Lanthanide Terminal Hydride Complexes Bearing Two Sterically

contrast, monomeric terminal hydrido lanthanide complexes are scarce.7 Teuben and .... (5) (a) Zinnen, H. A.; Pluth, J. J.; Evans, W. J. J. Chem. Soc...
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Organometallics 2009, 28, 5196–5203 DOI: 10.1021/om900453j

Lanthanide Terminal Hydride Complexes Bearing Two Sterically Demanding C5Me4SiMe3 Ligands. Synthesis, Structure, and Reactivity Yasumasa Takenaka and Zhaomin Hou* Organometallic Chemistry Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Received May 28, 2009

The acid-base reaction between lanthanide tris(alkyl) complexes Ln(CH2SiMe3)3(THF)2 and 2 equiv of HC5Me4SiMe3 in THF or hexane at room temperature resulted in the formation of metallocene complexes [(η5:η1-C5Me4SiMe2CH2)Ln(C5Me4SiMe3)(THF)] (Ln = Y (1a), Nd (1b), Sm (1c), Dy (1d), Lu (1e)), in which the metal center is bonded to one C5Me4SiMe3 ligand in a normal η5-form and to the other in a μ-η5:η1-chelate fashion through metalation of a methyl group of the SiMe3 substituent. Hydrogenolysis of 1a-e in toluene at room temperature afforded the corresponding metallocene terminal hydride complexes [(C5Me4SiMe3)2LnH(THF)] (Ln=Y (2a), Nd (2b), Sm (2c), Dy (2d), Lu (2e)). Complexes 2a,d,e were isolated and structurally characterized by X-ray analysis, whereas 2b,c, which possess larger metal ions, existed only in solution in the presence of H2. The reaction of the yttrium hydride complex 2a with 1 equiv of p-methoxyphenylisocyanide yielded the ethylene diamido complex [(C5Me4SiMe3)2YN(Ar)(CHd)]2 (Ar = C6H4-OMe-p (3)). The reaction of 2a, 2d, and 2e with a late transition metal hydride complex (C5Me5)IrH4 gave the corresponding Ln/Ir heterobimetallic trihydride complexes [(C5Me4SiMe3)2Ln(μ-H)3Ir(C5Me5)] (Ln = Y (4a), Dy (4b), Lu (4c)) with release of H2. Introduction Lanthanide hydride complexes occupy an important place in the development of organometallic chemistry of the lanthanides, because of their high activity in various stoichiometric and catalytic processes.1 Lanthanide hydride complexes reported so far in the literature are dominated *Corresponding author. E-mail: [email protected]. (1) Selected reviews: (a) Schaverrien, C. J. Adv. Organomet. Chem. 1994, 36, 283. (b) Schumann, H.; Meese-Markscheffel, J. A.; Esser, L. Chem. Rev. 1995, 95, 865. (c) Ephritikhine, M. Chem. Rev. 1997, 97, 2193. (d) Arndt, S.; Okuda, J. Chem. Rev. 2002, 102, 1953. (e) Molander, G. A.; Romero, J. A. C. Chem. Rev. 2002, 102, 2161. (f) Hoskin, A. J.; Stephan, D. W. Coord. Chem. Rev. 2002, 233-234, 107. (g) Hou, Z.; Wakatsuki, Y. In Science of Synthesis; Imamoto, T., Noyori, R., Eds.; Thiem: Stuttgart, 2002; Vol. 2, p 849. (h) Hou, Z.; Wakatsuki, Y. Coord. Chem. Rev. 2002, 231, 1. (i) Hou, Z. Bull. Chem. Soc. Jpn. 2003, 76, 2253. (j) Okuda, J. J. Chem. Soc., Dalton Trans. 2003, 2367. (j) Hou, Z.; Nishiura, M.; Shima, T. Eur. J. Inorg. Chem. 2007, 2535. (2) For examples of structurally characterized metallocene lanthanide(III) monohydride complexes, see: (a) Evans, W. J.; Meadows, J. H.; Wayda, A. L.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. 1982, 104, 2008. (b) Evans, W. J.; Meadows, J. H.; Wayda, A. L. J. Am. Chem. Soc. 1982, 104, 2015. (c) Evans, W. J.; Bloom, I.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. 1983, 105, 1401. (d) Schumann, H.; Genthe, W.; Hahn, E.; Hossain, M. B.; van der Helm, D. J. Organomet. Chem. 1986, 299, 67. (e) Evans, W. J.; Drummond, D. K.; Hanusa, T. P.; Doedens, R. J. Organometallics 1987, 6, 2279. (f) Evans, W. J.; Sollberger, M. S.; Khan, S. I.; Bau, R. J. Am. Chem. Soc. 1988, 110, 439. (g) Kretschmer, W. P.; Troyanov, S. I.; Meetsma, A.; Hessen, B.; Teuben, H. Organometallics 1998, 17, 284. (h) Stern, D.; Sabat, M.; Marks, T. J. J. Am. Chem. Soc. 1990, 112, 9558. (i) Evans, W. J.; Ulibarri, T. A.; Ziller, J. W. Organometallics 1991, 10, 134. (j) Gun'ko, Y. K.; Bulychev, B. M.; Soloveichik, G. L.; Belsky, V. K. J. Organomet. Chem. 1992, 424, 289. (k) Booij, M.; Deelman, B.-J.; Duchateau, R.; Postma, D. S.; Meetsma, A.; Teuben, J. H. Organometallics 1993, 12, 3531. (l) Qiao, K.; Fischer, R. D.; Paolucci, G. J. Organomet. Chem. 1993, 456, 185. (m) Deng, D.; Jiang, Y.; Qian, C.; Wu, G.; Zheng, P. J. Organomet. Chem. 1994, 470, 99. (n) Mitchell, J. P.; Hajela, S.; Brookhart, S. K.; Hardcastle, K. I.; Henling, L. M.; Bercaw, J. E. J. Am. Chem. Soc. 1996, 118, 1045. (o) Kirillov, E.; Lehmann, C. W.; Razavi, A.; Carpentier, J.-F. Organometallics 2004, 23, 2768. pubs.acs.org/Organometallics

Published on Web 08/19/2009

by the monohydrides bearing two ancillary ligands with a general formula of “L2MH” or “(L)(L0 )MH”,2-7 while dihydride complexes of type “LMH2” that are stabilized by one ancillary ligand became known very recently.6b-e A typical structural feature observed in the lanthanide hydride complexes is that they tend to form dimeric or further highly aggregated structures via hydride bridges.1-6 In contrast, monomeric terminal hydrido lanthanide complexes are scarce.7 Teuben and co-workers reported in 1987 that (3) For examples of structurally characterized half-sandwich lanthanide(III) monohydride complexes, see: (a) Shapiro, P. J.; Bunel, E.; Schaefer, W. P.; Bercaw, J. E. Organometallics 1990, 9, 867. (b) Shapiro, P. J.; Cotter, W. D.; Schaefer, W. P.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1994, 116, 4623. (c) Mu, Y.; Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J.; Young, V. G.Jr. Organometallics 1996, 15, 2720. (d) Hultzsch, K. C.; Spaniol, T. P.; Okuda, J. Angew. Chem., Int. Ed. 1999, 38, 227. (e) Arndt, S.; Voth, P.; Spaniol, T. P.; Okuda, J. Organometallics 2000, 19, 4690. (f) Trifonov, A. A.; Spaniol, T. P.; Okuda, J. Organometallics 2001, 20, 4869. (g) Voth, P.; Arndt, S.; Spaniol, T. P.; Okuda, J. Organometallics 2003, 22, 65. (h) Voth, P.; Spaniol, T. P.; Okuda, J. Organometallics 2003, 22, 3921. (i) Tardif, O.; Nishiura, M.; Hou, Z. Tetrahedron 2003, 59, 10525. (4) For examples of structurally characterized Cp-free lanthanide(III) monohydride complex, see: (a) Hagadorn, J. R.; Arbold, J. Organometallics 1996, 15, 984. (b) Duchateau, R.; van Wee, C. T.; Meetsma, A.; van Duijnen, P. Th.; Teuben, J. H. Organometallics 1996, 15, 2279. (c) Ferrence, G. M.; McDonald, R.; Takats, J. Angew. Chem., Int. Ed. 1999, 38, 2233. (d) Emslie, D. J. H.; Piers, W. E.; Parvez, M.; McDonald, R. Organometallics 2002, 21, 4226. (e) Trifonov, A. A.; Fedorova, E. A.; Fukin, G. K.; Bochkarev, M. N. Eur. J. Inorg. Chem. 2004, 4396. (5) (a) Zinnen, H. A.; Pluth, J. J.; Evans, W. J. J. Chem. Soc., Chem. Commun. 1980, 810. (b) Evans, W. J.; Engerer, S. C.; Coleson, K. M. J. Am. Chem. Soc. 1981, 103, 6672. (c) Schumann, H.; Genthe, W. J. J. Organomet. Chem. 1981, 213, C7. (d) Watson, P. L.; Roe, D. C. J. Am. Chem. Soc. 1982, 104, 6471. (e) Evans, W. J.; Meadows, J. H.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. 1984, 106, 1291. (f) Jaske, G.; Lauke, H.; Mauermann, H.; Swepston, P. N.; Schumann, H.; Marks, T. J. J. Am. Chem. Soc. 1985, 107, 8091. (g) Mauermann, H.; Swepston, P. N.; Schumann, H.; Marks, T. J. Organometallics 1985, 4, 200. (h) Qian, C.; Deng, D.; Ni, C.; Zhang, Z. Inorg. Chim. Acta 1988, 146, 129. r 2009 American Chemical Society

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Cp*2YH(THF) could adopt a monomeric form in C6D6.7a In 2004, Gavenonis and Tilley found that bis(heptamethylindenyl)yttrium hydride (Ind*)2YH(THF) could also exist in a monomeric form.7b However, all of these species were observed only in solution by 1H NMR spectroscopy. In 2005, Andersen and co-workers reported the X-ray structure of the monomeric cerium terminal hydride complex (1,3,4-tBu3C5H2)2CeH, which was stabilized by two sterically demanding C5Ht2Bu3-1,3,4 ligands.7c To the best of our knowledge, this is the only example of a structurally characterized lanthanide terminal hydride complex reported in the literature. We recently found that the C5Me4SiMe3 group can serve as a novel ancillary ligand for the stabilization of half-sandwich lanthanide dialkyl8 and dihydride6 complexes of the type “(C5Me4SiMe3)LnR2” (R = CH2SiMe3, CH2C6H4NMe2-o, allyl, or H) because of its large steric hindrance and high electron-donating property. These complexes showed unprecedented activity in various chemical transformations, such as olefin polymerization or hydrogenation of unsaturated C-C, C-N, and C-O bonds. During these studies, we became interested in the behavior of lanthanide metallocene alkyl and hydride complexes bearing two C5Me4SiMe3 ligands. We report here that a pair of sterically demanding C5Me4SiMe3 units can serve as an excellent ligand set for the stabilization of monomeric terminal lanthanide hydride complexes (C5Me4SiMe3)2LnH(THF) (Ln = Y, Dy, Lu), while the alkyl analogues (C5Me4SiMe3)2LnCH2SiMe3(THF) are not isolable and could undergo rapid intramolecular dehydrogenation of a methyl group in the SiMe3 substituent to give (C5Me4SiMe3)Ln(η5:η1-C5Me4SiMe2CH2)(THF). Preliminary studies on the reactivity of the hydride complexes are also described.

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Figure 1. ORTEP drawing of 1a with 30% thermal ellipsoids. Scheme 1

Results and Discussion Lanthanide Alkyl Complexes Bearing Two C5Me4SiMe3 Ligands. The reaction of the lanthanide trialkyl complexes Ln(CH2SiMe3)3(THF)2 (Ln = Y, Nd, Sm, Dy, Lu)9 with (6) For structurally characterized lanthanide(III) “dihydride” complexes, see: (a) Hou, Z.; Zhang, Y.; Tardif, O.; Wakatsuki, Y. J. Am. Chem. Soc. 2001, 123, 9216. (b) Tardif, O.; Nishiura, M.; Hou, Z. Organometallics 2003, 22, 1171. (c) Hultzsch, K. C.; Voth, P.; Spaniol, T. P.; Okuda, J. Z. Anorg. Allg. Chem. 2003, 629, 1272. (d) Cui, D.; Tardif, O.; Hou, Z. J. Am. Chem. Soc. 2004, 126, 1312. (e) Tardif, O.; Hashizume, D.; Hou, Z. J. Am. Chem. Soc. 2004, 126, 8080. (f) Luo, Y.; Baldamus, J.; Tardif, O.; Hou, Z. Organometallics 2005, 24, 4362. (g) Shima, T.; Hou, Z. J. Am. Chem. Soc. 2006, 128, 8124. (h) Li, X.; Baldamus, J.; Nishiura, M.; Tardif, O.; Hou, Z. Angew. Chem., Int. Ed. 2006, 45, 8184. (i) Yousufuddin, M.; Gutmann, M. J.; Baldamus, J.; Tardif, O.; Hou, Z.; Mason, S. A.; McIntyre, G. J.; Bau, R. J. Am. Chem. Soc. 2008, 130, 3888. (j) Ohashi, M.; Konkol, M.; Rosal, I. D.; Poteau, R.; Maron, L.; Okuda, J. J. Am. Chem. Soc. 2008, 130, 6920. (k) Cheng, J.; Saliu, K.; Kiel, G. Y.; Ferguson, M. J.; McDonald, R.; Takats, J. Angew. Chem., Int. Ed. 2008, 47, 4910. (7) For lanthanide complexes bearing a terminal hydrido ligand, see: (a) Haan, K. H. D.; Wielstra, Y.; Teuben, J. H. Organometallics 1987, 6, 2053. (b) Gavenonis, J.; Tilley, T. D. J. Organomet. Chem. 2004, 689, 870. (c) Maron, L.; Werkema, E. L.; Perrin, L.; Eisenstein, O.; Andersen, R. A. J. Am. Chem. Soc. 2005, 127, 279. (8) (a) Luo, Y.; Baldamus, J.; Hou, Z. J. Am. Chem. Soc. 2004, 126, 13910. (b) Li, X.; Baldamus, J.; Hou, Z. Angew. Chem., Int. Ed. 2005, 44, 962. (c) Li, X.; Hou, Z. Macromolecules 2005, 38, 6767. (d) Cui, D.; Nishiura, M.; Hou, Z. Macromolecules 2005, 38, 4089. (e) Cui, D.; Nishiura, M.; Hou, Z. Angew. Chem., Int. Ed. 2005, 44, 959. (f) Luo, Y.; Baldamus, J.; Tardif, O.; Hou, Z. Organometallics 2005, 24, 4362. (g) Zhang, L.; Luo, Y.; Hou, Z. J. Am. Chem. Soc. 2005, 126, 14562. (h) Li, X.; Nishiura, M.; Mori, K.; Mashiko, T.; Hou, Z. Chem. Commun. 2008, 4137. (i) Yu, N.; Nishiura, M.; Li, X.; Xi, Z.; Hou, Z. Chem. Asian J. 2008, 3, 1406. (9) (a) Hultzsch, K. C.; Voth, P.; Beckerle, K.; Spaniol, T. P.; Okuda, J. Organometallics 2000, 19, 228. (b) Arndt, S.; Voth, P.; Spaniol, T. P.; Okuda, J. Organometallics 2000, 19, 4690. (c) Bambirra, S.; Bouwkamp, M. W.; Meetsma, A.; Hessen, B. J. Am. Chem. Soc. 2004, 126, 9182.

2 equiv of HC5Me4SiMe3 in THF or hexane at room temperature gave (η5-C5Me4SiMe3)Ln(η5:η1-C5Me4SiMe2CH2)(THF) (Ln=Y (1a), Nd (1b), Sm (1c), Dy (1d), Lu (1e)) in moderate to high isolated yields (Scheme 1). X-ray diffraction studies revealed that all complexes 1a-e adopt a similar overall structure, in which the metal center is bonded to one Cp ligand in a η5-form and to the other Cp ligand in a μ-η5:η1-chelate fashion through metalation of a methyl group of the SiMe3 substituent. The ORTEP drawing of 1a is shown in Figure 1, and selected bond lengths and angles are summarized in Table 1. The bond distances of the Ln1-C1 bonds in 1a-e range between 2.411 and 2.545 A˚, which are comparable with those reported for the analogous lanthanide-alkyl bonds. All metal-ligand bond distances in 1a-e increased with an increase in the metal ion size, Nd > Sm>Dy>Y>Lu, as observed in other lanthanide complexes.10 The 1H and 13C NMR spectra (confirmed by DEPT) of the diamagnetic yttrium and lutetium complexes 1a,e in C6D6 are consistent with their solid structure, while the NMR spectra of 1b-d could not be fully assigned because of the influence of the paramagnetic metal ions. Apparently, complexes 1a-e could be formed through intramolecular hydrogen abstraction of a methyl group in (10) Shannon, B. R. D. Acta Crystallogr. 1976, A32, 751.

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Table 1. Selected Bond Distances (A˚) and Angles (deg) for Complexes 1a-e 1a (Y)

1b (Nd)

1c (Sm)

1d (Dy)

Table 2. Selected Bond Distances (A˚) and Angles (deg) for Complexes 2a, 2d, and 2e

1e (Lu) a

2a (Ln = Y)

2d (Ln = Dy)

2e (Ln = Lu)

Ln1-C1 Ln1-Cp1a Ln1-Cp2a Ln1-Ct1b Ln1-Ct2b Ln1-O1

2.457(3) 2.664(3) 2.691(3) 2.376 2.404 2.370(2)

2.545(3) 2.745(3) 2.778(3) 2.465 2.501 2.480(2)

2.511(5) 2.725(4) 2.753(5) 2.441 2.473 2.453(3)

2.475(4) 2.672(4) 2.699(4) 2.383 2.411 2.393(3)

2.411(4) 2.628(3) 2.651(3) 2.334 2.359 2.311(2)

Ln1-Cp1 Ln1-Cp2a Ln1-Ct1b Ln1-Ct2b Ln1-O1 Ln1-H1

2.683(3) 2.686(3) 2.399 2.398 2.386(2) 2.54(2)

2.678(4) 2.676(4) 2.391 2.389 2.375(3) 2.29(4)

2.607(5) 2.598(5) 2.314 2.306 2.283(3) 2.15(5)

Ct1-Ln1-Ct2 Ct1-Ln1-C1 Ct1-Ln1-O1 Ct2-Ln1-C1 Ct2-Ln1-O1 C1-Ln1-O1 Ln1-C1-Si1

140.56 96.95 105.43 105.36 105.89 91.82(9) 98.29(13)

141.20 94.54 1106.17 104.54 106.36 92.49(11) 98.12(15)

141.29 95.29 105.80 104.86 106.22 91.76(15) 98.4(2)

140.82 97.01 105.43 104.90 105.84 91.93(13) 97.56(17)

140.12 98.49 104.85 105.27 106.01 91.55(11) 97.94(16)

Ct1-Ln1-Ct2 Ct1-Ln1-H1 Ct1-Ln1-O1 Ct2-Ln1-H1 Ct2-Ln1-O1 H1-Ln1-O1

138.15 101.25 104.91 108.19 104.05 90.22

139.59 102.27 104.19 104.97 105.03 90.10

140.99 100.24 106.79 103.51 104.92 87.08

a

Cp1, Cp2 = Cp average. b Ct1, Ct2 = ring centroid.

a

Cp1, Cp2 = Cp average. b Ct1, Ct2 = ring centroid.

Scheme 2

the SiMe3 substituent of a Cp ligand by the CH2SiMe3 group in the metallocene alkyl intermediates [(C5Me4SiMe3)2Ln(CH2SiMe3)(THF)] initially formed by the acid-base reaction between Ln(CH2SiMe3)3(THF)2 and 2 equiv of HC5Me4SiMe3. However, such a metallocene alkyl intermediate species was not observed when monitoring the reaction of Y(CH2SiMe3)3(THF)2 with HC5Me4SiMe3 in toluene-d8 by 1H NMR. These results suggest that the dehydrogenation reaction by the CH2SiMe3 group should be very fast. As reported previously, the reaction of Y(CH2SiMe3)3(THF)2 with 1 equiv of HC5Me4SiMe3 gave only the half-sandwich yttrium dialkyl complex (C5Me4SiMe3)Y(CH2SiMe3)2(THF),8 whereas the intramolecular C-H bond activation reaction was not observed under the same conditions. The difference in reactivity between the mono(cyclopentadienyl) complexes and the bis(cyclopentadienyl) analogues could be due to the difference in steric hindrance around the metal center. The intramolecular C-H bond activation reactions in analogous zirconocene complexes11 and other sterically hindered lanthanide complexes such as [{1,3,4-(Me3C)3(C5H2)}2CeCH2C6H5],7c [{Me2Si(C5Me4)(μ-PC6Ht2Bu3-2,4,6)}Ln(CH2SiMe3)(THF)],3i and Gd{N(C6H3-iPr2-2,6)(SiMe3)}(CH2SiMe3)2(THF)12 were observed previously. Synthesis and Structural Characterization of Terminal Hydrido Complexes. Hydrogenolysis of complexes 1a-e with H2 (1 atm) in toluene-d8 at room temperature led to the disappearance of the methylene chelation and simultaneous formation of the corresponding metallocene hydride species [(C5Me4SiMe3)2LnH(THF)] (Ln = Y (2a), Nd (2b), Sm (2c), Dy (2d), Lu (2e)) (Scheme 2), as shown by 1H NMR. The Y, Dy, and Lu hydride complexes 2a, 2d, and 2e could be isolated as single crystals in high yields from toluene/hexane. Attempts to isolate 2b,c by evaporation of the solvent and  epnicka, P.; Kubista, J.; Fejfarova, K.; Gyepes, (11) Hor acek, M.; St R.; Mach, K. Organometallics 2003, 22, 861. (12) Luo, Y.; Nishiura, M.; Hou, Z. J. Organomet. Chem. 2007, 692, 536.

Figure 2. ORTEP drawing of 2a 3 C7H8 with 30% thermal ellipsoids. The lattice solvent is omitted for clarity.

recrystallization under N2 led to quantitative recovery of the starting materials 1b,c, apparently due to intramolecular dehydrogenation of the SiMe3 substituent by the hydride species. The 1H NMR spectrum of the Y complex 2a showed a doublet for the hydride H at δ 5.92 (JH-Y =74.83 Hz), suggesting that the hydride is bonded only to one Y atom, similar to those found in the terminal yttrium hydride complexes Cp*2YH(THF) (δ 6.17, d, JH-Y = 81.74 Hz)7a and (Ind*)2YH(THF) (δ 6.04, d, JH-Y = 82.0 Hz, Ind* = heptamethylindenyl).7b X-ray analyses established that all complexes 2a, 2d, and 2e adopt a monomeric structure, in which the central metal atom is bonded to two η5-C5Me4SiMe3 ligands, one THF ligand, and one terminal hydride ligand (Table 2 and Figure 2). The overall geometry around the metal center in 2a, 2d, and 2e is rather similar to that in 1a-e. The angles between the centroids of the two Cp ligands ( — Ct1-Ln1-Ct2) in 2a (138.2), 2d (139.6), and 2e (141.0) are comparable with those in 1a-e (140.1-141.3). The — H1-Ln1-O1 angles in 2a (90.2), 2d (90.1), and 2e (87.1) are close to right angle, though slightly smaller than the — C1-Ln1-O1 angles in 1a-e (91.6-92.5). The average bond distances of the Ln-Cp bonds in 2a (Y1-Cp1: 2.683(3); Y1-Cp2: 2.686(3) A˚) and 2d (Dy1-Cp1: 2.678(4); Dy1-Cp2: 2.676(4) A˚) are similar to those in 1a (Y1-Cp1: 2.664(3); Y1-Cp2: 2.691(3) A˚) and 1d (Dy1-Cp1: 2.672(4); Dy1-Cp2: 2.699(4) A˚), respectively, and so are the Ln1-O1 bonds (Tables 1 and 2). The average bond distances of

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Figure 3. ORTEP drawing of 3 3 2C7H8 with 30% thermal ellipsoids. The lattice solvent is omitted for clarity.

the Lu1-Cp bonds (Lu1-Cp1: 2.607(5); Lu1-Cp2: 2.598(5) A˚) and the Lu1-O1 bond (2.283(3) A˚) in the lutetium hydride complex 2e are slightly shorter than those in its alkyl precursor 1e (Lu1-Cp1: 2.628(3); Lu1-Cp2: 2.651(3); Lu1-O1: 2.311(2) A˚), respectively. The Ln1-H1 bond distances in 2a (2.54(2) A˚), 2d (2.29(4) A˚), and 2e (2.15(5) A˚) are in the bond distance range reported for the lanthanide-hydride bonds. Complexes 2a, 2d, and 2e represent the second example of structurally characterized lanthanide terminal hydride complexes.7 Reactivity of the Hydride Complexes. We recently found that the reactions of tetranuclear lanthanide polyhydrido complexes [{Cp0 Ln(μ-H)2}4(THF)] (Cp0 = η5-C5Me4SiMe3; Ln = Lu, Y) with nitriles RCN can offer a convenient route to the corresponding imido complexes [{Cp0 Ln(μ3-NCH2R)}4] by double addition of the Ln-H units across the CtN bond.6d In an attempt to examine the reactivity of the terminal hydride complexes, the reaction of Y complex 2a (colorless) with 1 equiv of isocyanide CtN-C6H4-OMe-p in toluene was carried out at room temperature, which afforded the corresponding ethylene diamido complex [(C5Me4SiMe3)2YN(Ar)(CHd)]2 (3, Ar=C6H4-OMe-p) as green crystals in 54% yield (Scheme 3). Complex 3 could be viewed as a reductive dimerization product of the isocyanide compound and 2a. An X-ray analysis revealed that 3 possesses a crystallographic inversion center at the center of the C31-C310 bond (Figure 3 and Table 3). The C31-C310 bond distance in 3 is 1.315(8) A˚ and could be assigned to a carbon-carbon double bond. The average bond distances of the Y-Cp bonds in 3 (Y1Cp1: 2.681(4); Y1-Cp2: 2.667(4) A˚) are comparable with those found in 1a and 2a. The Y1-N1 bond distances in 3 (2.302(3) A˚) are comparable with that found in Cp*2YN(SiMe3)2 (13) Den Hann, K. H.; De Boer, J. L.; Teuben, J. H.; Spek, A. L.; Kojic-Prodic, B.; Hays, G. R.; Huis, R. Organometallics 1986, 5, 1726.

Scheme 3

(2.274(5) A˚).13 Bonding interactions between the Y atom and the ipso-carbon atom and an ortho-C-H unit of the phenyl group are also observed (Y1-C25: 2.869(4); Y1-C30: 2.838(4); Y1-H30: 2.401 A˚). The 1H NMR spectrum of 3 in C6D6 at room temperature exhibited a coupling between the Y atom and the ortho-phenyl protons (δ 6.54, d of d, JH-Y = 2.2 Hz, JH-H = 8.5 Hz), suggesting that the interactions between the metal center and the phenyl unit remained in solution. However, the four ortho- and four meta-protons of the two phenyl groups each gave an identical signal, showing that the structure is fluxional. A possible reaction mechanism for the formation of 3 is shown in Scheme 4. Nucleophilic addition of the Y-H bond in 2a to the isocyanide compound would give the η2-iminoacyl intermediate A. Subsequent addition of the η2-iminoacyl group of A to another molecule of isocyanide could yield the ketenimine species C via intermediate B. Addition of the Y-H unit of another molecule of 2a to the CdN unit of C (cf. D) would yield the binuclear amido yttrium complex 3. As an analogue of A, formation of an iminosilaacyl scandium complex [Cp2Sc{η2-C(N-2,6-Me2C6H3)Si(SiMe3)3}(THF)] in the reaction of [Cp2Sc{Si(SiMe3)3}(THF)] with

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Table 3. Selected Bond Distances (A˚) and Angles (deg) for Complex 3 Y1-N1 Y1-C30 Y1-C25 Y1-H30 Y1-Cp1a Y1-Cp2a

2.302(3) 2.838(4) 2.869(4) 2.401 2.681(4) 2.667(4)

Y1-Ct1b Y1-Ct2b C31-C310 N1-C31 N1-C25

2.394 2.375 1.315(8) 1.407(5) 1.393(5)

Ct1-Y1-Ct2 Ct1-Y1-N1 Ct2-Y1-N1 N1-C31-C310 H31-C31-C310

138.0 110.3 110.3 125.5(5) 117.3

H31-C31-N1 C31-N1-C25 Y1-N1-C31 Y1-N1-C25 Y1-N1-C25

117.2 118.6(3) 137.5(3) 98.9(2) 98.9(2)

a

Cp1, Cp2 = Cp average. b Ct1, Ct2 = ring centroid.

Scheme 4

Figure 4. ORTEP drawing of 4a with 30% thermal ellipsoids. Table 4. Selected Bond Distances (A˚) and Angles (deg) for Complexes 4a-c

Scheme 5

4a (Ln = Y)

4b (Ln = Dy)

4c (Ln = Lu)

Ln1-Ir1 Ln1-Ct1a Ln1-Ct2a Ir1-Ct3a Ln1-Cp1b Ln1-Cp2b Ir1-Cp3b Ln1-H1 Ln1-H2 Ln1-H3 Ir1-H1 Ir1-H2 Ir1-H3

2.9267(5) 2.400 2.410 1.864 2.693(4) 2.685(4) 2.218(4) 2.37(3) 2.47(5) 2.33(4) 1.18(3) 1.00(5) 1.61(4)

2.9235(6) 2.413 2.425 1.866 2.699(5) 2.711(5) 2.227(5) 2.53(4) 2.46(4) 2.36(7) 0.87(5) 0.92(5) 1.46(7)

2.8716(6) 2.360 2.372 1.861 2.654(10) 2.662(9) 2.226(10) 2.51(8) 2.32(8) 2.37(8) 1.34(8) 1.44(8) 1.42(8)

Ct1-Ln1-Ct2 Ct1-Ln1-Ir1 Ct2-Ln1-Ir1 Ct3-Ir1-Ln1 Ln1-H1-Ir1 Ln1-H2-Ir1 Ln1-H3-Ir1

135.38 112.06 112.22 175.59 106.31 107.52 94.23

135.38 111.79 112.81 178.11 108.19 111.35 96.93

135.25 111.89 112.86 177.26 91.36 96.62 95.58

a

Ct1, Ct2, Ct3 = ring centroid. b Cp1, Cp2, Cp3 = Cp average.

The reactions of hydride complexes 2a,d,e with Cp*IrH416 were carried out in toluene at room temperature to examine their activity toward a late transition metal hydride,17,18 which rapidly gave the Ln/Ir heterobimetallic trihydride xylyl isocyanide was previously reported by Tilley and coworkers.14 Reductive coupling of isocyanide compounds by group 4 metal complexes are also known.15 (14) (a) Campion, B. K.; Heyn, R. H.; Tilley, T. D. J. Am. Chem. Soc. 1990, 112, 2011. (b) Campion, B. K.; Heyn, R. H.; Tilley, T. D. Organometallics 1993, 12, 2584. (15) For examples, see: (a) Acho, J. A.; Lippard, S. J. Organometallics 1994, 13, 1294. (b) Scott, J. M.; Lippard, S. J. J. Am. Chem. Soc. 1997, 119, 3411. (c) Scott, J. M.; Lippard, S. J. Organometallics 1997, 16, 5857. (d) Scott, J. M.; Lippard, S. J. Organometallics 1998, 17, 1769. (e) Steinhuebel, D. P.; Fuhrmann, P.; Lippard, S. J. Inorg. Chim. Acta 1998, 270, 527. (16) Gilbert, T. G.; Hollander, F. J.; Bergman, R. G. J. Am. Chem. Soc. 1985, 107, 3508.

(17) Evans, W. J.; Meadows, J. H.; Hanusa, T. P. J. Am. Chem. Soc. 1984, 106, 4454–4460. (18) The analogous reactions between lanthanide alkyls and d-block transition metal hydrides were reported. For examples, see: (a) Burns, C. J.; Andersen, R. A. J. Am. Chem. Soc. 1987, 109, 915. (b) Clair, M. A. St.; Santarsiero, B. D.; Bercaw, J. E. Organometallics 1989, 8, 17. (c) Alvarrez, D.Jr.; Caulton, K. G.; Evans, W. J.; Ziller, J. W. J. Am. Chem. Soc. 1990, 112, 5674. (d) Alvarrez, D.Jr.; Caulton, K. G.; Evans, W. J.; Ziller, J. W. Inorg. Chem. 1992, 31, 5500. (e) Beletskaya, I. P.; Voskoboynikov, A. Z.; Chuklanova, E. B.; Kirillova, N. I.; Shestakova, A. K.; Parshina, I. N.; Gusev, A. I.; Magomedov, G. K. I. J. Am. Chem. Soc. 1993, 115, 3156. (f) Schwartz, D. J.; Ball, G. E.; Andersen, R. A. J. Am. Chem. Soc. 1995, 117, 6027. (g) Shima, T.; Hou, Z. Chem. Lett. 2008, 298. (h) Butovskii, M. V.; Tok, O. L.; Wagner, F. R.; Kempe, R. Angew. Chem., Int. Ed. 2008, 47, 6469. (i) Shima, T.; Hou, Z. Organometallics 2009, 28, 2244–2252.

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Table 5. Summary of Crystallographic Data for Complexes 1a-e and 2a 3 C7H8 formula fw cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z μ (mm-1) Dcalcd (g cm-3) F(000) no. of reflns collected no. of indep reflns (R(int)) no. of params goodness of fit on F2 final R indices (I > 2σ(I)) R1 wR2 R indices (all data) R1 wR2

1a

1b

1c

1d

1e

2a 3 C7H8

C28H49OSi2Y 546.76 triclinic P1 9.7153(10) 11.3016(12) 13.7705(15) 89.164(2) 86.529(2) 75.198(2) 1459.1(3) 2 2.098 1.244 584 9267 6383 (0.0285) 302 0.795

C28H49NdOSi2 602.09 triclinic P1 9.8041(7) 11.3584(8) 13.9009(10) 89.7270(10) 86.6430(10) 74.0290(10) 1485.58(18) 2 1.845 1.346 626 9100 6326 (0.0197) 302 0.987

C28H49OSi2Sm 608.20 triclinic P1 9.7796(13) 11.3536(15) 13.8784(18) 89.536(2) 86.596(2) 74.417(2) 1481.73(3) 2 2.079 1.363 630 8909 6244 (0.0203) 302 1.042

C28H49DyOSi2 620.35 triclinic P1 9.7271(7) 11.2908(8) 13.7949(9) 89.1800(10) 86.4750(10) 75.0740(10) 1461.16(18) 2 2.656 1.410 638 8646 6090 (0.0162) 302 1.042

C28H49LuOSi2 632.82 triclinic P1 9.6715(6) 11.3089(7) 13.6474(8) 89.9770(10) 86.7580(10) 75.7040(10) 1444.12(15) 2 3.518 1.455 648 8933 6205 (0.0162) 302 0.992

C35H59OSi2Y 640.91 monoclinic P21/n 11.4585(15) 16.582(2) 18.038(2)

0.0418 0.0710

0.0308 0.0671

0.0381 0.0896

0.0339 0.0871

0.0255 0.0611

0.0440 0.1152

0.0749 0.0753

0.0384 0.0691

0.0510 0.0932

0.0357 0.0883

0.0288 0.0616

0.0704 0.1234

98.153(3) 3392.5(8) 4 1.815 1.255 1376 19 934 7563 (0.0246) 327 0.929

Table 6. Summary of Crystallographic Data for Complexes 2d,e, 3 3 2C7H8, and 4a-c formula fw cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z μ (mm-1) Dcalcd (g cm-3) F(000) no. of reflns collected no. of indep reflns (R(int)) no. of params goodness of fit on F2 final R indices (I > 2σ(I)) R1 wR2 R indices (all data) R1 wR2

2d

2e

3 3 2C7H8

4a

4b

4c

C28H51DyOSi2 662.37 triclinic P1 10.0451(12) 10.2204(13) 15.8218(19) 95.957(2) 96.941(2) 110.201(2) 1494.7(3) 2 2.597 1.383 642 9187 6406 (0.0248) 307 0.979

C28H51LuOSi2 634.84 triclinic P1 9.7717(12) 11.0338(13) 14.6970(18) 95.226(2) 101.419(2) 104.461(2) 1487.5(3) 2 3.416 1.417 652 8723 6256 (0.0234) 307 1.000

C78H100N2O2Si4Y2 1387.78 triclinic P1 11.4923(7) 13.5499(8) 14.0843(9) 105.8250(10) 100.4500(10) 108.5060(10) 1912.7(2) 2 1.616 1.205 732 11 996 8406 (0.0235) 397 0.855

C34H60IrSi2Y 806.11 monoclinic P21/n 10.0138(10) 18.5260(18) 20.020(2)

3695.5(6) 4 5.244 1.449 1632 22 940 8301 (0.0372) 374 0.917

C34H60DyIrSi2 879.70 triclinic P1 9.915(2) 10.976(3) 18.149(4) 85.138(4) 79.193(4) 68.926(4) 1810.17(7) 2 5.806 1.614 870 11 187 7776 (0.0263) 374 0.975

C34H60IrLuSi2 892.17 triclinic P1 9.8668(13) 10.8975(14) 18.259(2) 84.785(2) 79.258(2) 69.100(2) 1801.3(4) 2 6.501 1.645 880 10 908 7582 (0.0186) 374 1.182

0.0361 0.0722

0.0417 0.1040

0.0482 0.1149

0.0316 0.0639

0.0383 0.0918

0.0437 0.1039

0.0474 0.0750

0.0457 0.1056

0.0776 0.1235

0.0530 0.0680

0.0458 0.0948

0.0626 0.1226

complexes [(C5Me4SiMe3)2Ln(μ-H)3IrCp*] (Ln = Y (4a), Dy (4b), Lu (4c)) in high yields with evolution of H2 (Scheme 5). X-ray diffraction studies established that complexes 4a-c adopt a similar binuclear structure, in which the two metal centers are bridged by three hydride liagnds (Table 4 and Figure 4). The Ln and Ir atoms and the Cp* center in 4a-c align almost linearly ( — Ln-Ir-Cp*(centroid): 175-178). The average bond distances of the Ln-Cp bonds in 4a-c are somewhat longer than those found in the corresponding monohydride complexes 2a, 2d, and 2e, particularly in the case of the Dy (2d, 4b) and Lu (2e, 4c) complexes (see Tables 2 and 4). The μ2-H hydride species of the Y/Ir heterobinuclear complex 4a showed a doublet at -16.06 ppm with JH-Y=16.1 Hz in the 1H NMR spectrum analyzed in C6D6 at room temperature. The JH-Y coupling constant of the hydrides in 4a is slightly larger than

95.732(2)

that of the bridging hydrides between the yttrium and ruthenium atoms in [(Cp*Ru)4(C5Me4SiMe3)Y(μ-H)10] (JH-Y = 10.8 Hz),18i but significantly smaller than those of the homobinuclear yttrium complexes such as [Cp2Y(μ-H)(THF)2]2 (JH-Y = 27.0 Hz)2a and [Cp*2Y(μ-H)]2 (JH-Y = 37.5 Hz),2k and much smaller than that of the terminal hydride in 2a ((JH-Y=74.83 Hz). These results may suggest that the bridging hydride ligands in the Y/Ir complex 4a interact more strongly with the iridium atom than with yttrium.

Conclusion In summary, the reaction of lanthanide tris(alkyl) complexes Ln(CH2SiMe3)3(THF)2 (Ln = Y, Nd, Sm, Dy, Lu) with 2 equiv of C5HMe4SiMe3 afforded (C5Me4SiMe3)Ln(η5:η1C5Me4SiMe2CH2) (1a-e) via (C5Me4SiMe3)2Ln(CH2SiMe3)-

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(THF) as intermediates. Hydrogenolysis of 1a-e in toluene at room temperature led to formation of the metallocene terminal hydride complexes [(C5Me4SiMe3)2LnH(THF)] (1a-e), among which the Y (2a), Dy (2d), and Lu (2e) were isolated as single crystals and structurally characterized by X-ray analysis, whereas the larger Nd (2b) and Sm (2c) complexes existed only in solution in the presence of H2. Complexes 2a,d,e represent rare examples of structurally characterized lanthanide terminal hydride complexes. The yttrium hydride complex 2a reacted with p-methoxyphenylisocyanide to give the corresponding hydrodimerization product [(C5Me4SiMe3)2YN(Ar)(CHd)]2 (3, Ar = C6H4-OMe-p). Complexes 2a,d,e can undergo dehydrogenation reaction with (C5Me5)IrH4 to afford straightforwardly the corresponding Ln/Ir heterobimetallic tirihydride complexes [(C5Me4SiMe3)2Ln(μ-H)3Ir(C5Me5)] (4a-c). Further studies on the synthesis and reactivity of heteromultinuclear polyhydride complexes with other metal combinations are in progress.

Experimental Section General Methods. All reactions were carried out under a dry and oxygen-free argon atmosphere using Schlenk techniques and an MBraun glovebox. The argon was purified by being passed through a Dryclean column (4 A˚ molecular sieves, Nikka Seiko Co.) and a Gasclean CC-XR column (Nikka Seiko Co.). The nitrogen in the glovebox was constantly circulated trough a copper/molecular sieves (4 A˚) catalyst unit. The oxygen and moisture concentrations in the glovebox atmosphere were monitored by O2/H2O Combi-Analyzer (MBraun) to ensure both were always below 0.1 ppm. Samples for NMR spectroscopic measurements were prepared in the glovebox by use of J. Young valve NMR tubes. NMR (1H, 13C, 29Si) spectra were recorded on a JNM-ECP500 spectrometer. Assignment of the signals was also confirmed by 13C DEPT, 1H-1H COSY, 1H-13C HMQC, or 1H-29Si HMBC NMR experiments. IR spectra were recorded on a Shimazu IRPrestige-21 spectrometer using Nujol mulls between KBr disks. Elemental analyses were performed by Chemical Analysis Team, D & S Center, RIKEN. Solvents were distilled from sodium/benzophenone ketyl, degassed by the freeze-pump-thaw method (three times), and dried over fresh Na chips in the glovebox. HC5Me4SiMe3 and Li(CH2SiMe3) were obtained from Aldrich. Ln(CH2SiMe3)3(THF)2 (Ln = Y, Nd, Sm, Dy, Lu) was prepared according to the literature.9 (η5:η1-C5Me4SiMe2CH2)Y(η5-C5Me4SiMe3)(THF) (1a). HC5Me4SiMe3 (389 mg, 2.0 mmol) was added to a hexane solution (10 mL) of Y(CH2SiMe3)3(THF)2 (0.495 mg, 1.0 mmol) at room temperature and stirred for 2 h in the glovebox. After removal of the solvent under vacuum, the resulting pale yellow residue was extracted with hexane and filtered. The volatiles were removed under reduced pressure to yield 1a as a white crystalline powder (500 mg, 0.91 mmol, 91% yield). Colorless blocks of 1a suitable for X-ray analysis were obtained from a hexane solution at -35 C. 1 H NMR (C6D6, 23 C): δ -1.50 (br, 2H, YCH2Si), 0.40 (s, 9H, Si(CH3)3), 0.77 (s, 6H, YCH2Si(CH3)2)), 1.10 (t, 2JH-H= 6.7 Hz, 4H, β-CH2, THF), 2.00 (br, 24H, C5(CH3)4Si), 3.28 (t, 2 JH-H = 6.7 Hz, 4H, R-CH2, THF). 13C NMR (C6D6, 23 C): δ 3.22, 6.30, 8.09, 8.38, 11.91, 12.38, 13.90, 14.53, 24.89, 70.29, 110.52, 110.90, 122.22, 125.58. 29Si NMR (C6D6, 23 C): δ -12.20, -9.70. IR (Nujol): 632 (w), 677 (w), 706 (w), 733 (w), 835 (s), 1019 (m), 1126 (w), 1240 (m), 1318 (m), 1378 (w), 1455 (m), 2859 (s), 2924 (s), 2954 (s). Anal. Calcd for C28H49OSi2Y (1a): C, 61.51; H, 9.03. Calcd for C24H41Si2Y (1a-THF): C, 60.73; H, 8.71. Found: C, 60.36; H, 8.61. (η5:η1-C5Me4SiMe2CH2)Nd(η5-C5Me4SiMe3)(THF) (1b). A THF solution (20 mL) of LiCH2SiMe3 (564 mg, 6.0 mmol) was added to a THF solution (30 mL) of NdBr3 (710 mg, 1.85 mmol) at room temperature and stirred for 10 min in the glovebox.

Takenaka and Hou Subsequently, HC5Me4SiMe3 (776 mg, 4.0 mmol) was added to this reaction mixture at room temperature and stirred for 24 h. After removal of the solvent under vacuum, the resulting green residue was extracted with hexane and filtered. The volatiles were removed under reduced pressure to yield 1b as a light blue crystalline powder (600 mg, 1.00 mmol, 54% yield). Light blue blocks of 1b suitable for X-ray analysis were obtained from THF and hexane solution at -35 C. 1H NMR (C6D6, 25 C): δ -6.04 (br, 15H, Si(CH3)2, Si(CH3)3), -0.19 (br, 12H, C5(CH3)4Si), 0.89 (br, 4H, THF), 4.42 (br, 4H, THF), 17.72 (br, 12H, C5(CH3)4Si). The methylene proton in NdCH2SiMe2 could not be located, owing to the influence of the paramagnetic Nd(III) ion. 13C NMR (C6D6, 23 C): δ -14.54, -1.61, -0.03, 1.91, 4.14, 23.00, 24.16, 65.08. 29Si NMR (C6D6, 23 C): δ -11.60, 1.75. IR (Nujol): 629 (w), 683 (w), 754 (w), 842 (s), 895 (w), 1043 (m), 1128 (w), 1243 (m), 1326 (w), 1378 (w), 1458 (m), 2855 (s), 2923 (s), 2952 (s). Anal. Calcd for C28H49OSi2Nd (1b): C, 55.85; H, 8.20. Calcd for C24H41Si2Nd 3 0.4C4H8O (1b-0.6THF): C, 55.02; H, 7.97. Found: C, 55.04; H, 7.96. (η5:η1-C5Me4SiMe2CH2)Sm(η5-C5Me4SiMe3)(THF) (1c). Complex 1c was prepared in a similar manner as for 1a. It was obtained in 82% yield as orange crystals. 1H NMR (C6D6, 25 C): δ -1.65 (br, 15H, Si(CH3)2, Si(CH3)3), 0.07 (br, 12H, C5(CH3)4Si), 1.68 (br, 4H, THF), 4.02 (br, 4H, THF), 4.41 (br, 12H, C5(CH3)4Si). The methylene proton in SmCH2SiMe2 could not be located, owing to the influence of the paramagnetic Sm(III) ion. 13C NMR (C6D6, 23 C): δ 0.00, 15.92, 24.67, 25.75, 68.80, 110.89, 121.23, 129.30. 29Si NMR (C6D6, 23 C): δ -4.06. IR (Nujol): 630 (w), 684 (w), 755 (w), 843 (s), 897 (w), 1026 (w), 1046 (m), 1242 (m), 1329 (w), 1378 (w), 1460 (m), 2856 (s), 2924 (s), 2952 (s). Anal. Calcd for C28H49OSi2Sm (1c): C, 55.29; H, 8.12. Calcd for C24H41Si2Sm 3 0.8C4H8O (1c-0.2THF): C, 55.02; H, 8.05. Found: C, 54.99; H, 8.06. (η5:η1-C5Me4SiMe2CH2)Dy(η5-C5Me4SiMe3)(THF) (1d). Complex 1d was prepared in a similar manner to that for 1a. It was obtained in 71% yield as colorless crystals. An informative 1H NMR spectrum was not obtained for 1d, because of the influence of the paramagnetic Dy(III) ion. IR (Nujol): 631 (m), 679 (m), 707 (m), 732 (m), 752 (m), 833 (s), 1019 (s), 1126 (m), 1238 (s), 1318 (s), 1340 (m), 1379 (m), 1454 (s), 2858 (s), 2922 (s), 2955 (s). Anal. Calcd for C28H49OSi2Dy (1d): C, 54.21; H, 7.96. Calcd for C24H41Si2Dy 3 0.6C4H8O (1d-0.4THF): C, 53.61; H, 7.80. Found: C, 53.57; H, 7.89. (η5:η1-C5Me4SiMe2CH2)Lu(η5-C5Me4SiMe3)(THF) (1e). Complex 1e was prepared in a similar manner as for 1a. It was obtained in 73% yield as colorless crystals. 1H NMR (C6D6, 24 C): δ -1.42 (br, 2H, LuCH2Si), 0.40 (s, 9H, Si(CH3)3), 0.75 (s, 6H, YCH2Si(CH3)2)), 1.13 (br, 4H, β-CH2, THF), 1.99 (br, 12H, C5(CH3)4Si), 2.01 (br, 12H, C5(CH3)4Si), 3.31 (br, 4H, R-CH2, THF). 13C NMR (C6D6, 25 C): δ 3.30, 6.26, 9.41, 11.98, 13.98, 14.30, 14.76, 23.00, 25.01, 70.65, 109.99, 111.19, 121.66, 125.31, 127.80. 29Si NMR (C6D6, 24 C): δ -11.95, -9.42. IR (Nujol): 632 (m), 680 (m), 752 (m), 835 (s), 1018 (s), 1127 (w), 1239 (s), 1316 (s), 1378 (w), 1454 (s), 2857 (s), 2923 (s), 2955 (s). Anal. Calcd for C28H49OSi2Lu (1e): C, 53.14; H, 7.80. Calcd for C24H41Si2Lu 3 0.8C4H8O (1e-0.2THF): C, 52.83; H, 7.73. Found: C, 52.80; H, 7.75. (η5-C5Me4SiMe3)2YH(THF) (2a). A toluene solution (5 mL) of 1a (500 mg, 0.91 mmol) in a 300 mL Schlenk flask equipped with a J. Young valve was frozen in liquid nitrogen, pumped, and refilled with H2. The mixture was allowed to warm to room temperature and stirred for 2 h. For complete conversion, a second charge of H2 was carried out in an identical way, and the mixture was then further stirred for 2 h. After the solution was concentrated under reduced pressure, colorless crystals of 2a were precipitated, which afforded 2a as white powder (385 mg, 0.74 mmol, 82% yield) after being dried under vacuum. White blocks of 2a 3 C7H8 suitable for X-ray analysis were obtained from a toluene/hexane solution at -35 C. 1H NMR (C6D6, 23 C): δ 0.57 (s, 18H, Si(CH3)3), 1.11 (br, 4H, β-CH2, THF),

Article 2.01 (br, 24H, C5(CH3)4Si), 3.36 (br, 4H, R-CH2, THF), 5.92 (d, 1H, JH-Y = 74.8 Hz). 13C NMR (C6D6, 23 C): δ 3.36, 3.38, 11.92, 12.06, 14.11, 14.54, 24.41, 69.52, 113.00, 113.09, 123.12. 29 Si NMR (C6D6, 23 C): δ -9.16. IR (Nujol): 631 (m), 679 (m), 706 (w), 733 (w), 754 (m), 834 (s), 1018 (s), 1128 (w), 1236 (s), 1318 (m), 1333 (m), 1377 (w), 1456 (s), 2855 (s), 2923 (s), 2954 (s). Anal. Calcd for C28H51OSi2Y (2a): C, 61.28; H, 9.37. Calcd for C24H43Si2Y (2a-THF): C, 60.47; H, 9.09. Found: C, 59.73; H, 8.99. (η5-C5Me4SiMe3)2DyH(THF) (2d). Complex 2d was prepared in a similar manner to that for 2a. It was obtained in 86% yield as colorless crystals. An informative 1H NMR spectrum was not obtained for 2d, because of the influence of the paramagnetic Dy(III) ion. IR (Nujol): 629 (w), 680 (w), 751 (w), 834 (s), 1018 (m), 1079 (w), 1126 (w), 1241 (m), 1317 (m), 1339 (w), 1377 (w), 1455 (m), 2855 (s), 2923 (s), 2953 (s). Anal. Calcd for C28H51OSi2Dy (2d): C, 54.03; H, 8.26. Calcd for C24H43Si2Dy 3 0.2C4H8O (2d-0.8 THF): C, 52.94; H, 7.63. Found: C, 52.97; H, 7.91. (η5-C5Me4SiMe3)2LuH(THF) (2e). Complex 2e was prepared in a similar manner to that for 2a. It was obtained in 75% yield as colorless crystals. 1H NMR (C6D6, 23 C): δ 0.57 (s, 18H, Si(CH3)3), 1.22 (br, 4H, β-CH2, THF), 2.00 (s, 24H, C5(CH3)4Si), 3.44 (br, 4H, R-CH2, THF), 8.50 (s, 1H). 13C NMR (C6D6, 23 C): δ 3.39, 12.32, 14.00, 14.20, 14.76, 24.91, 68.82, 109.90, 111.16, 112.25. 29Si NMR (C6D6, 23 C): δ -9.32. IR (Nujol): 632 (s), 686 (s), 755 (s), 833 (s), 1017 (s), 1070 (m), 1130 (m), 1239 (s), 1316 (m), 1337 (m), 1356 (m), 1374 (m), 1397 (m), 1454 (s), 2856 (s), 2922 (s), 2953 (s). Anal. Calcd for C28H51OSi2Lu (2e): C, 52.97; H, 8.10. Calcd for C24H43Si2Lu 3 0.5C4H8O (2e-0.5THF): C, 52.33; H, 7.60. Found: C, 52.19; H, 7.95. [(η5-C5Me4SiMe3)2YN(C6H4-OMe-p)(CHd)]2 (3). A toluene solution (1.0 mL) of p-methoxy phenylisocyanide (13 mg, 0.10 mmol) was added to a toluene solution (2.0 mL) of 2a (50 mg, 0.10 mmol) at room temperature and placed for 2 h in the glovebox. After removal of the solvent under vacuum, the resulting dark green residue was washed with hexane and filtered. The volatiles were removed under reduced pressure to yield 3 as a green powder (30 mg, 0.027 mmol, 54% yield). Green blocks of 3 3 2C7H8 suitable for X-ray analysis were obtained from a toluene and hexane solution at -35 C. 1H NMR (C6D6, 23 C): δ 0.35 (s, 36H, Si(CH3)3), 1.91 (s, 12H, C5(CH3)4Si), 2.08 (s, 12H, C5(CH3)4Si), 2.31 (s, 12H, C5(CH3)4Si), 2.37 (s, 12H, C5(CH3)4Si), 3.50 (s, 6H, OCH3), 6.29 (s, 2H, CdCH), 6.54 (dd, 2JH-Y = 2.2 Hz, 3JH-H = 8.6 Hz, 4H, o-C6H4), 7.05 (d, 3 JH-H = 8.6 Hz, 4H, m-C6H4). A 13C NMR spectrum was not obtained for 3, because the solubility is low for solvents such as benzene-d6, toluene-d8, dichloromethane-d2, chloroform-d, THF-d8, and acetone-d6. 29Si NMR (C6D6, 23 C): δ -9.46. IR (Nujol): 838 (m), 1020 (w), 1038 (w), 1248 (m), 1321 (w), 1377 (w), 1459 (m), 1504 (w), 2326 (m), 2360 (m), 2854 (s), 2924 (s), 2953 (s). Anal. Calcd for C64H100O2N2Si4Y2 (3): C, 63.03; H, 8.26; N, 2.30. Found: C, 62.79; H, 8.02; N, 1.98. (η 5 -C 5 Me 4 SiMe 3 )2 Y(μ-H)3 Ir(C 5 Me 5 ) (4a). (C5Me5)IrH4 (33 mg, 0.10 mmol) was added to a toluene solution (1 mL) of 2a (55 mg, 0.010 mmol) at room temperature and placed for 2 h in the glovebox. After removal of the solvent under vacuum, the resulting pale yellow residue was washed with cold hexane. The volatiles were removed under reduced pressure to yield 4a as pale yellow crystals (87 mg, 0.099 mmol, 99% yield). 1H NMR (C6D6, 23 C): δ -16.09 (d, 1JH-Y = 16.50 Hz, 3H, Y(μH)3Ir), 0.33 (s, 9H, Si(CH3)3), 1.94 (s, 12H, C5(CH3)4Si), 2.12 (s, 15H, C5(CH3)5), 2.48 (s, 12H, C5(CH3)4Si). 13C NMR (C6D6, 23 C): δ 1.98, 11.67, 11.78, 12.08, 17.74, 88.47, 115.26, 123.34, 131.27. 29Si NMR (C6D6, 23 C): δ -10.95. IR (Nujol): 631 (w),

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686 (w), 753 (m), 839 (s), 1022 (w), 1074 (w), 1130 (w), 1246 (m), 1320 (m), 1377 (m), 1457 (m), 1866 (w), 1990 (w), 2855 (s), 2924 (s), 2954 (s). Anal. Calcd for C34H60Si2YIr: C, 50.66; H, 7.50. Found: C, 50.43; H, 7.38. (η5-C5Me4SiMe3)2Dy(μ-H)3Ir(C5Me5) (4b). Complex 4b was prepared in a similar manner to that for 4a. It was obtained in 95% yield as colorless crystals. An informative 1H NMR spectrum was not obtained for 4b, because of the influence of the paramagnetic Dy(III) ion. IR (Nujol): 628 (w), 683 (w), 752 (m), 834 (s), 1022 (m), 1073 (w), 1129 (w), 1243 (m), 1322 (m), 1377 (m), 1456 (m), 1864 (w), 1988 (m), 2854 (s), 2924 (s), 2953 (s). Anal. Calcd for C34H60Si2DyIr: C, 46.42; H, 6.87. Found: C, 44.50; H, 6.51. (η5-C5Me4SiMe3)2Lu(μ-H)3Ir(C5Me5) (4c). Complex 4c was prepared in a similar manner to that for 4a. It was obtained in 87% yield as colorless crystals. 1H NMR (C6D6, 23 C): δ -15.7 (s, 3H, LuH3Ir), 0.32 (s, 18H, Si(CH3)3), 1.94 (s, 12H, C5(CH3)4Si), 2.10 (s, 15H, C5(CH3)5), 2.52 (s, 12H, C5(CH3)4Si). 13 C NMR (C6D6, 23 C): δ 2.09, 11.63, 12.21, 18.15, 88.96, 114.29, 122.80, 132.17. 29Si NMR (C6D6, 23 C): δ -10.72. IR (Nujol): 631 (w), 685 (w), 722 (m), 753 (w), 840 (s), 1022 (w), 1131 (w), 1246 (m), 1320 (w), 1377 (m), 1461 (s), 1846 (w), 1994 (m), 2854 (s), 2924 (s), 2954 (s). Anal. Calcd for C34H60Si2LuIr: C, 45.77; H, 6.78. Found: C, 45.76; H, 6.77. X-ray Crystallographic Studies. Crystals for X-ray analysis were obtained as described in the preparations. The crystals were manipulated in the glovebox under a microscope and were sealed in thin-walled glass capillaries. Data collection was performed at -110 C on a Bruker SMART APEX diffractrometer with a CCD area detector, using graphite-monochromated Mo KR radiation (λ = 0.71069 A). The determination of crystal class and unit cell parameters was carried out by the SMART program package. The raw frame data were processed using SAINT and SADABS to yield the reflection data file. The structures were solved by using the SHELXTL program. Refinement for 1a-e, 2a 3 C7H8, 2d, 2e, 3 3 2C7H8, and 4a-c was performed on F2 anisotropically for all the non-hydrogen atoms by the full-matrix least-squares methods. The analytical scattering factors for neutral atoms were used throughout the analysis. The hydride atoms in 2a 3 C7H8, 2d, 2e, and 4a-c were located by difference Fourier synthesis, and their coordinates and isotropic parameters were refined. Other hydrogen atoms were placed at the calculated positions and were included in the structure calculation without further refinement of the parameters. The residual electron densities were of no chemical significance. Crystallographic data and processing parameters for 1a-e and 2a 3 C7H8 are summarized in Table 5, and those for 2d,e, 3 3 2C7H8, and 4a-c are given in Table 6.

Acknowledgment. This work was partly supported by a Grant-in-Aid for Scientific Research on Priority Areas (No. 18065020, “Chemistry of Concerto Catalysis”) from the Ministry of Education, Culture, Sports, Science and Technology of Japan and a Grant-in-Aid for Scientific Research (S) (No. 21225004) from the Japan Society for the Promotion of Science (JSPS). We thank Dr. M. Nishiura and Mr. J. Baldamus for help in X-ray analyses and Dr. H. Koshino for help in NMR analyses. Supporting Information Available: ORTEP drawings and tables of crystallographic data, atomic coordinates, thermal parameters, and bond distances and angles for 1a-e, 2a 3 C7H8,d,e, 3 3 2C7H8, and 4a-c (PDF). This material is available free of charge via the Internet at http://pubs.acs.org.