Formaldehyde–amino­guanidine condensation and amino­guanidine self-condensation products: syntheses, crystal structures and characterization

Guanidine is the functional group on the side chain of arginine, one of the fundamental building blocks of life. In recent years, a number of compounds based on the aminoguanidine (AG) moiety have been described as presenting high anti­cancer activities. The product of condensation between two mol­ecules of AG and one mol­ecule of formaldehyde was isolated in the protonated form as the dinitrate salt (systematic name: 2,8-di­amino-1,3,4,6,7,9-hexa­aza­nona-1,8-diene-1,9-diium dinitrate), C₃H₁₄N₈²⁺·2NO₃⁻, (I). The cation lacks crystallographically imposed symmetry and comprises two terminal planar guani­dinium groups, which share an N—C—N unit. Each cation in (I) builds 14 N—H...O hydrogen bonds and is separated from adjacent cations by seven nitrate anions. The AG self-condensation reaction in the presence of copper(II) chloride and chloride anions led to the formation of the organic–inorganic hy­brid 1,2-bis­(di­amino­methyl­idene)hydrazine-1,2-diium tetra­chlorido­cup­rate(II), (C₂H₁₀N₆)[CuCl₄], (II). Its asymmetric unit is composed of half a diprotonated 1,2-bis­(di­amino­methyl­idene)hydrazine-1,2-diium dication and half a tetra­chlorido­cuprate(II) dianion, with the Cu^II atom situated on a twofold rotation axis. The planar guanidinium fragments in (II) have their planes twisted by approximately 77.64 (5)° with respect to each other. The tetra­hedral [CuCl₄]²⁻ anion is severely distorted and its pronounced `planarity' must originate from its involvement in multiple N—H...Cl hydrogen bonds. It was reported that [CuCl₄]²⁻ anions, with a trans-Cl—Cu—Cl angle (Θ) of ∼140°, are yellow–green at room temperature, with the colour shifting to a deeper green as Θ increases and toward orange as Θ decreases. Brown salt (II), with a Θ value of 142.059 (8)°, does not fit the trend, which emphasizes the need to take other structural factors into consideration. In the crystal of salt (II), layers of cations and anions alternate along the b axis, with the minimum Cu...Cu distance being 7.5408 (3) Å inside a layer. The structures of salts (I) and (II) were substanti­ated via spectroscopic data. The endothermic reaction involved in the thermal decomposition of (I) requires additional oxygen. The title salts may be useful for the screening of new substances with biological activity.

Computing details

For both structures, data collection: CrysAlis PRO (Rigaku OD, 2016); cell refinement: CrysAlis PRO (Rigaku OD, 2016); data reduction: CrysAlis PRO (Rigaku OD, 2016). Program(s) used to solve structure: SHELXT (Sheldrick, 2015a) for (I); SIR92 (Altomare et al., 1994) for (II). For both structures, program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012).

2,8-Diamino-1,3,4,6,7,9-hexaazanona-1,8-diene-1,9-diium dinitrate (I)

Crystal data

C3H14N8^2+·2NO3^−	F(000) = 1200
Mr = 286.24	Dx = 1.624 Mg m^−3
Orthorhombic, Pccn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2ac	Cell parameters from 2603 reflections
a = 12.6989 (4) Å	θ = 2.6–29.3°
b = 13.0236 (6) Å	µ = 0.15 mm^−1
c = 14.1585 (5) Å	T = 100 K
V = 2341.61 (15) Å^3	Block, colourless
Z = 8	0.37 × 0.24 × 0.06 mm

Data collection

Oxford diffraction Gemini diffractometer	3255 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo)-ray Source	2307 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
Detector resolution: 10.4738 pixels mm^-1	θmax = 30.8°, θmin = 2.2°
ω scans	h = −11→17
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD, 2016) .	k = −18→11
Tmin = 0.968, Tmax = 1	l = −19→8
8505 measured reflections

Refinement

Refinement on F^2	11 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.052	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.115	w = 1/[σ^2(Fo^2) + (0.0413P)^2 + 0.674P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
3255 reflections	Δρmax = 0.25 e Å^−3
220 parameters	Δρmin = −0.29 e Å^−3

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. All N-H hydrogen aioms were refined with N-H distances restrained to ideal values.

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

	x	y	z	Uiso*/Ueq
C1	0.21357 (13)	0.60635 (14)	0.46673 (12)	0.0175 (4)
N11	0.19182 (12)	0.63126 (14)	0.55552 (11)	0.0236 (4)
N12	0.13797 (12)	0.59940 (13)	0.40314 (11)	0.0190 (3)
N2	0.31350 (12)	0.59018 (13)	0.44313 (11)	0.0199 (3)
N3	0.33748 (11)	0.55401 (13)	0.35225 (10)	0.0195 (3)
C4	0.38560 (13)	0.63247 (16)	0.29400 (12)	0.0208 (4)
H4A	0.3327	0.6868	0.282	0.025*
H4B	0.404	0.6015	0.2323	0.025*
N5	0.48020 (11)	0.68072 (13)	0.33326 (11)	0.0194 (3)
N6	0.57409 (11)	0.63746 (13)	0.29624 (11)	0.0197 (3)
C7	0.65775 (13)	0.63107 (14)	0.35375 (12)	0.0171 (4)
N71	0.64592 (12)	0.64372 (13)	0.44527 (11)	0.0197 (3)
N72	0.75106 (12)	0.60993 (14)	0.31675 (12)	0.0257 (4)
N10	0.60067 (11)	0.63915 (12)	0.05062 (10)	0.0183 (3)
O11	0.69065 (9)	0.63666 (10)	0.08552 (9)	0.0229 (3)
O12	0.52494 (9)	0.66907 (12)	0.10032 (9)	0.0275 (3)
O13	0.58491 (10)	0.61236 (11)	−0.03341 (9)	0.0225 (3)
N20	0.04438 (11)	0.61546 (12)	0.17039 (10)	0.0186 (3)
O21	0.02224 (9)	0.58917 (11)	0.08758 (8)	0.0222 (3)
O22	0.13665 (9)	0.64234 (12)	0.19105 (9)	0.0263 (3)
O23	−0.02482 (9)	0.61388 (10)	0.23304 (9)	0.0230 (3)
H11A	0.1270 (13)	0.6482 (17)	0.5690 (15)	0.032 (6)*
H11B	0.2437 (15)	0.6359 (17)	0.5962 (14)	0.038 (7)*
H12A	0.0736 (12)	0.6060 (15)	0.4198 (14)	0.019 (5)*
H12B	0.1511 (16)	0.5866 (18)	0.3441 (12)	0.033 (6)*
H1	0.3593 (17)	0.5972 (16)	0.4845 (16)	0.028 (6)*
H3	0.3814 (13)	0.5020 (14)	0.3569 (14)	0.023 (5)*
H5	0.4794 (15)	0.7474 (13)	0.3191 (14)	0.024 (6)*
H6	0.5840 (15)	0.6467 (16)	0.2363 (11)	0.027 (6)*
H71A	0.5820 (13)	0.6511 (17)	0.4688 (15)	0.032 (6)*
H71B	0.6974 (14)	0.6361 (16)	0.4832 (14)	0.030 (6)*
H72A	0.8055 (15)	0.6022 (18)	0.3533 (15)	0.039 (7)*
H72B	0.7564 (17)	0.5998 (18)	0.2574 (12)	0.037 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0173 (8)	0.0197 (10)	0.0156 (8)	−0.0011 (7)	−0.0016 (6)	0.0018 (7)
N11	0.0151 (8)	0.0399 (11)	0.0158 (7)	−0.0008 (7)	0.0009 (6)	−0.0031 (7)
N12	0.0140 (7)	0.0286 (9)	0.0144 (7)	0.0020 (6)	−0.0011 (6)	−0.0007 (7)
N2	0.0150 (7)	0.0317 (10)	0.0130 (7)	0.0004 (6)	−0.0023 (6)	−0.0017 (7)
N3	0.0173 (7)	0.0251 (9)	0.0162 (7)	0.0025 (6)	0.0015 (6)	−0.0030 (7)
C4	0.0167 (8)	0.0300 (11)	0.0156 (8)	0.0001 (7)	−0.0031 (7)	0.0027 (8)
N5	0.0155 (7)	0.0215 (9)	0.0212 (8)	0.0015 (6)	−0.0005 (6)	0.0017 (7)
N6	0.0160 (7)	0.0296 (9)	0.0137 (7)	0.0003 (6)	−0.0001 (6)	−0.0003 (7)
C7	0.0155 (8)	0.0190 (9)	0.0169 (8)	−0.0025 (7)	−0.0009 (6)	−0.0009 (7)
N71	0.0144 (7)	0.0292 (10)	0.0156 (7)	−0.0001 (6)	−0.0019 (6)	−0.0004 (7)
N72	0.0170 (8)	0.0418 (11)	0.0182 (8)	0.0017 (7)	−0.0012 (7)	−0.0053 (8)
N10	0.0175 (7)	0.0210 (8)	0.0164 (7)	−0.0012 (6)	0.0015 (6)	0.0021 (7)
O11	0.0153 (6)	0.0337 (8)	0.0196 (6)	0.0001 (5)	−0.0018 (5)	0.0002 (6)
O12	0.0181 (6)	0.0455 (9)	0.0189 (6)	0.0044 (6)	0.0037 (5)	−0.0084 (6)
O13	0.0207 (6)	0.0332 (8)	0.0137 (6)	−0.0008 (6)	0.0010 (5)	−0.0031 (6)
N20	0.0169 (7)	0.0230 (9)	0.0160 (7)	−0.0002 (6)	0.0012 (6)	−0.0014 (6)
O21	0.0221 (6)	0.0322 (8)	0.0122 (6)	−0.0025 (5)	−0.0014 (5)	−0.0038 (6)
O22	0.0160 (6)	0.0436 (9)	0.0194 (7)	−0.0057 (6)	−0.0001 (5)	−0.0067 (6)
O23	0.0201 (6)	0.0304 (8)	0.0185 (6)	−0.0042 (5)	0.0068 (5)	−0.0041 (6)

Geometric parameters (Å, º)

C1—N12	1.319 (2)	N5—H5	0.892 (16)
C1—N11	1.327 (2)	N6—C7	1.341 (2)
C1—N2	1.329 (2)	N6—H6	0.866 (15)
N11—H11A	0.873 (15)	C7—N71	1.315 (2)
N11—H11B	0.877 (16)	C7—N72	1.324 (2)
N12—H12A	0.855 (15)	N71—H71A	0.882 (15)
N12—H12B	0.868 (16)	N71—H71B	0.852 (15)
N2—N3	1.404 (2)	N72—H72A	0.869 (16)
N2—H1	0.83 (2)	N72—H72B	0.853 (16)
N3—C4	1.448 (2)	N10—O11	1.2454 (18)
N3—H3	0.880 (15)	N10—O12	1.2538 (18)
C4—N5	1.465 (2)	N10—O13	1.2558 (18)
C4—H4A	0.99	N20—O23	1.2488 (18)
C4—H4B	0.99	N20—O21	1.2533 (18)
N5—N6	1.419 (2)	N20—O22	1.2573 (18)
N12—C1—N11	120.77 (16)	N6—N5—C4	112.24 (15)
N12—C1—N2	120.82 (17)	N6—N5—H5	108.3 (13)
N11—C1—N2	118.40 (16)	C4—N5—H5	108.9 (13)
C1—N11—H11A	117.7 (15)	C7—N6—N5	117.78 (15)
C1—N11—H11B	118.8 (15)	C7—N6—H6	119.2 (13)
H11A—N11—H11B	123 (2)	N5—N6—H6	115.4 (14)
C1—N12—H12A	120.1 (14)	N71—C7—N72	121.20 (16)
C1—N12—H12B	122.1 (14)	N71—C7—N6	120.00 (15)
H12A—N12—H12B	117.9 (19)	N72—C7—N6	118.78 (16)
C1—N2—N3	119.39 (15)	C7—N71—H71A	119.4 (14)
C1—N2—H1	118.3 (15)	C7—N71—H71B	121.2 (15)
N3—N2—H1	122.1 (15)	H71A—N71—H71B	119 (2)
N2—N3—C4	112.13 (15)	C7—N72—H72A	120.0 (15)
N2—N3—H3	109.1 (14)	C7—N72—H72B	119.5 (15)
C4—N3—H3	108.6 (13)	H72A—N72—H72B	120 (2)
N3—C4—N5	115.62 (14)	O11—N10—O12	119.28 (15)
N3—C4—H4A	108.4	O11—N10—O13	120.99 (14)
N5—C4—H4A	108.4	O12—N10—O13	119.72 (14)
N3—C4—H4B	108.4	O23—N20—O21	120.14 (14)
N5—C4—H4B	108.4	O23—N20—O22	119.67 (15)
H4A—C4—H4B	107.4	O21—N20—O22	120.18 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···O22^i	0.99	2.6	3.287 (2)	127
C4—H4B···O12	0.99	2.57	3.298 (2)	130
N11—H11A···O12^ii	0.87 (2)	2.00 (2)	2.867 (2)	173 (2)
N11—H11B···O22^ii	0.88 (2)	2.03 (2)	2.907 (2)	178 (2)
N12—H12A···O13^ii	0.86 (2)	2.12 (2)	2.9742 (19)	176 (2)
N12—H12B···O22	0.87 (2)	2.29 (2)	3.055 (2)	146 (2)
N2—H1···O21^ii	0.83 (2)	2.10 (2)	2.9214 (19)	171 (2)
N3—H3···N20^iii	0.88 (2)	2.60 (2)	3.446 (2)	161 (2)
N3—H3···O21^iii	0.88 (2)	2.29 (2)	3.116 (2)	157 (2)
N3—H3···O23^iii	0.88 (2)	2.31 (2)	3.049 (2)	142 (2)
N5—H5···O23^i	0.89 (2)	2.25 (2)	3.081 (2)	154 (2)
N6—H6···O11	0.87 (2)	2.53 (2)	3.330 (2)	154 (2)
N6—H6···O12	0.87 (2)	2.09 (2)	2.873 (2)	151 (2)
N71—H71A···O21^ii	0.88 (2)	2.29 (2)	3.021 (2)	141 (2)
N71—H71B···O11^iv	0.85 (2)	2.03 (2)	2.8738 (19)	171 (2)
N72—H72A···O13^iv	0.87 (2)	2.13 (2)	2.973 (2)	164 (2)
N72—H72B···O11	0.85 (2)	2.62 (2)	3.380 (2)	150 (2)

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

1,2-Bis(diaminomethylidene)hydrazine-1,2-diium tetrachloridocuprate(II) (II)

Crystal data

(C2H10N6)[CuCl4]	F(000) = 644
Mr = 323.5	Dx = 1.929 Mg m^−3
Orthorhombic, Pnna	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2a 2bc	Cell parameters from 15421 reflections
a = 8.4242 (1) Å	θ = 2.9–40.8°
b = 10.0515 (2) Å	µ = 2.89 mm^−1
c = 13.1557 (2) Å	T = 100 K
V = 1113.97 (3) Å^3	Prism, brown
Z = 4	0.42 × 0.34 × 0.25 mm

Data collection

Oxford Diffraction Xcalibur diffractometer	3567 independent reflections
Graphite monochromator	3368 reflections with I > 2σ(I)
Detector resolution: 16.0009 pixels mm^-1	Rint = 0.023
ω scans	θmax = 40.5°, θmin = 2.9°
Absorption correction: analytical [CrysAlis PRO (Agilent, 2014), analytical numeric absorption correction (Clark & Reid, 1995)]	h = −14→15
Tmin = 0.449, Tmax = 0.591	k = −18→14
26253 measured reflections	l = −24→24

Refinement

Refinement on F^2	1 restraint
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.024	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.061	w = 1/[σ^2(Fo^2) + (0.0271P)^2 + 0.3155P] where P = (Fo^2 + 2Fc^2)/3
S = 1.18	(Δ/σ)max = 0.001
3567 reflections	Δρmax = 0.69 e Å^−3
64 parameters	Δρmin = −0.29 e Å^−3

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. The hydrogen atom on N3 was refined with geometries restrained to ideal values.

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

	x	y	z	Uiso*/Ueq
Cu1	0.75	0.5	0.26228 (2)	0.01276 (3)
Cl1	0.59826 (3)	0.38922 (2)	0.37468 (2)	0.01837 (4)
Cl2	0.94848 (2)	0.47042 (2)	0.14937 (2)	0.01657 (4)
N1	0.78060 (10)	0.18798 (8)	0.53593 (6)	0.01885 (13)
H1A	0.7397	0.2135	0.4776	0.023*
H1B	0.8465	0.1201	0.538	0.023*
N2	0.64504 (10)	0.35367 (8)	0.62144 (6)	0.01798 (12)
H2A	0.6021	0.3817	0.5644	0.022*
H2B	0.6225	0.3938	0.6791	0.022*
N3	0.80531 (9)	0.20604 (7)	0.70930 (5)	0.01361 (10)
C4	0.74303 (9)	0.25160 (8)	0.62057 (6)	0.01403 (12)
H3	0.8806 (18)	0.1548 (16)	0.7038 (12)	0.026 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.01123 (6)	0.01669 (6)	0.01036 (6)	−0.00096 (4)	0	0
Cl1	0.01731 (8)	0.02403 (9)	0.01375 (7)	−0.00382 (6)	−0.00047 (6)	0.00524 (6)
Cl2	0.01361 (8)	0.02138 (8)	0.01472 (7)	−0.00179 (6)	0.00197 (6)	−0.00513 (6)
N1	0.0218 (3)	0.0231 (3)	0.0117 (3)	0.0017 (2)	0.0013 (2)	−0.0031 (2)
N2	0.0201 (3)	0.0187 (3)	0.0151 (3)	0.0046 (2)	−0.0027 (2)	0.0000 (2)
N3	0.0140 (3)	0.0156 (2)	0.0113 (2)	0.0023 (2)	0.00016 (19)	−0.00135 (18)
C4	0.0145 (3)	0.0162 (3)	0.0114 (2)	−0.0006 (2)	0.0004 (2)	−0.0005 (2)

Geometric parameters (Å, º)

Cu1—Cl1^i	2.2496 (2)	N2—C4	1.3169 (11)
Cu1—Cl1	2.2496 (2)	N2—H2A	0.88
Cu1—Cl2	2.2562 (2)	N2—H2B	0.88
Cu1—Cl2^i	2.2562 (2)	N3—C4	1.3592 (10)
N1—C4	1.3225 (11)	N3—N3^ii	1.3885 (14)
N1—H1A	0.88	N3—H3	0.820 (13)
N1—H1B	0.88
Cl1^i—Cu1—Cl1	97.805 (12)	C4—N2—H2A	120
Cl1^i—Cu1—Cl2	94.408 (8)	C4—N2—H2B	120
Cl1—Cu1—Cl2	142.059 (8)	H2A—N2—H2B	120
Cl1^i—Cu1—Cl2^i	142.059 (8)	C4—N3—N3^ii	116.61 (8)
Cl1—Cu1—Cl2^i	94.410 (8)	C4—N3—H3	115.7 (12)
Cl2—Cu1—Cl2^i	97.652 (12)	N3^ii—N3—H3	117.9 (12)
C4—N1—H1A	120	N2—C4—N1	122.28 (8)
C4—N1—H1B	120	N2—C4—N3	119.80 (7)
H1A—N1—H1B	120	N1—C4—N3	117.89 (7)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1	0.88	2.52	3.3092 (9)	149
N1—H1B···Cl2^iii	0.88	2.72	3.4954 (9)	148
N1—H1B···Cl2^iv	0.88	2.76	3.2369 (8)	115
N2—H2A···Cl1	0.88	2.5	3.2896 (8)	150
N2—H2B···Cl2^v	0.88	2.8	3.6346 (8)	159
N3—H3···Cl2^iii	0.82 (1)	2.45 (1)	3.2454 (7)	163 (2)

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