06; ¹³C (DSS ref): δ58.0 (Me₄N, ¹J_C—N = 4 Hz), 127.0(C≡N), 171.1 (C=O); ¹⁵N(NH₄NO₃ ref): δ22.5 (Me₄N), 62.22 (m, NH₂), 72.18 (N), 150.45 (C≡N).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The structure was refined as a two-component twin with a fractional contribution of 0.0409 (11) for the minor domain.

Table 3
Experimental details

Crystal data
Chemical formula	C₄H₁₂N⁺·C₂H₂N₃O⁻
M_r	158.21
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	8.8120 (4), 8.7561 (4), 12.1093 (6)
β (°)	110.897 (2)
V (Å³)	872.88 (7)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.09
Crystal size (mm)	0.25 × 0.12 × 0.05

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.651, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections	17548, 4340, 2752
R_int	0.156
(sin θ/λ)_max (Å⁻¹)	0.836

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.081, 0.174, 1.04
No. of reflections	4340
No. of parameters	105
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.44, −0.27
Computer programs: APEX2 and SAINT (Bruker, 2016), SHELXT (Sheldrick 2015a ), SHELXL2018/3 (Sheldrick, 2015b ), and SHELXTL (Sheldrick 2008 ).

Structural data

CCDC reference: 2116890

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314621010981/bt4118sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314621010981/bt4118Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314621010981/bt4118Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick 2008); software used to prepare material for publication: SHELXTL (Sheldrick 2008).

Tetramethylammonium (Z)-N'-cyanocarbamimidate top

Crystal data top

C₄H₁₂N⁺·C₂H₂N₃O⁻	F(000) = 344
M_r = 158.21	D_x = 1.204 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.8120 (4) Å	Cell parameters from 3088 reflections
b = 8.7561 (4) Å	θ = 2.9–36.0°
c = 12.1093 (6) Å	µ = 0.09 mm⁻¹
β = 110.897 (2)°	T = 100 K
V = 872.88 (7) Å³	Prism, colourless
Z = 4	0.25 × 0.12 × 0.05 mm

Data collection top

Bruker APEXII CCD diffractometer	2752 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.156
Absorption correction: multi-scan (Sadabs; Bruker, 2016)	θ_max = 36.4°, θ_min = 2.9°
T_min = 0.651, T_max = 0.747	h = −14→14
17548 measured reflections	k = −14→14
4340 independent reflections	l = −20→20

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.081	H-atom parameters constrained
wR(F²) = 0.174	w = 1/[σ²(F_o²) + (0.064P)² + 0.1366P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
4340 reflections	Δρ_max = 0.44 e Å⁻³
105 parameters	Δρ_min = −0.27 e Å⁻³

Special details top

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. Refined as a 2-component twin. The structure was solved using SHELXT (Sheldrick, 2015a) and refined with SHELXL2018 (Sheldrick, 2015b). The locations of all hydrogen atoms for the major component were located in difference Fourier maps and refined in idealized position using a riding model with atomic displacement parameters of U_iso(H) = 1.2U_eq(C, N) [1.5U_eq(C) for CH₃], with N—H distance of 0.88 Å and C—H distances ranging from 0.95 to 0.99 Å, respectively.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.52001 (13)	0.39529 (14)	0.77065 (11)	0.0155 (2)
C1	0.65132 (18)	0.3158 (2)	0.86761 (18)	0.0271 (3)
H1A	0.717795	0.391510	0.923711	0.041*
H1B	0.719731	0.257919	0.834033	0.041*
H1C	0.602538	0.245780	0.908689	0.041*
C2	0.4173 (2)	0.2805 (2)	0.68548 (17)	0.0289 (3)
H2A	0.367659	0.211613	0.726730	0.043*
H2B	0.484911	0.221365	0.651990	0.043*
H2C	0.331794	0.333191	0.621804	0.043*
C3	0.41712 (17)	0.4843 (2)	0.82257 (14)	0.0215 (3)
H3A	0.484635	0.559198	0.878912	0.032*
H3B	0.367829	0.414567	0.863515	0.032*
H3C	0.331387	0.537379	0.759369	0.032*
C4	0.5940 (2)	0.5019 (2)	0.70750 (15)	0.0238 (3)
H4A	0.666165	0.573678	0.764306	0.036*
H4B	0.507855	0.558664	0.647290	0.036*
H4C	0.656586	0.443175	0.669525	0.036*
O1	0.16653 (13)	0.63130 (14)	0.57913 (9)	0.0193 (2)
N2	0.04603 (16)	0.59992 (17)	0.38199 (11)	0.0232 (3)
H2D	−0.024142	0.534851	0.391904	0.028*
H2E	0.041806	0.623148	0.310245	0.028*
N3	0.26105 (14)	0.76503 (15)	0.45058 (11)	0.0172 (2)
N4	0.46972 (16)	0.89392 (18)	0.61890 (12)	0.0230 (3)
C5	0.15986 (15)	0.66395 (15)	0.47658 (12)	0.0139 (2)
C6	0.36986 (15)	0.82986 (16)	0.54310 (12)	0.0150 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0151 (4)	0.0119 (4)	0.0204 (5)	−0.0002 (4)	0.0074 (4)	0.0002 (4)
C1	0.0182 (6)	0.0206 (7)	0.0386 (9)	0.0056 (5)	0.0053 (6)	0.0070 (7)
C2	0.0337 (7)	0.0235 (7)	0.0285 (8)	−0.0118 (6)	0.0099 (7)	−0.0097 (7)
C3	0.0202 (5)	0.0247 (7)	0.0223 (6)	0.0058 (5)	0.0109 (5)	0.0006 (5)
C4	0.0322 (7)	0.0196 (7)	0.0257 (7)	−0.0061 (5)	0.0179 (6)	−0.0015 (5)
O1	0.0229 (4)	0.0226 (5)	0.0125 (4)	−0.0056 (4)	0.0062 (4)	0.0014 (4)
N2	0.0280 (5)	0.0266 (6)	0.0124 (5)	−0.0125 (5)	0.0040 (4)	−0.0013 (5)
N3	0.0199 (5)	0.0182 (5)	0.0130 (4)	−0.0040 (4)	0.0052 (4)	0.0008 (4)
N4	0.0232 (5)	0.0280 (7)	0.0167 (5)	−0.0061 (5)	0.0058 (4)	−0.0017 (5)
C5	0.0156 (5)	0.0121 (5)	0.0137 (5)	0.0006 (4)	0.0047 (4)	0.0002 (4)
C6	0.0160 (5)	0.0155 (5)	0.0148 (5)	0.0013 (4)	0.0069 (4)	0.0022 (4)

Geometric parameters (Å, º) top

N1—C2	1.492 (2)	C3—H3C	0.9800
N1—C3	1.4937 (17)	C4—H4A	0.9800
N1—C1	1.494 (2)	C4—H4B	0.9800
N1—C4	1.4958 (19)	C4—H4C	0.9800
C1—H1A	0.9800	O1—C5	1.2550 (16)
C1—H1B	0.9800	N2—C5	1.3464 (18)
C1—H1C	0.9800	N2—H2D	0.8800
C2—H2A	0.9800	N2—H2E	0.8800
C2—H2B	0.9800	N3—C6	1.3155 (19)
C2—H2C	0.9800	N3—C5	1.3703 (17)
C3—H3A	0.9800	N4—C6	1.1641 (18)
C3—H3B	0.9800

C2—N1—C3	109.42 (12)	N1—C3—H3B	109.5
C2—N1—C1	109.76 (14)	H3A—C3—H3B	109.5
C3—N1—C1	109.17 (12)	N1—C3—H3C	109.5
C2—N1—C4	109.55 (13)	H3A—C3—H3C	109.5
C3—N1—C4	109.31 (12)	H3B—C3—H3C	109.5
C1—N1—C4	109.62 (12)	N1—C4—H4A	109.5
N1—C1—H1A	109.5	N1—C4—H4B	109.5
N1—C1—H1B	109.5	H4A—C4—H4B	109.5
H1A—C1—H1B	109.5	N1—C4—H4C	109.5
N1—C1—H1C	109.5	H4A—C4—H4C	109.5
H1A—C1—H1C	109.5	H4B—C4—H4C	109.5
H1B—C1—H1C	109.5	C5—N2—H2D	120.0
N1—C2—H2A	109.5	C5—N2—H2E	120.0
N1—C2—H2B	109.5	H2D—N2—H2E	120.0
H2A—C2—H2B	109.5	C6—N3—C5	114.79 (12)
N1—C2—H2C	109.5	O1—C5—N2	120.31 (12)
H2A—C2—H2C	109.5	O1—C5—N3	124.73 (13)
H2B—C2—H2C	109.5	N2—C5—N3	114.95 (12)
N1—C3—H3A	109.5	N4—C6—N3	174.73 (15)

C6—N3—C5—O1	−0.5 (2)	C6—N3—C5—N2	178.60 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1C···O1ⁱ	0.98	2.63	3.487 (2)	147
C2—H2A···O1ⁱ	0.98	2.57	3.447 (2)	149
C3—H3B···O1ⁱ	0.98	2.62	3.484 (2)	147
C3—H3C···O1	0.98	2.30	3.253 (2)	164
C4—H4A···N3ⁱⁱ	0.98	2.54	3.450 (2)	155
C4—H4C···N3ⁱⁱⁱ	0.98	2.59	3.536 (2)	162
N2—H2D···O1^iv	0.88	2.03	2.9084 (16)	174
N2—H2E···N4^v	0.88	2.18	3.0126 (19)	158

Symmetry codes: (i) −x+1/2, y−1/2, −z+3/2; (ii) x+1/2, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) −x, −y+1, −z+1; (v) x−1/2, −y+3/2, z−1/2.

Funding information

RJB wishes to acknowledge the ONR Summer Faculty Research Program for funding in 2019 and 2020.

References

Britton, D. (1987). Acta Cryst. C43, 2442–2443. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Harris, R. L. N. (1981). Synthesis, pp. 907–908. CrossRef Google Scholar
Ling, I., Skelton, B. W., Sobolev, A. N., Alias, Y. & Raston, C. L. (2014). CrystEngComm, 16, 5159–5164. Web of Science CSD CrossRef CAS Google Scholar
Lotsch, B. V. & Schnick, W. (2004). Z. Naturforsch. Teil B, 59, 1229–1240. CAS Google Scholar
Magomedova, N. S. & Zvonkova, Z. V. (1974). J. Struct. Chem. 15, 156–157. CrossRef Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Yang, C.-I., Cheng, K.-H., Nakano, M., Lee, G.-H. & Tsai, H.-L. (2009). Polyhedron, 28, 1842–1851. Web of Science CSD CrossRef CAS Google Scholar

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