Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

(CH3CN)2[PF6], which servers as a synthetic equivalent for a. 14-electron fragment, has been reacted with 1,6-diyne only to form the allylcarbene comp...
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Organometallics 2009, 28, 5204–5211 DOI: 10.1021/om9004516

Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne Ming-Chung Lui, Chia-Pei Chung, Wei-Chen Chang, Ying-Chih Lin,* Yu Wang, and Yi-Hong Liu Department of Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China Received May 27, 2009

Reactions of the four 1,6-diynes 1-3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]-Cl ([Ru]=Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C-C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]-Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]-Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to CR. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P-C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru-Cl bond, giving complex 12 in high yield. From the reaction of [Ru]-Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]-Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis.

Introduction Transition-metal-catalyzed reactions of organic molecules with multiple unsaturated functional groups have been the *To whom correspondence should be addressed. E-mail: yclin@ntu. edu.tw. (1) (a) Ma, S.; Yu, S.; Gu, Z. Angew. Chem., Int. Ed. 2006, 45, 200– 203. (b) Jimenez-N u~ nez, E.; Echavarren, A. M. Chem. Commun. 2007, 333– 346. (c) Fukamizu, K.; Miyake, Y.; Nishibayashi, Y. Angew. Chem., Int. Ed. 2009, 48, 2534–2537. (d) Zou, Y.; Garayalde, D.; Wang, Q.; Nevado, C.; Goeke, A. Angew. Chem., Int. Ed. 2008, 47, 10110–10113. (e) JimenezN u~ nez, E.; Claverie, C. K.; Bour, C.; Cardenas, D. J.; Echavarren, A. M. Angew. Chem., Int. Ed. 2008, 47, 7892–7895. (f) Chen, M.; Weng, Y.; Guo, M.; Zhang, H.; Lei, A. Angew. Chem., Int. Ed. 2008, 47, 2279–2282. (g) Trost, B. M.; Toste, F. D.; Pinkerton, A. B. Chem. Rev. 2001, 101, 2067– 2096. (h) Jimínez-N u~ nez, E.; Echavarren, A. M. Chem. Rev. 2008, 108, 3326–3350. (i) Nakamura, I.; Yamamoto, Y. Chem. Rev. 2004, 104, 2127– 2198. (j) Mori, M.; Tanaka, D.; Saito, N.; Sato, Y. Organometallics 2008, 27, 6313–6320. (k) Yao, L.-F.; Shi, M. Chem. Eur. J. 2009, 15, 3875–3881. (2) (a) Yoshida, K.; Shishikura, Y.; Takahashi, H.; Imamoto, T. Org. Lett. 2008, 10, 2777–2780. (b) García-Rubín, S.; Varela, J. A.; Castedo, L.; Saa, C. Chem. Eur. J. 2008, 14, 9772–9778. (c) Yamamoto, Y.; Kinpara, K.; Ogawa, R.; Nishiyama, H.; Itoh, K. Chem. Eur. J. 2006, 12, 5618–5631. (d) Tanaka, D.; Sato, Y.; Mori, M. Organometallics 2006, 25, 799–801. (e) Yamamoto, Y.; Ishii, J.; Nishiyama, H.; Itoh, K. J. Am. Chem. Soc. 2005, 127, 9625–9631. (f) Chopade, P. R.; Louie, J. Adv. Synth. Catal. 2006, 348, 2307–2327. (g) Varela, J. A.; Saa, C. Chem. Rev. 2003, 103, 3787–3802. (h) Mori, M.; Saito, N.; Tanaka, D.; Takimoto, M.; Sato, Y. J. Am. Chem. Soc. 2003, 125, 5606–5607. (i) Yamamoto, Y.; Takagishi, H.; Itoh, K. J. Am. Chem. Soc. 2002, 124, 6844–6845. (j) Jones, A. L.; Snyder, J. K. J. Org. Chem. 2009, 74, 2907–2910. (k) Hara, H.; Hirano, M.; Tanaka, K. Org. Lett. 2009, 11, 1337–1340. pubs.acs.org/Organometallics

Published on Web 08/18/2009

focus of many recent studies.1 Particularly, metal-catalyzed reactions of 1,6-diynes and 1,6-enynes under mild conditions have emerged as economical and useful methods for the construction of cyclic or polycyclic organic skeletons. Now, these multiply unsaturated molecules are versatile substrates due to their straightforward synthetic pathway and simplicity of change in functionality. There have been numerous studies of the intermolecular reaction of diynes with other synthetic units, e.g. [2 þ 2þ2] cyclization,2 Bergman cycloaromatization,3 and diyne cyclization.4 A comprehensive understanding of the intramolecular pathways of diynes is indispensable for the enhancement of selectivity and reactivity. As was reported in our earlier study, the ruthenium metal moiety migrated between two alkynyl groups of 1,5-diyne via π-coordination of the C-C triple bonds with no C-C bond formation in the transformation.5 Herein, we report the reaction of [Ru]-Cl with a number of 1,6-diynes. The (3) (a) Bergman, R. G. Acc. Chem. Res. 1973, 6, 25–31. (b) Lockhart, T. P.; Bergman, R. G. J. Am. Chem. Soc. 1981, 103, 4091–4096. (c) Odedra, A.; Wu, C.-J.; Pratap, T. B.; Huang, C.-W.; Ran, Y.-F.; Liu, R.-S. J. Am. Chem. Soc. 2005, 127, 3406–3412. (4) (a) Trost, B. M.; Rudd, M. T. J. Am. Chem. Soc. 2003, 125, 11516– 11517. (b) Kim, H.; Goble, S. D.; Lee, C. J. Am. Chem. Soc. 2007, 129, 1030–1031. (c) Gonzalez-Rodríguez, C.; Varela, J. A.; Castedo, L.; Saa, C. J. Am. Chem. Soc. 2007, 129, 12916–12917. (d) Sperger, C.; Fiksdahl, A. Org. Lett. 2009, 11, 2449–2452. (5) Yen, Y. S.; Lin, Y. C.; Huang, S. L.; Liu, Y. H.; Sung, H. L.; Wang, Y. J. Am. Chem. Soc. 2005, 127, 18037–18045. r 2009 American Chemical Society

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Scheme 1

Scheme 2

Figure 1. ORTEP drawing of 9 with thermal ellipsoids shown at the 30% probability level. For clarity, hydrogen atoms, aryl groups of triphenylphosphine ligands on Ru except the ipso carbons, and PF6 are omitted.

Synthesis of Four Propargyl Diynes. The diyne compound 1 was prepared following the literature methods.6 Two other diyne compounds 2 and 3 were prepared from the reaction of

the Grignard reagent HCtCMgBr with the corresponding aromatic ketone7 in high yield, as shown in Scheme 1. These diyne compounds have been characterized by spectroscopic methods. Synthesis of diyne 7 from 48 is also shown in Scheme 1. Addition of n-BuLi and Me3SiCl to a solution of 4 in THF was followed by quenching the reaction with a saturated aqueous NH4Cl solution to give the product 5. Then pyridinium chlorochromate (PCC) was used as an oxidizing agent to transform the hydroxymethyl group to an aldehyde group and the crude product was purified by chromatography to yield 6. Subsequent treatment of 6 with HCtCMgBr afforded the propargylic diyne 7, characterized by the 1H NMR study. The 1H NMR spectrum of 7 shows two doublet signals at δ 3.26 and 3.14 with 2JHH= 16.6 Hz assignable to the CH2 group. Allenylidene and Phosphonium Acetylide Complexes from Diyne 1. The reaction of 1,6-diyne 1 with [Ru]-Cl ([Ru]= Cp(PPh3)2Ru) in the presence of KPF6 in CH2Cl2 at room temperature yielded a mixture of the allenylidene complex [Ru]dCdCdCHC6H4CtCTMS[PF6] (8) and the phosphonium acetylide complex [Ru]CtCCH(PPh3)C6H4CtCTMS[PF6] (9) (Scheme 2). The ratio of 8:9 is ca. 2:1, and the total yield of 8 and 9 is ca. 67%. The mixture was passed through a column packed with acidic Al2O3. The first deep red band eluted by CH2Cl2 yielded complex 9. Use of acetone or ethyl acetate as a more polar eluent would not elute complex 8. Complex 8 in pure form was obtained from treatment of 9 with dimethyl acetylenedicarboxylate (DMAD). To obtain a higher yield of 9, the reaction of 1 with [Ru]-Cl was carried out in the presence of both KPF6 and PPh3 at room temperature. Indeed, this reaction gave only 9 in 93% yield. The structural assignment of 9 is based on NMR data, including 1H, 31P, and 13C spectra, as well as X-ray diffraction analysis of its single crystal. With the presence of a

(6) (a) Hughes, T. S.; Carpenter, B. K. J. Chem. Soc., Perkin Trans. 2 1999, 2291–2298. (b) Suffert, J. Tetrahedron Lett. 1990, 7437–7440. (c) Acheson, R. M.; Lee, G. C. M. J. Chem. Soc., Perkin Trans. 1 1987, 2321–2332. (d) Bedard, T. C.; Moore, J. S. J. Am. Chem. Soc. 1995, 117, 10662–10671.

(7) (a) Casey, C. P.; Strotman, N. A. ; Guzei, I. A. Beilstein J. Org. Chem. 2005, 1, doi:10.1186/1860-5397-1-18. (b) Iwasawa, N.; Shido, M.; Maeyama, K.; Kusama, H. J. Am. Chem. Soc. 2000, 122, 10226–10227. (8) Nakamura, I.; Chan, C. S.; Araki, T.; Terada, M.; Yamamoto, Y. Org. Lett. 2008, 10, 309–312.

electronic as well as steric effects of substituted groups on the carbon chain of these 1,6-diynes influence the coordination mode with the ruthenium metal moiety to produce two different types of products: a vinylidene complex via simple coordination of the terminal triple bond and a vinylcarbene complex from C-C bond formation of two triple bonds on the metal.

Results and Discussion

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Table 1. Selected Bond Distances (A˚) and Angles (deg) for 9 Bond Lengths (A˚) Ru(1)-C(1) C(1)-C(2) C(2)-C(3)

2.007(3) 1.203(4) 1.464(4)

C(3)-P(1) C(3)-C(4)

1.848(3) 1.527(4)

Bond Angles (deg) Ru(1)-C(1)-C(2) C(1)-C(2)-C(3) C(2)-C(3)-P(1)

176.3(3) 173.7(3) 110.7(2)

C(2)-C(3)-C(4) P(1)-C(3)-C(4)

117.2(2) 108.5(2)

stereogenic carbon center in the alkynyl ligand, the 31P NMR spectrum of 9 in CDCl3 exhibits three multiplet resonances of an ABM spin system. The signals due to the two PPh3 ligands appear as doublet and doublet of doublets resonances at δ 48.80 and 50.77, respectively. The doublet signal at δ 15.79 is assigned to the phosphonium group bonded to the acetylide ligand coupled with only one of two metal-bonded PPh3 ligands. The structure of 9 has been confirmed by an X-ray diffraction study. An ORTEP drawing of the solid-state structure of 9 is shown in Figure 1, with selected bond distances and angles given in Table 1. The molecule exhibits the usual acetylide structure in a three-legged piano-stool geometry. The acetylide ligand, which is nearly linear with a Ru(1)-C(1)-C(2) bond angle of 176.3(3)°, is bound to the ruthenium, showing bond lengths of 2.007(3) A˚ for Ru(1)-C(1) and 1.203(4) A˚ for C(1)-C(2). The C(3)-P(3) distance of 1.848(3) A˚ is on the same order of a regular P-C bond distance observed in the literature.9 The bond angle of C(2)-C(3)-C(4) is 117.2(2)°, slightly distorted from tetrahedral sp3 hybridization possibly because of the two bulky substituents at C(3). Treatment of 9 with DMAD in CH2Cl2 afforded 8 and phosphine oxide, which could be monitored by 1H and 31P NMR spectra.10 The structure assignment of 8 is based on NMR studies, including 1H, 31P, and 13C spectra. The 1H NMR spectrum in CDCl3 shows a downfield singlet resonance at δ 9.70 assigned to CH of the allenylidene ligand. The characteristic feature in the 13C NMR spectrum of 8 is a downfield triplet resonance at δ 302.43 with 2JCP =18.9 Hz assignable to CR. For the formation of 9, it is possible that the high electrophilicity of Cγ of the allenylidene ligand is responsible for the abstraction of PPh3 from other Ru species present in solution.9 Therefore, the high-yield formation of 9 in the presence of added PPh3 could be due to the availability of sufficient PPh3 and, thus, less decomposition caused by abstraction of the ligand from other molecules. Different acetylide phosphonium complexes have been prepared from ruthenium(II) indenyl allenylidene complexes and excess PR3.11 Allylcarbene Complex from Diyne 2. Treatment of the methyl-substituted diyne 2 with [Ru]-Cl in the presence of KPF6 in CH2Cl2 at room temperature afforded the purpleblue allylcarbene complex 11 in 51% yield (Scheme 2) after (9) Bustelo, E.; Jimenez-Tenorio, M.; Puerta, M. C.; Valerga, P. Organometallics 1999, 18, 4563–4573. (10) (a) Weiss, R.; Bess, M.; Huber, S. M.; Heinemann, F. W. J. Am. Chem. Soc. 2008, 130, 4610–4617. (b) Maghsoodlou, M. T.; HabibiKhorassani, S. M.; Heydari, R.; Hassankhani, A.; Marandi, G.; Nassiri, M.; Mosaddeg, E. Mol. Diversity 2007, 11, 87–91. (c) Al-Zaydi, K. M.; Borik, R. M. Molecules 2007, 12, 2061–2079. (11) Cadierno, V.; Gamasa, M. P.; Gimeno, J.; L opez-Gonzalez, M. C.; Borge, J.; Garcı´ a-Granda, S. Organometallics 1997, 16, 4453–4463.

Figure 2. ORTEP drawing of 11, with thermal ellipsoids shown at the 30% probability level. For clarity, hydrogen atoms, aryl groups of triphenylphosphine ligands except the ipso carbons, and PF6 are omitted. Table 2. Selected Bond Distances (A˚) and Angles (deg) for 11 Bond Lengths (A˚) Ru(1)-C(4) Ru(1)-C(1) Ru(1)-C(2) Ru(1)-C(3)

1.921(3) 2.125(3) 2.137(3) 2.176(3)

C(1)-C(2) C(2)-C(3) C(3)-C(4) P(1)-C(1)

1.436(4) 1.429(4) 1.418(4) 1.783(3)

Bond Angles (deg) C(1)-C(2)-C(3) C(2)-C(3)-C(4)

122.6(3) 117.8(2)

Ru(1)-C(1)-P(1) Ru(1)-C(1)-Si(1)

121.90(16) 137.08(17)

purification by column chromatography. The structure of 11 was established by 1H and 13C NMR spectroscopy as well as a single-crystal structural determination. The 1H NMR spectrum of 11 exhibits a doublet resonance at δ 6.23 with 2 JHP = 7.5 Hz assigned to the unique syn hydrogen on the allylic ligand. The downfield 13C doublet resonance at δ 274.68 with 4JCP=4.9 Hz of the carbene carbon atom and the doublet resonance at δ 25.53 with 1JCP =68.9 Hz assignable to the terminal allylic carbon bearing the phosphonium substituent in the 13C NMR spectrum are two characteristic features revealing the structure of 11. The structure of 11 has also been confirmed by X-ray crystallography. An ORTEP drawing is shown in Figure 2. Selected bond distances and angles are given in Table 2. The Ru(1)-C(4) bond length of 1.932(3) A˚ is relatively short, suggesting that C(4) is an alkylidene carbon bonded to the ruthenium center with a double bond. The remaining three carbon atoms with Ru-C(1), Ru-C(2), and Ru-C(3) distances of 2.125(3), 2.137(3), and 2.176(3) A˚, respectively, are approximately equally bonded to the Ru center. Obviously a C-C bond formation had occurred between two internal sp carbon atoms of the 1,6-diyne, forming a five-membered ring. The resulting allylcarbene ligand with all four carbon atoms bonded to the Ru metal is considered as a five-electrondonor ligand. The carbene carbon C(4) is at the anti site of the allylic portion with a C(3)-C(4) bond length of 1.418(4) A˚, and the phosphonium group is also in an anti configuration. However, while the allylcarbene ligand and the two rings of the ligand are coplanar, steric repulsion between the

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Table 3. Selected Bond Distances (A˚) and Angles (deg) for 12 Bond Lengths (A˚) Ru(1)-C(4) Ru(1)-C(1) Ru(1)-C(2) Ru(1)-C(3)

2.264(3) 2.152(3) 2.167(3) 2.204(3)

C(1)-C(2) C(2)-C(3) C(3)-C(4) P(1)-C(1)

1.422(4) 1.441(4) 1.392(4) 1.789(3)

Bond Angles (deg) C(1)-C(2)-C(3) C(2)-C(3)-C(4) P(1)-C(1)-C(2)

126.2(3) 122.5(2) 128.1(2)

Si(1)-C(4)-C(3) Cl(1)-Ru(1)-C(1)

132.3(3) 90.83(8)

Scheme 3

Figure 3. ORTEP drawing of 12 with thermal ellipsoids shown at the 30% probability level. For clarity, hydrogen atoms, aryl groups of triphenylphosphine ligands except the ipso carbons, solvated MeOH, and PF6 are omitted.

phosphine and Cp groups causes the phosphonium group to significantly bend back away from the metal center. Therefore, the phosphonium group and the methyl group on the five-membered ring are on the same side of the plane made of four coordinated carbon atoms.12-17 A possible mechanism to account for the formation of 11 involves a dissociation of the chloride and one phosphine ligand accompanied with coordination of two triple bonds of diyne 2 followed by C-C bond formation, giving the unobserved metallacyclopentatriene intermediate 10 shown in Scheme 2. Subsequent phosphine addition or migration to the less sterically hindered and more electrophilic carbene carbon atom of 10 leads to the formation of the allylcarbene complex 11.16,17 The allylcarbene complex was known to react with both nucleophiles and electrophiles.14 Thus, treatment of 11 with 10% HCl in acetone at room temperature afforded the η4diene chloride complex 12 in high yield. Spectroscopic data of 12 are significantly different from those of 11. The 1H NMR spectrum of 12 in acetone-d6 displays a new singlet resonance at δ 1.55 assigned to the hydrogen derived from HCl addition. The structure of 12 has been confirmed by an X-ray diffraction study. Figure 3 shows the structure result from a singlecrystal X-ray diffraction study of 12. Selected bond distances and angles are given in Table 3. The bond distances C(1)-C(2), C(2)-C(3), and C(3)-C(4) of 1.422(4), 1.441(4), and 1.392(4) A˚, respectively, show a short-long-short pattern for the (12) (a) Crocker, M.; Green, M.; Orpen, A. G.; Neumann, H.-P.; Schaverien, C. J. J. Chem. Soc., Chem. Commun. 1984, 1351–1353. (b) Crocker, M.; Green, M.; Nagle, K. R.; Orpen, A. G.; Neumann, H.-P.; Morton, C. E.; Schaverien, C. J. Organometallics 1990, 9, 1422–1434. (13) (a) R€ uba, E.; Mereiter, K.; Schmid, R.; Valentin, N. S.; Kirchner, K.; Schottenberger, H.; Calhorda, M. J.; Luis, F. V. Chem. Eur. J. 2002, 8, 3948–3961. (b) R€ uba, E.; Mereiter, K.; Schmid, R.; Kirchner, K.; Bustelo, E.; Puerta, M. C.; Valerga, P. Organometallics 2002, 21, 2912–2920. (14) (a) R€ uba, E.; Mauthner, K.; Mereiter, K.; Schmid, R.; Kirchner, K. Chem. Commun. 2001, 1996–1997. (b) Becker, E.; R€uba, E.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 2001, 20, 3851–3853. (15) Mauthner, K.; Soldouzi, K. M.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 1999, 18, 4681–4683. (16) Cadierno, V.; Gamasa, M. P.; Gimeno, J. Coord. Chem. Rev. 2004, 248, 1627–1657. (17) Ferre, K.; Toupet, L.; Guerchais, V. Organometallics 2002, 21, 2578–2580.

butadienyl ligand.18-20 Addition of HCl is clearly seen from the formation of a new Ru-Cl bond. A significantly longer Ru-C(4) bond of 2.264(3) A˚ compared to the corresponding 1.921(3) A˚ in 11 indicates a change of bonding mode. The dihedral angle of C(1)-C(2)-C(3)-C(4) in the diene portion of complex 12 is 6.7°, making the four atoms almost coplanar. Two kinds of reaction pathways are observed in the reactions of the different propargylic 1,6-diynes 1 and 2 with [Ru]-Cl. One involves only the propargylic portion, such as the reaction of 1, and the other comprises both triple bonds leading to C-C bond formation: i.e., the reaction of 2 giving the allylcarbene complex. The cationic complex Cp(PR3)Ru(CH3CN)2[PF6], which servers as a synthetic equivalent for a 14-electron fragment, has been reacted with 1,6-diyne only to form the allylcarbene complex. With two labile ligands, two vacant sites are readily available, promoting the simultaneous coordination of both triple bonds leading to the allylcarbene complex. In our case the relatively more difficult dissociation of phosphine or chloride ligand from [Ru]-Cl is required in order to provide an available vacant site for coordination; therefore, two pathways are feasible. For the formation of the allylcarbene complex 11, two triple bonds in 2 are both coordinated to the metal center. However, the moderate yield of 11 in the reaction of 2 may possibly indicate that both pathways are feasible. However, other possible products derived from only the propargylic portion are perhaps not stable enough for isolation. As is known in the literature, the reaction of dimethylpropargylic alcohol with [Ru]-Cl was previously reported to proceed via formation of both dimethyl allenylidene and vinyl vinylidene (18) Ingham, S. L.; Magennis, S. W. J. Organomet. Chem. 1999, 574, 302–310. (19) Gemel, C.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 1995, 14, 1405–1409. (20) M€ uller, J.; Qiao, K.; Siewing, M.; Westphal, B. J. Organomet. Chem. 1993, 458, 219–224. (21) (a) Selegue, J. P. J. Am. Chem. Soc. 1983, 105, 5921–5923. (b) Bustelo, E.; Jimenez-Tenorio, M.; Puerta, M. C.; Valerga, P. Eur. J. Inorg. Chem. 2001, 2391–2398.

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Scheme 4

Scheme 5

Figure 4. ORTEP drawing of 16 with thermal ellipsoids shown at the 30% probability level. For clarity, hydrogen atoms and aryl groups of triphenylphosphine ligands except for the ipso carbons are omitted.

intermediates by dehydrations at different neighboring groups.21 This was followed by a coupling of these two species to give a diruthemium complex in high yield.21a In our case, if only the propargylic portion of 2 reacts with [Ru]-Cl, then two possible dehydration processes should lead to 80 and A, shown in Scheme 3. For 80 , there is the reasonable resonance form 800 , with the cationic charge localized next to the methyl group. As no product related to 8, 800 , and A was isolated in the reaction of 2, these species as well as B produced from deprotonation of 800 and A may be active species, thus leading to decomposition. It is known that such species required a more electron donating ligand such as C5Me5 for stabilization.21b From the solid-state structure of 9 it is also clear that two triple bonds are indeed not in proximity, making the simultaneous coordination more difficult. As for the P-C bond formation, different regioselectivities are observed for these two diynes 1 and 2. For 1 with no methyl substituent, the reaction proceeded via the allenylidene intermediate followed by phosphine addition at Cγ to give the phosphonium acetylide complex 9. For 2 with only one extra methyl group, the reaction with [Ru]-Cl produced the allylcarbene complex and phosphine addition occurred at CR. Other 1,6-Diynes That Yield Both Types of Complexes. As shown in Scheme 4, the reaction of [Ru]-Cl with 3 in the presence of KPF6 afforded a mixture of the allenylidene complex 13 and the allylcarbene complex 14 in a ratio of ca. 10:1 from NMR data. The total yield of the mixture is ca. 94%. The dehydration process in the reaction of 3 containing a tert-butyl group is limited to give only the allenylidene complex 13. The bulkier tert-butyl group inhibits addition of a phosphine molecule at Cγ. The lower yield of 14 could be due to the large steric repulsion between the tert-butyl and triphenylphosphine groups, which could be in proximity, on the basis of the structure of the allylcarbene complex 11.

The reaction of [Ru]-Cl with the more flexible diyne 7 is also expected to lead to both types of products. Indeed, as shown in Scheme 5, treatment of [Ru]-Cl with 7 and NH4PF6 in CH2Cl2 afforded initially a mixture of the vinylidene complex 15 and the allylcarbene complex 17 in a ratio of ca. 2:1 from NMR data. No allenylidene or phosphonium acetylide complex was observed, even at higher temperature. The dehydration process was hampered possibly by lack of a conjugation system shown in 8 or 13, where the allenylidene and TMS-bound alkyne are forming a conjugation system via a phenyl group. After removal of the solvent, the residue was extracted with diethyl ether, giving a mixture of 15 and 17 which could be separated by chromatography. The mixture in CH2Cl2 solution was passed through a column packed with neutral Al2O3. The first yellow band eluted by CH2Cl2 yielded the acetylide complex 16, derived from the deprotonation of 15 in the column. Acetone was then used as a more polar eluent for the collection of a purple band yielding complex 17. In the 31P NMR spectrum of 17 no phosphine ligand directly bonded to the metal was detected (Scheme 5). The protonation of 16 with HBF4 gave back the pure vinylidene complex 15 for identification. The structure assignments of 15-17 are based on NMR studies, including 1H, 31P, and 13C spectra. In the 31P NMR spectrum of 15 in CDCl3, two doublet resonances at δ 43.79 and 42.39 with 2JPP =26.2 Hz are in the range of vinylidene complexes. In the 13C NMR spectrum of 15 the triplet resonance at δ 346.47 with 2JCP =15.0 Hz is assigned to CR and a singlet resonance at δ 115.74 is assigned to Cβ. In the 31 P NMR spectrum of 16 two doublet resonances at δ 51.45 and 51.11 with 2JPP=36.4 Hz fall in the range of an acetylide complex. The 1H NMR spectrum displays a doublet resonance at δ 5.83 with 3JHH = 6.6 Hz assigned to the Cγ-H coupled with the OH group at δ 1.46. The 13C NMR spectrum displays a triplet resonance at δ 108.33 with 2Jcp= 24.7 Hz assignable to CR and a singlet resonance at δ 111.68 assignable to Cβ. The structure of 16 has been confirmed by an X-ray diffraction study. An ORTEP drawing of the solid -state structure of 16 is shown in Figure 4 ,with selected bond distances and angles being given in Table 4. The molecule

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Table 4. Selected Bond Distances (A˚) and Angles (deg) for 16 Bond Lengths (A˚) Ru(1)-C(1) C(1)-C(2)

2.025(3) 1.194(3)

C(2)-C(3) C(3)-C(4)

1.471(4) 1.556(4)

Bond Angles (deg) Ru(1)-C(1)-C(2) C(1)-C(2)-C(3)

176.3(3) 173.6(3)

C(2)-C(3)-C(4)

113.1(3)

exhibits the usual acetylide structure in the three-legged piano-stool geometry. The acetylide ligand is nearly linear with a Ru(1)-C(1)-C(2) angle of 176.3(3)°, showing bond lengths Ru(1)-C(1) = 2.025(3) A˚ and C(1)-C(2) = 1.194(3) A˚. The bond angle of C(2)-C(3)-C(4) of 113.1(3)° is slightly distorted from the tetrahedral sp3 hybridization. As was mentioned above, the two triple bonds in 16 are not in proximity for an intramolecular coupling reaction on the metal. The 31P NMR spectrum of 17 displays a singlet resonance at δ 30.16 assigned to the phosphonium group. The 1H NMR spectrum of 17 exhibits a doublet resonance at δ 6.26 with 2 JHP=7.2 Hz assigned to CHPPh3 of the allylic ligand. Also, two resonances at δ 5.99 and 2.47 are assigned to CHOH and OH, respectively, with 3JHH = 7.2 Hz. Two characteristic features revealing the structure of 17 are shown in the 13C NMR spectrum. The downfield doublet resonance at δ 273.22 with 4JCP =5.2 Hz is assigned to the carbene carbon atom, and the doublet resonance at δ 27.38 with 1JCP = 71.8 Hz is assigned to the terminal allylic carbon atom bearing the phosphonium substituent. The reaction of 17 and 10% HCl in acetone also gave the η4-diene chloride complex 18 in high yield. The structure assignment of 18 is based on NMR data, including 1H, 31P, 13 C, and 2-D spectra. The 1H resonance of the OH group at δ 2.81 is broad and disappears in the presence of D2O. The characteristic feature in the 13C NMR spectrum is the doublet resonance at δ 28.76 with 1JCP=70.8 Hz assignable to the CPPh3 coupled with the phosphonium group. The vinylidene complex and the allylcarbene complex are not interconvertible, even at high temperature. Concluding Remarks. Two different types of products, the allenylidene/acetylide/vinylidene and the allylcarbene complexes, are observed in the reactions of four 1,6-diynes with [Ru]-Cl. Formation of the phosphonium acetylide complex proceeds via simple coordination of a terminal triple bond, giving an allenylidene intermediate followed by addition of a phosphine molecule at Cγ. The allylcarbene complex is formed from a C-C coupling reaction between two triple bonds possibly both coordinated on the metal center. The strong affinity of diyne with the metal center seems to readily induce phosphine dissociation from the metal and causes P-C bond formation. The regioselectivity of the P-C bond formation is affected by a small change on the diyne substrates. These two types of products are not interconvertible. Addition of HCl to the allylcarbene complexes leads to formation of the corresponding η4-diene metal chloride complexes.

Experimental Section General Procedures and Instruments. The manipulations were performed under an atmosphere of dry nitrogen using vacuumline and standard Schlenk techniques. Solvents were dried by standard methods and distilled under nitrogen before use.

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Hexanes and CH2Cl2 were distilled from CaH2, diethyl ether and THF were distilled from sodium benzophenone ketyl, and methanol was distilled from Mg/I2. All reagents were obtained from commercial suppliers and used without further purification. The ruthenium complex Cp(PPh3)2RuCl,22 1,6 20 -(trimethylsilylethynyl)acetophenone,7a 1-{o-(trimethylsilylethynylphenyl)}-2,2-dimethyl-1-propanone,7b and 48 were prepared by following the methods reported in the literature. Elemental analyses were carried out with a Elementar Vario EL III microanalyzer. Mass spectra were recorded using LCQ Advantage (ESI) and Finnigan TSQ 700 spectrometers (EI). X-ray diffraction studies were carried out at the Regional Center of Analytical Instrument at the National Taiwan University. NMR spectra were recorded on Bruker Avance-400 and DMX500 FT-NMR spectrometers at room temperature (unless stated otherwise) and are reported in units of δ with residual protons in the solvents as a standard (CDCl3, δ 7.26; C6D6, δ 7.15; acetoned6, δ 2.05). Preparation of 2. A THF solution (20 mL) of 20 -(trimethylsilylethynyl)acetophenone (1.08 g, 5 mmol) with ethynylmagnesium bromide (0.5 M, 11 mL, 5.5 mmol) was stirred at room temperature for 12 h under nitrogen. Then the reaction was quenched with a saturated aqueous NH4Cl solution (20 mL) and CH2Cl2 (310 mL) was used to extract the crude product. The combined organic layers were dried under vacuum, and the residue was purified by column chromatography to give 2 (1.14 g, 94% yield). Spectroscopic data for 2 are as follows. 1H NMR (δ, CDCl3): 7.68-7.25 (m, Ph), 4.17 (br, OH), 2.62 (s, tCH), 1.98 (s, CH3), 0.27 (s, TMS). 13C NMR (δ, CDCl3): 146.25-119.47 (Ph), 104.01 (PhCt), 102.72 (tCTMS), 86.36 (CCt), 72.72 (tCH), 69.63 (COH), 29.90 (CH3), -0.45 (TMS). Anal. Calcd for C15H18OSi: C, 74.33; H, 7.49. Found: C, 74.41; H, 7.54. MS EI: m/z 241.1 (M - 1)þ. Preparation of 3. A THF solution (20 mL) of 1-{o-(trimethylsilylethynylphenyl)}-2,2-dimethyl-1-propanone (1.29 g, 5 mmol) with ethynylmagnesium bromide (0.5 M, 11 mL, 5.5 mmol) was stirred at room temperature for 48 h under nitrogen. Then the solution was quenched with a saturated aqueous NH4Cl solution (20 mL), and CH2Cl2 (3  10 mL) was used to extract the crude product. The combined organic layers were dried under vacuum, and the residue was purified by silica gel column chromatography using 10% CH2Cl2/90% hexane to provide the yellow liquid product 3 (1.04 g, 73% yield). Spectroscopic data for 3 are as follows. 1H NMR (δ, CDCl3): 7.66-7.01 (m, Ph), 4.8 (br, OH), 2.55 (s, tCH), 1.01 (s, t-Bu), 0.19 (s, TMS). 13C NMR (δ, CDCl3): 144.80-124.21 (Ph), 105.41 (PhCt), 101.07 (tCTMS), 85.85 (CCt), 73.72 (tCH), 67.73 (COH), 41.97 (C(CH3)3), 25.68 (CH3), -0.47 (TMS). Anal. Calcd for C18H24OSi: C, 76.00; H, 8.50. Found: C, 76.11; H, 8.64. MS EI: m/z 283.16 (M - 1)þ. Preparation of 7. To a stirred solution of 4 (2.10 g, 0.089 mol) in dry THF (60 mL) at -78 °C was added n-BuLi (2.5 M, 7.80 mL, 0.195 mol) dropwise, and the solution was stirred for 30 min at -78 °C. Then chlorotrimethylsilane (2.13 g, 0.196 mol) was added to the mixture and the solution was further stirred for 1 h at -78 °C. The solution was warmed to room temperature, and an aliquot of 2 M HCl (60 mL) was added to the mixture. After further stirring for 3 h, the reaction mixture was extracted with ether, and the organic phase was washed with aqueous NaHCO3 and NaCl and dried over MgSO4. Solvent was then removed under reduced pressure to give 5 (2.69 g, 98% yield), and this residue was used for the preparation of 6 without further purification. To a solution of pyridinium chlorochromate (7.30 g, 0.340 mol) in dry CH2Cl2 (40 mL) at -78 °C was added 5 (2.62 g, 85 mmol), and the solution was warmed to room temperature and stirred overnight. The solution was filtered through silica gel to remove the insoluble precipitates. The solvent was removed under vacuum to yield the product 6 (22) Bruce, M. I.; Wallis, R. C. Aust. J. Chem. 1979, 32, 1471–1485.

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Organometallics, Vol. 28, No. 17, 2009

(2.50 g, 97% yield), and this residue was directly used for the preparation of 7. The solution of 6 (2.53 g, 0.083 mol) and ethynylmagnesium bromide (0.5 M, 20 mL, 0.010 mol) in 20 mL of THF was stirred for 12 h under nitrogen at room temperature. Then the reaction was quenched with a saturated aqueous NH4Cl solution. The product was extracted with ethyl acetate, the organic phase was washed with aqueous NaCl solution (3 10 mL), and the organic extract was dried over MgSO4. Solvent was then removed under reduced pressure, and the residue was purified by column chromatography using 10% ethyl acetate/ 90% hexane to provide the yellow liquid product 7 (2.66 g, 97% yield). Spectroscopic data for 7 are as follows. 1H NMR (δ, CDCl3): 7.34-7.25 (m, 10H, Ph), 5.38 (dd, 3JHH=8.0 Hz, 4JHH= 2.0 Hz, CH), 3.26 (d, 2JHH=16.6 Hz, CHH), 3.14 (d, 2JHH=16.6 Hz, CHH), 2.48 (d, 4JHH=2.0 Hz, tCH), 2.02 (d, 3JHH=8.0 Hz, OH), 0.03 (s, TMS). 13C NMR (δ, CDCl3): 142.43-126.87 (Ph), 103.55 (CtCTMS), 88.98 (CtCTMS), 82.61 (CtCH), 76.54 (CH), 66.47 (CtCH), 55.36 (CPh2), 30.14 (CH2), -0.21 (TMS). Anal. Calcd for C22H24OSi: C, 79.47; H, 7.28. Found: C, 79.51; H, 7.31. MS ESI: m/z 334.4 (Mþ1)þ. Preparation of 9. A solution of [Ru]-Cl (0.10 g, 0.129 mmol), 1 (0.028 g, 0.150 mmol), PPh3 (0.039 g, 0.150 mmol), and KPF6 (0.026 g, 0.142 mmol) in 5 mL of CH2Cl2 was stirred at room temperature for 24 h under nitrogen. Then the solution was filtered through Celite to remove insoluble precipitates. Subsequently, the volume of the solution was reduced to ca. 1 mL under vacuum, followed by addition of excess diethyl ether to produce precipitates. Filtration, followed by drying and collection of the solid, gave complex 9 (0.157 g, 93% yield). Recrystallization by slow diffusion of ether into a concentrated CH2Cl2 solution gave single crystals of 9 suitable for X-ray diffraction analysis. Spectroscopic data for 9 are as follows. 1H NMR (δ, CDCl3): 7.77-6.99 (m, 49H, Ph), 6.40 (d, br, 2JHP = 16.8 Hz. tCCH), 4.24 (s, Cp), 0.12 (s, TMS). 31P NMR (δ, CDCl3): 48.80 (d, 2JPP =36.1 Hz, PPh3), 50.77 (dd, 2JPP =36.1 Hz and 5JPP = 5.5 Hz, PPh3), 15.79 (d, 5Jpp = 5.5 Hz, CPPh3). 13C NMR (δ, CDCl3): 138.49-127.23 (Ph), 117.40 (Cβ), 97.04 (d, 2JCP = 9.6 Hz, CR), 93.76 (TMSCt), 84.84 (Cp), 65.81 (tCPh), 38.91 (d, 1JCP = 46.7 Hz, Cγ), -0.10 (TMS). Anal. Calcd for C75H69F6O0.5P4RuSi (single crystals containing 1/2 equiv of diethyl ether were used for analysis): C, 66.95; H, 5.17. Found: C, 66.77; H, 5.07. MS ESI: m/z 901.1 (M - PPh3)þ. Preparation of 8. A mixture of 9 (0.157 g, 0.120 mmol) and dimethyl acetylenedicarboxylate (DMAD; 0.021 g, 0.150 mmol) in 1 mL of CHCl3 was stirred for 5 min under nitrogen at room temperature. (DMAD was purified before use: a C6H6 solution of DMAD was washed with NaHCO3/H2O, the organic layer was separated and dried over Na2SO4 and then filtered, the solvent was evaporated, and the residue was distilled under vacuum.) Then the solvent was removed under vacuum followed by addition of excess diethyl ether to the residue to produce precipitates. Filtration of the precipitate is followed by drying the solid under vacuum to give 8 (0.122 g, 97%). Spectroscopic data for 8 are as follows. 1H NMR (δ, CDCl3): 9.70 (s, CH), 7.73-7.08 (m, Ph), 5.14 (s, Cp), 0.36 (s, TMS). 31P NMR (δ, CDCl3): 46.68 (s, PPh3). 13C NMR (δ, CDCl3): 302.43 (t, 2JCP= 18.9 Hz, CR), 135.13-126.84 (Ph), 217.47 (Cβ), 143.59 (Cγ), 102.29 (TMSCtC), 97.36 (Cp), 86.86 (TMSCt), -0.18 (TMS). Anal. Calcd for C55H49F6P3RuSi: C, 63.15; H, 4.72. Found: C, 63.26; H, 4.90. MS ESI m/z: 901.1 (M)þ. Synthesis of 11. A CH2Cl2 solution (5 mL) of [Ru]-Cl (0.20 g, 0.258 mmol), 2 (0.072 g, 0.300 mmol), and KPF6 (0.052 g, 0.284 mmol) was stirred for 24 h under nitrogen at room temperature. Then the solution was filtered through Celite to remove insoluble precipitates. Subsequently the volume of the solution was reduced to ca. 1 mL under vacuum, followed by addition of excess ether to produce precipitates. After filtration the crude product was redissolved in CH2Cl2 and the solution was passed through a column packed with acidic Al2O3. Collecting the blue band eluted by CH2Cl2 followed by drying under vacuum gave

Lui et al. the allylcarbene complex 11 (0.110 g, 51% yield). Recrystallization by slow diffusion of ether into a concentrated CH2Cl2 solution gave crystals of 11 suitable for X-ray diffraction analysis. Spectroscopic data for 11 are as follows. 1H NMR (δ, CDCl3): 7.55-7.22 (m, 19H, Ph), 6.23 (d, 2JHP = 7.5 Hz, CHPPh3), 5.00 (s, Cp), 2.98 (s, OH), 2.00 (s, CH3), 0.09 (s, TMS). 31 P NMR (δ, CDCl3): 30.44 (s, PPh3). 13C NMR (δ, CDCl3): 274.68 (d, 4JCP=4.9 Hz, CTMS), 134.48-108.28 (Ph), 118.33 (d, 2 JCP =5.9 Hz, CCPPh3), 90.68 (s, Cp), 76.36 (d, 3JCP =3.8 Hz, COHCH3), 53.43 (CCTMS), 27.78 (CH3), 25.53 (d, 1JCP =68.9 Hz, CHPPh3), -0.13 (s, TMS). Anal. Calcd for C38H38F6OP2RuSi: C, 55.95; H, 4.69. Found: C, 55.63; H, 5.04. MS ESI: m/z 671.4 (M)þ. Synthesis of 12. To a solution of 11 (0.162 g, 0.194 mmol) in acetone (2.7 mL) was added HCl (1.2 N, 0.3 mL) and the solution was stirred at room temperature for 30 min, whereupon the color of the solution changed from violet to yellow. Addition of diethyl ether caused precipitation of a yellow solid, which was filtered through a glass frit. After it was washed with ether twice, the solid product was dried under vacuum to give 12 (0.161 g, 93% yield). Recrystallization by slow diffusion of diethyl ether into a concentrated CH2Cl2/MeOH solution gave crystals suitable for X-ray diffraction analysis. Spectroscopic data for 12 are as follows. 1H NMR (δ, acetone-d6): 8.00-7.46 (m, 19H, Ph), 6.37 (d, 2JHP=4.8 Hz, CHPPh3), 6.12 (s, OH), 5.20 (s, Cp), 2.84 (s, CH3), 1.55 (s, CHTMS), 0.11 (s, TMS). 31P NMR (δ, acetone-d6): 24.37 (s, PPh3). 13C NMR (δ, acetone-d6): 138.58-123.47 (Ph), 129.41 (br, PPh3CHdC), 110.43 (TMSCHdC), 91.23 (Cp), 80.87 (COHCH3), 65.40 (TMSCHd), 26.58 (d, 1JCP = 78.0 Hz, CHPPh3), 1.03 (TMS). Anal. Calcd for C39H43ClF6O2P2RuSi (crystals with a MeOH molecule were used for analysis): C, 52.97; H, 4.90. Found: C, 52.80; H, 5.15. MS ESI: m/z 707.1 (M)þ. Synthesis of 13 and 14. A solution of [Ru]-Cl (0.300 g, 0.387 mmol), 3 (0.135 g, 0.480 mmol), and KPF6 (0.087 g, 0.426 mmol) in MeOH (30 mL) was stirred for 24 h under nitrogen at room temperature. Then the solvent was removed under vacuum and the residue was extracted with CH2Cl2. The solution was filtered through Celite to remove insoluble precipitates. The volume of the solution was then reduced to ca. 3 mL under vacuum, followed by addition of excess petroleum ether to produce a precipitate. After filtration this crude product was found to contain 13 and 14 by 1H and 31P NMR spectra in the ratio 13:14=10:1. The crude products were dissolved in CH2Cl2, and the solution was passed through a column of neutral Al2O3 that was eluted with CH2Cl2. The first band after drying under vacuum yielded the ruthenium allenylidene complex 13 (0.363 g, 85.5% yield), and the blue band yielded the allylcarbene complex 14 (27 mg, 9% yield). Spectroscopic data for 13 are as follows. 1H NMR (δ, CDCl3): 7.56-6.92 (m, 33H, Ph), 5.84 (d, 3JHH = 7.6 Hz, Ph), 5.09 (s, Cp), 1.49 (s, t-Bu), -0.08 (s, TMS). 31P NMR (δ, CDCl3): 46.35 (s, PPh3). 13C NMR (δ, CDCl3): 315.80 (t, 2 JCP=17.6 Hz, CR), 211.84 (Cβ), 108.74 (Cγ), 147.36-118.96 (Ph), 104.04 (CtCTMS), 99.54 (CtCTMS), 94.11 (Cp), 50.34 (C(CH3)3), 28.99 (CH3), -0.35 (TMS). Anal. Calcd for C59H57F6P3RuSi: C, 64.30; H, 5.20. Found: C, 64.51; H, 5.56. MS ESI: m/z 957.27 (M)þ. Spectroscopic data for 14 are as follows. 1 H NMR (δ, CDCl3): 7.56-7.05 (m, 19H, Ph), 6.37 (d, 2JHP =8.3 Hz, CHPPh3), 4.80 (s, Cp), 2.63 (s, br, OH), 1.13 (s, t-Bu), 0.13 (s, TMS). 31P NMR (δ, CDCl3): 29.30 (s, PPh3). Anal. Calcd for C41H44F6OP2RuSi: C, 57.40; H, 5.17. Found: C, 57.50; H, 5.22. MS ESI: m/z 713.20 (M)þ. Synthesis of 16 and 17. A solution of [Ru]-Cl (0.10 g, 0.129 mmol), 7 (0.053 g, 0.160 mmol), and NH4PF6 (0.023 g, 0.142 mmol) in CH2Cl2 (15 mL) was stirred for 24 h under nitrogen at room temperature. Then the solution was filtered through Celite to remove insoluble precipitates. The volume of the solution was reduced to ca. 1 mL under vacuum, followed by addition of excess petroleum ether to produce a precipitate. After filtration this crude product was detected to contain 15 and 17 by 1H and 31P NMR spectra in the ratio 15:17=2:1. The

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Organometallics, Vol. 28, No. 17, 2009

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Table 5. Crystal Data and Refinement Parameters for Complexes 9, 11, 12, and 16

formula mass (amu) space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3), Z θmax (deg) abs coeff, μ(Mo KR) (mm-1) no. of indep rflns; Rint no. of params R1, I > 2σ(I) wR2, all data goodness of fit on F2

9

11

12

16

C75H69F6O0.5P4RuSi 1345.34 P21/n 20.14723(3) 15.1598(2) 22.6842(4) 90 105.3290(10) 90 6681.89(16), 4 25.25 0.408 11 929; 0.0245 790 0.0427 0.1369 0.965

C38H38F6OP2RuSi 815.78 P21/c 14.8263(3) 14.1439(2) 19.0298(4) 90 110.636(2) 90 3734.54(12), 4 27.50 0.597 8575; 0.0942 446 0.0451 0.1037 0.943

C39H43ClF6O2P2RuSi 884.28 P21/c 15.4806(2) 10.19870(10) 25.1873(3) 90 98.7070(10) 90 3930.79 (8), 4 27.50 0.641 8974; 0.0295 472 0.0435 0.1321 1.026

C63H58OP2RuSi 1022.19 P1 10.2984(5) 13.2748(4) 19.8929(6) 94.076(2) 96.325(3) 107.292(3) 2565.33(17), 2 27.50 0.434 11 611; 0.0429 623 0.0468 0.0684 0.798

crude products were dissolved in CH2Cl2, and the solution was passed through a column of neutral Al2O3 that was eluted with CH2Cl2. After drying under vacuum, the first yellow band yielded the ruthenium acetylide complex 16 (0.043 g, 38% yield) and the blue band yielded the allylcarbene complex 17 (0.080 g, 60% yield). Recrystallization by slow evaporation of a concentrated acetone solution of 16 gave single crystals suitable for X-ray diffraction analysis. Spectroscopic data for 16 are as follows. 1H NMR (δ, C6D6): 7.83-6.86 (m, 40H, Ph), 5.83 (d, 3JHH=6.6 Hz, CHOH), 4.32 (s, Cp), 3.69 (d, 2JHH=16.0 Hz, CHH), 3.62 (d, 2JHH =16.0 Hz, CHH), 1.46 (d, 3JHH =6.6 Hz, OH), 0.12 (s, TMS). 31P NMR (δ, C6D6): 51.45, 51.11 (2 d, 2JPP= 36.4 Hz, PPh3). 13C NMR (δ, C6D6): 145.75-126.13 (Ph), 116.68 (Cβ), 108.33 (t, 2JCP = 24.7 Hz, CR), 106.68 (CtCTMS), 87.64 (CtCTMS), 85.78 (Cp), 69.49 (Cγ), 56.84 (CPh2), 30.94 (CH2), 0.22 (TMS). Anal. Calcd for C63H58OP2RuSi: C, 74.02; H, 5.72. Found: C, 73.93; H, 5.56. MS ESI: m/z 1023.4 (Mþ1)þ. Spectroscopic data for 17 are as follows. 1H NMR (δ, CDCl3): 7.65-7.17 (m, 25H, Ph), 6.26 (d, 2JHP = 7.2 Hz, CHPPh3), 5.99 (d, 3JHH=7.2 Hz, CHOH), 4.77 (s, Cp), 3.64 (d, 2JHH = 15.2 Hz, CHH), 3.39 (d, 2JHH = 15.2 Hz, CHH), 2.47 (d, 3JHH =7.2 Hz, OH), 0.02 (s, TMS). 31P NMR (δ, CDCl3): 30.16 (s, PPh3). 13C NMR (δ, CDCl3): 273.22 (d, 4JCP = 5.2 Hz, CTMS), 147.25-113.82 (Ph), 109.45 (d, 2JCP=5.2 Hz, CCHPPh3), 76.50 (d, 3JCP=3.8 Hz, CHOH), 69.49 (CCTMS), 53.68 (CPh2), 37.98 (CH2), 27.38 (d, 1JCP = 71.8 Hz, CHPPh3), -0.36 (TMS). Anal. Calcd for C45H44F6OP2RuSi: C, 59.66; H, 4.90. Found: C, 59.82; H, 5.03. MS ESI: m/z 762.2 (Mþ1)þ. Synthesis of 15. A dilute solution of HBF4 3 Et2O (48%, 0.02 mL, 0.109 mmol) in diethyl ether was added dropwise at 0 °C to a stirred solution of 16 (0.100 g, 0.098 mmol) in 20 mL of diethyl ether. Immediately, an insoluble solid precipitated but the addition was continued until no further solid was formed. The solution was then decanted, and the brown solid was washed with diethyl ether (3  5 mL) and dried in vacuo to yield 15 (0.098 g, 90% yield). Spectroscopic data for 15 are as follows. 1H NMR (δ, CDCl3): 7.65-6.93 (m, 40H, Ph), 5.59 (t, 3JHH=7.8 Hz, CHOH), 4.98 (Cp), 4.48 (d, 3JHH= 7.8 Hz, CH), 3.19 (d, 2JHH =16.9 Hz, CHH), 3.10 (d, 2JHH = 16.9 Hz, CHH), 2.27 (d, 3JHH = 7.8 Hz, OH), -0.04 (TMS). 31 P NMR (δ, CDCl3): 43.79, 42.39 (2d, 2JPP = 26.2 Hz, PPh3). 13C NMR (δ, CDCl3): 346.47 (t, 2JCP = 15.0 Hz, CR), 134.20-126.58 (Ph), 115.74 (Cβ), 104.36 (CtCTMS), 94.71 (Cp), 89.05 (CtCTMS), 70.12 (Cγ), 55.87 (CPh2), 29.71 (CH2), -0.23 (TMS). Anal. Calcd for C63H59BF4OP2RuSi: C,

68.17; H, 5.36. Found: C, 67.96; H, 5.57. MS ESI: m/z 1024.2 (Mþ1)þ. Synthesis of 18. To a solution of 17 (0.180 g, 0.198 mmol) in acetone (3 mL) was added HCl (1.2 N, 0.3 mL), and the solution was stirred for 30 min, whereupon the color changed from violet to yellow. Addition of diethyl ether led to formation of a yellow precipitate, which was collected on a glass frit, washed with diethyl ether twice, and dried under vacuum to yield 18 (0.169 g, 91% yield). Spectroscopic data for 18 are as follows. 1H NMR (δ, acetone-d6): 8.14-7.02 (m, 25H, Ph), 6.61 (s, br, CHPPh3), 6.13 (s, br, CHOH), 5.73 (s, Cp), 3.93 (d, 2JHH=15.1 Hz, CHH), 3.59 (d, 2JHH = 15.1 Hz, CHH), 2.81 (s, br, OH), 1.59 (s, CHTMS), 0.06 (s, TMS). 31P NMR (δ, acetone-d6): 24.95 (PPh3). 13C NMR (δ, acetone-d6): 145.60-126.99 (Ph), 128.22 (d, 2JCP = 1.9 Hz, CCPPh3), 110.35 (CCHTMS), 91.64 (Cp), 81.17 (COH), 67.82 (CHTMS), 62.46 (CPh2), 43.19 (CH2), 28.76 (d, 1JCP = 70.8 Hz, CHPPh3), 0.10 (TMS). Anal. Calcd for C45H45ClF6OP2RuSi: C, 57.35; H, 4.81. Found: C, 57.53; H, 5.01. MS ESI: m/z 798.9 (Mþ1)þ. X-ray Structure Determination of 9, 11, 12, and 16. A single crystal of 9 suitable for an X-ray diffraction study was glued to a glass fiber and mounted on a Nonius Kappa CCD diffractometer. The diffraction data were collected using 3 kW sealedtube molybdenum KR radiation (T=295 K). The exposure time was 5 s per frame. Multiscan absorption correction was applied, and decay was negligible. Data were processed, and the structures were solved and refined by the SHELXTL program.23 The structure was solved using direct methods and confirmed by Patterson methods refined on intensities of all data to give R1 and wR2 for unique observed reflections (I > 2σ(I)). Hydrogen atoms were placed geometrically using the riding model with thermal parameters set to 1.2 times those for the atoms to which the hydrogens are attached and 1.5 times those for the methyl hydrogen atoms. Solid-state structure determinations were similarly carried out for 11, 12, and 16. Table 5 gives parameters of the crystal data and refinement for complexes 9, 11, 12, and 16.

Acknowledgment. We thank the National Science Council, Taiwan, Republic of China, for financial support. Supporting Information Available: CIF files giving complete crystallographic data for 9, 11, 12, and 16. This material is available free of charge via the Internet at http://pubs.acs.org. (23) SHELXTL: Structure Analysis Program, version 5.04; Siemens Industrial Automation, 1995.