[W 6 S 8 ] Octahedral Tungsten Clusters Functionalized with Thiophene Derivatives: toward Polymerizable Building Blocks Sandrine Perruchas,* ,†,‡ Samuel Flores, † Bruno Jousselme, § Emil Lobkovsky, † Hector Abrun ˜ a, † and Francis J. DiSalvo* ,† Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell UniVersity, Ithaca, New York 14853-1301, and Chimie des Surfaces et Interfaces, CEA Saclay, 91191 Gif-sur-YVette, France Received June 1, 2007 The functionalization of octahedral [W 6 S 8 ] clusters with a family of phosphino-thiophene ligands has been investigated with the goal of synthesizing extended networks of [W 6 S 8 ] units covalently linked to one another through thiophene- conjugated bridges. In addition to new phosphino-thiophene ligands, eight clusters were synthesized and characterized by 1 H and 31 P NMR spectroscopies, elemental analysis, and UV-vis absorption. These clusters are formulated [W 6 S 8 (T-PPh 2 ) 6 ](1a), [W 6 S 8 (T-PEt 2 ) 6 ](1b), [W 6 S 8 (2T-PPh 2 ) 6 ](2a), [W 6 S 8 (2T-PEt 2 ) 6 ](2b), [W 6 S 8 (3T-PPh 2 ) 6 ](3a), [W 6 S 8 (3T-PEt 2 ) 6 ](3b), [W 6 S 8 ((2T) 3 P) 6 ](4), and [W 6 S 8 (2EDOT-PEt 2 ) 6 ](5) (T ) thiophene and EDOT ) 3,4- ethylenedioxythiophene). The molecular structure of six of them has been obtained by single-crystal X-ray diffraction analysis. All of them crystallize in the P1 h triclinic space group except 3b, which has the P2 1 /c monoclinic symmetry. The redox behavior of both the ligands and the corresponding functionalized clusters has been investigated by cyclic voltammetry. An attempt to electropolymerize these species is also reported. Introduction Since their discovery more than 30 years ago, the Chevrel phases M′ x [Mo 6 Q 8 ] (M′ ) Pb, Sn, Cu, ...; X ) S, Se, Te) have been intensively studied due to various properties including superconductivity, high thermoelectric figures of merit, fast-ionic conductivity, and catalytic activity. 1 The Chevrel phases are built of octahedral molybdenum chalco- genide units formulated [Mo 6 Q 8 ] and connected to one another by M-Q bonds. Surprisingly, no tungsten analogues of the Chevrel phases have ever been reported. However, molecular tungsten clusters formulated [W 6 S 8 L 6 ] 2 have been obtained in solution in analogy with the molybdenum species [Mo 6 S 8 L 6 ]. 3 These clusters can be described as octahedra of metallic atoms (M ) Mo, W) with their faces capped by eight triply bridging sulfur atoms and six terminal ligands (L) to complete the coordination sphere of the M atoms (Scheme 1). The terminal ligands of these soluble molecular forms can be exchanged by a variety of other ligands. Theoretical work has shown that extended networks based on [W 6 Q 8 ] units covalently linked together by π-conjugated ditopic ligands might exhibit interesting electronic properties due to electronic communication through the networks. 4,5 We are interested in preparing such organic-inorganic hybrid materials, and several directions have been pursued. One way is to replace the monodentade ligands (L) on the clusters with ditopic ligands such as 4-4′-bipyridine. Unfortunately, these coordination experiments systematically led to insoluble amorphous products. The characterization of these products was thus very difficult, and it is even possible that the product precipitated before complete hexasubstitution of the [W 6 Q 8 ] unit occurred. Other attempts using clusters with mixed axial ligands that have different binding energies gave the same * To whom correspondence should be addressed. E-mail: sandrine.perruchas@polytechnique.edu (S.P.), fjd3@cornell.edu (F.J.D.). † Cornell University. ‡ Present address: Laboratoire de Physique de la Matie `re Condense ´e, CNRS, Ecole Polytechnique, 91128 Palaiseau, France. § CEA Saclay. (1) (a) Chevrel, R.; Sergent, M.; Prigent, J. J. Solid State Chem. 1971, 3, 515-519. (b) Chevrel, R.; Hirrien, M.; Sergent, M. Polyhedron 1986, 5, 87-94. (2) Saito, T.; Yoshikawa, A.; Yamagata, T.; Imoto, H.; Unoura, K. Inorg. Chem. 1989, 28, 3588-3592. (3) (a) Saito, T.; Yamamoto, N.; Yamagata, T.; Imoto, H. J. Am. Chem. Soc. 1988, 110, 1646-1647. (b) Saito, T.; Yamamoto, N.; Nagase, T.; Tsuboi, T.; Kobayashi, K.; Yamagata, T.; Imoto, H.; Unoura, K. Inorg. Chem. 1990, 29, 764-770. (4) Hughbanks, T.; Hoffman, R. J. Am. Chem. Soc. 1983, 105, 1150- 1162. (5) Malik, A.-S. Thesis, Cornell University, Ithaca, NY, 1998. Inorg. Chem. 2007, 46, 8976-8987 8976 Inorganic Chemistry, Vol. 46, No. 21, 2007 10.1021/ic7010748 CCC: $37.00 © 2007 American Chemical Society Published on Web 09/21/2007