Bis(1-carbamoyl­guanidinium) di­aqua­tetra­chloro­cobaltate(II)

The crystal structure of the title compound, (C₂H₇N₄O)₂[CoCl₄(H₂O)₂], contains a molecular network of (C₂H₇N₄O)⁺ cations and trans-[Co(H₂O)₂Cl₄]²⁻ octahedral anions (Co site symmetry 2/m). An extensive network of N—H...Cl, N—H...(Cl,Cl), N—H...O, O—H...O and O—H...Cl hydrogen bonds results in a structure with a three-dimensional hydrogen-bond network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Co-O) = 0.001 Å
• R factor = 0.027
• wR factor = 0.068
• Data-to-parameter ratio = 29.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The title compound, (I), arose as a side product during our synthetic investigations of organically templated cobalt phosphate networks (Cowley & Chippindale, 1999). It is isostructural with (C₂H₇N₄O)₂[CuCl₄(H₂O)₂] (Begley et al., 1988) and (C₂H₇N₄O)₂[MnCl₄(H₂O)₂] (Bremner & Harrison, 2003).

In (I), Co1 (site symmetry 2/m) has flattened, trans, octahedral coordination by two O (water) atoms and four Cl atoms. The cis bond angles lie between 84.64 (3) and 95.36 (3)°. The Co—O bond distance of 2.1000 (9) Å and the average Co—Cl separation of 2.4695 (4) Å correlate reasonably well with the ionic radius (IR) sums for the species involved [d_IR(Co—O) = 2.09 Å and d_IR(Co—Cl) = 2.56 Å], assuming the presence of high-spin Co²⁺ (Shannon, 1976). The [CuCl₄(H₂O)₂]²⁻ grouping in (C₂H₇N₄O)₂[CuCl₄(H₂O)₂] (Begley et al., 1988) is much more distorted, with a Cu—O distance of 1.992 (3) Å and Cu—Cl bond lengths of 2.305 (1) and 2.791 (1) Å, which can be ascribed to a typical Jahn–Teller distortion for the d⁹ Cu²⁺ species.

The 1-carbamoylguanidinium (guanylurea) cation has normal geometrical parameters [d_av(N—C) = 1.339 (3) Å], indicating significant delocalization of electrons over the non-hydrogen skeleton (Zaman & Darlow, 1986; Begley et al., 1988) and is essentially planar (for the non-H atoms, the r.m.s. deviation from the least-squares plane = 0.029 Å). A very acute (θ = 129°) intramolecular N4—H9···O2 hydrogen bond is present, which is typical for (C₂H₇N₄O)⁺ (Bremner & Harrison, 2002).

The component species in (I) interact by way of an extensive hydrogen-bonding network (Table 2). The N—H···Cl hydrogen bonds to chloride ion acceptors involving H5 and H6 are bifurcated [d_av(H···Cl) = 2.72 Å, d_av(N···Cl) = 3.398 (2) Å and θ_av(N—H···Cl) = 138°], which is a characteristic `synthon' bonding motif for these species (Brammer et al., 2001). In this case, the pairs of chloride ions occupy an octahedral edge, with Cl1···Cl2 and Cl1ⁱ···Cl2ⁱⁱ [symmetry codes: (i) 1/2 − x, 1/2 + y, 1/2 − z; (ii) 1/2 + x, 3/2 − y, 1/2 + z] separations of 3.4662 (5) and 3.5190 (5) Å for the interactions involving H5 and H6, respectively. The hydrogen bonds involving H3, H7 and H8 are simple N—H···Cl links [d_av(H···Cl) = 2.52 Å d_av(N···Cl) = 3.329 (2) Å and θ_av(N—H···Cl) = 159°]. Overall, Cl1 accepts three and Cl2 accepts five hydrogen bonds.

The hydrogen-bonding scheme in (I) results in stacks of alternating [Co(H₂O)₂Cl₄]²⁻ octahedra and pairs of 1-carbamoylguanidinium species propagating along [010] (Fig. 2), which are held together by the O1—H1···O2ⁱ, N1—H3···Cl1ⁱⁱⁱ, N3—H6···Cl2^iv, and N4—H8···Cl2^iv bonds (see Table 2 for the acceptor-atom symmetry codes). There may be pseudo π–π-stacking interactions involving the parallel 1-carbamoylguanidinium pairs, with resulting short contact distances of C1···N4^vi = 3.346 (2) Å and C2···O2^vi = 3.364 (2) Å [symmetry code: (vi) 1 − x, 1 − y, 1 − z].

The stacks are fused into (101) pseudo-sheets by way of the N1—H4···O1, N2—H5···(Cl1, Cl2), N3—H6···Cl1^v, and N3—H7···Cl2 bonds, which in turn are crosslinked by the O1—H2···Cl2ⁱⁱ bonds (symmetry codes as in Table 2), resulting in a three-dimensional structure.

S2. Experimental

10 ml of 1 M CoCl₂ solution, 10 ml of 1M H₃PO₄ solution and 0.5 g dicyandiamide were mixed together in a plastic bottle and heated to 353 K for 24 h, resulting in a purple solution. The solution was cooled to room temperature, and rod-like crystals of (I) grew as the solvent slowly evaporated. The dicyandiamide was transformed to guanylurea by slow acid hydrolysis.

S3. Refinement

The H atoms attached to atom O1 were located in difference maps and refined by riding in their as-found positions. The other H atoms were placed in idealized locations [d(N—H) = 0.86 Å] and refined by riding on their parent atom, with U_iso(H) = 1.2U_eq(parent atom) in all cases.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 1999); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Component species of (I) (50% displacement ellipsoids, arbitrary spheres for the H atoms and hydrogen bonds indicated by dashed lines). [Symmetry code: (i) −x, 1 − y, −z.]
	Fig. 2. Detail of (I), showing an [010] stack of alternating cation pairs and anions. Colour key: Co(H2O)2Cl4 octahedra purple, Cl atoms green, C atoms blue, N atoms yellow, and H atoms grey (all radii arbitrary). The intramolecular H···O, other H···O, H···Cl portions of the hydrogen bonds and the pseudo-π–π-stacking contacts (see text) are coloured light blue, orange, yellow, and purple, respectively.
	Fig. 3. Unit-cell packing in (I), viewed down [010]. Colour key as in Fig. 2 (pseudo-π–π-stacking contacts have been omitted for clarity).

(I)

Crystal data

(C2H7N4O)2[CoCl4(H2O)2]	F(000) = 450
Mr = 443.00	Dx = 1.818 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.3488 (3) Å	Cell parameters from 3083 reflections
b = 11.3392 (5) Å	θ = 2.6–32.4°
c = 11.5436 (5) Å	µ = 1.75 mm^−1
β = 103.1180 (1)°	T = 293 K
V = 809.34 (6) Å^3	Block, purple
Z = 2	0.26 × 0.19 × 0.13 mm

Data collection

Bruker SMART1000 CCD diffractometer	2914 independent reflections
Radiation source: fine-focus sealed tube	2160 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
ω scans	θmax = 32.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −8→9
Tmin = 0.650, Tmax = 0.810	k = −17→17
7802 measured reflections	l = −16→17

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)] = 0.027	Hydrogen site location: difmap (O-H) and geom (N-H)
wR(F^2) = 0.068	H-atom parameters constrained
S = 0.96	w = 1/[σ^2(Fo^2) + (0.0356P)^2] where P = (Fo^2 + 2Fc^2)/3
2914 reflections	(Δ/σ)max < 0.001
98 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.29 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.

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

	x	y	z	Uiso*/Ueq
Co1	0.0000	0.5000	0.0000	0.02519 (8)
Cl1	0.00034 (6)	0.49559 (3)	0.21078 (3)	0.03329 (9)
Cl2	0.31559 (6)	0.63849 (3)	0.04533 (3)	0.03150 (9)
O1	0.23677 (16)	0.36722 (8)	0.02831 (9)	0.0288 (2)
H1	0.2265	0.2989	0.0004	0.035*
H2	0.3452	0.3945	0.0025	0.035*
O2	0.70085 (19)	0.35117 (9)	0.44223 (10)	0.0409 (3)
N1	0.4719 (2)	0.29772 (10)	0.27020 (12)	0.0394 (3)
H3	0.4909	0.2236	0.2843	0.047*
H4	0.3858	0.3211	0.2056	0.047*
N2	0.5279 (2)	0.49248 (9)	0.31399 (12)	0.0306 (3)
H5	0.4288	0.5041	0.2506	0.037*
N3	0.5648 (2)	0.69217 (10)	0.32110 (12)	0.0398 (3)
H6	0.6197	0.7563	0.3548	0.048*
H7	0.4714	0.6951	0.2543	0.048*
N4	0.7651 (2)	0.58169 (11)	0.47313 (11)	0.0372 (3)
H8	0.8224	0.6445	0.5086	0.045*
H9	0.8009	0.5137	0.5044	0.045*
C1	0.5749 (2)	0.37577 (12)	0.34769 (13)	0.0301 (3)
C2	0.6237 (2)	0.58962 (12)	0.37173 (13)	0.0286 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.02434 (14)	0.02235 (12)	0.02850 (14)	0.00140 (9)	0.00516 (10)	0.00021 (10)
Cl1	0.0347 (2)	0.03586 (18)	0.03060 (18)	0.00071 (14)	0.01009 (15)	−0.00024 (14)
Cl2	0.02900 (17)	0.02758 (15)	0.03733 (19)	−0.00376 (13)	0.00631 (13)	0.00077 (14)
O1	0.0291 (5)	0.0225 (4)	0.0360 (5)	0.0002 (4)	0.0100 (4)	−0.0018 (4)
O2	0.0451 (6)	0.0284 (5)	0.0408 (6)	0.0001 (5)	−0.0077 (5)	0.0070 (4)
N1	0.0484 (8)	0.0255 (6)	0.0380 (7)	−0.0015 (5)	−0.0035 (6)	0.0025 (5)
N2	0.0304 (6)	0.0242 (5)	0.0329 (6)	0.0013 (4)	−0.0018 (5)	0.0025 (5)
N3	0.0536 (8)	0.0245 (6)	0.0366 (7)	0.0025 (5)	0.0002 (6)	0.0008 (5)
N4	0.0386 (7)	0.0290 (6)	0.0384 (7)	−0.0001 (5)	−0.0028 (6)	−0.0019 (5)
C1	0.0287 (7)	0.0262 (6)	0.0347 (8)	−0.0001 (5)	0.0059 (6)	0.0033 (5)
C2	0.0282 (7)	0.0265 (6)	0.0316 (7)	0.0009 (5)	0.0078 (6)	−0.0009 (5)

Geometric parameters (Å, º)

Co1—O1	2.1000 (9)	N1—H4	0.8600
Co1—O1^i	2.1000 (9)	N2—C2	1.3577 (17)
Co1—Cl1	2.4332 (4)	N2—C1	1.3926 (16)
Co1—Cl1^i	2.4332 (4)	N2—H5	0.8600
Co1—Cl2^i	2.5057 (3)	N3—C2	1.3170 (17)
Co1—Cl2	2.5057 (3)	N3—H6	0.8600
O1—H1	0.8362	N3—H7	0.8600
O1—H2	0.8667	N4—C2	1.3066 (19)
O2—C1	1.2297 (18)	N4—H8	0.8600
N1—C1	1.3212 (19)	N4—H9	0.8600
N1—H3	0.8600
O1—Co1—O1^i	180.0	C1—N1—H3	120.0
O1—Co1—Cl1	89.51 (3)	C1—N1—H4	120.0
O1^i—Co1—Cl1	90.49 (3)	H3—N1—H4	120.0
O1—Co1—Cl1^i	90.49 (3)	C2—N2—C1	126.17 (13)
O1^i—Co1—Cl1^i	89.51 (3)	C2—N2—H5	116.9
Cl1—Co1—Cl1^i	180.0	C1—N2—H5	116.9
O1—Co1—Cl2^i	95.36 (3)	C2—N3—H6	120.0
O1^i—Co1—Cl2^i	84.64 (3)	C2—N3—H7	120.0
Cl1—Co1—Cl2^i	90.869 (12)	H6—N3—H7	120.0
Cl1^i—Co1—Cl2^i	89.131 (12)	C2—N4—H8	120.0
O1—Co1—Cl2	84.64 (3)	C2—N4—H9	120.0
O1^i—Co1—Cl2	95.36 (3)	H8—N4—H9	120.0
Cl1—Co1—Cl2	89.131 (12)	O2—C1—N1	124.84 (13)
Cl1^i—Co1—Cl2	90.869 (12)	O2—C1—N2	121.23 (13)
Cl2^i—Co1—Cl2	180.000 (12)	N1—C1—N2	113.93 (13)
Co1—O1—H1	127.9	N4—C2—N3	121.77 (14)
Co1—O1—H2	106.7	N4—C2—N2	121.61 (13)
H1—O1—H2	101.3	N3—C2—N2	116.62 (13)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2^ii	0.84	1.82	2.6587 (13)	179
O1—H2···Cl2^iii	0.87	2.37	3.1465 (10)	149
N1—H3···Cl1^iv	0.86	2.59	3.4349 (12)	170
N1—H4···O1	0.86	2.12	2.9586 (17)	166
N2—H5···Cl1	0.86	2.66	3.2905 (14)	132
N2—H5···Cl2	0.86	2.77	3.5040 (13)	144
N3—H6···Cl2^v	0.86	2.56	3.3245 (14)	148
N3—H6···Cl1^vi	0.86	2.87	3.4749 (12)	129
N3—H7···Cl2	0.86	2.48	3.2743 (15)	155
N4—H8···Cl2^v	0.86	2.50	3.2778 (13)	151
N4—H9···O2	0.86	2.03	2.6571 (16)	129

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