Bis(thio­carbohydrazide)dithio­cyanato­iron(II)

In the title compound, [Fe^II(NCS)₂(CH₆N₄S)₂], the Fe^II cation is surrounded by two S atoms and two N atoms from thio­carbohydrazide groups and by two N atoms from thio­cyanate groups. The geometry around the Fe^II cation, which is located on a center of inversion, is distorted octa­hedral. The thio­carbohydrazide mol­ecule assumes a cis–trans conformation, which is reinforced by an N—H...N hydrogen bond. Mol­ecules of the title compound are connected via inter­molecular N—H...S and N—H...N hydrogen bonds to form a three-dimensional network structure.

S1. Comment

Previously, bis[4-amino-3-methyl-1H-1,2,4-triazole-5(4H) -thione]dichlorocopper(II) dihydrate has been synthesized in our laboratory (Cai et al., 2004). In a similar tentative synthetic procedure, FeCl₃ was used instead of CuCl₂ to prepare iron compounds of the ligand. Unexpectedly, the title compound, (I), was synthesized, where the thiocarbohydrazide (TCH) ligand and thiocyanate anion maybe result from reaction of 4-amino-1,2,4-triazole-5-thione (ATT). From the search of the Cambridge Structural Database (CSD), it is known that only five crystal structures of TCH compounds (Braibanti et al., 1969, 1971, 1972; Bigoli et al., 1971, 1972) have been reported so far. In this paper, we make a careful study of the structure of (I) (Table 1).

In (I) (Fig. 1 and Table 1), owing to the obvious differences of bond lengths and bond angles around the Fe^II ion, which is located at an inversion center, the coordination is distorted octahedral. The equatorial plane consists of two amine N atoms and two S atoms from two TCH ligands, and the axial positions are filled by two N atoms from thiocyanate anions. The bond lengthd in the thiocyanate anion agrees with the data reported previously (Petrucenko et al., 1997; Wharf & Simard, 1998). The Fe^II ion is located in the C1/N1/N2/S1 plane, which has an a r.m.s. deviation of 0.057 (2) Å [or is this the deviation of Fe from the plane?]. The structure is similar to that of the bis(TCH)–dichloro–cadmium compound, except for the fact that in the latter the Cd atom lies out of the equivalent plane (Bigoli et al., 1971).

TCH molecules may assume cis--trans or cis–cis conformations (see scheme below). In the title compound, TCH assumes a cis–trans conformation, which has also been found in neutral TCH (Braibanti et al., 1969), bis(TCH)–dichloro–cadmium (Bigoli et al., 1971) and TCH hemihydrochloride (Braibanti et al., 1972). Conversely, the cis--cis conformation has been observed in TCH dihydrochloride dihydrate (Braibanti et al., 1971) and TCH sulfate (Bigoli et al., 1972). Interestingly, the cis–trans comformation is reinforced by an N1—H1···N4 hydrogen bond [2.590 (3) Å; Fig. 1 and Table 2).

There are six kinds of intramolecular N—H···S hydrogen bonds with H···S distances shorter than 2.9 Å, the sum of the van der Waals radii of H and S atoms (Allen et al., 1997). As shown in Fig. 2, (I) is connected by N4—H4B···S1ⁱⁱⁱ and N4—H4A···S2^iv hydrogen bonds to form one-dimensional chains along the [001] direction (Fig. 2 and Table 2). Neighboring chains are associated with one another by an N1—H1···S2ⁱ hydrogen bond and are interrelated by translation to result in a supramolecular layer parallel to (100). There are various hydrogen-bonded rings embedded in the layer (Fig. 2), which can be described in graph-set notation (Etter, 1990; Grell et al., 2000) as R₁¹(5), R₂²(8), R₂²(10), R₂²(14) and R₄⁴(8). The layers are associated to form the whole structure by N2—H2A···S2ⁱⁱ, N2—H2B···S1ⁱⁱ and N3—H3···S1^v hydrogen bonds.

S2. Experimental

The title compound was synthesized by a hydrothermal method from a mixture of ATT (4 mmol, 0.76 g), FeCl₃ (1 mmol, 0.16 g) and water (20 ml) in a 30 ml Tefon-lined stainless steel reactor. The solution was heated to 415 K for three days. After the reaction system was slowly cooled to room temperature, pale-blue block-shaped crystals were collected and washed with distilled water.

S3. Refinement

All H atoms were located in a difference Fourier map and were refined with fixed positions and U_iso(H) set to 0.08.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The formula unit of (I), with atom labels, showing 40% probability displacement ellipsoids. Hydrogen bonds are illustrated as dashed lines.
	Fig. 2. Part of the crystal structure, showing a supramolecular layer of N—H···S hydrogen bonds, which is built up from hydrogen-bonded N—H···S chains. Hydrogen bonds are shown as dashed lines. Atoms labeled with a hash (#), an asterisk (*) or two asterisks (**) are at the symmetry positions (x, y, z − 1), (−x, −y + 1, −z − 1) and (−x, −y, −z), respectively.

Bis(thiocarbohydrazide)thiocyanatoiron(II)

Crystal data

[Fe(NCS)2(CH6N4S)2]	Z = 1
Mr = 384.37	F(000) = 196.0
Triclinic, P1	Dx = 1.786 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.2176 (6) Å	Cell parameters from 856 reflections
b = 8.0061 (9) Å	θ = 2.6–24.3°
c = 8.7683 (10) Å	µ = 1.64 mm^−1
α = 78.662 (2)°	T = 273 K
β = 84.150 (2)°	Block, pale blue
γ = 88.891 (2)°	0.37 × 0.16 × 0.12 mm
V = 357.26 (7) Å^3

Data collection

Bruker SMART APEX CCD area-detector diffractometer	1299 independent reflections
Radiation source: fine-focus sealed tube	1240 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.009
ϕ and ω scans	θmax = 25.3°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −6→5
Tmin = 0.729, Tmax = 0.824	k = −9→9
1926 measured reflections	l = −10→9

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.080	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0396P)^2 + 0.3522P] where P = (Fo^2 + 2Fc^2)/3
1276 reflections	(Δ/σ)max < 0.001
88 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.48 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
Fe	0.0000	0.5000	0.0000	0.02507 (17)
S1	0.27457 (11)	0.51899 (8)	−0.26337 (7)	0.02761 (18)
S2	0.53874 (14)	0.02470 (9)	0.22669 (9)	0.0404 (2)
N1	−0.0853 (4)	0.2790 (3)	−0.2442 (2)	0.0284 (5)
N2	−0.1998 (4)	0.3175 (3)	−0.1019 (2)	0.0270 (4)
N5	0.2314 (4)	0.2958 (3)	0.1009 (2)	0.0333 (5)
N4	0.0759 (5)	0.1786 (3)	−0.5005 (3)	0.0354 (5)
N3	0.2054 (4)	0.3123 (3)	−0.4562 (2)	0.0305 (5)
C1	0.1197 (4)	0.3603 (3)	−0.3228 (3)	0.0224 (5)
C2	0.3557 (5)	0.1816 (3)	0.1526 (3)	0.0287 (5)
H1	−0.1681	0.1989	−0.2831	0.080*
H2A	−0.2155	0.2154	−0.0245	0.080*
H2B	−0.3669	0.3530	−0.1190	0.080*
H4B	0.0179	0.2264	−0.5949	0.080*
H3	0.3390	0.3686	−0.5169	0.080*
H4A	0.2010	0.1055	−0.5153	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe	0.0247 (3)	0.0286 (3)	0.0232 (3)	0.00152 (19)	−0.00230 (19)	−0.0085 (2)
S1	0.0252 (3)	0.0315 (3)	0.0274 (3)	−0.0061 (2)	0.0007 (2)	−0.0100 (2)
S2	0.0388 (4)	0.0338 (4)	0.0457 (4)	0.0068 (3)	−0.0077 (3)	0.0004 (3)
N1	0.0289 (11)	0.0327 (11)	0.0260 (11)	−0.0078 (9)	0.0047 (8)	−0.0145 (9)
N2	0.0250 (11)	0.0339 (11)	0.0230 (10)	−0.0013 (8)	0.0029 (8)	−0.0101 (8)
N5	0.0328 (12)	0.0365 (12)	0.0289 (11)	0.0079 (10)	−0.0030 (9)	−0.0033 (9)
N4	0.0486 (14)	0.0321 (11)	0.0279 (11)	−0.0022 (10)	−0.0013 (9)	−0.0129 (9)
N3	0.0344 (12)	0.0321 (11)	0.0255 (11)	−0.0036 (9)	0.0047 (9)	−0.0104 (9)
C1	0.0215 (11)	0.0231 (11)	0.0225 (11)	0.0033 (9)	−0.0025 (9)	−0.0042 (9)
C2	0.0265 (13)	0.0338 (13)	0.0253 (12)	−0.0042 (11)	0.0029 (10)	−0.0070 (10)

Geometric parameters (Å, º)

Fe—N5^i	2.118 (2)	N1—H1	0.917
Fe—N5	2.118 (2)	N2—H2A	0.953
Fe—N2^i	2.187 (2)	N2—H2B	0.929
Fe—N2	2.187 (2)	N5—C2	1.156 (3)
Fe—S1	2.5699 (6)	N4—N3	1.414 (3)
Fe—S1^i	2.5699 (6)	N4—H4B	0.919
S1—C1	1.710 (2)	N4—H4A	0.885
S2—C2	1.634 (3)	N3—C1	1.333 (3)
N1—C1	1.320 (3)	N3—H3	0.903
N1—N2	1.414 (3)
N5^i—Fe—N5	180.00 (11)	N2—N1—H1	116.2
N5^i—Fe—N2^i	87.93 (8)	N1—N2—Fe	117.36 (14)
N5—Fe—N2^i	92.07 (8)	N1—N2—H2A	109.12
N5^i—Fe—N2	92.07 (8)	Fe—N2—H2A	106.08
N5—Fe—N2	87.93 (8)	N1—N2—H2B	106.40
N2^i—Fe—N2	180.00 (9)	Fe—N2—H2B	111.20
N5^i—Fe—S1	90.09 (6)	H2A—N2—H2B	106.2
N5—Fe—S1	89.91 (6)	C2—N5—Fe	177.9 (2)
N2^i—Fe—S1	100.82 (5)	N3—N4—H4B	104.8
N2—Fe—S1	79.18 (5)	N3—N4—H4A	103.2
N5^i—Fe—S1^i	89.91 (6)	H4B—N4—H4A	109.5
N5—Fe—S1^i	90.09 (6)	C1—N3—N4	118.4 (2)
N2^i—Fe—S1^i	79.18 (5)	C1—N3—H3	119.3
N2—Fe—S1^i	100.82 (5)	N4—N3—H3	122.2
S1—Fe—S1^i	180.00 (3)	N1—C1—N3	116.2 (2)
C1—S1—Fe	96.41 (8)	N1—C1—S1	123.98 (18)
C1—N1—N2	122.55 (19)	N3—C1—S1	119.85 (18)
C1—N1—H1	121.1	N5—C2—S2	178.0 (2)
N5^i—Fe—S1—C1	−97.09 (10)	N2^i—Fe—N5—C2	−159 (6)
N5—Fe—S1—C1	82.91 (10)	N2—Fe—N5—C2	21 (6)
N2^i—Fe—S1—C1	175.00 (9)	S1—Fe—N5—C2	−58 (6)
N2—Fe—S1—C1	−5.00 (9)	S1^i—Fe—N5—C2	122 (6)
S1^i—Fe—S1—C1	175 (100)	N2—N1—C1—N3	−179.2 (2)
C1—N1—N2—Fe	−6.6 (3)	N2—N1—C1—S1	0.7 (3)
N5^i—Fe—N2—N1	96.30 (17)	N4—N3—C1—N1	−1.2 (3)
N5—Fe—N2—N1	−83.70 (17)	N4—N3—C1—S1	178.82 (17)
N2^i—Fe—N2—N1	−125 (100)	Fe—S1—C1—N1	4.1 (2)
S1—Fe—N2—N1	6.60 (15)	Fe—S1—C1—N3	−175.93 (18)
S1^i—Fe—N2—N1	−173.40 (15)	Fe—N5—C2—S2	142 (5)
N5^i—Fe—N5—C2	0 (100)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···N4	0.92	2.21	2.590 (3)	104
N1—H1···S2^ii	0.92	2.60	3.397 (2)	145
N2—H2A···S2^iii	0.95	2.65	3.510 (2)	151
N2—H2B···S1^iii	0.93	2.57	3.443 (2)	157
N4—H4B···S1^iv	0.92	2.70	3.482 (2)	143
N4—H4A···S2^v	0.89	2.89	3.597 (2)	138
N3—H3···S1^vi	0.90	2.68	3.565 (2)	167

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