[Cl₅Ta([mu]-O)TaCl₃{ⁱPrS(CH₂)₂SⁱPr}] and [(TaCl₄)₂([mu]-O)([mu]-Me₂Se₂)]: two chalco­geno­ether complexes of Ta₂OCl₈ with very different geometries

The title compounds, [1,2-bis­(isopropyl­sulfan­yl)ethane-2[kappa]²S,S']octa­chlorido-1[kappa]⁵Cl,2[kappa]³Cl-[mu]-oxido-ditantalum(V), [Ta₂Cl₈O(C₈H₁₈S₂)], (I), and [mu]-dimethyl­diselane-[kappa]²Se:Se'-[mu]-oxido-bis­[tetra­chloridotantalum(V)], [Ta₂Cl₈O(C₂H₆Se₂)], (II), contain six-coordinate Ta^V centres linked by a nonlinear oxide bridge. Compound (I) contains one Ta^V centre bonded to a chelating dithio­ether and three terminal chloride ligands, with the second Ta^V centre bonded to five terminal chloride ligands. In (II), two tetra­chloridotantalum(V) residues are bridged by the diselenide, giving a puckered five-membered Ta/O/Ta/Se/Se ring. The Ta-O distances in the bridges are short in both compounds, indicating that significant multiple-bond character is retained despite the deviation from linearity, and the bond lengths reveal a clear trans influence order of O > Cl > S > Se on the hard Ta^V centre. The structures are compared with the [Ta₂Cl₁₀O]^2- anion, which contains a linear oxide bridge.

S1. Comment

The centrosymmetric [Ta₂OCl₁₀]^2– anion, often obtained by serendipitous hydrolysis in syntheses using TaCl₅, has D_4h symmetry with a linear Ta—O—Ta unit and short Ta—O bonds (1.88–1.90 Å), indicative of some multiple-bonding character [O(pπ)→Ta(dπ)] (Cotton & Najjar, 1981; Noll & Mueller, 1999; Xi et al., 2010). The parent oxidechloride, Ta₂OCl₈, is unknown and analogues with neutral ligands have not been described hitherto. During studies of the complexes of MX₅ (M = Nb or Ta; X = F, Cl or Br) with chalcogenoether ligands (Benjamin et al., 2011; Jura et al., 2010, 2009), we obtained crystals of the title compounds, the first two examples of such complexes, [Cl₅Ta(µ-O)TaCl₃{ⁱPrS(CH₂)₂SⁱPr}], (I), and [(TaCl₄)₂(µ-O)(µ-Me₂Se₂)], (II), which show very different architectures and significant differences in bond lengths and angles. The formation of these complexes is clearly the result of adventitious hydrolysis during attempts at crystal growth of the corresponding TaCl₅ complexes. In (I), the dithioether chelates to one TaCl₃ unit which is linked via the oxo-bridge to a TaCl₅ unit, whilst in (II) the chalcogen ligand bridges the Ta—O—Ta unit to give a puckered five-membered ring.

The deep-yellow crystals of (I) contain a distorted square-pyramidal TaCl₅ unit about atom Ta2 (Fig. 1), with the sixth position occupied by the bridging oxo group [Ta2—O1 = 2.057 (4) Å; Table 1], whereas atom Ta1 has a more distorted octahedral geometry composed of three mer chloride ligands, two cis S atoms from a chelating dithioether and a markedly shorter bond to the bridging oxo group [Ta1—O1 = 1.787 (4) Å]. The dithioether is in the DL conformation (the ⁱPr groups are on opposite sides of the TaS₂ plane) with long Ta—S bonds (Table 1), reflecting the weak affinity of the hard Ta^V centre for the soft neutral S donor. The bond-length distribution about the Ta centres shows clear evidence for the trans influence order O > Cl > S on the hard Ta^V centre. The Ta2—O1—Ta1 bridge is nonlinear [165.9 (3) °], in contrast with that in [Ta₂OCl₁₀]^2-.

The deep-orange crystals of (II) also contain a nonlinear [164.3 (2)°] oxo-bridge, with Ta1—O1 = 1.874 (2) Å and Ta2—O1 = 1.917 (2) Å (Table 2), linking two distorted octahedral Ta^V centres. The diselenide bridges the Ta—O—Ta unit [Ta1—Se1 = 2.8715 (4) and Ta2—Se2 = 2.8701 (4) Å; Table 2], forming a nonplanar five-membered ring with acute O—Ta—Se angles and much wider Ta—Se—Se angles (Table 2). The Se—Se distance is rather longer than in the gas-phase diselenide [2.326 (3) Å; D'Antonio et al., 1971]. Notably, the Ta—O—Ta angles in both (I) and (II) differ by <2°, suggesting that the constraints of the ring in (II) are not responsible for the deviation from linearity.

Comparison of the core geometries in (I), (II) and [Ta₂OCl₁₀]^2- (Cotton & Najjar, 1981) reveal that in [Ta₂OCl₁₀]^2- the Ta—Cl_transO bond [2.381 (6) Å] is longer than the Ta—Cl_transCl bond. In (II), the corresponding trend is not clear. However, as noted above, in (I) the bridging oxide interacts more strongly with Ta1 [Ta1—O1 = 1.787 (4) Å], with greater [O(pπ)→Ta(dπ)] donation compensating for the presence of only three π-donor chlorides and weak donation from the S atoms. In contrast, for atom Ta2, which carries five π-donor chlorides, the Ta2—O1 bond is much longer [2.057 (4) Å], and this correlates with Ta—Cl_transO being shorter [2.292 (2) Å] than Ta—Cl_transCl [2.317 (2)–2.362 (2) Å]. Consideration of the patterns in the bond lengths and the trans influence order described above would suggest that, despite the different architectures in the three compounds, the dominant interactions are those between the electron-poor Ta^V centres and the π-donor oxo and chloride ligands, with the neutral chalcogenoethers weakly bound and filling available coordination sites. The strong Ta—O—Ta bonds are evident from the IR spectra of all three compounds, which show a very strong and broad feature at ca 800 cm^-1 ascribed to the antisymmetric stretching vibration of this unit (Dehnicke & Prinz, 1982).

Related literature

For related literature, see: Benjamin et al. (2011); Cotton & Najjar (1981); D'Antonio, George, Lowrey & Karle (1971); Dehnicke & Prinz (1982); Jura et al. (2009, 2010); Noll & Mueller (1999); Sheldrick (2008); Xi et al. (2010).

S2. Experimental

[Cl₅Ta(µ-O)TaCl₃{ⁱPrS(CH₂)₂SⁱPr}], (I), was prepared as follows. [(TaCl₅)₂{µ-ⁱPrS(CH₂)₂SⁱPr}] (0.2 g) [prepared from TaCl₅ and ⁱPrS(CH₂)₂SⁱPr in anhydrous CH₂Cl₂] was dissolved in anhydrous CH₂Cl₂ (3 ml), n-hexane (2 ml) was layered on top, and the mixture refrigerated. Small yellow crystals of (I) grew after a few days, and these were isolated by decanting off the mother liquor and then dried in vacuo. Spectroscopic analysis: ¹H NMR (CD₂Cl₂, 295 K, δ, p.p.m.): 1.43 [d, J = 6 Hz (6H)], 1.63 [d, J = 6 Hz (6H)], 3.29 [m, (2H)], 3.54 [m, (2H)], 3.62–3.69 [m, (2H)]; IR (Nujol, ν, cm^-1): 801 (vs, br) (Ta—O—Ta), 368 (m), 349 (s), 317 (s) (Ta—Cl).

[(TaCl₄)₂(µ-O)(µ-Me₂Se₂)], (II), was prepared as follows. TaCl₅ (0.36 g, 1.0 mmol) was suspended in anhydrous CH₂Cl₂ (10 ml) and stirred whilst Me₂Se₂ (0.37 g, 1.0 mmol) was slowly added. The reaction mixture rapidly turned a deep orange and after 10 min was concentrated to 3 ml in vacuo. The orange precipitate was separated off and washed with dry hexane (10 ml). Refrigeration of the filtrate for several days gave deep-orange crystals of (II), which were manually separated from an orange oil and rinsed with n-hexane. Spectroscopic analysis: ¹H NMR (CD₂Cl₂, 295 K, δ, p.p.m.): 3.15 (s); IR (Nujol, ν, cm^-1): 800 (vs) (Ta—O—Ta), 336 (sh), 315 (vs, br) (Ta—Cl).

S3. Refinement

H atoms were placed in calculated positions, with C—H = 0.98 (methyl H) or 0.99 Å (CH₂), and with U_iso(H) = 1.5U_eq(methyl C) or 1.2U_eq(methylene C). The AFIX 137 command (SHELXL97; Sheldrick, 2008) was used with the Me groups to estimate their initial conformations.

Computing details

For both compounds, data collection: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); cell refinement: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); data reduction: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: DIRDIF99 (Beurskens et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The discrete molecule of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity.
	Fig. 2. The discrete molecule of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity.

(I) [1,2-bis(isopropylsulfanyl)ethane-2κ²S,S']octachlorido- 1κ⁵Cl,2κ³Cl-µ-oxido-ditantalum(V)

Crystal data

[Ta2Cl8O(C8H18S2)]	Dx = 2.488 Mg m^−3
Mr = 839.84	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 100483 reflections
a = 15.684 (3) Å	θ = 2.9–27.5°
b = 13.007 (2) Å	µ = 10.89 mm^−1
c = 21.981 (4) Å	T = 120 K
V = 4484.4 (14) Å^3	Plate, yellow
Z = 8	0.15 × 0.06 × 0.01 mm
F(000) = 3104

Data collection

Bruker Nonius APEXII CCD camera on κ-goniostat diffractometer	5139 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	4364 reflections with I > 2σ(I)
10cm confocal mirrors monochromator	Rint = 0.055
Detector resolution: 4096x4096pixels / 62x62mm pixels mm^-1	θmax = 27.5°, θmin = 3.0°
ϕ and ω scans	h = −14→20
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	k = −16→16
Tmin = 0.425, Tmax = 0.897	l = −28→28
36044 measured reflections

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + 47.4498P] where P = (Fo^2 + 2Fc^2)/3
5139 reflections	(Δ/σ)max = 0.001
194 parameters	Δρmax = 1.26 e Å^−3
0 restraints	Δρmin = −1.23 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
Ta1	0.122173 (17)	0.67937 (2)	0.450206 (12)	0.02203 (7)
Ta2	0.028140 (18)	0.85299 (2)	0.327462 (12)	0.02434 (8)
Cl1	0.15077 (11)	0.54250 (13)	0.38585 (8)	0.0309 (4)
Cl2	0.13947 (11)	0.79462 (12)	0.53118 (8)	0.0288 (3)
Cl3	−0.00818 (10)	0.62581 (12)	0.48379 (8)	0.0293 (4)
Cl4	0.06825 (12)	0.72523 (13)	0.25984 (8)	0.0333 (4)
Cl5	−0.09426 (11)	0.75863 (14)	0.35272 (8)	0.0334 (4)
Cl6	0.00228 (11)	0.96675 (13)	0.40917 (8)	0.0320 (4)
Cl7	0.15599 (11)	0.93887 (13)	0.30790 (8)	0.0326 (4)
Cl8	−0.04585 (12)	0.94923 (14)	0.25791 (8)	0.0367 (4)
O1	0.0917 (3)	0.7684 (3)	0.3922 (2)	0.0273 (10)
S1	0.28316 (11)	0.73779 (12)	0.43775 (7)	0.0252 (3)
S2	0.19843 (10)	0.53807 (12)	0.52560 (7)	0.0238 (3)
C1	0.2940 (5)	0.7191 (7)	0.3132 (3)	0.0386 (18)
H1A	0.2359	0.6912	0.3132	0.058*
H1B	0.3249	0.6932	0.2777	0.058*
H1C	0.2916	0.7943	0.3116	0.058*
C2	0.3397 (5)	0.6857 (6)	0.3710 (3)	0.0308 (15)
H2	0.3403	0.6089	0.3732	0.037*
C3	0.4306 (4)	0.7255 (6)	0.3725 (4)	0.0377 (17)
H3A	0.4583	0.7031	0.4102	0.057*
H3B	0.4301	0.8008	0.3708	0.057*
H3C	0.4621	0.6984	0.3375	0.057*
C4	0.3349 (5)	0.6676 (5)	0.4989 (3)	0.0312 (15)
H4A	0.3974	0.6713	0.4931	0.037*
H4B	0.3213	0.7016	0.5381	0.037*
C5	0.3088 (4)	0.5558 (5)	0.5029 (3)	0.0272 (14)
H5A	0.3462	0.5204	0.5325	0.033*
H5B	0.3177	0.5231	0.4627	0.033*
C6	0.1081 (5)	0.5689 (6)	0.6289 (3)	0.0364 (17)
H6A	0.0738	0.6178	0.6055	0.055*
H6B	0.1058	0.5868	0.6721	0.055*
H6C	0.0856	0.4993	0.6230	0.055*
C7	0.2003 (4)	0.5730 (6)	0.6070 (3)	0.0286 (15)
H7	0.2228	0.6446	0.6117	0.034*
C8	0.2563 (5)	0.4987 (6)	0.6428 (3)	0.0383 (17)
H8A	0.3148	0.5020	0.6274	0.057*
H8B	0.2343	0.4286	0.6381	0.057*
H8C	0.2556	0.5178	0.6859	0.057*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.02237 (14)	0.02247 (14)	0.02124 (13)	−0.00038 (10)	−0.00053 (11)	0.00019 (10)
Ta2	0.02700 (15)	0.02398 (14)	0.02203 (14)	−0.00050 (11)	−0.00095 (11)	0.00123 (11)
Cl1	0.0339 (9)	0.0302 (8)	0.0286 (8)	0.0014 (7)	−0.0016 (7)	−0.0061 (7)
Cl2	0.0339 (9)	0.0261 (8)	0.0263 (8)	−0.0001 (7)	0.0012 (7)	−0.0025 (6)
Cl3	0.0244 (8)	0.0288 (8)	0.0348 (9)	−0.0025 (6)	0.0022 (7)	0.0033 (7)
Cl4	0.0385 (10)	0.0316 (9)	0.0297 (9)	0.0030 (7)	−0.0062 (7)	−0.0058 (7)
Cl5	0.0309 (9)	0.0367 (9)	0.0326 (9)	−0.0065 (7)	−0.0027 (7)	0.0031 (7)
Cl6	0.0317 (9)	0.0335 (9)	0.0306 (9)	−0.0007 (7)	0.0040 (7)	−0.0050 (7)
Cl7	0.0345 (9)	0.0297 (8)	0.0337 (9)	−0.0068 (7)	0.0077 (7)	−0.0036 (7)
Cl8	0.0401 (10)	0.0407 (10)	0.0293 (9)	0.0110 (8)	−0.0011 (8)	0.0083 (8)
O1	0.030 (2)	0.028 (2)	0.024 (2)	0.003 (2)	−0.003 (2)	0.000 (2)
S1	0.0255 (8)	0.0249 (8)	0.0250 (8)	−0.0027 (6)	0.0028 (7)	0.0005 (6)
S2	0.0242 (8)	0.0230 (8)	0.0240 (8)	0.0010 (6)	−0.0013 (7)	0.0009 (6)
C1	0.030 (4)	0.060 (5)	0.025 (4)	0.007 (4)	0.006 (3)	0.004 (4)
C2	0.033 (4)	0.033 (4)	0.027 (3)	−0.005 (3)	0.009 (3)	−0.003 (3)
C3	0.027 (4)	0.048 (5)	0.038 (4)	0.001 (3)	0.005 (3)	0.001 (4)
C4	0.029 (4)	0.036 (4)	0.028 (4)	−0.007 (3)	−0.002 (3)	0.006 (3)
C5	0.028 (4)	0.029 (3)	0.025 (3)	0.001 (3)	0.004 (3)	0.010 (3)
C6	0.037 (4)	0.047 (4)	0.025 (4)	0.004 (3)	0.004 (3)	−0.004 (3)
C7	0.031 (4)	0.035 (4)	0.020 (3)	−0.003 (3)	−0.001 (3)	0.000 (3)
C8	0.039 (4)	0.047 (4)	0.029 (4)	0.001 (4)	0.000 (3)	0.004 (3)

Geometric parameters (Å, º)

Ta1—O1	1.787 (4)	C2—C3	1.518 (10)
Ta1—Cl3	2.2826 (17)	C2—H2	1.0000
Ta1—Cl1	2.3177 (16)	C3—H3A	0.9800
Ta1—Cl2	2.3429 (17)	C3—H3B	0.9800
Ta1—S1	2.6511 (17)	C3—H3C	0.9800
Ta1—S2	2.7486 (16)	C4—C5	1.513 (9)
Ta2—O1	2.057 (4)	C4—H4A	0.9900
Ta2—Cl8	2.2916 (17)	C4—H4B	0.9900
Ta2—Cl4	2.3166 (17)	C5—H5A	0.9900
Ta2—Cl7	2.3354 (17)	C5—H5B	0.9900
Ta2—Cl5	2.3452 (17)	C6—C7	1.525 (10)
Ta2—Cl6	2.3622 (17)	C6—H6A	0.9800
S1—C4	1.817 (7)	C6—H6B	0.9800
S1—C2	1.844 (7)	C6—H6C	0.9800
S2—C5	1.817 (7)	C7—C8	1.524 (10)
S2—C7	1.846 (7)	C7—H7	1.0000
C1—C2	1.521 (10)	C8—H8A	0.9800
C1—H1A	0.9800	C8—H8B	0.9800
C1—H1B	0.9800	C8—H8C	0.9800
C1—H1C	0.9800
O1—Ta1—Cl3	100.88 (16)	C3—C2—C1	111.3 (6)
O1—Ta1—Cl1	96.58 (15)	C3—C2—S1	108.0 (5)
Cl3—Ta1—Cl1	97.83 (6)	C1—C2—S1	109.4 (5)
O1—Ta1—Cl2	99.07 (15)	C3—C2—H2	109.4
Cl3—Ta1—Cl2	93.06 (6)	C1—C2—H2	109.4
Cl1—Ta1—Cl2	158.87 (6)	S1—C2—H2	109.4
O1—Ta1—S1	89.74 (15)	C2—C3—H3A	109.5
Cl3—Ta1—S1	166.90 (6)	C2—C3—H3B	109.5
Cl1—Ta1—S1	88.44 (6)	H3A—C3—H3B	109.5
Cl2—Ta1—S1	77.57 (6)	C2—C3—H3C	109.5
O1—Ta1—S2	168.44 (15)	H3A—C3—H3C	109.5
Cl3—Ta1—S2	89.47 (6)	H3B—C3—H3C	109.5
Cl1—Ta1—S2	76.71 (6)	C5—C4—S1	113.8 (5)
Cl2—Ta1—S2	85.38 (5)	C5—C4—H4A	108.8
S1—Ta1—S2	80.76 (5)	S1—C4—H4A	108.8
O1—Ta2—Cl8	177.98 (14)	C5—C4—H4B	108.8
O1—Ta2—Cl4	85.94 (13)	S1—C4—H4B	108.8
Cl8—Ta2—Cl4	95.81 (6)	H4A—C4—H4B	107.7
O1—Ta2—Cl7	88.12 (14)	C4—C5—S2	113.3 (5)
Cl8—Ta2—Cl7	92.91 (7)	C4—C5—H5A	108.9
Cl4—Ta2—Cl7	89.53 (6)	S2—C5—H5A	108.9
O1—Ta2—Cl5	87.30 (14)	C4—C5—H5B	108.9
Cl8—Ta2—Cl5	91.68 (7)	S2—C5—H5B	108.9
Cl4—Ta2—Cl5	89.93 (7)	H5A—C5—H5B	107.7
Cl7—Ta2—Cl5	175.41 (6)	C7—C6—H6A	109.5
O1—Ta2—Cl6	83.78 (13)	C7—C6—H6B	109.5
Cl8—Ta2—Cl6	94.48 (7)	H6A—C6—H6B	109.5
Cl4—Ta2—Cl6	169.68 (6)	C7—C6—H6C	109.5
Cl7—Ta2—Cl6	89.30 (6)	H6A—C6—H6C	109.5
Cl5—Ta2—Cl6	90.42 (6)	H6B—C6—H6C	109.5
Ta1—O1—Ta2	165.9 (3)	C6—C7—C8	111.1 (6)
C4—S1—C2	100.9 (3)	C6—C7—S2	106.4 (5)
C4—S1—Ta1	101.8 (2)	C8—C7—S2	110.7 (5)
C2—S1—Ta1	115.8 (2)	C6—C7—H7	109.5
C5—S2—C7	102.7 (3)	C8—C7—H7	109.5
C5—S2—Ta1	99.4 (2)	S2—C7—H7	109.5
C7—S2—Ta1	115.3 (2)	C7—C8—H8A	109.5
C2—C1—H1A	109.5	C7—C8—H8B	109.5
C2—C1—H1B	109.5	H8A—C8—H8B	109.5
H1A—C1—H1B	109.5	C7—C8—H8C	109.5
C2—C1—H1C	109.5	H8A—C8—H8C	109.5
H1A—C1—H1C	109.5	H8B—C8—H8C	109.5
H1B—C1—H1C	109.5
S1—C4—C5—S2	−67.7 (6)

(II) µ-dimethyldiselane-κ²Se:Se'-µ-oxido- bis[tetrachloridotantalum(V)]

Crystal data

[Ta2Cl8O(C2H6Se2)]	F(000) = 3008
Mr = 849.49	Dx = 3.450 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 28.447 (3) Å	Cell parameters from 19057 reflections
b = 8.2681 (5) Å	θ = 2.9–27.5°
c = 16.2051 (10) Å	µ = 19.10 mm^−1
β = 120.875 (5)°	T = 120 K
V = 3271.3 (4) Å^3	Prism, yellow
Z = 8	0.15 × 0.10 × 0.04 mm

Data collection

Bruker Nonius APEXII CCD camera on κ-goniostat diffractometer	3762 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	3585 reflections with I > 2σ(I)
10cm confocal mirrors monochromator	Rint = 0.035
Detector resolution: 4096x4096pixels / 62x62mm pixels mm^-1	θmax = 27.6°, θmin = 2.9°
ϕ and ω scans	h = −36→26
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	k = −10→10
Tmin = 0.219, Tmax = 0.466	l = −21→21
21221 measured reflections

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)] = 0.018	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.041	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + 21.4847P] where P = (Fo^2 + 2Fc^2)/3
3762 reflections	(Δ/σ)max = 0.004
138 parameters	Δρmax = 0.89 e Å^−3
0 restraints	Δρmin = −1.16 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
Ta1	0.634454 (6)	0.603645 (17)	0.482247 (10)	0.01236 (5)
Ta2	0.580482 (6)	0.728943 (18)	0.641016 (9)	0.01242 (5)
Se1	0.688628 (15)	0.89793 (4)	0.57786 (3)	0.01552 (8)
Se2	0.612013 (15)	1.00843 (4)	0.57574 (2)	0.01501 (8)
Cl1	0.56640 (4)	0.77033 (11)	0.36969 (6)	0.01810 (18)
Cl2	0.68325 (4)	0.64564 (12)	0.40248 (6)	0.01975 (18)
Cl3	0.71437 (4)	0.49008 (11)	0.61030 (6)	0.02066 (19)
Cl4	0.59268 (4)	0.36547 (11)	0.41676 (6)	0.01928 (18)
Cl5	0.67014 (4)	0.73427 (12)	0.77105 (6)	0.0214 (2)
Cl6	0.55522 (4)	0.92489 (12)	0.71354 (7)	0.0238 (2)
Cl7	0.49864 (4)	0.77211 (11)	0.49799 (6)	0.01925 (19)
Cl8	0.55424 (4)	0.50337 (11)	0.68478 (6)	0.02059 (19)
O1	0.60785 (10)	0.6356 (3)	0.56555 (17)	0.0144 (5)
C1	0.68573 (18)	1.0363 (5)	0.4778 (3)	0.0222 (8)
H1A	0.6487	1.0337	0.4211	0.033*
H1B	0.7120	0.9971	0.4603	0.033*
H1C	0.6950	1.1475	0.5017	0.033*
C2	0.64923 (18)	1.1504 (5)	0.6876 (3)	0.0252 (9)
H2A	0.6727	1.0856	0.7450	0.038*
H2B	0.6220	1.2080	0.6963	0.038*
H2C	0.6717	1.2287	0.6777	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta1	0.01322 (8)	0.01403 (8)	0.01283 (7)	0.00285 (5)	0.00883 (6)	0.00179 (5)
Ta2	0.01289 (8)	0.01520 (8)	0.01164 (7)	−0.00059 (5)	0.00806 (6)	−0.00125 (5)
Se1	0.01300 (18)	0.01649 (18)	0.01897 (17)	0.00161 (13)	0.00956 (15)	0.00215 (13)
Se2	0.01533 (19)	0.01437 (18)	0.01838 (17)	0.00213 (14)	0.01085 (15)	0.00126 (13)
Cl1	0.0171 (5)	0.0208 (4)	0.0158 (4)	0.0051 (3)	0.0080 (4)	0.0047 (3)
Cl2	0.0201 (5)	0.0264 (5)	0.0205 (4)	0.0027 (4)	0.0159 (4)	0.0019 (4)
Cl3	0.0161 (5)	0.0247 (5)	0.0208 (4)	0.0075 (4)	0.0092 (4)	0.0071 (4)
Cl4	0.0241 (5)	0.0164 (4)	0.0207 (4)	−0.0006 (4)	0.0139 (4)	−0.0013 (3)
Cl5	0.0179 (5)	0.0250 (5)	0.0155 (4)	−0.0030 (4)	0.0044 (4)	0.0009 (3)
Cl6	0.0318 (6)	0.0246 (5)	0.0238 (4)	0.0011 (4)	0.0205 (4)	−0.0062 (4)
Cl7	0.0126 (4)	0.0247 (5)	0.0182 (4)	0.0024 (3)	0.0063 (4)	−0.0019 (3)
Cl8	0.0252 (5)	0.0207 (4)	0.0197 (4)	−0.0058 (4)	0.0143 (4)	−0.0007 (3)
O1	0.0126 (13)	0.0135 (12)	0.0156 (12)	0.0024 (10)	0.0061 (10)	0.0013 (10)
C1	0.025 (2)	0.022 (2)	0.032 (2)	0.0074 (17)	0.0232 (18)	0.0106 (16)
C2	0.028 (2)	0.0173 (19)	0.031 (2)	−0.0052 (17)	0.0159 (19)	−0.0102 (17)

Geometric parameters (Å, º)

Ta1—O1	1.874 (2)	Ta2—Se2	2.8701 (4)
Ta1—Cl4	2.2632 (9)	Se1—C1	1.952 (4)
Ta1—Cl1	2.3130 (9)	Se1—Se2	2.3471 (6)
Ta1—Cl3	2.3483 (9)	Se2—C2	1.953 (4)
Ta1—Cl2	2.3578 (9)	C1—H1A	0.9800
Ta1—Se1	2.8715 (4)	C1—H1B	0.9800
Ta2—O1	1.917 (2)	C1—H1C	0.9800
Ta2—Cl8	2.2543 (9)	C2—H2A	0.9800
Ta2—Cl7	2.3198 (9)	C2—H2B	0.9800
Ta2—Cl6	2.3215 (9)	C2—H2C	0.9800
Ta2—Cl5	2.3305 (10)
O1—Ta1—Cl4	98.71 (8)	O1—Ta2—Se2	77.46 (7)
O1—Ta1—Cl1	90.00 (8)	Cl8—Ta2—Se2	177.01 (2)
Cl4—Ta1—Cl1	97.07 (3)	Cl7—Ta2—Se2	81.44 (3)
O1—Ta1—Cl3	89.17 (8)	Cl6—Ta2—Se2	82.02 (3)
Cl4—Ta1—Cl3	95.95 (3)	Cl5—Ta2—Se2	85.07 (3)
Cl1—Ta1—Cl3	166.93 (3)	C1—Se1—Se2	96.71 (12)
O1—Ta1—Cl2	160.54 (8)	C1—Se1—Ta1	105.43 (13)
Cl4—Ta1—Cl2	100.73 (3)	Se2—Se1—Ta1	94.861 (16)
Cl1—Ta1—Cl2	88.27 (3)	C2—Se2—Se1	99.40 (13)
Cl3—Ta1—Cl2	88.17 (3)	C2—Se2—Ta2	105.35 (13)
O1—Ta1—Se1	78.18 (8)	Se1—Se2—Ta2	98.318 (16)
Cl4—Ta1—Se1	176.03 (2)	Ta1—O1—Ta2	164.26 (15)
Cl1—Ta1—Se1	85.46 (3)	Se1—C1—H1A	109.5
Cl3—Ta1—Se1	81.60 (3)	Se1—C1—H1B	109.5
Cl2—Ta1—Se1	82.36 (3)	H1A—C1—H1B	109.5
O1—Ta2—Cl8	100.14 (8)	Se1—C1—H1C	109.5
O1—Ta2—Cl7	87.27 (8)	H1A—C1—H1C	109.5
Cl8—Ta2—Cl7	96.72 (4)	H1B—C1—H1C	109.5
O1—Ta2—Cl6	159.48 (8)	Se2—C2—H2A	109.5
Cl8—Ta2—Cl6	100.34 (4)	Se2—C2—H2B	109.5
Cl7—Ta2—Cl6	89.18 (4)	H2A—C2—H2B	109.5
O1—Ta2—Cl5	88.29 (8)	Se2—C2—H2C	109.5
Cl8—Ta2—Cl5	96.69 (3)	H2A—C2—H2C	109.5
Cl7—Ta2—Cl5	166.42 (4)	H2B—C2—H2C	109.5
Cl6—Ta2—Cl5	90.49 (4)