Inorganic Chemistry Communications 13 (2010) 1191–1194

Contents lists available at ScienceDirect

Inorganic Chemistry Communications

j ourna l homepage: www.e lsev ie r.com/ locate / inoche

Synthesis and crystal structure of an Ag20 cluster incorporating in situ generatedbipodal [ArP(OEt)S2]− and tripodal [ArPOS2]2− ligands (Ar=4-methoxyphenyl)

Di Sun, Zhan-Hua Wei, Cheng-Feng Yang, Na Zhang, Rong-Bin Huang ⁎, Lan-Sun ZhengState Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China

⁎ Corresponding author. Fax: +86 592 2183047.E-mail address: rbhuang@xmu.edu.cn (R.-B. Huang)

1387-7003/$ – see front matter © 2010 Elsevier B.V. Aldoi:10.1016/j.inoche.2010.06.048

a b s t r a c t

a r t i c l e i n f o

Article history:Received 10 April 2010Accepted 30 June 2010Available online 1 August 2010

Keywords:Silver(I) clusterLawesson's reagentCrystal structure

The ultrasonic reaction of Lawesson's reagent (2,4-bis(4-methoxyphenyl)-1,3-dithiadiphosphetane-2,4-disulfide, LR) with Ag(OAc) and Ph3P (triphenylphosphane) gave an Ag20 cluster {[Ag20(ArP(OEt)S2)6(ArPOS2)6(Ph3P)8]·2(OAc)·8(H2O)·(CHCl3)} (1) (Ar=4-methoxyphenyl). The core of this cluster is an Ag-based propeller comprised of one triangle central axis and three distorted rectangle leaves. The bipodal andtripodal P/S-containing ligands were generated from in situ P–S bond cleavage and P–O bond formationprocess.

.

l rights reserved.

© 2010 Elsevier B.V. All rights reserved.

Organophosphorus sulfide reagents like P4S10, Lawesson's reagent(2,4-bis(4-methoxyphenyl)-1,3-dithiadiphosphetane-2,4-disulfide,LR), and modified LR such as Davy's reagent, Japanese reagent andBelleau's reagent have been employed successfully as thionationagent for organic substrates to give thiolactones and thiocarbonyls [1].The Lawesson's reagent containing a four-membered P2S2 ring withalternating P and S atoms can be in equilibrium with a highly reactivedithiophosphine ylide [ArPS2]− (Ar=4-methoxyphenyl) whichreacts with carbonyl-containing compounds to form P/S-containinganionic ligands. Subsequent organization of anionic subunits intolarger aggregates incorporating closed-shell d10 metal atoms wasreported as an efficient synthetic route to a broader variety ofcoordination polymers or clusters [2]. On the other hand, largechalcogenide nanoclusters are usually stabilized by either organicligating or high charge density ligands. Owing to their good affinity tometal, thiolates and tertiary phosphanes have been widely used asstabilizing agents in the synthesis of a series of Ag/S clusters (e.g.,Ag65, Ag70, Ag76, Ag88, Ag123, Ag188, Ag262, Ag320, Ag344, Ag352 andAg490) [3]. However, formation of huge silver clusters was inevitablysupported by E2− (E=S, Se or Te) bridges or other anion-templates.The pure-Ag core within the cluster built through Ag···Ag argento-philic interactions, then protected by the outshell ligands is still rare.

Herein, we report an alternative way to construct the discrete Agcluster. Within the synthetic route, the precursor, Lawesson's reagent,was converted into two kinds of anionic ligands, bipodal [ArP(OEt)S2]−

and tripodal [ArPOS2]2− (Scheme 1) which combine the Ph3P neutralligand toproduce a high-nuclearity cluster, namely {[Ag20(ArP(OEt)S2)6(ArPOS2)6(Ph3P)8]·2(OAc)·8(H2O)·(CHCl3)} (1), which shows an

unprecedented Ag-based propeller comprised of one triangle centralaxis and three distorted rectangle leaves.

In a typical synthesis, complex 1 was synthesized by the reaction ofLawesson's reagent, Ag(OAc) and Ph3P (molar ratio=1:4:4) inchloroform under ultrasonic treatment [4]. The colorless crystals wereobtained using diffusion method with diethyl ether or THF (tetrahy-drofuran) as diffusion solvents. The solid IR spectrum of 1 (Fig. S1)displayed two bands at 1241 and 1289 cm−1 due to νas(C–O–C) andcharacteristic P=S stretching band at 693 cm−1 [5]. Phase purity of 1 issustained by its powder X-ray diffraction pattern, which is consistentwith that simulated on the basis of the single-crystal X-ray diffractiondata (Fig. S2).

The molecular structure of 1 determined from single-crystal X-raydiffraction data [6] is illustrated in Fig. 1. Selected bond lengths andangles are presented in Table S1. It's a quasi-sphere molecule,inorganic part of which has a diameter of approximately 13 Å; if theorganic protection shell is also taken into account, the total size isapproximately 24 Å. The asymmetric unit contains twenty Ag ions, six[ArP(OEt)S2]−, six [ArP(O)S2]2−, eight Ph3P, two OAc−, eight H2O andone CHCl3. In 1, twenty Ag(I) ions have linear, trigonal-planar, ortetrahedral coordination geometries, and from inside to outside, thecoordination numbers of Ag(I) gradually varied from 2 to 4 withoutconsideration of Ag···Ag interactions. In details, three inner Ag(I)ions are linearly coordinated by S atoms with the S–Ag–S anglesranging from 157.543(2) to 159.991(2)°, five Ag(I) ions have trigonal-planar geometry (∑S–Ag–S=358.87–359.96°) with S atoms coor-dinated. In contrast, twelve Ag(I) ions adopt three kinds of distortedtetrahedral geometries (5PS3, 3PSO2, 4S3O), the distortion of thetetrahedron can be indicated by the calculated value of the τ4parameter introduced by Houser [7] to describe the geometry of afour-coordinate metal system, which are in the range of 0.722–0.878(for perfect tetrahedral geometry, τ4=1) (Table S2). The observed

Scheme 1. Synthesis of 1 involving in situ generated two kinds of anionic ligands. (Ar=4-methoxyphenyl).

1192 D. Sun et al. / Inorganic Chemistry Communications 13 (2010) 1191–1194

Ag–S, Ag–P and Ag–O distances in 1 lie in the range of 2.3806(2)–2.8549(4), 2.3669(2)–2.5973(3) and 2.3344(3)–2.38027(11)Å, re-spectively, all of which fall within the expected ranges [8]. Oneimportant structural feature of 1 is the presence of pure-Ag propellerwith the radius of ca. 5.6 Å which is comprised of one triangle centralaxis (Ag1–Ag3) and three distorted rectangle leaves (Ag4–Ag12).Within it, the Ag···Ag distances vary from 2.9600(3) to 3.1653(2)Åwhich are obviously shorter than twice the van der Waals radii ofsilver (3.44 Å), indicating the presence of argentophilic interactions

Fig. 1. The top view (a) and side view (b) of 1. Violet sphere, Ag; yellow spheres, S; orangecarbon atoms, solvents and OAc− are omitted for clarity.

[9]. The total of twenty Ag(I) ions can be geometrically divided intofour categories: three in the interior forming the axis of propeller, ninesurrounded the triangle axis to build three leaves, six positioned at theequatorial periphery and two perpendicularly capped on the overallquasi-sphere cluster. At the periphery, two kinds of anionic ligands,bipodal [ArP(OEt)S2]− and tripodal [ArP(O)S2]2−, generating from insitu decomposition of LR, combined with Ph3P ligands to completecoordination of the quasi-sphere cluster, in which three tripodal [ArP(O)S2]2− ligands adopt three different coordination fashions

spheres, P; red spheres, O. All Ag atoms in the core are bound in blue dashed lines. All

Fig. 2. The packing diagrams of clusters in unit cell along different planes.

1193D. Sun et al. / Inorganic Chemistry Communications 13 (2010) 1191–1194

1194 D. Sun et al. / Inorganic Chemistry Communications 13 (2010) 1191–1194

(μ6–ηO1:ηS

2:ηS3, μ6–ηO

2:ηS2:ηS

2 and μ7–ηO2:ηS

2:ηS3) to bound on Ag(I) ions

and surround one Ph3P ligand sitting on the polar site, whereas at theequator, the Ph3P ligands and bipodal [ArP(OEt)S2]− (μ4–ηS

2:ηS2 and

μ3–ηS1:ηS

2) are alternately arranged to complete the cluster. Comparedto previously reported huge Ag/E clusters, no E2− (E=S, Se or Te)bridges or other anions were doped in the inner of 1, whichsignificantly limited its nuclearity.

Although disassociation of LR into S2−, [ArP(O)S2]2−, [ArS2P–O–PS2Ar]2−, [ArPS3]2− and [ArP(O)(OAc)S]− ligands waswell documented[2a,c], it's worthy to note that the simultaneous generation of bothbipodal [ArP(OEt)S2]− and tripodal [ArP(O)S2]2− ligands in the course ofthe reaction between AgOAc and LR is observed for the first time. Theformation of bipodal [ArP(OEt)S2]− and tripodal [ArP(O)S2]2− involvedthe P–S and C–O bond cleavages of LR and OAc− respectively. Theequivalent two different anions in 1 could be explained by thedisassociation of LR under the existence of OAc− as shown in SchemeS1. In addition, attempts to grow single crystals in the presence of THFcould also lead to the isolation of 1 which proved that the formation of[ArP(OEt)S2]− was independent on diffusion solvent diethyl ether. As toour best knowledge, the P–O bond is much stronger than the P–S bond,which makes vulnerable LR easily to be attacked by potentialnucleophiles, electrophiles and radicals as demonstrated by Rauchfusswhereby the LR underwent reversible cleavage to give ArPS2· radicals[10]. This could be concluded as one of the significant thermodynamicdriving forces behind the formations of both P/S ligands.

As shown in Fig. 2, the clusters crystallize in P2(1)/c space groupwith an intercluster distance of ca. 19.1 Å (center to center). Theintercluster space is occupied by charge balancing anions, OAc− andwater and chloroform molecules.

In conclusion, a novel Ag20 cluster with mixed three kinds ofligands, one neutral and two kinds of anionic ligands, wassynthesized and its structure was investigated. It was establishedthat 1 is the rare polynuclear Ag(I) complex with unprecedented Ag-based propeller comprised of one triangle central axis and threedistorted rectangle leaves. The results prompted us to extend thesynthesis of novel larger Ag(I) cluster complexes via the fragmen-tation of P–S bonds in sulfur-analogs to phosphorus or phosphonousacid anhydrides.

Acknowledgments

This work was financially supported by the National NaturalScience Foundation of China (No. 20721001), 973 Project (Grant2007CB815301) from MSTC and the National Science Fund of Chinafor Fostering Talents in Basic Science (No. J0630429).

Appendix A. Supplementary material

CCDC 772352 contains the supplementary crystallographic data forthis paper. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/ retrieving.html, or from the Cambridge Crystal-lographic Data Centre, 12 Union Road, Cambridge CB 21EZ, UK; fax:(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk. Supplemen-tary data associated with this article can be found, in the online version,at 10.1016/j.inoche.2010.06.048.

References

[1] (a) S. Scheibye, S.O. Lawesson, C. Romming, Acta Chem. Scand. 35 (1981) 239;(b) T. Strehlow, J. Voss, R. Spohnholz, G. Adiwidjaja, Chem. Ber. 124 (1991) 1397;(c) M. Jesberger, T.P. Davis, L. Barner, Synthesis (2003) 1929;(d) T. Ozturk, E. Ertas, O. Mert, Chem. Rev. 107 (2007) 5210;(e) M.S. John Foreman, J.D. Woollins, J. Chem. Soc., Dalton Trans. (2000) 1533;(f) B.S. Pedersen, S. Scheibye, K. Clausen, S.O. Lawesson, Bull. Soc. Chim. Belg. 87

(1978) 293.

[2] (a) W. Shi, R. Ahlrichs, C.E. Anson, A. Rothenberger, C. Schrodt, M. Shafaei-Fallah,Chem. Commun. (2005) 5893;

(b) W. Shi, A. Rothenberger, Eur. J. Inorg. Chem. (2005) 2935;(c) W. Shi, M. Shafaei-Fallah, C.E. Anson, A. Rothenberger, Dalton Trans. (2005)

3909;(d) W. Shi, M. Shafaei-Fallah, L. Zhang, C.E. Anson, E. Matern, A. Rothenberger,

Chem. Eur. J. 13 (2007) 598;(e) W. Shi, M. Shafaei-Fallah, C.E. Anson, A. Rothenberger, Dalton Trans. (2006)

3257;(f) W. Shi, A. Rothenberger, Eur. J. Inorg. Chem. (2005) 2935;(g) I.P. Gray, H.L. Milton, A.M.Z. Slawin, J.D. Woollins, Dalton Trans. (2004) 2477;(h) I.P. Gray, H.L. Milton, A.M.Z. Slawin, J.D. Woollins, Dalton Trans. (2003) 3450;(i) A. Rothenberger, W. Shi, M. Shafaei-Fallah, Chem. Eur. J. 13 (2007) 5974;(j) A. Rothenberger, M. Shafaei-Fallah, W. Shi, Chem. Commun. (2007) 1499.

[3] (a) D. Fenske, C. Persau, S. Dehnen, C.E. Anson, Angew. Chem. Int. Ed. 43 (2004)305;

(b) S. Chitsaz, D. Fenske, O. Fuhr, Angew. Chem. Int. Ed. 45 (2006) 8055;(c) C.E. Anson, A. Eichhöfer, I. Issac, D. Fenske, O. Fuhr, P. Sevillano, C. Persau, D.

Stalke, J.T. Zhang, Angew. Chem. Int. Ed. 47 (2008) 1326;(d) X.J. Wang, T. Langetepe, C. Persau, B.S. Kang, G.S. Sheldrick, D. Fenske, Angew.

Chem. Int. Ed. 41 (2002) 3818;(e) D. Fenske, C.E. Anson, A. Eichölfer, O. Fuhr, A. Ingendoh, C. Persau, C. Richert,

Angew. Chem. Int. Ed. 44 (2005) 5242.[4] Synthesis of 1: a mixture of Lawesson's reagent 202 mg (0.50 mmol), AgOAc

334 mg (2.00 mmol) and Ph3P 520 mg (2.00 mmol) was dissolved in 10 mLchloroform. The mixture was treated under the ultrasonic condition (50 °C,160 W, 40 KHz, 20 min), during which time the solution changes from colorless toyellow. The mixture was filtered and solvent diffusion diethyl ether into thereaction mixture produced colorless crystals of 1 after two weeks. Yield: ca. 35%based on AgOAc. Elemental analysis: Anal. Calc. for Ag20P20S24Cl3C245H257O36: C39.60, H 3.49. Found: C 39.81, H 3.72%. Selected IR peaks (cm−1): 3426 (s, H2O),3067 (w), 2964 (w), 2936 (w), 1589 (s), 1564 (s), 1494 (m), 1482 (m), 1436 (s),1385 (s), 1289 (w), 1241 (s), 1180 (w), 1110 (m), 1031 (s), 933 (m), 832 (w), 799(w), 741 (m), 693 (s, P S), 638 (s), 623 (s), 546 (m), 510 (m), 485 (m), 449 (m).

[5] (a) L.J. Bellamy, The Infrared Spectra of Complex Molecules, Wiley, New York,1958;

(b) R.G. Cavell, W. Byers, E.D. Day, P.M. Watkins, Inorg. Chem. 11 (1972) 1598.[6] Crystal data for 1: crystal size 0.10 mm×0.08 mm×0.08 mm, M=7430.42,

colorless block, monoclinic, space group P21/c (No. 14), a=37.733(3) Å,b=23.3150(9) Å, c=38.246(4) Å, β=108.695(10)° V=31871(4) Å3, Z=4,Dc=1.531 g cm−3, μ(Cu-Kα)=12.903 mm−1. A total of 121,713 reflections werecollected on an Oxford Gemini S Ultra system. Absorption corrections wereapplied by using the program CrysAlis (multi-scan) using the ω scan mode withCu-Kα radiation λ=1.54178 Å at 123(2)K, of which 44,293 were independentreflections (Rint=0.1098). Structure solution and refinement were routine [11].Final R indices for the 19,346 observed reflections (IN2σ(I): R1=0.0811,wR2=0.1615, max./min. residual electron density, 1.447/−2.480 e Å−3. Thesilver, sulfur, and phosphorus atoms were refined anisotropically, and part ofcarbon and oxygen atoms isotropically. One chloroform molecule was disorderedover two different positions with partial occupancies. Some of the ligands werealso disordered. The hydrogen atoms on water molecules and chloroformmolecule were not treated, but included in formula and formula weight.

[7] L. Yang, D.R. Powell, R.P. Houser, Dalton Trans. (2007) 955.[8] (a) K. Tang, X. Jin, H. Yan, X. Xie, C. Liu, Q. Gong, J. Chem. Soc., Dalton Trans.

(2001) 1374;(b) X. Jin, K. Tang, W. Liu, H. Zeng, H. Zhao, Y. Ouyang, Y. Tang, Polyhedron 15

(1996) 1207;(c) K. Tang, T. Xia, X. Jin, Y. Tang, Polyhedron 12 (1993) 2895;(d) X. Jin, K. Tang, S. Jia, Y. Tang, Polyhedron 15 (1996) 2617;(e) X. Jin, X. Xie, H. Qian, K. Tang, C. Liu, X. Wang, Q. Gong, Chem. Commun.

(2002) 600;(f) K. Tang, X. Xie, Y. Zhang, X. Zhao, X. Jin, Chem. Commun. (2002) 1024;(g) J.-X. Chen, Q.-F. Xu, Y. Xu, Y. Zhang, Z.-N. Chen, J.-P. Lang, Eur. J. Inorg. Chem.

(2004) 4247;(h) J.-X. Chen, Q.-F. Xu, Y. Zhang, Z.-N. Chen, J.-P. Lang, J. Organomet. Chem. 689

(2004) 1071.[9] (a) A. Bondi, J. Phys. Chem. 68 (1964) 441;

(b) M. Jansen, Angew. Chem. Int. Ed Engl. 26 (1987) 1098.[10] T.B. Rauchfuss, G.A. Zank, Tetrahedron Lett. 27 (1986) 3445.[11] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.