Fragmentation reactions of realgar caused by early transition metal hydrides

Inorganica Chimica Acta 386 (2012) 50–55

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Fragmentation reactions of realgar caused by early transition metal hydrides Walter Meier a, Yves Mugnier b, Patrick Schwarz a, Manfred Scheer a, Joachim Wachter a,⇑, Manfred Zabel a a b

Institut für Anorganische Chemie der Universität Regensburg, 93040 Regensburg, Germany Institut de Chimie Moléculaire de l’Université de Bourgogne ICMUB-UMR CNRS 5260, Faculté des Sciences Mirande, Université de Bourgogne, 21100 Dijon, France

a r t i c l e

i n f o

Article history: Received 1 December 2011 Received in revised form 26 January 2012 Accepted 31 January 2012 Available online 15 February 2012 Keywords: Arsenic sulfides Niobium Tantalum Coordination compounds

a b s t r a c t The reaction of realgar with [Cp0 2MH3] in boiling toluene gave [Cp0 2M2As2S6] (Cp0 = t-BuC5H4; M = Nb: 1; Ta: 2), while [Cp2WH2] (Cp = C5H5) reacted with As4S4 to give [Cp2W(H)(g1-As5S2)] (6). The structures were determined by X-ray crystallography. Compounds 1 and 2 are dimers in which two Cp0 M units are symmetrically bridged by a l,g2:2-AsS3 ligand, a sulfide ligand and a heteroallylic l,g2:2-AsS2 ligand. The structure of 6 belongs to the type of bent metallocenes in which tungsten is surrounded tetrahedrally by two Cp ligands, a crystallographically found hydride atom and the new As5S2 cage. The reaction of 1 with W(CO)5THF gave [Cp0 2Nb2As2S6W(CO)5] (3) and [Cp0 2Nb2As2S6W(CO)3W(CO)5] (4). Compound 3 is a monoadduct of 1 bearing the W(CO)5 fragment at the As atom of the AsS3 ligand. The structure of 4 contains a distorted cubane-like Nb2WS4As cluster with an integrated W(CO)3 unit. A similar cluster 5 containing a CuI fragment instead of W(CO)3 was prepared from 1 and CuI. The structure is completed by an attached As4S3 cage, the As3 basis of which is oriented towards iodide. Electrochemical investigations of 1, 3, and 4 shows for each compound quasi-reversible one-electron reductions with E1/2 = 0.73 V (1), 0.55 V (3) and 0.67 V (4), respectively. Ó 2012 Elsevier B.V. All rights reserved.

1. Introduction The current interest in the chemistry of ligand complexes with mixed group 15 (E)/group 16 (Q) ligands is based on their potential ability as building blocks in coordination polymers. While the role of Pn ligand complexes in supramolecular chemistry has been summarized recently [1], that of Asn ligand complexes is still going to be explored [2]. A valuable source for the synthesis of Asn ligand complexes is realgar, As4S4 [3], which upon degradation of its cage by reactive organometallic complexes also forms metal complexes with heteroatomic As/S ligands [4]. These are stable hybrid clusters with inorganic cores and peripheral organometallic groups, which exhibit coordination properties corresponding to group 15 and/or group 16 ligand complexes [5]. Usual synthetic strategies for 15/16 ligand complexes include the reduction of binary E/Q phases by nucleophilic coordination compounds [6], the insertion of metal complex fragments into neutral or anionic cage molecules [7], and the thermal degradation of As4S4 by [Cp⁄2M2(CO)4] (M = Mo [3], Fe [8], Ru [9]; Cp⁄ = C5Me5) or [Cp⁄2Co2(CO)2] [10] complexes. In this work we report on the fragmentation reactions of realgar with early transition metal hydrides, e.g. [Cp0 2NbH3] (Cp0 = t-BuC5H4) and [Cp2WH2] (Cp = C5H5), respectively. First attempts to prepare heterometallic clusters or

⇑ Corresponding author. Fax: +49 941 943 4439. E-mail address: [email protected] (J. Wachter). 0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2012.01.064

coordination polymers from the resulting As/S ligand complexes and copper(I) halides are described. 2. Results 2.1. Reactions of As4S4 with Cp0 2MH3 (M = Nb, Ta; Cp0 = t-BuC5H4) The reaction of realgar with [Cp0 2NbH3] in boiling toluene gives after chromatographic workup violet [Cp0 2Nb2As2S6] (1) in nearly quantitative yield (Scheme 1). The composition of 1 was determined crystallographically and confirmed by elemental analysis. The field desorption mass spectrum (FDMS) in toluene contains the parent ion at m/z = 770.2. The 1H NMR spectrum of 1 in C6D6 reveals a singlet at d = 1.21 ppm for the t-Bu groups of the Cp0 ligands and four multiplets at 5.97, 6.13, 6.18 and 6.28 ppm for the aromatic protons. The observed pattern is in agreement with the structure of the compound. The analogous reaction of As4S4 and [Cp0 2TaH3] gives red [Cp0 2Ta2As2S6] (2) in 51% yield. The red solid transforms in the solid state slowly into golden leaves, which are no more soluble in any solvent. Single crystals of 2 were obtained by recrystallization of the red solid from toluene at 24 °C. The obtained red crystals also change their color at room temperature, but elemental analyses of the partially converted material confirm the composition found by X-ray crystallography. An explanation for this irreversible chromatic change cannot yet be given. The FD mass spectrum of 2 exhibits the parent ion at m/z = 946.0 and the 1H NMR spectrum

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W. Meier et al. / Inorganica Chimica Acta 386 (2012) 50–55

As S Cp'2MH2 + As4S4

toluene 110 °C

[M] S

S S As

S [M] S

[M] = Cp'2Nb: 1 [M] = Cp'2Ta: 2

Scheme 1.

in C6D6 shows five signals in the ratio 9:1:1:1:1, what is in agreement with equivalent Cp0 ligands in solution. Crystal structure analyses of 1and 2 show that in both complexes two Cp0 M units (M = Nb, Ta) are symmetrically bridged by a l,g2:2-AsS3 ligand, a sulfide ligand (S5) and a l,g2:2-AsS2 ligand (Fig. 1). This description suggests a formal oxidation state for each metal atom of +4, diamagnetism may be achieved by formation of a metal–metal bond. The observed Nb–Nb (3.289 Å) and Ta–Ta distances (3.284 Å) (Table 1) do not exclude bonding interactions [11]. The As–S distances within the trigonal w-AsS3 pyramid are inequivalent, so the distance As2–S3 is longer than the other ones. Organometallic complexes with the AsS33 ligand are rare [12] because of the pronounced tendency of thioarsenate(III) solutions to oligomerize under loss of sulfur [4]. Of great interest is the new AsS2 bridge. The small differences observed for the distances of the pairs As1–S1(S6) and M1(M2)– As1 are in agreement with an allylic character of the ligand, which may be described by the resonance formulas A and B (Scheme 2), in analogy with the NO2 ion. Contrary to the l,g1:3-AsS2 ligand in [(C5Me5)2Mo2(CO)2As2S42Cr(CO)5] [13] the central arsenic atom As1 interacts with the metal centers only weakly. The corresponding M–As bonds vary between 2.814(1) and 2.830(1) Å (Table 1).

Table 1 Selected distances (Å) of [Cp0 2M2As2S6] [M = Nb (1), M = Ta (2)]. 1

2

Nb1–Nb2 Nb1–S1 Nb1–S2 Nb1–S3 Nb1–S5 Nb2–S3 Nb2–S4 Nb2–S5 Nb2–S6 As1–S1 As1–S6 As2–S2 As2–S3 As2–S4 Nb1As1 Nb2As1

3.289(1) 2.372(1) 2.532(1) 2.556(1) 2.420(1) 2.569(1) 2.550(1) 2.386(1) 2.383(1) 2.271(1) 2.257(1) 2.250(1) 2.289(1) 2.260(1) 2.830(1) 2.821(1)

Ta1–Ta2 Ta1–S1 Ta1–S2 Ta1–S3 Ta1–S5 Ta2–S3 Ta2–S4 Ta2–S5 Ta2–S6 As1–S1 As1–S6 As2–S2 As2–S3 As2–S4 Ta1As1 Ta2As1

As

As S

S

S

3.284(2) 2.366(2) 2.516(2) 2.548(2) 2.418(2) 2.559(2) 2.529(2) 2.381(2) 2.375(2) 2.272(2) 2.263(2) 2.248(2) 2.287(2) 2.260(2) 2.825(1) 2.814(1)

S

B

A Scheme 2.

Cp'2Nb2As2S6 W(CO)5 3 +

W(CO)5THF

Cp'2Nb2As2S 6W(CO)3 W(CO)5

Cp'2Nb2As2S6

1

4 CuI

(Cp'2Nb2As2S6CuI)As4S3

5 2.2. Cluster formation reactions Scheme 3.

The reaction of 1 with three equivalents of W(CO)5THF in THF at room temperature gave after chromatographic workup and recrystallization brown crystals of [Cp0 2Nb2As2S6W(CO)5] (3) and redbrown needles of [Cp0 2Nb2As2S6W(CO)3W(CO)5] (4) (Scheme 3). Both samples were contaminated with W(CO)6, which could not be completely removed by high vacuum sublimation. X-ray diffraction analyses prove the composition of 3 and 4 and the FD mass spectrum of 4 exhibits the parent ion (m/z = 1362.9) and a weak peak at m/z = 1037.2. The latter can be assigned to the cluster core [Cp0 2Nb2As2S6W(CO)3]+. From the structural studies it is evident that compound 3 may be considered as intermediate monoadduct of 1, which quickly reacts with W(CO)5THF under formation of

Fig. 1. Molecular structure of [Cp0 2M2As2S6] (M = Nb (1), Ta (2)).

cluster 4. Attempts to increase the low yield of 3 by modifying the stoichiometry of the starting materials failed. The IR spectrum of 3 shows m(CO) absorptions at 1933 and 2073 cm1 typical of the W(CO)5 fragment. The CO absorptions in the spectrum of 4 at 1871, 1893, 1917, 1942 and 2077 cm1 may be assigned to superposed patterns of W(CO)5 and W(CO)3 groups. The 1H NMR spectra of 3 and 4 in C6D6 each show a singlet for the t-Bu groups at d = 1.14 (3) and 1.35 (4) ppm and four multiplets between d = 4.4 and 6.5 ppm. These patterns are in agreement with both structures (see below). Layering of solutions of 1 in CH2Cl2 with the respective solution of CuX (X = Cl, Br, I) in acetonitrile gave after complete diffusion voluminous yellow precipitates and, in the case of CuI, dark rods of 5 (Scheme 3). These have according to X-ray diffraction analysis the composition [Cp0 2Nb2As2S6CuIAs4S3]. 2.2.1. Molecular structures of 3 and 4 The molecular structure of 3 is closely related to that of 1, except that As1 bears a W(CO)5 fragment (Fig. 2). Compared to the cluster core of 1 the distances and angles of 3 are nearly the same (Table 2). The observed As–W distance of 2.540(1) Å is typical of a coordinative As–W single bond [14]. The central feature of the structure of 4 is a distorted cubanelike Nb2WS4As cluster, in which one metal atom is substituted by the main group element As [15]. However, the edge As2–S2 (d = 3.691(2) Å) has clearly nonbonding character. This means that the adduct 3 acts as a 6e-tripod ligand which binds to a W(CO)3

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W. Meier et al. / Inorganica Chimica Acta 386 (2012) 50–55 Table 3 Selected distances (Å) of [Cp0 2Nb2As2S6W(CO)3W(CO)5] (4).

Fig. 2. Molecular structure of [Cp0 2Nb2As2S6W(CO)5] (3).

Table 2 Selected distances (Å) of [Cp0 2Nb2As2S6W(CO)5] (3). Nb1–Nb2 Nb1–S1 Nb1–S2 Nb1–S3 Nb1–S4 Nb2–S1 Nb2–S2 Nb2–S5 Nb2–S6 As1–W1 As1–S1 As1–S3 As1–S6 As2–S4 As2–S5 Nb1As2 Nb2As2

3.314(2) 2.579(2) 2.402(2) 2.567(2) 2.369(2) 2.575(2) 2.396(2) 2.373(2) 2.557(2) 2.540(1) 2.245(2) 2.211(2) 2.208(2) 2.258(2) 2.263(2) 2.831(1) 2.839(1)

Nb1–Nb2 Nb1–S1 Nb1–S2 Nb1–S5 Nb1–S6 Nb2–S2 Nb2–S3 Nb2–S4 Nb2–S5 As1–W1 As1–S1 As1–S2 As1–S3 As2–S4 As2–S6 W2–S4 W2–S5 W2–S6 Nb1As2 Nb2As2 Nb1W2 Nb2W2 As2S2

3.230(2) 2.581(2) 2.572(2) 2.433(2) 2.431(2) 2.584(2) 2.589(2) 2.428(2) 2.438(2) 2.540(1) 2.226(2) 2.261(2) 2.222(2) 2.319(2) 2.332(2) 2.527(2) 2.432(2) 2.532(2) 2.852(1) 2.837(1) 3.092(2) 3.093(2) 3.690(2)

4 with 3 shows an average lengthening of As–S bonds by 0.069 Å within the AsS2 ligand.

2.2.2. Electrochemical investigations of 1, 3, and 4 Because of the structural relationships between compounds 1, 3 and 4 we investigated their electrochemical properties by using cyclic voltammetry, rotating disk electrolysis (RDE) and electrolysis methods. The cyclic voltammogram of 1 on carbon electrode in THF shows a quasi-reversible system A1/A0 1 (DEp = 80 mV at 0.1 V s1) with E1/2 = 0.73 V (Fig. 4a). Further irreversible reduction waves were found by RDE at 1.56 and 2.13 V. After electrolysis at 1 V and consumption of 1 e wave A1 is still observed but its intensity is smaller than the initial wave, the resulting solution is ESR silent. After consumption of 2 e wave A1 is still present but with lower intensity. In the anodic area an anodic current is detected but without a well defined wave. This means that the reversible reduction of 1 gives [Cp0 2Nb2As2S6], but the formed paramagnetic [1] is stable only at the time scale of cyclic voltammetry. Similar results are obtained at 30 °C in CH2Cl2. The cyclovoltammograms of 3 and 4 in THF contain the reversible one-electron processes A2/A0 2 (3) and A3/A0 3 (4) (Fig. 4b and c). The observed potentials E1/2 = 0.55 V and E1/2 = 0.67 V, respectively, for 3 and 4 are less negative than that of 1. The cyclovoltammogram of 3 contains another reversible process, which may be explained by formation of small quantities of W(CO)5 and 1.

Fig. 3. Molecular structure of [Cp0 2Nb2As2S6W(CO)3W(CO)5] (4).

unit via S4 and S6 of the AsS2 ligand and S5 (Fig. 3). Thus, W2 is octahedrally surrounded by three S atoms and three terminal carbonyl ligands giving rise to a closed valence shell. The Nb–Nb distance of 3.230(2) Å is by 0.08 Å shorter than in 3 or 0.05 Å shorter than in 1 (Table 3). A comparison of other geometrical values of

Fig. 4. Cyclic voltammograms of 1 (a), 3 (b) and 4 (c) on carbon electrode in THF/ Bu4NPF6 solution (c = 0.2 mol L1); starting potential 0 V, scan rate 100 mV s1.

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Further reductions of 3 and 4 at more negative potentials are irreversible. 2.2.3. Structure of [Cp0 2Nb2As2S6CuIAs4S3] (5) Central structural feature of 5 is a distorted cubane-like Nb2CuS4As cluster. According to the isoelectronic relationship between the 12-electron fragments W(CO)3 and CuI the structure of the cluster core of 5 is analogous to that of 4. The structure is completed by an attached As4S3 cage, the As3 basis of which is oriented towards iodide (Fig. 5). The corresponding AsI distances range between 3.576(2) and 3.704(2) Å. AsI interactions in the same range are responsible for the construction of polymeric frameworks starting from the building blocks As4S3 [16], As4S4 [17] or PAs3S3 [18] and copper(I) iodide. The geometrical parameters of the Nb2As2S6 skeleton of 5 are close to those of the parent complex 1 (Table 4). While the formation of the heterocubane-like cluster cores of 4 and 5 may be a consequence of a stable valence electron count of 52 e, the existence of As4S3 appears surprising and may be explained by oxidative fragmentation of the starting material 1 followed by formation of the relatively stable As4S3 cage. The recombination of small As/S ligands within the coordination sphere of organometallic complexes is already well documented [4,9,10] and recently we have reported on copper(I) halide mediated As4S3/As4S4 transformations in solution [17]. 2.3. Reaction of Cp2WH2 with As4S4 The reaction of [Cp2WH2] (Cp = C5H5) with As4S4 in boiling toluene gives after chromatographic workup and recrystallization red platelets of [Cp2W(H)(As5S2)] (6), the composition of which was determined crystallographically. Solutions of 6 are not stable and also crystals show decomposition tendency even at low temperature. The FD mass spectrum of 6 shows the parent ion at m/z = 755.8. The 1H NMR spectrum in C6D6 contains a high-field resonance at d = 11.91 ppm with corresponding satellites (1J(H-183W) = 32.8 Hz). Two relatively broad signals (half width 16.4 Hz) at d = 3.85 and 3.77 ppm may be assigned to magnetically non-equivalent Cp ligands. The structure of 6 (Fig. 6) belongs to the type of bent metallocenes in which tungsten is surrounded tetrahedrally by four ligands. These are composed of two Cp ligands, the crystallographically found hydride H11 and the new As5S2cage, which is coordinated to W via As1. The corresponding distance W–As1 (2.582(1) Å) is

Table 4 Selected distances (Å) of [Cp0 2Nb2As2S6CuIAs4S3] (5). Nb(1)–Nb(2) Nb(1)–S(1) Nb(1)–S(2) Nb(1)–S(3) Nb(1)–S(5) Nb(2)–S(3) Nb(2)–S(4) Nb(2)–S(5) Nb(2)–S(6) Cu(1)–S(2) Cu(1)–S(3) Cu(1)–S(6) Cu(1)–I(1) As(1)–S(1) As(1)–S(4) As(1)–S(5) As(2)–S(2) As(2)–S(6) As(3)–S(7) As(3)–S(8) As(3)–S(9) As(4)–S(7) As(5)–S(8) As(6)–S(9) As(4)–As(5) As(4)–As(6) As(5)–As(6) Nb(1)Cu(1) Nb(2)Cu(1) Nb(1)As(2) Nb(2)As(2) As(4)I(1) As(5)I(1) As(6)I(1)

3.230(2) 2.561(2) 2.400(2) 2.426(2) 2.572(2) 2.446(2) 2.529(2) 2.576(2) 2.387(2) 2.385(2) 2.249(2) 2.354(2) 2.514(1) 2.272(2) 2.273(2) 2.274(2) 2.319(2) 2.337(2) 2.238(2) 2.237(2) 2.262(2) 2.219(2) 2.226(2) 2.232(2) 2.467(1) 2.489(2) 2.471(1) 2.962(1) 2.949(2) 2.820(1) 2.836(1) 3.704(2) 3.576(2) 3.595(2)

Fig. 6. Molecular structure of [Cp2W(H)(As5S2)] (6).

slightly longer than d(W–As1) in 3 and 4 (2.540(1) Å). Complex 6 is a new metalated member of the series As4S3, As5S2, As6S2 and As73, in which the anions are generated by replacement of one or more sulfur atoms by As [4]. The existence of the labile As5S2 anion has been first postulated in the complex [(C5Me5)Fe(CO)2As5S2] [19]. Compared to the structure of As4S3 the distances As1–As2 and As1–As3 are longer by ca. 0.2 Å than the distances of the corresponding As–S–As edge, while the other geometric parameters remain nearly unaffected (Table 5) [20]. 3. Experimental 3.1. General

Fig. 5. Structure of [Cp0 2Nb2As2S6CuIAs4S3] (5).

All manipulations were carried out under an inert atmosphere using Schlenk-line techniques and dry solvents. Elemental analyses

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W. Meier et al. / Inorganica Chimica Acta 386 (2012) 50–55 Table 5 Selected distances (Å) of [Cp2W(H)(As5S2)] (6). W(1)–As(1) W(1)–H(11) As(1)–As(2) As(1)–As(3) As(3)–As(4) As(3)–As(5) As(4)–As(5) As(2)–S(1) As(2)–S(2) As(4)–S(1) As(5)–S(2)

Table 7 Crystallographic data for [Cp2W(H)(As5S2)] (6).

2.582(1) 1.81(3) 2.424(2) 2.413(2) 2.445(2) 2.447(2) 2.463(2) 2.247(2) 2.244(2) 2.254(2) 2.222(2)

6

were performed by the Mikroanalytisches Laboratorium, Universität Regensburg. IR spectra were obtained with a Varian-Digilab Scimitar FTS800 spectrometer, FD mass spectra were measured on a ThermoQuest Finnigan TSQ7000 instrument. The 1H spectra were recorded on Bruker Avance 300 and 400 instruments. [Cp0 2MH3] [21], [Cp2WH2] [22], and As4S4 [23] were prepared according to literature methods. Voltammetric analyses were carried out in a standard threeelectrode cell, with a EG&G Princeton Applied Research (PAR) Model 263 A potentiostat, connected to an interfaced computer that employed Electrochemistry Power Suite software. The reference electrode was a saturated calomel electrode (SCE) separated from the solution by a sintered glass disk. The auxiliary electrode was a Pt wire separated from the solution by a sintered glass disk. For all voltammetric measurements, the working electrode was a Pt electrode (Ø = 2 mm). The controlled potential electrolysis was performed with an Amel 552 potentiostat coupled with an Amel 721 electronic integrator. 3.2. Synthesis of [Cp0 2Nb2As2S6] (1) The suspension of 1.26 g (2.95 mmol) of As4S4 and 1.00 g (2.95 mmol) of [Cp0 2NbH3] in 100 mL of toluene was stirred for

Formula Formula weight Crystal size (mm) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) b (°) V (Å3) Z Dcalc (g cm3) l (mm1) k (Å) Instrument T (K) hmin, hmax (°) No. of reflections measured (total) No. of reflections measured (unique) No. of variables Absorption correction Transmission maximum/minimum Residual electron density (e Å3) R1, wR2 (I > 2r(I)) R1, wR2 (all data)

C10H11As5S2W 753.8 0.08  0.06  0.006 monoclinic P21/c 9.078(1) 11.974(1) 14.521(1) 98.4(1) 1561.2(1) 4 3.203 27.824 1.54184 Oxf. Diff. Gemini Ultra 123 3.08 < h < 66.55 11 740 2356 167 analytical 1.1106/0.8757 0.652/1.079 0.035, 0.098 0.039, 0.100

3 days at 110 °C. After cooling to room temperature the solvent was concentrated to 25 mL. The resulting dark brown suspension was transferred to the top of a column (15  3 cm) filled with SiO2. With toluene first a yellow band was eluted, which could not be identified, followed by a brown band containing after evaporation of the solvent and washing with pentane 1.09 g (1.41 mmol; 96%) of 1 as a violet solid. Recrystallization from 10 mL of toluene at 24 °C gave dark violet needles. Compound 1: 1H NMR (300 MHz, C6D6): d = 1.21 (s, 18H), 5.97 (m, 2H), 6.13 (m, 2H), 6.18 (m, 2H), 6.28 (m, 2H) ppm. FDMS

Table 6 Crystallographic data for [Cp0 2Nb2As2S6] (1), [Cp0 2Ta2As2S6] (2), [Cp0 2Nb2As2S6W(CO)5] (3), [Cp0 2Nb2As2S6 W(CO)3W(CO)5] (4), and [Cp0 2Nb2As2S6CuIAs4S3] (5).

Formula Formula weight Crystal size (mm) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dcalc (g cm3) l (mm1) k (Å) Instrument T (K) hmin, hmax (°) No. of reflections measured (total) No. of reflections measured (unique) No. of variables Absorption correction Transmission maximum/minimum Residual electron density (e Å3) R1, wR2 (I > 2r(I)) R1, wR2 (all data)

1

2

3

4

5

C18H26As2Nb2S6C7H8 862.54 0.17  0.07  0.02 monoclinic C2/c

C18H26As2S6Ta2C7H8 1038.83 0.16  0.07  0.008 monoclinic C2/c

C23H23As2Nb2O5S6W 1094.36 0.24  0.09  0.065 triclinic  P1

C26H26As2Nb2O8S6W2 1362.23 0.32  0.01  0.004 monoclinic P21/c

C18H26As2CuINb2S6As4S3 1356.81 0.24  0.02  0.01 tetragonal P42/n

28.298(1) 17.566(1) 12.476(1)

28.271(2) 17.548(2) 12.463(2)

15.268(1) 6.955(1) 35.544(1)

30.527(1) 30.527(1) 7.412(1)

93.7(1)

93.7(1)

6189.1(1) 8 1.852 12.315 1.54184 Oxf. Diff. Gemini Ultra 123 2.96 < h < 66.63 13 296 4730 294 semi-empirical 1.0000/0.3959 0.866/1.077 0.035, 0.090 0.040, 0.092

6169.7(2) 8 2.237 19.148 1.54184 Oxf. Diff. Gemini Ultra 123 3.13 < h < 65.06 10 698 4299 342 semi-empirical 1.0000/0.4928 2.689/1.677 0.048, 0.123 0.056, 0.127

7.169(1) 12.643(2) 18.251(2) 96.0(1) 94.0(1) 96.6(1) 1620.5(3) 2 2.243 18.254 1.54184 Oxf. Diff. Gemini Ultra 123 2.44 < h < 66.38 10 124 4640 358 semi-empirical 1.0000/0.5621 0.927/1.339 0.028, 0.065 0.035, 0.068

99.1(1) 3727.2(2) 4 2.428 21.505 1.54184 Oxf. Diff. Gemini Ultra 123 2.11 < h < 63.01 13 344 5183 415 semi-empirical 1.0000/0.3675 2.215/0.940 0.037, 0.090 0.047, 0.092

6907.6(2) 8 2.609 24.654 1.54184 Oxf. Diff. SuperNova 123 4.10 < h < 68.46 13 124 5268 305 analytical 0.818/0.216 2.924/1.065 0.036, 0.083 0.045, 0.088

W. Meier et al. / Inorganica Chimica Acta 386 (2012) 50–55

(toluene): m/z 770.2 ([1]+). Anal. Calc. for C18H26As2Nb2S6 (770.46): C, 28.06; H, 3.40; S, 24.97. Found: C, 28.19; H, 3.41, S, 24.82%. 3.3. Synthesis of [Cp0 2Ta2As2S6] (2) The suspension of 267 mg (0.62 mmol) of As4S4 and 264 mg (0.62 mmol) of [Cp0 2TaH3] in 100 mL of toluene was stirred for 3 days at 110 °C. Chromatographic workup (see compound 1) gave a red band containing 151 mg (0.16 mmol; 51%) of 2 as a red solid. Recrystallization at 24 °C gave red crystals of 2. These transformed at room temperature rapidly into fine golden, amorphous leaves. Compound 2: 1H NMR (300 MHz, C6D6): d = 1.23 (s, 18H), 5.91 (m, 2H), 6.06 (m, 2H), 6.11 (m, 2H) 6.21 (m, 2H) ppm. FDMS (toluene): m/z 946.0 ([2]+). Anal. Calc. for C18H26As2S6Ta2 (946.54): C, 22.84; H, 2.77; S, 20.33. Found: C, 23.35; H, 2.59; S, 20.12%.

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Compound 6: 1H NMR (400 MHz, C6D6): 11.91 (s, 1H; JH,W = 32.8 Hz), 3.77 (s, br, 5H), 3.84 (s, br, 5H) ppm. FDMS (toluene): m/z = 754.0 (C10H11As5S2W). 3.7. X-ray structure determination of compounds 1–6 Crystal data were collected on Oxford Diffraction Gemini Ultra (1–5) and Oxford Diffraction SuperNova (6) diffractometers. Crystallographic details are given in Tables 6 and 7. The structures were solved by direct methods and refined by full-matrix least-squares (SHELXL97 program) with all reflections. All non-hydrogen atoms were refined with anisotropic displacement parameters, the H atoms were calculated geometrically and a riding model was used during the refinement process. Acknowledgements We thank Mme. Sophie Fournier for her technical assistance.

3.4. Reaction of 1 with W(CO)5THF Appendix A 470 mg (0.61 mmol) of 1were added to 65 mL (1.82 mmol) of a W(CO)5THF [24] solution in THF (c = 0.028 mmol L1). The mixture was stirred at room temperature and the solvent was removed after 18 h. Chromatography on SiO2 (column 15  3 cm) gave after elution with toluene a bright brown band containing 300 mg (0.22 mmol; 36%) of a mixture of [Cp0 2Nb2As2S6W(CO)5W(CO)3] (4) and W(CO)6. A dark brown band was eluted with acetone, which after extraction with toluene and recrystallization at 24 °C gave a few crystals of 3. Redbrown needles of 4 were obtained after removal of W(CO)6 in high vacuum and subsequent recrystallization from 12 mL of toluene/pentane 2:1. Compound 3: 1H NMR (300 MHz, C6D6): d = 1.14 (s, 18H), 6.12 (m, 4H), 6.02 (m, 2H), 5.86 (m, 2H) ppm. IR (KBr, cm1; mCO): 1933s, 1962s, 2073 m. Compound 4: 1H NMR (300 MHz, C6D6): d = 1.35 (s, 18H), 5.71 (m, 2H), 5.17 (m, 4H), 4.48 (m, 2H) ppm. FDMS (toluene): m/z 1362.9 ([4]+), m/z 1037.2([4-W(CO)5]+). IR (KBr, cm1; mCO): 1871m, 1893s, 1917s, 1942s,br, 1972m, 2077m. 3.5. Reaction of 1 with CuI The solution of 185 mg (0.24 mmol) of 1 in 15 mL of CH2Cl2 was carefully layered with a solution of 55 mg (0.29 mmol) CuI in 25 mL of CH3CN. During the diffusion process a yellow powder precipitated and a mixture of black rods and redbrown needles crystallized. The solvent was decanted and washed with pentane until all the powder was removed. The black rods were identified by X-ray diffraction analysis as [Cp0 2Nb2As2S6CuIAs4S3] (5). 3.6. Synthesis of [Cp2W(H)(As5S2)] (6) The suspension of 255 mg (0.81 mmol) of [Cp2WH2] and 350 mg (0.82 mmol) of As4S4 in 100 mL of toluene was stirred for 4 h at 110 °C. After evaporation of the solvent in vacuum the remaining brown solid was suspended in 15 mL of toluene and transferred to the top of a column (20  3 cm) filled with SiO2. Elution with toluene gave a broad orange band containing 90 mg (0.12 mmol, 15%) of orange 6. Crystals suitable for crystallography were obtained from toluene/pentane 1:1 at 24 °C.

CCDC-852526 (for 1), -852527 (for 2) -852528 (for 3), -852529 (for 4), -852530 (for 5), -852531 (for 6) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. References [1] M. Scheer, Dalton Trans. (2008) 4372. [2] (a) L.J. Gregoriades, H. Krauss, J. Wachter, A.V. Virovets, M. Sierka, M. Scheer, Angew. Chem., Int. Ed. 45 (2006) 4189; (b) H. Krauss, G. Balázs, M. Bodensteiner, M. Scheer, Chem. Sci. 1 (2010) 337. [3] I. Bernal, H. Brunner, W. Meier, H. Pfisterer, J. Wachter, M.L. Ziegler, Angew. Chem., Int. Ed. Engl. 23 (1984) 438. [4] J. Wachter, Angew. Chem., Int. Ed. 37 (1998) 750. [5] M. Pronold, M. Scheer, J. Wachter, M. Zabel, Inorg. Chem. 46 (2007) 1396. [6] G.W. Drake, J.W. Kolis, Coord. Chem. Rev. 137 (1994) 131. [7] (a) M. Di Vaira, P. Stoppioni, M. Peruzzini, Inorg. Chim. Acta 132 (1987) 37; (b) M. Di Vaira, P. Stoppioni, M. Peruzzini, Comments Inorg. Chem. 11 (1990) 1; (c) M. Di Vaira, P. Stoppioni, Coord. Chem. Rev. 120 (1992) 259; (d) L.Y. Goh, Coord. Chem. Rev. 185 (1999) 257. [8] (a) H. Brunner, L. Poll, J. Wachter, B. Nuber, J. Organomet. Chem. 471 (1994) 117; (b) O. Blacque, H. Brunner, M.M. Kubicki, F. Leis, D. Lucas, Y. Mugnier, B. Nuber, J. Wachter, Chem. Eur. J. 7 (2001) 1342. [9] H. Brunner, B. Nuber, L. Poll, G. Roidl, J. Wachter, Chem. Eur. J. 3 (1997) 57. [10] (a) H. Brunner, H. Kauermann, L. Poll, B. Nuber, J. Wachter, Chem. Ber. 129 (1996) 657; (b) H. Brunner, F. Leis, J. Wachter, B. Nuber, Organometallics 16 (1997) 4954. [11] H. Brunner, H. Cattey, D. Evrard, M.M. Kubicki, Y. Mugnier, E. Vigier, J. Wachter, R. Wanninger, M. Zabel, Eur. J. Inorg. Chem. (2002) 1315. and references therein. [12] G.A. Zank, T.B. Rauchfuss, S.R. Wilson, A.L. Rheingold, J. Am. Chem. Soc. 106 (1984) 7621. [13] H. Brunner, F. Leis, J. Wachter, M. Zabel, J. Organomet. Chem. 627 (2001) 139. [14] B.P. Johnson, M. Schiffer, M. Scheer, Organometallics 19 (2000) 3404. [15] B. Bechlars, I. Issac, R. Feuerhake, R. Clérac, O. Fuhr, D. Fenske, Eur. J. Inorg. Chem. (2008) 1632. [16] P. Schwarz, J. Wachter, M. Zabel, Eur. J. Inorg. Chem. (2008) 5460. [17] P. Schwarz, J. Wachter, M. Zabel, Inorg. Chem. 50 (2011) 12692. [18] P. Schwarz, J. Wachter, M. Zabel, Inorg. Chem. 50 (2011) 8477. [19] H. Brunner, L. Poll, J. Wachter, Polyhedron 15 (1996) 573. [20] (a) H.J. Whitfield, J. Chem. Soc. A (1970) 1800; (b) H.J. Whitfield, J. Chem. Soc., Dalton Trans. (1973) 1737. [21] P. Sauvageot, C. Moise, Bull. Soc. Chim. Fr. 133 (1996) 177. [22] M.L.H. Green, J.A. McCleverty, L. Pratt, G. Wilkinson, J. Chem. Soc. (1961) 4854. [23] G.B. Street, J. Inorg. Nucl. Chem. 32 (1970) 3769. [24] W. Strohmeier, F.J. Müller, Chem. Ber. 102 (1969) 3608.