Tetra-n-butylammonium bis(2-thioxo-1,3-dithiole-4,5-dithiolato-[kappa]²S⁴,S⁵)nickelate(III)

The crystal structure of the title compound, (C₁₆H₃₆N)[Ni(C₃S₅)₂], is isomorphous with that of the corresponding Pt complex but different from the structures reported for compounds of the same chemical composition, and so provides a new crystalline phase of this complex. The nickel complex anion has good planarity and lies on a crystallographic inversion centre. There is disorder in the two terminal C atoms of two of the butyl chains of the tetra-n-butyl­ammonium cation, the N atom of which is located on a twofold axis.

S1. Comment

Nickel complexes of 4,5-dimercapto-1,3-dithiole-2-thione (dmit) and their π-conjugation-extended derivatives have received steady interest in the field of molecular conductors (Lei et al., 1996; Narvor et al., 1996; Tanaka et al., 2001). Recently, the title compound, (I), was synthesized using a more direct method (see Experimental), instead of the commonly used dibenzoyl derivative of dmit (Valade et al., 1985, and references therein). It was also found that several different crystal structures of (I) have been reported (Table 2). Thus, it was postulated that compound (I) synthesized using the direct method might crystallize in a new structure, and this was the first reason for the present determination of (I). Another reason is due to the fact that the fluorescence emission spectra of (I) and the analogous bis(tetra-n-butylammonium) bis(2-thioxo-1,3-dithiole-4,5-dithiolato)zincate(II) have recently been measured (Reference?) and found to be almost the same. However, it is known that the latter compound has a tetragonal coordination at the Zn centre and the former has a planar square coordination at the Ni centre, for the cases reported to date, and so the extent of delocalization of the electrons of (I) is larger than that of the latter and they would be expected to have different spectra. Thus, a planar structure of the Ni-dmit complex synthesized using the current method was suspected. In order to clarify these two points, the present crystal structure determination of (I) was performed and the results are reported here. Please check rephrasing. \sch

The Ni-dmit complex anion of (I) (17 atoms) exhibits good planarity and the maximum deviation from the least squares plane is 0.043 (2) Å (atoms S1 and S1a the two terminal atoms of the anion). Thus, the close similarity of the two fluorescence emission spectra remains unexplained, assuming there are no mistakes in the spectroscopic measurements. The geometric parameters of the anion of (I) do not differ considerably from those reported (Mentzafos et al., 1988; Valade et al., 1985), although they agree better with the data reported by Mentzafos et al. (1988; Ni, j = 2).

The four S atoms around Ni adopt a centrosymmetric arrangement with each pair of trans S atoms equivalent (Table 1). In our opinion, the four S atoms should not be regarded as equivalent, even within the range of experimental uncertainty; referring to Fig. 1 and Table 1, the Ni1—S4 and Ni1—S5 bond lengths are 2.1541 (15) and 2.1638 (15) Å, respectively, and the S4—Ni1—S5a and S4—Ni1—S5 bond angles are 87.37 (6) and 92.63 (6)°, respectively. A similar result was seen in the molecular structure of nickel diethyldithiocarbamate (Bonamico et al., 1965). As far as the tetra-n-butylammonium cation is concerned (Fig. 1), two of the four butyl chains are disordered, as observed and described by Mentzafos et al. (1988).

The crystal packing of (I) is basically isostructural with that of the corresponding Pt complex (Mentzafos et al., 1988), but there are fairly large differences from the structures reported (Table 2) for other compounds of the same chemical composition (Mentzafos et al., 1988, and references therein). Taking only the packing of the Ni complex anion into account, and referring to Fig. 2, the anions form stacks along the c axis. In the stack, the anions form a zigzag array and there are short S···S contacts [3.597 (2) Å for both S4···S4 and S4a···S4a] between neighbouring anions, but there are no short interstack S···S contacts. All of these results are in almost perfect agreement with those of the corresponding Pt complex (Mentzafos et al., 1988).

S2. Experimental

Nickel chloride hexahydrate (0.476 g, 2 mmol) was dissolved in a mixture of water, methanol and acetone (3:2:2). The resulting clear green solution was reacted with a solution of bis(tetra-n-butylammonium) bis(2-thioxo-1,3-dithiole-4,5-dithiolato)zincate(II) [1.88 g, 2 mmol; prepared according to the method of Valade et al. (1985)] in acetone for several days or longer, until all the solvents except water had evaporated completely. The resulting mixture was filtered to give a green-black solid, and this solid was then redissolved in acetone to recrystallize. After several days, the solvent was evaporated off to give shiny stick-like green-black crystals of (I).

S3. Refinement

After checking their presence in the difference map, all H atoms were geometrically fixed and allowed to ride on their attached atoms, with C—H = 0.96–0.97 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: PLATON (Spek, 2001).

Figures

	Fig. 1. A view of (I) with the atomic numbering scheme; primed labels indicate the disordered component. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The packing of the nickel anion of (I).

Tetra-n-butylammonium bis(2-thioxo-1,3-dithiole-4,5-dithiolato)nickelate(III)

Crystal data

(C16H36N)[Ni(C3S5)2]	F(000) = 1452
Mr = 693.91	Dx = 1.456 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 32 reflections
a = 20.191 (2) Å	θ = 5.1–12.5°
b = 13.4041 (14) Å	µ = 1.29 mm^−1
c = 12.1408 (14) Å	T = 293 K
β = 105.554 (8)°	Prism, black
V = 3165.5 (6) Å^3	0.38 × 0.30 × 0.20 mm
Z = 4

Data collection

Bruker P4 diffractometer	1834 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.028
Graphite monochromator	θmax = 25.0°, θmin = 1.9°
θ/2θ scans	h = −1→24
Absorption correction: ψ scan (XSCANS; Siemens, 1996)	k = −1→15
Tmin = 0.636, Tmax = 0.773	l = −14→14
3338 measured reflections	3 standard reflections every 97 reflections
2791 independent reflections	intensity decay: 1%

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)] = 0.059	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.157	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0504P)^2 + 7.7955P] where P = (Fo^2 + 2Fc^2)/3
2789 reflections	(Δ/σ)max < 0.001
155 parameters	Δρmax = 0.74 e Å^−3
7 restraints	Δρmin = −0.53 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	Occ. (<1)
Ni1	0.0000	0.0000	0.0000	0.0618 (3)
S1	−0.34892 (9)	0.09595 (18)	−0.0172 (2)	0.1137 (7)
S2	−0.20012 (8)	0.12642 (14)	0.08469 (16)	0.0902 (6)
S3	−0.24403 (8)	0.00017 (14)	−0.11304 (15)	0.0826 (5)
S4	−0.04975 (8)	0.08814 (13)	0.10294 (14)	0.0818 (5)
N1	−0.5000	0.2118 (4)	0.2500	0.0556 (14)
C1	−0.2684 (3)	0.0754 (5)	−0.0147 (6)	0.0815 (18)
C2	−0.1348 (3)	0.0708 (4)	0.0364 (5)	0.0690 (15)
C3	−0.1553 (3)	0.0127 (4)	−0.0565 (5)	0.0666 (14)
C4	−0.5111 (3)	0.1444 (4)	0.1458 (4)	0.0663 (15)
H4A	−0.4700	0.1047	0.1534	0.080*
H4B	−0.5484	0.0988	0.1459	0.080*
C5	−0.5274 (4)	0.1962 (6)	0.0327 (5)	0.107 (2)
H5A	−0.4884	0.2364	0.0279	0.129*
H5B	−0.5663	0.2405	0.0263	0.129*
C6	−0.5442 (4)	0.1224 (7)	−0.0651 (5)	0.124 (3)
H6A	−0.5785	0.0763	−0.0525	0.149*
H6B	−0.5031	0.0841	−0.0627	0.149*
C7	−0.5707 (6)	0.1660 (8)	−0.1842 (6)	0.194 (5)
H7A	−0.5795	0.1130	−0.2395	0.292*
H7B	−0.5368	0.2103	−0.1993	0.292*
H7C	−0.6124	0.2021	−0.1893	0.292*
C8	−0.5613 (3)	0.2787 (5)	0.2402 (5)	0.0813 (18)
H8A	−0.5644	0.3246	0.1772	0.098*
H8B	−0.5536	0.3181	0.3095	0.098*
C9	−0.6299 (3)	0.2248 (6)	0.2212 (6)	0.115 (3)
H9A	−0.6362	0.1957	0.2909	0.138*
H9B	−0.6367	0.1744	0.1618	0.138*
C10	−0.6752 (4)	0.3177 (6)	0.1828 (13)	0.109 (5)*	0.533 (12)
H10A	−0.6608	0.3703	0.2389	0.131*	0.533 (12)
H10B	−0.6692	0.3415	0.1106	0.131*	0.533 (12)
C11	−0.7516 (4)	0.2936 (10)	0.1688 (12)	0.114 (6)*	0.533 (12)
H11A	−0.7775	0.3545	0.1593	0.172*	0.533 (12)
H11B	−0.7564	0.2593	0.2356	0.172*	0.533 (12)
H11C	−0.7684	0.2521	0.1028	0.172*	0.533 (12)
C10'	−0.6963 (5)	0.2767 (8)	0.2300 (10)	0.083 (5)*	0.467 (12)
H10C	−0.6895	0.3065	0.3050	0.100*	0.467 (12)
H10D	−0.7335	0.2287	0.2186	0.100*	0.467 (12)
C11'	−0.7140 (7)	0.3579 (9)	0.1369 (11)	0.102 (6)*	0.467 (12)
H11D	−0.7547	0.3928	0.1416	0.154*	0.467 (12)
H11E	−0.7219	0.3273	0.0629	0.154*	0.467 (12)
H11F	−0.6764	0.4040	0.1480	0.154*	0.467 (12)
S5	−0.09697 (7)	−0.04710 (13)	−0.11339 (14)	0.0780 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0574 (6)	0.0608 (6)	0.0729 (6)	−0.0082 (5)	0.0274 (5)	−0.0046 (5)
S1	0.0636 (10)	0.1463 (19)	0.1424 (18)	0.0031 (11)	0.0469 (11)	0.0059 (15)
S2	0.0675 (10)	0.1020 (13)	0.1129 (13)	−0.0050 (9)	0.0448 (9)	−0.0224 (11)
S3	0.0576 (8)	0.0922 (11)	0.0994 (12)	−0.0109 (8)	0.0233 (8)	−0.0052 (10)
S4	0.0620 (9)	0.0960 (12)	0.0940 (11)	−0.0151 (8)	0.0323 (8)	−0.0321 (9)
N1	0.062 (4)	0.049 (3)	0.060 (3)	0.000	0.022 (3)	0.000
C1	0.067 (4)	0.085 (4)	0.104 (5)	−0.005 (3)	0.041 (3)	0.016 (4)
C2	0.057 (3)	0.072 (4)	0.087 (4)	−0.008 (3)	0.036 (3)	−0.005 (3)
C3	0.062 (3)	0.060 (3)	0.085 (4)	−0.008 (3)	0.032 (3)	0.001 (3)
C4	0.086 (4)	0.061 (3)	0.056 (3)	0.014 (3)	0.024 (3)	−0.002 (3)
C5	0.143 (7)	0.124 (6)	0.063 (4)	0.032 (5)	0.041 (4)	0.019 (4)
C6	0.143 (7)	0.170 (8)	0.062 (4)	0.031 (6)	0.032 (5)	−0.013 (5)
C7	0.277 (14)	0.168 (10)	0.101 (7)	−0.041 (10)	−0.014 (8)	−0.015 (7)
C8	0.077 (4)	0.081 (4)	0.082 (4)	0.016 (3)	0.014 (3)	−0.025 (3)
C9	0.067 (4)	0.174 (8)	0.107 (5)	0.010 (5)	0.029 (4)	−0.028 (6)
S5	0.0618 (9)	0.0860 (11)	0.0878 (11)	−0.0052 (8)	0.0228 (8)	−0.0220 (9)

Geometric parameters (Å, º)

Ni1—S4	2.1541 (15)	C6—H6B	0.9700
Ni1—S4^i	2.1541 (15)	C7—H7A	0.9600
Ni1—S5	2.1638 (15)	C7—H7B	0.9600
Ni1—S5^i	2.1638 (15)	C7—H7C	0.9600
S1—C1	1.642 (6)	C8—C9	1.525 (8)
S2—C1	1.712 (7)	C8—H8A	0.9700
S2—C2	1.748 (5)	C8—H8B	0.9700
S3—C1	1.732 (7)	C9—C10'	1.5394 (10)
S3—C3	1.747 (6)	C9—C10	1.5410 (10)
S4—C2	1.706 (6)	C9—H9A	0.9700
N1—C8^ii	1.507 (6)	C9—H9B	0.9700
N1—C8	1.507 (6)	C10—C11	1.5396 (11)
N1—C4	1.521 (6)	C10—H10A	0.9700
N1—C4^ii	1.521 (6)	C10—H10B	0.9700
C2—C3	1.341 (8)	C11—H11A	0.9600
C3—S5	1.715 (6)	C11—H11B	0.9600
C4—C5	1.494 (7)	C11—H11C	0.9600
C4—H4A	0.9700	C10'—C11'	1.5403 (10)
C4—H4B	0.9700	C10'—H10C	0.9700
C5—C6	1.512 (9)	C10'—H10D	0.9700
C5—H5A	0.9700	C11'—H11D	0.9600
C5—H5B	0.9700	C11'—H11E	0.9600
C6—C7	1.517 (5)	C11'—H11F	0.9600
C6—H6A	0.9700
S4—Ni1—S4^i	180.00 (11)	H7A—C7—H7B	109.5
S4—Ni1—S5	92.63 (6)	C6—C7—H7C	109.5
S4^i—Ni1—S5	87.37 (6)	H7A—C7—H7C	109.5
S4—Ni1—S5^i	87.37 (6)	H7B—C7—H7C	109.5
S4^i—Ni1—S5^i	92.63 (6)	N1—C8—C9	115.0 (5)
S5—Ni1—S5^i	180.00 (11)	N1—C8—H8A	108.5
C1—S2—C2	97.5 (3)	C9—C8—H8A	108.5
C1—S3—C3	97.1 (3)	N1—C8—H8B	108.5
C2—S4—Ni1	102.5 (2)	C9—C8—H8B	108.5
C8^ii—N1—C8	106.9 (6)	H8A—C8—H8B	107.5
C8^ii—N1—C4	110.7 (3)	C8—C9—C10'	123.2 (7)
C8—N1—C4	110.6 (3)	C8—C9—C10	95.9 (6)
C8^ii—N1—C4^ii	110.6 (3)	C8—C9—H9A	112.6
C8—N1—C4^ii	110.7 (3)	C10'—C9—H9A	78.6
C4—N1—C4^ii	107.2 (5)	C10—C9—H9A	112.6
S1—C1—S2	123.5 (4)	C8—C9—H9B	112.6
S1—C1—S3	123.2 (4)	C10'—C9—H9B	114.5
S2—C1—S3	113.3 (3)	C10—C9—H9B	112.6
C3—C2—S4	121.4 (4)	H9A—C9—H9B	110.1
C3—C2—S2	116.1 (4)	C11—C10—C9	111.0 (3)
S4—C2—S2	122.5 (4)	C11—C10—H10A	109.4
C2—C3—S5	121.3 (4)	C9—C10—H10A	109.4
C2—C3—S3	116.0 (4)	C11—C10—H10B	109.4
S5—C3—S3	122.6 (4)	C9—C10—H10B	109.4
C5—C4—N1	115.8 (5)	H10A—C10—H10B	108.0
C5—C4—H4A	108.3	C10—C11—H11A	109.5
N1—C4—H4A	108.3	C10—C11—H11B	109.5
C5—C4—H4B	108.3	H11A—C11—H11B	109.5
N1—C4—H4B	108.3	C10—C11—H11C	109.5
H4A—C4—H4B	107.4	H11A—C11—H11C	109.5
C4—C5—C6	111.5 (6)	H11B—C11—H11C	109.5
C4—C5—H5A	109.3	C9—C10'—C11'	107.6 (3)
C6—C5—H5A	109.3	C9—C10'—H10C	110.2
C4—C5—H5B	109.3	C11'—C10'—H10C	110.2
C6—C5—H5B	109.3	C9—C10'—H10D	110.2
H5A—C5—H5B	108.0	C11'—C10'—H10D	110.2
C5—C6—C7	116.4 (7)	H10C—C10'—H10D	108.5
C5—C6—H6A	108.2	C10'—C11'—H11D	109.5
C7—C6—H6A	108.2	C10'—C11'—H11E	109.5
C5—C6—H6B	108.2	H11D—C11'—H11E	109.5
C7—C6—H6B	108.2	C10'—C11'—H11F	109.5
H6A—C6—H6B	107.3	H11D—C11'—H11F	109.5
C6—C7—H7A	109.5	H11E—C11'—H11F	109.5
C6—C7—H7B	109.5	C3—S5—Ni1	102.1 (2)

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