Inorg. Chem. 2002, 41, 121−126 Chalcogen Rich Lanthanide Clusters from Halide Starting Materials (II): Selenido Compounds Anna Kornienko, J. H. Melman, G. Hall, T. J. Emge, and John G. Brennan* Department of Chemistry, Rutgers, the State UniVersity of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854-8087 Received July 11, 2001 Lanthanides reduce mixtures of I2 and PhSeSePh in THF, and the resultant heteroligand mixture reacts further with elemental Se in pyridine to give (THF)6Ln4I2(SeSe)4(µ4-Se)‚THF (Ln ) Tm, Ho, Er, Yb). These selenium rich - clusters contain a square array of Ln(III) ions connected through a single (µ4-Se) ligand. There are two I ligands coordinating nonadjacent Ln(III) ions on the side of the cluster opposite the (µ4-Se), and the edges of the square are bridged by µ2-SeSe groups. The electronic spectrum of the Yb compound contains two absorption maxima that can tentatively be assigned as Se2- to Yb and SeSe to Yb charge-transfer absorptions, by comparison with the featureless absorption spectra of the Tm, Ho, and Er derivatives. With a 1/1/1/1 Yb/I/Ph2S2/Se stoichiometry, chalcogen rich compounds are not obtained, but instead, in Yb chemistry, the selenido cluster (THF)10Yb6Se6I6 can be isolated in 51% yield. The molecular structure of this compound contains a Yb4Se4 cubane fragment, with an additional - Yb2Se2 layer capping one face of the cube. Each Yb coordinates a terminal I . This intensely colored compound also has an absorption maximum in the visible spectrum. Upon thermolysis, the selenium rich compounds give Ln2Se3 that is free of iodide contamination. Introduction Chalcogenido (E2-) cluster chemistry of the lanthanides Recent interest in lanthanide (Ln; Ln ) La-Lu) com- is less well developed. The most general synthetic approach pounds with only chalcogen (E; E ) S, Se, or Te) based to these materials involves the reduction of elemental E by 5 anionic ligands continues to be motivated both by a Ln(EPh)3, with concomitant oxidative elimination of PhEEPh. fundamental interest in the nature of the Ln-E bond and by This reactivity has been controlled to give crystalline homo- the potential applications of Ln ions in chalcogenido based and heterometallic clusters, heterovalent compounds, and pigments1 and optical fibers.2 Only in the past decade, with clusters with most combinations of Ln, E, EPh, and neutral the synthesis of Ln(ER)x (R ) organic; x ) 2, 3) com- 3 (3) (a) Nief, F. Coord. Chem. ReV. 1998, 178-80, 13. (b) Lee, J.; pounds, has it become apparent that highly electronegative, Freedman, D.; Melman, J.; Brewer, M.; Sun, L.; Emge, T. J.; Long, sterically saturating ancillary ligands4 (e.g., Cp*) are not a F. H.; Brennan, J. G. Inorg. Chem. 1998, 37, 2512. (c) Freedman, D.; prerequisite for the successful isolation and characterization Kornienko, A.; Emge, T.; Brennan, J. G. Inorg. Chem. 2000, 39, 2168. (d) Melman, J.; Emge, T.; Brennan, J. G. Inorg. Chem. 2001, 40, 1078. of molecular compounds with Ln-E bonds. (4) (a) Schumann, H.; Albrecht, I.; Hahn, E. Angew. Chem., Int. Ed. Engl. 1985, 24, 985. (b) Berg, D.; Burns, C.; Andersen, R. A.; Zalkin, A. * Author to whom correspondence should be addressed. E-mail: Organometallics 1988, 7, 1858. (c) Berg, D. J.; Burns, C.; Andersen, [email protected]. R. A.; Zalkin, A. Organometallics 1989, 8, 1865. (d) Zalkin, A.; Berg, (1) (a) Macaudiere, P. U.S. Patent 5,968,247, 1999. (b) Chopin, T.; D. J. Acta Crystallogr. 1988, 44C, 1488-1489. (e) Evans, W.; Grate, Guichon, H.; Touret, O. U.S. Patent 5,348,581, 1994. (c) Chopin, T.; J. W.; Bloom, I.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. Dupuis, D. U.S. Patent 5,401,309, 1995. 1985, 107, 405. (f) Evans, W.; Rabe, G.; Ziller, J.; Doedens, R. Inorg. (2) (a) Tawarayama, H.; Ishikawa, E.; Toratani, H. J. Am. Ceram. Soc. Chem. 1994, 33, 2719. (g) Welder, M.; Noltemeyer, M.; Pieper, U.; 2000, 83, 792. (b) Griscom, L. S.; Adam, J.-L.; Binnemans, K. J. Schmidt, H.; Stalke, D.; Edelmann, F. Angew. Chem., Int. Ed. Engl. Non-Cryst. Solids 1999, 256/257, 383. (c) Choi, Y. G.; Kim, K. H.; 1990, 29, 894. Heo, J. J. Appl. Phys. 2000, 88, 3832. (d) Shin, Y. B.; Heo, J.; Kim, (5) (a) Freedman, D.; Emge, T. J.; Brennan, J. G. J. Am. Chem. Soc. 1997, H. S. Chem. Phys. Lett. 2000, 317, 637. (e) Choi, Y. G.; Kim, K. H.; 119, 11112. (b) Melman, J. H.; Emge, T. J.; Brennan, J. G. Chem. Heo, J. J. Appl. Phys. Lett. 2001, 78, 1249. (f) Cole, B.; Shaw, L. B.; Commun. 1997, 2269. (c) Melman, J. H.; Emge, T. J.; Brennan, J. G. Aggarwal, I. D. J. Non-Cryst. Solids 1999, 256/257, 253. (g) Adam, Inorg. Chem. 1999, 38, 2117. (d) Freedman, D.; Emge, T. J.; Brennan, J.-L.; Doualan, J.-L.; Moncorge, R. J. Non-Cryst. Solids 1999, 256/ J. G. Inorg. Chem. 1999, 38, 4400. (e) Freedman, D.; Melman, J. H.; 257, 276. (h) Furniss, D.; Seddon, A. B. J. Mater. Sci. Lett. 1998, 17, Emge, T. J.; Brennan, J. G. Inorg. Chem. 1998, 37, 4162. (f) Freedman, 1541. (i) Harbison, B. B.; Sanghera, J. S.; Shaw, L. B.; Aggarwal, I. D.; Safik, S.; Emge, T. J.; Croft, M.; Brennan, J. G. J. Am. Chem. D. U.S. Patent 6,015,765, 2000. Soc. 1999, 121, 11713. 10.1021/ic010740o CCC: $22.00 © 2002 American Chemical Society Inorganic Chemistry, Vol. 41, No. 1, 2002 121 Published on Web 12/14/2001 Kornienko et al. -1 -1 donor ligands, usually in high yields. The cubic octanuclear UV-vis (THF): λmax ) 387 nm (425 L mol cm ). IR: 3166 array of Ln ions in the Ln8E6(EPh)12 series is observed for (s), 2877 (w), 2728 (m), 2670 (s), 2423 (s), 2361 (s), 2342 (s), most Ln (Ce-Er),5a-d while the smaller Ln (Tm, Yb) tend 2206 (s), 2037 (s), 1903 (s), 1788 (s), 1670 (s), 1642 (m), 1460 to form clusters with cubane5e based geometries. Because (w), 1377 (w), 1316 (m), 1261 (s), 1168 (s), 1156 (s), 1097 (s), the structural, magnetic, and electronic properties of the 1076 (s), 1035 (s), 1007 (m), 917 (s), 848 (s), 805 (s), 772 (s), 723 -1 molecular chalcogenolate compounds were well understood, (m) cm . ‚ the corresponding cluster properties were readily interpreted. Synthesis of (THF)6Tm4 I2(SeSe)4(µ4-Se) THF (2). Tm (338 mg, 2.0 mmol), diphenyl diselenide (780 mg, 2.5 mmol), iodine As single source precursors to solid-state materials, these (127 mg, 0.5 mmol), and Hg (50 mg, 0.25 mmol) were mixed in molecular chalcogenolates and chalcogenido cluster com- THF (50 mL). The mixture was stirred until all the metal was pounds have one significant flaw: thermal decomposition consumed to give a yellow solution. Elemental Se (355 mg, 4.5 relies on a long known thermolytic pathway6 involving mmol) was added, and after 2 days, the mixture was filtered to cleavage of an E-C bond and the elimination of RER. remove a small amount of yellow precipitate. The orange solution Unfortunately, E-C cleavage reactions invariably trap was concentrated to ∼30 mL and layered with hexanes (10 mL) to organic residues in the thermolysis product, and useful give yellow crystals (0.19 g, 19%) that do not melt but turn dark ° electronic materials rarely tolerate significant impurity levels. brown at 210 C. Anal. Calcd for C28H56O7I2Se9Tm4: C, 15.7; H, The recent isolation and structural characterization of 2.63. Found: C, 17.1; H, 2.74. The compound does not show an optical absorption maximum from 300 to 800 nm in THF or (THF)6Yb4I2(SS)4(µ4-S) represented the first single source pyridine. IR: 3165 (s), 2879 (w), 2724 (m), 2670 (s), 2401 (s), precursor to solid-state LnEx that did not require elimination 2343 (s), 2174 (s), 2033 (s), 1751 (s), 1461 (w), 1377 (w), 1306 of RER. Thermolysis of this compound gave LnS that was x (m), 1262 (s), 1208 (s), 1155 (s), 1065 (s), 1036 (s), 1007 (m), 673 both free of carbon contamination and significant iodide (s), 918 (s), 852 (s), 801 (s), 772 (s), 722 (m), 608 (s) cm-1. incorporation.7 Here, we describe our initial investigations Synthesis of (THF) Er I (SeSe) (µ -Se)‚THF (3). As for 2,Er into the halogenated cluster chemistry of the LnSe system, 6 4 2 4 4 x (334 mg, 2.0 mmol), diphenyl diselenide (780 mg, 2.5 mmol), including the first halogenated lanthanide cubane. iodine (127 mg, 0.5 mmol), and Hg (50 mg, 0.25 mmol) in THF (50 mL), followed by Se powder (355 mg, 4.5 mmol), gave yellow Experimental Section crystals (0.21 g, 20%) that do not melt but turn dark brown at 245 °C. Anal. Calcd for C H O I Se Er : C, 15.7; H, 2.64. Found: General Methods. All syntheses were carried out under ultrapure 28 56 7 2 9 4 C, 15.7; H, 2.59. The compound does not show an optical absorption nitrogen (JWS), using conventional drybox or Schlenk techniques. maximum from 300 to 800 nm in THF or pyridine. IR: 3163 (s), Solvents (Fisher) were refluxed continuously over molten alkali metals or K/benzophenone and collected immediately prior to use. 2895 (w), 2724 (m), 2670 (s), 2362 (s), 2343 (s), 2153 (s), 2021 Anhydrous pyridine was purchased from Aldrich and refluxed over (s), 1719 (s), 1655 (s), 1543 (s), 1461 (w), 1377 (w), 1306 (m), KOH.