Dicarbon­yl(pyrazine-1,3-dithiol­ato-κ² S,S′)bis­(trimethyl­phosphane-κP)iron(II)

Abstract

The title compound, [Fe(C₄H₂N₂S₂)(C₃H₉P)₂(CO)₂], was obtained as a mononuclear by-product during the treatment of [Fe₂(μ-S₂C₄N₂H₂)(CO)₆] in excess trimethyl­phosphane. The Fe atom is six-coordinated by two thiol­ate S atoms, two phosphane P atoms and two carbonyl C atoms in a distorted octa­hedral geometry. The average Fe—C(O) distance (1.771 Å) is relatively shorter than that of its parent hexa­carbonyl­diiron compound, and differs by 0.511 Å from the average Fe—P(Me)₃ distance. The five-membered FeC₂S₂ chelate ring plane is close to being perpendicular to the P/Fe/P plane [86.5 (2)°].

Related literature

For general background to iron sulfides, see: Cody et al. (2000 ▶); Georgakaki et al. (2003 ▶); Capon et al. (2005 ▶); Song (2005 ▶); Li et al. (2005 ▶); Liu & Xiao (2011 ▶). For related structures and the synthesis, see: Durgaprasad et al. (2011 ▶).

Experimental

Crystal data

• [Fe(C₄H₂N₂S₂)(C₃H₉P)₂(CO)₂]

• M _r = 406.21

• Orthorhombic,

• a = 12.2078 (10) Å

• b = 11.951 (1) Å

• c = 25.326 (2) Å

• V = 3694.9 (5) ų

• Z = 8

• Mo Kα radiation

• μ = 1.22 mm⁻¹

• T = 273 K

• 0.30 × 0.25 × 0.20 mm

Data collection

• Bruker APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 1997 ▶) T _min = 0.711, T _max = 0.793

• 18679 measured reflections

• 3628 independent reflections

• 3166 reflections with I > 2σ(I)

• R _int = 0.025

Refinement

• R[F ² > 2σ(F ²)] = 0.029

• wR(F ²) = 0.073

• S = 1.09

• 3628 reflections

• 190 parameters

• H-atom parameters constrained

• Δρ_max = 0.30 e Å⁻³

• Δρ_min = −0.56 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2001 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Fe1—C8	1.761 (2)
Fe1—C7	1.780 (2)
Fe1—P1	2.2793 (6)
Fe1—P2	2.2840 (6)
Fe1—S2	2.3058 (6)
Fe1—S1	2.3170 (6)

supplementary crystallographic information

Comment

Recently iron sulfides have been proposed as being central to the emergence of life due to their structural resemblance to the active site of hydrogenases (Cody et al., 2000, Georgakaki et al., 2003, Capon et al., 2005). Various dinuclear complexes featured [Fe₂(µ-SR)₂(CO)_6-γL_γ] (L = CO, PR₃et al., γ = 1 or 2) have been investigated as the structural and functional models for the active site of [FeFe]-hydrogenases (Song, 2005, Li et al., 2005, Liu & Xiao, 2011). [Fe₂(µ-S₂C₄N₂H₂)(CO)₆] (Durgaprasad et al., 2011) was prepared for the purpose to lower the reduction potentials of the iron sulfides. When we investigated the CO displacement of above complex by PMe₃, a mononuclear byproduct was obtained accompanied with PMe₃-disubstituted diiron compounds. Herein, we report this crystal structure.

In the title compound the central Fe atom is six-coordinated by the two thiolate-sulfur atoms, two phosphane-phosphorus atoms, and two carbonyl-carbon atoms in a distorted octahedral geometry (Fig. 1 and Table 1). The average Fe—C(O) distance (1.77 Å) is relatively shorter than that of its parent hexacarbonyl diiron compound [Fe₂(µ-S₂C₄N₂H₂)(CO)₆] (Durgaprasad et al., 2011), and differs by 0.51 Å from the average Fe—P(Me)₃ distance, consistent with the better donating role of the tertiary phosphane ligands vs. the carbonyl groups. The two S—Fe bonds are nearly perpendicular, and S1—Fe1—S2 angle is 89.198 (19) °. The P1—Fe1—P2 angle is quasilinear [177.45 (2) °] and the deviation of the iron atom from the calculated plane of the –SC₄N₂H₂S– bridge is 0.126 Å. The angle between the calculated rigid dithiolate bridge and the P1Fe1P2 plane deviates from 90° by 3.2° for the title compound, resulting in the asymmetric molecular structure.

Experimental

Commercially available materials, Me₃NO and trimethylphosphane were reagent grade and used as received. The starting material [Fe₂(µ-S₂C₄N₂H₂)(CO)₆] was prepared according to the literature procedure (Durgaprasad et al., 2011). [Fe₂(µ-S₂C₄N₂H₂)(CO)₆] (0.42 g, 1.0 mmol) and degassed CH₃CN (20 ml) was stirred in an argon-filled Schlenk flask until the salvation was completed. Me₃NO (0.24 g, 2.2 mmol) was added to the above solution in one portion. The mixture was changed to dark red after 10 min. Then the trimethylphosphane (0.15 g, 2.0 mmol) was added dropwise. The solvent was allowed to evaporate on a rotary evaporator after 20 min. The crude product was purified by column chromatography on Al₂O₃, using CH₂Cl₂/hexane as eluent, yielded two bands. The coral band was collected and the crystals of the title compound suitable for X-ray study were obtained by the recrystallization in the CH₂Cl₂/pentane solution (yield 0.12 g, 30%).

Refinement

The H atoms attached to C were placed in geometrically calculated positions (C—H = 0.93–0.97 Å) and refined as riding, with U_iso(H) = 1.2U_eq(C).

Figures

Fig. 1.

The molecular structure of the title compound with displacement ellipsoids drawn at 30% probability level.

Crystal data

[Fe(C4H2N2S2)(C3H9P)2(CO)2]	F(000) = 1680
Mr = 406.21	Dx = 1.460 Mg m−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 9947 reflections
a = 12.2078 (10) Å	θ = 2.3–27.5°
b = 11.951 (1) Å	µ = 1.22 mm−1
c = 25.326 (2) Å	T = 273 K
V = 3694.9 (5) Å3	Block, orange
Z = 8	0.30 × 0.25 × 0.20 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	3628 independent reflections
Radiation source: fine-focus sealed tube	3166 reflections with I > 2σ(I)
graphite	Rint = 0.025
phi and ω scans	θmax = 26.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 1997)	h = −15→14
Tmin = 0.711, Tmax = 0.793	k = −14→8
18679 measured reflections	l = −31→31

Refinement

Refinement on F2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.029	w = 1/[σ2(Fo2) + (0.0363P)2 + 1.1092P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.073	(Δ/σ)max = 0.001
S = 1.09	Δρmax = 0.30 e Å−3
3628 reflections	Δρmin = −0.56 e Å−3
190 parameters

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
Fe1	0.374999 (19)	0.76447 (2)	0.389085 (10)	0.03519 (9)
S1	0.38945 (4)	0.57419 (4)	0.37296 (2)	0.04420 (13)
P2	0.39648 (4)	0.71975 (5)	0.47615 (2)	0.04635 (14)
S2	0.56151 (4)	0.78108 (4)	0.37704 (2)	0.05021 (14)
P1	0.35858 (4)	0.80265 (5)	0.30127 (2)	0.04756 (14)
O1	0.13778 (12)	0.74340 (14)	0.39685 (7)	0.0643 (4)
C7	0.23021 (16)	0.75098 (15)	0.39447 (7)	0.0430 (4)
C9	0.60519 (15)	0.64370 (18)	0.36700 (7)	0.0446 (4)
O2	0.38260 (15)	1.00089 (14)	0.41494 (8)	0.0817 (5)
C10	0.53051 (15)	0.55283 (16)	0.36640 (6)	0.0407 (4)
N1	0.56545 (15)	0.44788 (15)	0.36180 (6)	0.0519 (4)
C8	0.37676 (16)	0.90822 (17)	0.40424 (9)	0.0502 (5)
C12	0.74509 (18)	0.5207 (2)	0.35593 (9)	0.0667 (7)
H12A	0.8193	0.5059	0.3516	0.080*
C11	0.6742 (2)	0.4338 (2)	0.35706 (7)	0.0589 (6)
H11A	0.7018	0.3615	0.3545	0.071*
C6	0.52289 (18)	0.6505 (2)	0.49459 (9)	0.0626 (6)
H6A	0.5227	0.6361	0.5319	0.094*
H6B	0.5839	0.6978	0.4859	0.094*
H6C	0.5291	0.5811	0.4757	0.094*
N2	0.71250 (14)	0.62810 (18)	0.36084 (7)	0.0612 (5)
C2	0.2200 (2)	0.8015 (3)	0.27602 (9)	0.0830 (9)
H2B	0.2208	0.8183	0.2390	0.125*
H2C	0.1772	0.8567	0.2943	0.125*
H2D	0.1883	0.7289	0.2814	0.125*
C3	0.4080 (3)	0.9401 (3)	0.28305 (11)	0.0997 (11)
H3A	0.3988	0.9508	0.2457	0.150*
H3B	0.4842	0.9463	0.2919	0.150*
H3C	0.3671	0.9961	0.3018	0.150*
C4	0.29368 (19)	0.6241 (2)	0.50169 (9)	0.0728 (7)
H4A	0.3080	0.6093	0.5383	0.109*
H4B	0.2963	0.5552	0.4822	0.109*
H4C	0.2224	0.6571	0.4981	0.109*
C1	0.4288 (2)	0.7111 (3)	0.25558 (10)	0.0827 (8)
H1B	0.4155	0.7358	0.2201	0.124*
H1C	0.4021	0.6361	0.2598	0.124*
H1D	0.5060	0.7129	0.2626	0.124*
C5	0.3912 (3)	0.8351 (3)	0.52247 (11)	0.0983 (11)
H5A	0.4011	0.8073	0.5577	0.147*
H5B	0.3213	0.8716	0.5199	0.147*
H5C	0.4483	0.8876	0.5144	0.147*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Fe1	0.03369 (15)	0.03112 (15)	0.04075 (16)	0.00071 (9)	−0.00012 (10)	0.00066 (10)
S1	0.0391 (2)	0.0349 (2)	0.0586 (3)	−0.00252 (18)	0.00205 (19)	−0.0062 (2)
P2	0.0529 (3)	0.0452 (3)	0.0409 (3)	0.0026 (2)	−0.0055 (2)	−0.0013 (2)
S2	0.0355 (2)	0.0422 (3)	0.0729 (3)	−0.0058 (2)	0.0009 (2)	0.0035 (2)
P1	0.0472 (3)	0.0532 (3)	0.0423 (3)	−0.0029 (2)	−0.0002 (2)	0.0065 (2)
O1	0.0383 (8)	0.0691 (11)	0.0856 (12)	0.0028 (7)	0.0084 (7)	0.0101 (9)
C7	0.0424 (11)	0.0387 (10)	0.0479 (10)	0.0035 (8)	0.0032 (8)	0.0037 (8)
C9	0.0377 (9)	0.0518 (11)	0.0442 (10)	0.0056 (8)	0.0000 (7)	0.0026 (9)
O2	0.0976 (14)	0.0380 (9)	0.1097 (15)	0.0031 (8)	−0.0022 (11)	−0.0105 (9)
C10	0.0428 (10)	0.0435 (10)	0.0358 (9)	0.0075 (8)	0.0015 (7)	−0.0015 (8)
N1	0.0616 (11)	0.0483 (10)	0.0458 (9)	0.0136 (8)	0.0018 (7)	−0.0040 (7)
C8	0.0510 (11)	0.0384 (11)	0.0613 (12)	0.0032 (8)	−0.0005 (9)	0.0009 (9)
C12	0.0460 (12)	0.0879 (19)	0.0661 (14)	0.0269 (13)	0.0043 (10)	0.0017 (13)
C11	0.0665 (14)	0.0675 (15)	0.0428 (10)	0.0308 (13)	0.0019 (9)	−0.0026 (10)
C6	0.0600 (13)	0.0693 (15)	0.0584 (12)	0.0014 (11)	−0.0192 (10)	0.0096 (11)
N2	0.0382 (9)	0.0730 (13)	0.0723 (12)	0.0083 (9)	0.0024 (8)	0.0048 (10)
C2	0.0597 (14)	0.135 (3)	0.0548 (13)	0.0022 (16)	−0.0134 (11)	0.0142 (15)
C3	0.152 (3)	0.081 (2)	0.0660 (16)	−0.043 (2)	−0.0189 (17)	0.0327 (15)
C4	0.0638 (14)	0.099 (2)	0.0552 (12)	−0.0068 (14)	0.0009 (11)	0.0253 (13)
C1	0.0862 (18)	0.112 (2)	0.0493 (13)	0.0191 (17)	0.0164 (12)	−0.0033 (14)
C5	0.160 (3)	0.076 (2)	0.0591 (15)	0.0244 (19)	−0.0146 (17)	−0.0217 (14)

Geometric parameters (Å, °)

Fe1—C8	1.761 (2)	C12—C11	1.352 (4)
Fe1—C7	1.780 (2)	C12—H12A	0.9300
Fe1—P1	2.2793 (6)	C11—H11A	0.9300
Fe1—P2	2.2840 (6)	C6—H6A	0.9600
Fe1—S2	2.3058 (6)	C6—H6B	0.9600
Fe1—S1	2.3170 (6)	C6—H6C	0.9600
S1—C10	1.7488 (18)	C2—H2B	0.9600
P2—C5	1.811 (3)	C2—H2C	0.9600
P2—C6	1.812 (2)	C2—H2D	0.9600
P2—C4	1.817 (2)	C3—H3A	0.9600
S2—C9	1.745 (2)	C3—H3B	0.9600
P1—C1	1.808 (2)	C3—H3C	0.9600
P1—C2	1.809 (2)	C4—H4A	0.9600
P1—C3	1.810 (3)	C4—H4B	0.9600
O1—C7	1.134 (2)	C4—H4C	0.9600
C9—N2	1.332 (2)	C1—H1B	0.9600
C9—C10	1.418 (3)	C1—H1C	0.9600
O2—C8	1.142 (3)	C1—H1D	0.9600
C10—N1	1.330 (3)	C5—H5A	0.9600
N1—C11	1.343 (3)	C5—H5B	0.9600
C12—N2	1.349 (3)	C5—H5C	0.9600
C8—Fe1—C7	94.81 (9)	N1—C11—C12	122.6 (2)
C8—Fe1—P1	91.05 (7)	N1—C11—H11A	118.7
C7—Fe1—P1	90.32 (6)	C12—C11—H11A	118.7
C8—Fe1—P2	90.95 (7)	P2—C6—H6A	109.5
C7—Fe1—P2	91.08 (6)	P2—C6—H6B	109.5
P1—Fe1—P2	177.45 (2)	H6A—C6—H6B	109.5
C8—Fe1—S2	86.14 (6)	P2—C6—H6C	109.5
C7—Fe1—S2	176.78 (6)	H6A—C6—H6C	109.5
P1—Fe1—S2	86.58 (2)	H6B—C6—H6C	109.5
P2—Fe1—S2	91.98 (2)	C9—N2—C12	115.7 (2)
C8—Fe1—S1	174.39 (7)	P1—C2—H2B	109.5
C7—Fe1—S1	90.01 (6)	P1—C2—H2C	109.5
P1—Fe1—S1	91.79 (2)	H2B—C2—H2C	109.5
P2—Fe1—S1	86.09 (2)	P1—C2—H2D	109.5
S2—Fe1—S1	89.198 (19)	H2B—C2—H2D	109.5
C10—S1—Fe1	103.59 (7)	H2C—C2—H2D	109.5
C5—P2—C6	102.18 (13)	P1—C3—H3A	109.5
C5—P2—C4	102.93 (15)	P1—C3—H3B	109.5
C6—P2—C4	102.08 (12)	H3A—C3—H3B	109.5
C5—P2—Fe1	116.29 (10)	P1—C3—H3C	109.5
C6—P2—Fe1	116.96 (8)	H3A—C3—H3C	109.5
C4—P2—Fe1	114.31 (8)	H3B—C3—H3C	109.5
C9—S2—Fe1	103.89 (7)	P2—C4—H4A	109.5
C1—P1—C2	102.28 (13)	P2—C4—H4B	109.5
C1—P1—C3	103.18 (15)	H4A—C4—H4B	109.5
C2—P1—C3	103.19 (14)	P2—C4—H4C	109.5
C1—P1—Fe1	117.49 (9)	H4A—C4—H4C	109.5
C2—P1—Fe1	115.19 (8)	H4B—C4—H4C	109.5
C3—P1—Fe1	113.66 (9)	P1—C1—H1B	109.5
O1—C7—Fe1	178.51 (19)	P1—C1—H1C	109.5
N2—C9—C10	121.58 (19)	H1B—C1—H1C	109.5
N2—C9—S2	116.69 (17)	P1—C1—H1D	109.5
C10—C9—S2	121.72 (14)	H1B—C1—H1D	109.5
N1—C10—C9	121.13 (17)	H1C—C1—H1D	109.5
N1—C10—S1	117.51 (15)	P2—C5—H5A	109.5
C9—C10—S1	121.35 (14)	P2—C5—H5B	109.5
C10—N1—C11	116.28 (19)	H5A—C5—H5B	109.5
O2—C8—Fe1	176.9 (2)	P2—C5—H5C	109.5
N2—C12—C11	122.7 (2)	H5A—C5—H5C	109.5
N2—C12—H12A	118.7	H5B—C5—H5C	109.5
C11—C12—H12A	118.7
C8—Fe1—S1—C10	−29.4 (8)	S2—Fe1—P1—C2	178.35 (12)
C7—Fe1—S1—C10	−178.74 (8)	S1—Fe1—P1—C2	89.26 (12)
P1—Fe1—S1—C10	90.93 (6)	C8—Fe1—P1—C3	23.20 (15)
P2—Fe1—S1—C10	−87.66 (6)	C7—Fe1—P1—C3	118.01 (15)
S2—Fe1—S1—C10	4.37 (6)	P2—Fe1—P1—C3	−118.6 (5)
C8—Fe1—P2—C5	6.40 (15)	S2—Fe1—P1—C3	−62.87 (13)
C7—Fe1—P2—C5	−88.43 (14)	S1—Fe1—P1—C3	−151.96 (13)
P1—Fe1—P2—C5	148.2 (5)	C8—Fe1—C7—O1	78 (8)
S2—Fe1—P2—C5	92.57 (13)	P1—Fe1—C7—O1	−13 (8)
S1—Fe1—P2—C5	−178.37 (13)	P2—Fe1—C7—O1	169 (8)
C8—Fe1—P2—C6	−114.62 (11)	S2—Fe1—C7—O1	−29 (9)
C7—Fe1—P2—C6	150.55 (11)	S1—Fe1—C7—O1	−105 (8)
P1—Fe1—P2—C6	27.1 (5)	Fe1—S2—C9—N2	−177.54 (14)
S2—Fe1—P2—C6	−28.45 (9)	Fe1—S2—C9—C10	1.34 (16)
S1—Fe1—P2—C6	60.61 (9)	N2—C9—C10—N1	2.8 (3)
C8—Fe1—P2—C4	126.20 (12)	S2—C9—C10—N1	−176.04 (14)
C7—Fe1—P2—C4	31.37 (12)	N2—C9—C10—S1	−178.48 (14)
P1—Fe1—P2—C4	−92.0 (5)	S2—C9—C10—S1	2.7 (2)
S2—Fe1—P2—C4	−147.63 (10)	Fe1—S1—C10—N1	173.69 (13)
S1—Fe1—P2—C4	−58.57 (10)	Fe1—S1—C10—C9	−5.10 (16)
C8—Fe1—S2—C9	173.53 (10)	C9—C10—N1—C11	−0.9 (3)
C7—Fe1—S2—C9	−79.2 (11)	S1—C10—N1—C11	−179.71 (13)
P1—Fe1—S2—C9	−95.18 (7)	C7—Fe1—C8—O2	153 (4)
P2—Fe1—S2—C9	82.72 (7)	P1—Fe1—C8—O2	−117 (4)
S1—Fe1—S2—C9	−3.34 (7)	P2—Fe1—C8—O2	62 (4)
C8—Fe1—P1—C1	143.77 (13)	S2—Fe1—C8—O2	−30 (4)
C7—Fe1—P1—C1	−121.41 (13)	S1—Fe1—C8—O2	4(5)
P2—Fe1—P1—C1	2.0 (5)	C10—N1—C11—C12	−1.2 (3)
S2—Fe1—P1—C1	57.70 (12)	N2—C12—C11—N1	1.8 (3)
S1—Fe1—P1—C1	−31.39 (12)	C10—C9—N2—C12	−2.2 (3)
C8—Fe1—P1—C2	−95.58 (14)	S2—C9—N2—C12	176.63 (16)
C7—Fe1—P1—C2	−0.76 (13)	C11—C12—N2—C9	0.1 (3)
P2—Fe1—P1—C2	122.7 (5)