Ruthenium Seleno- and Tellurocarbonyl Complexes: Selenium and

Jan 12, 2010 - Bunkyo-ku, Tokyo 112-8551, Japan and ‡Department of Chemistry and Biochemistry, Graduate School of. Humanities and Sciences ... bonyl...
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Organometallics 2010, 29, 519–522 DOI: 10.1021/om901029w

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Ruthenium Seleno- and Tellurocarbonyl Complexes: Selenium and Tellurium Atom Transfer to a Terminal Carbido Ligand Yuichiro Mutoh,*,† Naoki Kozono,† Miho Araki,† Noriko Tsuchida,‡ Keiko Takano,‡ and Youichi Ishii*,† †

Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan and ‡Department of Chemistry and Biochemistry, Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan Received November 28, 2009

Summary: The first five-coordinate selenocarbonyl complex, [RuCl2(CSe)(H2IMes)(PCy3)] (2-CSe; H2IMes = 1,3-dimesitylimidazolin-2-ylidene), and the tellurocarbonyl complex [RuCl2(CTe)(H2IMes)(dmap)2] (3-CTe; dmap = 4-(dimethylamino)pyridine) was obtained by selenium and tellurium atom transfer reaction to the carbido complex [RuCl2(C) (H2IMes)(PCy3)]. Systematic elucidation of the complete series of chalcogenocarbonyl complexes revealed that tellurocarbonyl complex 3-CTe is a potential tellurium atom transfer reagent. Since the first thiocarbonyl (CS) complex [RhCl(CS)(PPh3)2] was prepared in 1966,1 many efforts have been devoted to the synthesis of CS complexes, and their rich chemistry has been established.2 They are usually prepared using CS2 as a CS source. In contrast, their heavier chalcogen analogues, i.e., seleno- and tellurocarbonyl (CSe and CTe) complexes, have been scarcely exploited because of the lack of suitable synthetic routes. For example, [RuCl2(CO)(CSe)(PPh3)2]3,4 was prepared from the toxic and hardly available CSe2, and the use of an organomercury reagent and prereduction of chalcogen atoms or toxic gaseous hydrogen chalcogenides were required for the first systematic synthesis of the chalcogenocarbonyl (CE) complexes [OsCl2(CO)(CE)(PPh3)2] (E = O, S, Se, Te).5 Similarly, another series of CE complexes, [Tp*Mo(CO)2(CE)]- (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate; E=S, Se, Te), were prepared

by using E2-, but no details for the structures of the complexes were described.6 Consequently, there is little information available for the reactivities of CSe and CTe complexes in spite of their potential utility in chemistry, where CO and CS complexes are recognized as important chemical species. Now, we have successfully developed a practical route for monomeric CSe and CTe complexes of ruthenium by adopting the chalcogen atom transfer reaction to a terminal carbido ligand.7 This method enabled the systematic studies of CE complexes as well as the observation of unprecedented reactivities of the CTe complex isolated here. It should be mentioned that related reactions of anionic terminal carbido complexes ([MotC]-) with chalcogens have recently been examined to give anionic complexes ([MotC-E]-), but their structural details have not been clarified.8 Initially, we attempted the synthesis of [RuCl2(CSe)(PCy3)2] (Cy = cyclohexyl), because the reaction of the carbido complex [RuCl2(C)(PCy3)2] with S8 is known to give the CS complex [RuCl2(CS)(PCy3)2].9 Unfortunately, however, the desired CSe complex could not be isolated due to the concomitant formation of SedPCy3, suggesting that the PCy3 ligand is easily dissociated to lead to the degradation of the product. To avoid this process, we replaced one of the PCy3 ligands in the carbido complex

*To whom correspondence should be addressed. E-mail: ymutoh@ kc.chuo-u.ac.jp (Y.M.); [email protected] (Y.I.). (1) Baird, M. C.; Wilkinson, G. J. Chem. Soc., Chem. Commun. 1966, 267–268. (2) For reviews, see: (a) Butler, I. S.; Fenster, A. E. J. Organomet. Chem. 1974, 66, 161–194. (b) Yaneff, P. V. Coord. Chem. Rev. 1977, 23, 183–220. (c) Butler, I. S. Acc. Chem. Res. 1977, 10, 359–365. (d) Broadhurst, P. V. Polyhedron 1985, 4, 1801–1846. (d) Butler, I. S. Pure Appl. Chem. 1988, 60, 1241–1244. (e) Moltzen, E. K.; Klabuunde, K. J.; Senning, A. Chem. Rev. 1988, 88, 391–406. (f) Petz, W. Coord. Chem. Rev. 2008, 252, 1689– 1733. (3) Clark, G. R.; Grundy, K. R.; Harris, R. O.; James, S. M.; Roper, W. R. J. Organomet. Chem. 1975, 90, C37–C39. (4) For other examples of CSe complexes, see: (a) Butler, I. S.; Cozak, D.; Stobart, S. R. J. Chem. Soc., Chem. Commun. 1975, 103–104. (b) Saillard, J.-Y.; Grandjean, D. Acta Crystallogr., Sect. B: Struct. Sci. 1978, 34, 3772–3775. (c) Brothers, P. J.; Headford, C. E. L.; Roper, W. R. J. Organomet. Chem. 1980, 195, C29–C33. (d) Cozak, D.; Butler, I. S.; Baibich, I. M. J. Organomet. Chem. 1979, 169, 381–393. (e) Battioni, J.-P.; Mansuy, D.; Chottard, J.-C. Inorg. Chem. 1980, 19, 791–792. (f) Gorce, J.-N.; Bottomley, L. A. Inorg. Chem. 1985, 24, 1431–1436. (g) Ismail, A. A.; Butler, I. S.; Bonnet, J.-J.; Askenazy, S. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1985, 41, 1582–1585. (5) (a) Clark, G. R.; Marsden, K.; Roper, W. R.; Wright, L. J. J. Am. Chem. Soc. 1980, 102, 1206–1207. (b) Clark, G. R.; Marsden, K.; Rikard, C. E. F.; Roper, W. R.; Wright, L. J. J. Organomet. Chem. 1988, 338, 393–410.

(6) Desmond, T.; Lalor, F. J.; Ferguson, G.; Parvez, M. J. Chem. Soc., Chem. Commun. 1984, 75–77. (7) Related reactions of nitrido complexes with elemental sulfur and selenium leading to thio- and selenonitrosyl complexes have been reported. The first thionitrosyl complex, [Mo(NS){S2CNMe2}3]: (a) Chatt, J.; Dilworth, J. R. J. Chem. Soc., Chem. Commun. 1974, 508. The first selenonitrosyl complex, [TpOs(NSe)Cl2] (Tp = hydrotris(1pyrazolyl)borate): (b) Crevier, T. J.; Lovell, S.; Mayer, J. M.; Rheingold, A. L.; Guzei, I. A. J. Am. Chem. Soc. 1998, 120, 6607–6608. (8) “K[MotC-Te]” was described as a dimer: (a) Greko, J. B.; Peters, J. C.; Baker, T. A.; Davis, W. M.; Cummins, C. C.; Wu, G. J. Am. Chem. Soc. 2001, 123, 5003–5013. Although anionic complexes Li[MotC-E] could be generated in situ, only their trapping reaction with MeI leading to [MotCEMe] was reported; see: (b) Cordiner, R. L.; Hill, A. F.; Wagler, J. Organometallics 2008, 27, 5177–5179. During the preparation of this paper, further reactivities of [MotC-Se]- were reported: (c) Cade, I. A.; Hill, A. F.; McQueen, C. M. A. Organometallics 2009, 28, 6639–6641. (9) (a) Caskey, S. R.; Stewart, M. H.; Kivela, J. E.; Stootsman, J.; Johnson, M. J. A.; Kampf, J. W. J. Am. Chem. Soc. 2005, 127, 16750– 16751. Sulfur atom transfer to the carbidoosmium complex [OsCl2(C)(PCy3)2] leading to the CS complex [OsCl2(CS)(PCy3)2] has also been reported: (b) Stewart, M. H.; Johnson, M. J. A.; Kampf, J. W. Organometallics 2007, 26, 5102–5110. (10) (a) Carlson, R. G.; Gile, M. A.; Happert, J. A.; Mason, M. H.; Powell, D. R.; Vander Velde, D.; Vilain, J. M. J. Am. Chem. Soc. 2002, 124, 1580–1581. (b) Romero, P. E.; Piers, W. E.; McDonald, R. Angew. Chem., Int. Ed. 2004, 43, 6161–6165. (c) Dubberley, S. R.; Romero, P.; Piers, W. E.; Parvez, M. Inorg. Chim. Acta 2006, 359, 2658–2664.

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Scheme 1

with an N-heterocyclic carbene ligand. Thus, when the carbido complex [RuCl2(C)(H2IMes)(PCy3)] (1; H2IMes = 1,3-dimesitylimidazolin-2-ylidene)10 was allowed to react with elemental selenium (5 equiv) at room temperature in benzene, the CSe complex [RuCl2(CSe)(H2IMes)(PCy3)] (2CSe) was obtained in high yield as a yellow microcrystalline solid (Scheme 1).11 In the 13C{1H} NMR, a signal due to the CSe ligand is observed at δ 287.9 (d, JPC=14.4 Hz), whereas an IR absorption of νCSe is observed at 1150 cm-1. The molecular structure of 2-CSe has been unambiguously established by X-ray analysis (Figure 1). The complex 2-CSe has a distorted-square-pyramidal geometry with an apical CSe ligand, where the ruthenium center adopts a 16e configuration, providing the first example of a crystallographically characterized five-coordinate CSe complex. The C-Se bond distance (1.723(4) A˚) in 2-CSe falls in the range of those in six-coordinate CSe complexes ([RuCl2(CO)(CSe)(PPh3)2], 1.67(2) A˚;3 [Cr(η6-C6H5CO2Me)(CO)2(CSe)], 1.73(1) A˚;4b [Cr(CO)2(CSe){P(OMe)3}3], 1.750(3) A˚4g) and is slightly shorter than those in selenoketones (1.774(6)12a and 1.790(4) A˚12b). The Ru-CSe bond distance (1.729(4) A˚) is longer than that in the carbido complex 1 (1.652(2) A˚10a) but still much shorter than those in the carbene and vinylidene (11) A mixture of 1 (114 mg, 0.148 mmol) and elemental selenium (59.7 mg, 0.756 mmol, 5 equiv) in benzene (2.0 mL) was stirred at room temperature for 96 h. The 31P{1H} NMR analysis of the reaction mixture indicated complete conversion of the starting material (δP 33.8) into a single product (δP 18.5). The resulting mixture was filtered through a plug of Celite, and the filtrate was dried under reduced pressure. The residue was washed with hexanes (2 mL  2) at -40 °C and dried in vacuo to afford essentially pure 2-CSe (122 mg, 0.143 mmol, 96% yield) as a yellow microcrystalline solid. Samples for elemental analysis were obtained by recrystallization from CH2Cl2/hexanes followed by drying under vacuum. Single crystals suitable for an X-ray analysis were obtained by recrystallization from benzene/hexanes. IR (cm-1): 1150 (νCSe). 1H NMR (CDCl3): δ 6.95, 6.88 (s, 2H each, Ar of Mes), 4.00-3.96, 3.92-3.87 (m, 2H each, N(CH2)2N), 2.55-2.46 (multiple peaks, 15H, o-CH3 of Mes and CH of PCy3), 2.28, 2.23 (s, 3H each, pCH3 of Mes), 1.93-1.86 (br m, 6H, CH2 of PCy3), 1.68-1.58 (br m, 9H, CH2 of PCy3), 1.21-1.09 (br m, 15H, CH2 of PCy3). 13C{1H} NMR (CDCl3): δ 287.9 (d, JCP =14.4 Hz, RuCSe), 210.0 (d, JCP =98.4 Hz, Ru-C(N)2), 138.8 (Ar), 138.7 (Ar), 138.6 (Ar), 138.0 (Ar), 137.4 (Ar), 133.8 (Ar), 129.9 (Ar), 129.7 (Ar), 52.8 (N(CH2)2N), 51.9 (N(CH2)2N), 32.8 (d, JCP=19.2 Hz, CH of PCy3), 29.5 (CH2 of PCy3), 27.7 (d, JCP=9.6 Hz, CH2 of PCy3), 26.1 (CH2 of PCy3), 21.1 (CH3), 21.0 (CH3), 19.8 (CH3), 18.8 (CH3). 31P{1H} NMR (C6D6): δ 18.8 (s, PCy3). Anal. Calcd for C40H59Cl2N2PRuSe 3 0.5C6H14: C, 57.84; H, 7.45; N, 3.14. Found: C, 57.83; H, 7.51; N, 3.33. (12) (a) Brooks, R. R.; Counter, J. A.; Bishop, R.; Tiekink, E. R. E. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1991, 47, 1939–1941. (b) Okuma, K.; Kojima, K.; Kaneko, I.; Tsujimoto, Y.; Ohta, H.; Yokomori, Y. J. Chem. Soc., Perkin Trans. 1 1994, 2151–2159.

Figure 1. ORTEP drawing of the CSe complex 2-CSe. Thermal ellipsoids are shown at the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond lengths (A˚): Se1-C1, 1.723(4); Ru1-C1, 1.729(4); Ru1-C2, 2.118(3); Ru1P1, 2.4158(11). Selected bond angles (deg): Ru1-C1-Se1, 176.9(2); P1-Ru1-C2, 166.56(11); Cl1-Ru1-Cl2, 165.78(4).

complexes [RuCl2(dCHPh)(H2IMes)(PCy3)] (1.835(2) A˚13a) and [CpRu(dCdC(Ph)C6H4OMe-p)(dppe)][BArF4] (Cp = η5-C5H5, dppe = Ph2PCH2CH2PPh2, ArF = 3,5-(CF3)2C6H3); 1.838(4) A˚13b). In these contexts, the multiple-bond character of the Ru-C and C-Se bonds has been supported by the Wiberg bond index (WBI) in the natural atomic orbital (NAO) analysis of 2-CSe (Ru-C, 1.5561; C-Se, 2.0499).14 These results suggest that electrons on the ruthenium atom are efficiently delocalized into the CSe ligand, and the contribution of the RudCdSe canonical structure is more important to 2-CSe than that of the RudCdO structure to the CO complex 2-CO. Next, we attempted the synthesis of CTe complexes by a similar method, but 1 failed to react with elemental tellurium (excess) even at elevated temperature for several days.15 However, in the presence of pyridine, slow conversion of 1 to form TedPCy3 was observed by 31P{1H} NMR spectroscopy. Mass spectrometric analysis of the crude product suggested the formation of [RuCl2(CTe)(H2IMes)(pyridine)2], but this species could not be isolated because of its lability during purification. Judging from the π-acidic nature of CSe ligand, we anticipated that more donating ligands can effectively stabilize CTe complexes. In fact, treatment of 1 with elemental tellurium (10 equiv) in the presence of excess 4-(dimethylamino)pyridine (DMAP) afforded the CTe complex [RuCl2(CTe)(H2IMes)(dmap)2] (3-CTe) in 52% yield as orange crystals (Scheme 1).16 Complex 3-CTe exhibits a 13 C{1H} NMR signal of the CTe ligand at δ 327.9 and an IR absorption of νCTe at 1024 cm-1. The molecular structure of 3-CTe has been confirmed by an X-ray analysis (Figure 2). Complex 3-CTe is a six-coordinate 18e complex in which the DMAP ligands are located trans to the CTe and H2IMes ligands. The Ru-C-Te bond is somewhat bent (162.1(2)°), probably because of the steric repulsion between the tellurium atom and a Mes group of the H2IMes ligand. The C-Te bond distance (1.952(5) A˚) in 3-CTe is close to those in [OsCl2(CO)(CTe)(PPh3)2] (1.923(12) A˚) and [Os(CO)2(CTe)(PPh3)2] (13) (a) Love, J. A.; Sanford, M. S.; Day, M. W.; Grubbs, R. H. J. Am. Chem. Soc. 2003, 125, 10103–10109. (b) Mutoh, Y.; Ikeda, Y.; Kimura, Y.; Ishii, Y. Chem. Lett. 2009, 35, 534–535. (14) Density functional theory (DFT) calculations were performed at the B3P86/SBKJC(d) level. See the Supporting Information for details. (15) Preliminary DFT studies suggest that a five-coordinate CTe complex with distorted-square-pyramidal geometry may be found as a local minimum structure.

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Scheme 2

Figure 2. ORTEP drawing of the CTe complex 3-CTe 3 CH2Cl2. Thermal ellipsoids are shown at the 50% probability level. Hydrogen atoms and a CH2Cl2 solvate molecule are omitted for clarity. Selected bond lengths (A˚): Te1-C1, 1.952(5); Ru1C1, 1.748(5); Ru1-C2, 2.087(4); Ru1-N3, 2.333(4); Ru1-N5, 2.189(3). Selected bond angles (deg): Te1-C1-Ru1, 162.1(2); N3-Ru1-C1, 162.06(18); N5-Ru1-C2, 173.69(18); Cl1Ru1-Cl2, 175.01(4).

(1.947(20) A˚)17 but still shorter than that in the η1-telluroketone tungsten complex [W(CO)5(η1-1,1,3,3-tetramethylindantellone)] (1.987(5) A˚).18 The Ru-CTe bond distance (1.748(5) A˚) in 3-CTe is close to that in 2-CSe. In accordance with these observations, WBI in NAO analysis of 3-CTe indicated the Ru-C and C-Te multiple-bond character (16) A mixture of 1 (58.1 mg, 0.075 mmol), elemental tellurium (96.2 mg, 0.754 mmol, 10 equiv), and DMAP (368 mg, 3.01 mmol, 40 equiv) in THF (1.5 mL) was stirred at room temperature. The reaction was monitored by 31P{1H} NMR analysis. After 96 h, consumption of the starting material (δP 33.8) and formation of TedPCy3 (δP 28.8, JPTe = 1700.8 Hz) were confirmed, and the resulting mixture was dried under vacuum. The residue was extracted into CH2Cl2 and filtered through a plug of Celite. After removal of all volatiles from the filtrate under vacuum, the residue was washed with hot hexanes (5 mL  10) at ca. 60 °C, to remove TedPCy3 and excess DMAP, and recrystallized from CH2Cl2/Et2O to afford 3-CTe 3 0.5Et2O (33.8 mg, 0.038 mmol, 52% yield) as orange crystals. Single crystals suitable for X-ray analysis were obtained by further recrystallization from CH2Cl2/Et2O/toluene in the presence of a small amount of DMAP. The complex 3-CTe decomposes in solution without DMAP at room temperature, even under a nitrogen atmosphere, but is stable in the solid state in air. For this reason, 13C{1H} NMR of 3-CTe was measured in the presence of DMAP, and several signals were overlapped. IR (cm-1): 1024 (νCTe). 1H NMR (CD2Cl2): δ 8.27 (br d, J=6.0 Hz, 2H, dmap), 8.18 (br s, 2H, dmap), 6.70 (br s, 4H, Ar of Mes), 6.15 (d, J=6.0 Hz, 2H, dmap), 6.08 (br s, 2H, dmap), 3.93 (s, 4H, N(CH2)2N), 2.93, 2.90 (s, 6H each, NMe2), 2.49 (s, 12H, o-CH3 of Mes), 2.18 (s, 6H, p-CH3 of Mes). 13C{1H} NMR (CD2Cl2): δ 327.9 (RuCTe), 208.1 (Ru-C(N)2), 153.2 (p-C of dmap), 152.6 (p-C of dmap), 149.6 (o-C of dmap), 149.3 (o-C of dmap, overlapped with free DMAP), 138.3, (br, Ar of Mes), 137.7 (br, Ar of Mes), 137.5 (br, Ar of Mes), 129.3 (Ar of Mes), 106.1 (m-C of dmap, overlapped with free DMAP), 105.5 (m-C of dmap), 52.3 (N(CH2)2N), 38.5 (NMe2, overlapped with free DMAP), 38.4 (NMe2), 20.5 (Me), 18.6 (br, Me). Anal. Calcd for C36H46Cl2N6RuTe 3 0.5Et2O: C, 50.74; H, 5.72; N, 9.34. Found: C, 50.38; H, 5.58; N, 9.09. (17) Roper, W. R. J. Organomet. Chem. 1986, 300, 167–190. (18) Minoura, M.; Kawashima, T.; Tokitoh, N.; Okazaki, R. Chem. Commun. 1996, 123–124. (19) The CO complex [RuCl2(CO)(H2IMes)(dmap)2] (3-CO) was simply prepared by ligand substitution of [RuCl2(CO)(H2IMes)(PCy3)] (2-CO) with DMAP. See the Supporting Information.

(Ru-C, 1.5453; C-Te, 1.9517). These features suggest that the π-acidity of CTe is even stronger than that of CSe, and the RudCdTe canonical structure is considered to be the major contributor to 3-CTe. The complete series of the CE complexes [RuCl2(CE)(H2IMes)(dmap)2] (3-CE) were obtained by the above method and structurally characterized.19 A detailed comparison of the molecular structures (see the Supporting Information) revealed that the order of π-acidity and trans influence of CE ligands is CTe > CSe > CS > CO. Similar results have been observed with the series of osmium complexes [OsCl2(CO)(CE)(PPh3)2] (E=S, Se, Te),5b though the properties of CE ligands in the [Tp*Mo(CO)(CE)]- series have not been reported in the literature.6 The order of π-acidity is also reflected in the 13C{1H} NMR data; the CSe (δ 317.3) and CTe (δ 327.9) signals appear in the vinylidene region. This trend is also in accordance with the observation of the osmium series and the [M(Ring)(CO)2(CE)] (M = Cr, Mn; Ring=arene, Cp; E=O, S, Se) series.4d Theoretical studies have suggested that the donor and acceptor abilities of the CE ligand increase on going down the periodic table.20 Finally, the reactivities of CE complexes were explored. When CH2Cl2 solutions of the five-coordinate complexes [RuCl2(CE)(H2IMes)(PCy3)] (2-CE) were allowed to stand under atmospheric CO (Scheme 2), 2-CO was transformed into the dicarbonyl complex trans-[RuCl2(CO)2(H2IMes)(PCy3)] (4-CO) in 0.5 h, whereas no reaction was observed with 2-CS and 2-CSe even after 3 days. This result is clearly accounted for by the aforementioned order of trans influence. Extrusion and exchange of the chalcogen atoms in 3-CE were also tested (Scheme 3). Reactions of 3-CSe and 3-CTe with PCy3 (5 equiv) smoothly proceeded to give 1 in quantitative yield along with E = PCy3, DMAP. In contrast, no abstraction of oxygen and sulfur atoms in 3-CO and 3-CS was observed, and 2-CO and 2-CS were formed instead in low to moderate yields.21 Treatment of 3-CTe with S8 gave the CS complex 3-CS in 85% NMR yield22 concomitant with precipitation of tellurium at room temperature,23 though 3-CSe failed to react with S8 under ambient conditions. These results suggest that 3-CTe can be used as a tellurium atom transfer reagent. (20) (a) Saillard, J.-Y.; Grandjean, D.; Caillet, P.; Le Beuze, A. J. Organomet. Chem. 1980, 190, 371–379. (b) Ziegler, T. Inorg. Chem. 1986, 25, 2721–2727. (21) Oxygen and sulfur atom abstraction reactions of CO and CS complexes [RuCl2(CE)(PCy3)2] (E = O, S) using PCy3 were also unsuccessful.9a (22) A similar chalcogen exchange reaction of 4,40 -dimethoxyselenobenzophenone with sulfur was described in ref 12b. (23) We have also found that deposition of tellurium takes place on dissolution of 3-CTe in solvents (CH2Cl2, benzene, and acetone); the grayish black powder that precipitated in this process was unambiguously confirmed to be elemental tellurium by a powder X-ray diffraction study. Although we have to await further investigation, we believe that DMAP plays an important role in stabilizing the ruthenium species with a highly π-acidic CTe ligand, as described in the main text. Now we are examining degradation of 3-CTe in detail, experimentally and theoretically, and the results will be reported in due course.

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elemental selenium and tellurium. Systematic elucidation for chemical properties of the complete series of CE complexes revealed that the CTe complex could work as a tellurium atom transfer reagent. Further studies on the reactivities of CE complexes will be reported in due course.

Acknowledgment. This work was supported by KAKENHI (No. 21750066) from the MEXT of Japan. We thank Profs. Yasushi Mizobe and Hidetake Seino for measurement of mass spectra and Prof. Katsuyoshi Oh-ishi for the measurement of powder X-ray diffraction analysis of tellurium.

In summary, we have successfully established a straightforward synthetic route to CSe and CTe complexes by utilizing reactions of the terminal carbido complex with

Supporting Information Available: Text, figures, tables, and CIF files giving experimental procedures, details of DFT calculations, and crystallographic data. This material is available free of charge via the Internet at http:// pubs.acs.org.