Synthesis and Reactions of Coordinatively Unsaturated Half

Organometallics 2010, 29, 1761–1770 DOI: 10.1021/om100006r

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Synthesis and Reactions of Coordinatively Unsaturated Half-Sandwich Rhodium and Iridium Complexes Having a 2,6-Dimesitylbenzenethiolate Ligand Mayumi Sakamoto, Yasuhiro Ohki,* and Kazuyuki Tatsumi* Department of Chemistry, Graduate School of Science and Research Center for Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan Received January 5, 2010

Coordinatively unsaturated rhodium and iridium complexes bearing a bulky thiolate ligand, [Cp*M(SDmp)](BArF4) (2a, M = Rh; 2b, M = Ir; Cp* = η5-C5Me5; Dmp = 2,6-(mesityl)2C6H3; ArF = 3,5-(CF3)2C6H3) were synthesized from the reactions of [Cp*MCl]2(μ-Cl)2 with LiSDmp and NaBArF4. The metal centers in 2a and 2b weakly interact with the ipso-carbon of one of the mesityl groups in the SDmp ligand, while the ipso-carbon dissociates from the coordination sphere in the reactions with donor ligands. Treatment of 2a or 2b with 2,20 -bipyridine (bpy) or 1,10-phenanthroline (phen) led to the formation of [Cp*M(SDmp)(bpy)](BArF4) (3a, M = Rh; 3b, M = Ir) or [Cp*M(SDmp)(phen)](BArF4) (4a, M=Rh; 4b, M = Ir), respectively. The reactions of 2a and 2b with 2 equiv of tert-butylisocianide or 1 atm of CO gave rise to the bis-adducts [Cp*M(SDmp)(L)2](BArF4) (5a, M=Rh, L=CNtBu; 5b, M = Ir, L = CNtBu; 6a, M = Rh, L=CO; 6b, M = Ir, L = CO). The coupling of terminal alkynes and SDmp took place upon the addition of excess 1-pentyne or phenylacetylene to solutions of 2a or 2b, affording cationic complexes with an S-arylated thiophene group, [Cp*M(η4-2, 4-R2C4H2S-Dmp)](BArF4) (7a, M = Rh, R = nPr; 7b, M = Ir, R = nPr; 7c, M = Rh, R = Ph; 7d, M = Ir, R = Ph).

Introduction Coordinatively unsaturated transition-metal thiolate complexes are relatively rare but deserve particular interest in terms of their relevancy to the active sites of cysteine-rich metalloenzymes such as hydrogenases, acetyl CoA synthase, CO dehydrogenases, and nitrogenases.1 We have been investigating coordinatively unsaturated thiolate complexes with respect to (1) the reactions of metal-sulfur bonds

toward H2 and other small molecules,2 (2) the synthesis of biomimetic metal-sulfur clusters,3-5 and (3) the unique coordination modes of thiolate ligands.2a,6 Among the bulky thiolate ligands used for these studies, 2,6-di(mesityl)benzenethiolate (SDmp)7 is unique, in that mesityl carbons are able to interact with metals in an η1- or η6-fashion. The η1-interaction is labile,6b,8 and the dissociation of the mesityl carbon from metal centers can create a reactive vacant site. We have previously reported the synthesis and reactions of Cp*Ru(SDmp) (Chart 1), in which the Ru atom forms an η1-interaction with one of the mesityl ipso-carbons.6b This complex was found to facilitate the trimerization of phenylacetylene to afford the cationic arene complex [Cp*Ru(η6C6H3Ph3)](SDmp), with liberation of the SDmp ligand as the counteranion. In this report, we extended our study on the half-sandwich SDmp complex of ruthenium to the analogous cationic complexes of rhodium and iridium,

*Corresponding authors. E-mail: [email protected] (K.T.); [email protected] (Y.O.). (1) Reviews of cysteine-rich metalloenzymes: (a) Rees, D. C.; Howard, J. B. Science 2003, 300, 929–931. (b) Fontecilla-Camps, J. C.; Amara, P.; Cavazza, C.; Nicolet, Y.; Volbeda, A. Nature 2009, 460, 814–822. (2) (a) Ohki, Y.; Takikawa, Y.; Sadohara, H.; Kesenheimer, C.; Engendahl, B.; Kapatina, E.; Tatsumi, K. Chem. Asian J. 2008, 3, 1625–1635. (b) Ohki, Y.; Sakamoto, M.; Tatsumi, K. J. Am. Chem. Soc. 2008, 130, 11610–11611. (c) Sakamoto, M.; Ohki, Y.; Kehr, G.; Erker, G.; Tatsumi, K. J. Organomet. Chem. 2009, 694, 2820–2824. (3) Nitrogenase models: (a) Ohki, Y.; Sunada, Y.; Honda, M.; Katada, M.; Tatsumi, K. J. Am. Chem. Soc. 2003, 125, 4052–4053. (b) Ohki, Y.; Ikagawa, Y.; Tatsumi, K. J. Am. Chem. Soc. 2007, 129, 10457– 10465. (c) Ohta, S.; Ohki, Y.; Ikagawa, Y.; Suizu, R.; Tatsumi, K. J. Organomet. Chem. 2007, 692, 4792–4799. (d) Ohki, Y.; Imada, M.; Murata, A.; Sunada, Y.; Ohta, S.; Honda, M.; Sasamori, T.; Tokitoh, N.; Katada, M.; Tatsumi, K. J. Am. Chem. Soc. 2009, 131, 13168–13178. (4) Hydrogenase models: (a) Li, Z.; Ohki, Y.; Tatsumi, K. J. Am. Chem. Soc. 2005, 127, 8950–8951. (b) Ohki, Y.; Yasumura, K.; Kuge, K.; Tanino, S.; Ando, M.; Li, Z.; Tatsumi, K. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 7652–7657. (c) Tanino, S.; Li, Z.; Ohki, Y.; Tatsumi, K. Inorg. Chem. 2009, 48, 2358–2360. (d) Pal, S.; Ohki, Y.; Yoshikawa, I.; Kuge, K.; Tatsumi, K. Chem. Asian J. 2009, 4, 961–968. (e) Ohki, Y.; Yasumura, K.; Ando, M.; Shimokata, S.; Tatsumi, K. Proc. Natl. Acad. Sci. U.S.A. 2010, 107, doi:10.1073/pnas.0913399107.

(5) Acetyl CoA synthase models: (a) Ito, M.; Kotera, M.; Song, Y.; Matsumoto, T.; Tatsumi, K. Inorg. Chem. 2009, 48, 1250–1256. (b) Ito, M.; Matsumoto, T.; Tatsumi, K. Inorg. Chem. 2009, 48, 2215–2223. (c) Song, Y.; Ito, M.; Kotera, M.; Matsumoto, T.; Tatsumi, K. Chem. Lett. 2009, 38, 184–185. (d) Ito, M.; Kotera, M.; Matsumoto, T.; Tatsumi, K. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 11862–11866. (6) (a) Komuro, T.; Matsuo, T.; Kawaguchi, H.; Tatsumi, K. J. Am. Chem. Soc. 2003, 125, 2070–2071. (b) Ohki, Y.; Sadohara, H.; Takikawa, Y.; Tatsumi, K. Angew. Chem., Int. Ed. 2004, 43, 2290–2293. (7) Ellison, J. J.; Ruhlandt-Senge, K.; Power, P. P. Angew. Chem., Int. Ed. Engl. 1994, 33, 1178–1180. (8) Nguyen, T.; Panda, A.; Olmstead, M. M.; Richards, A. F.; Stender, M.; Brynda, M.; Power, P. P. J. Am. Chem. Soc. 2005, 127, 8545–8552.

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Chart 1

Scheme 1. Synthesis of Coordinatively Unsaturated Rh- and Ir-SDmp Complexes 2a and 2b Figure 1. Structure of the cation of 2a with thermal ellipsoids at the 50% probability level. Table 1. Selected Bond Distances (A˚) and Angles (deg) for 2a and 2b

[Cp*M(SDmp)](BArF4) (2a, M=Rh; 2b, M=Ir). As expected, these complexes were found to generate vacant metal sites and to accommodate substrates. In contrast to Cp*Ru(SDmp), however, treatment of the rhodium and iridium complexes with terminal alkynes led to the unexpected coupling of the alkynes and SDmp ligand to produce the S-arylated thiophene derivatives bound to the metals.

Results and Discussion Synthesis and Structures of [Cp*M(SDmp)](BArF4) (2a, M = Rh; 2b, M = Ir). We have reported that the reactions of [Cp*MCl]2(μ-Cl)2 (M=Rh, Ir)9 with LiSDmp afford the half-sandwich rhodium(III) and iridium(III) complexes Cp*M(SDmp)(Cl) (1a, M = Rh; 1b, M = Ir).2b Treatment of 1a and 1b with 1 equiv of NaBArF4 (ArF = 3,5-(CF3)2C6H3)10 led to the removal of chloride, giving rise to the cationic complexes [Cp*M(SDmp)](BArF4) (2a, M=Rh; 2b, M = Ir) as green crystals with an 89% yield for both (Scheme 1). These complexes are air- and moisture-sensitive in solution and need to be handled under an inert atmosphere. The molecular structures of 2a and 2b were determined by X-ray crystallography. The cationic part of 2a is shown in Figure 1, and selected bond distances and angles of 2a and 2b are listed in Table 1. The cations of 2a and 2b have a geometry very similar to that of the ruthenium(II) analogue Cp*Ru(SDmp),6b and in fact the metal center interacts with the ipso-carbon of one of the mesityl groups. Similar Pd---Ar interactions are found in palladium complexes of orthobiaryl phosphines PR2(C6H4-2-Ar) (R = alkyl or phenyl, (9) White, C.; Yates, A.; Maitlis, P. M. Inorg. Synth. 1992, 29, 228– 234. (10) Brookhart, M.; Grant, B.; Volpe, J. Organometallics 1992, 11, 3920–3922.

M-S M-C3 S-C1 C3-C4 C4-C5 C5-C6 C6-C7 C7-C8 C8-C3 S-M-C3 M-S-C1 C2-C3-centroid(mesityl)

2a

2b

2.2280(8) 2.318(2) 1.752(2) 1.424(4) 1.394(5) 1.396(5) 1.371(5) 1.379(5) 1.437(4) 83.08(8) 105.95(11) 157.9(2)

2.229(2) 2.256(6) 1.761(6) 1.442(10) 1.405(12) 1.366(12) 1.382(12) 1.381(12) 1.412(10) 83.0(2) 105.7(2) 152.7(5)

Ar = aryl), which serve as efficient catalysts for carbonnitrogen and carbon-carbon bond forming reactions.11 The metal-bound mesityl groups in 2a and 2b are bent away from the metals, as can be seen from the C2-C3-centroid(mesityl) angles of 157.9(2)° (2a) and 152.7(5)° (2b). These angles are comparable to those of Cp*Ru(SDmp) (153.1°)6b and the PR2(C6H4-2-Ar) complexes of palladium (141.7161.1°).11 Due to the M-C(ipso) interaction, the C3-C4 and C3-C8 bonds (2a, 1.424(4), 1.437(4) A˚; 2b, 1.442(10), (11) (a) Kocovsky, P.; Vyskocil, S.; Cı´ sarova, I.; Sejbal, J.; Tislerova, I.; Smrcina, M.; Lloyd-Jones, G. C.; Stephen, S. C.; Butts, C. P.; Murray, M.; Langer, V. J. Am. Chem. Soc. 1999, 121, 7714–7715. (b) Barder, T. E.; Walker, S. D.; Martinelli, J. R.; Buchwald, S. L. J. Am. Chem. Soc. 2005, 127, 4685–4696. (c) Buchwald, S. L.; Mauger, C.; Mignani, G.; Scholz, U. Adv. Synth. Catal. 2006, 348, 23–39. (d) Barder, T. E.; Biscoe, M. R.; Buchwald, S. L. Organometallics 2007, 26, 2183–2192. (12) (a) Porzio, W.; Zocchi, M. J. Am. Chem. Soc. 1978, 100, 2048– 2052. (b) Bowyer, W. J.; Merkert, J. W.; Geiger, W. E.; Rheingold, A. L. Organometallics 1989, 8, 191–198. (c) Chin, R. M.; Dong, L.; Duckett, S. B.; Partridge, M. G.; Jones, W. D.; Perutz, R. N. J. Am. Chem. Soc. 1993, 115, 7685–7695. (d) Lenges, C. P.; Brookhart, M. Angew. Chem., Int. Ed. 1999, 38, 3533–3537. (e) Fooladi, E.; Dalhus, B.; Tilset, M. Dalton Trans. 2004, 3909–3917. (f) Moussa, J.; Guyard-Duhayon, C.; Herson, P.; Amouri, H.; Rager, M. N.; Jutand, A. Organometallics 2004, 23, 6231–6238. (g) Cadenbach, T.; Gemel, C.; Schmid, R.; Fischer, R. A. J. Am. Chem. Soc. 2005, 127, 17068–17078. (13) (a) Robertson, G. B.; Wickramasinghe, W. A. Acta Crystallogr. 1988, C44, 1383–1386. (b) Zahn, I.; Polborn, K.; Wagner, B.; Beck, W. Chem. Ber. 1991, 124, 1065–1073. (c) Brookhart, M.; Hauptman, E. J. Am. Chem. Soc. 1992, 114, 4437–4439. (d) Burger, P.; Bergman, R. G. J. Am. Chem. Soc. 1993, 115, 10462–19463. (e) Batchelor, R. J.; Einstein, F. W. B.; Lowe, N. D.; Palm, B. A.; Yan, X.; Sutton, D. Organometallics 1994, 13, 2041–2052. (f) Amouri, H.; Bras, J. L.; Vaissermann, J. Organometallics 1998, 17, 5850–5857. (g) Prinz, M.; Grosche, M.; Herdtweck, E.; Herrmann, W. A. Organometallics 2000, 19, 1692–1694. (h) Bourgeois, C. J.; Hughes, R. P.; Yuan, J.; DiPasquale, A. G.; Rheingold, A. L. Organometallics 2006, 25, 2908–2910.

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1.412(10) A˚) are slightly longer than the other C-C bonds in the mesityl ring (2a, 1.371(5)-1.396(5) A˚; 2b, 1.366(12)1.405(12) A˚). Although the M-C(ipso) interaction is not very strong, as manifested by the long M-C3 distances of 2.318(2) A˚ (2a) and 2.256(6) A˚ (2b) relative to the MC(olefin) distances (2.08-2.24 A˚)12,13 and the M-C(arene) distances (2.01-2.15 A˚),14,15 this interaction is effective in stabilizing the coordinatively unsaturated metal center. The M-C3 distance is longer for Rh (2a, 2.318(2) A˚) than Ir (2b, 2.256(6) A˚), while the reason is unclear. The Rh-S and Ir-S bonds (2a, 2.2280(8) A˚; 2b, 2.229(2) A˚) are short compared with those of electronically saturated thiolate complexes of rhodium and iridium (2.32-2.38 A˚),16,17 which is reasonable, since 2a and 2b are electron deficient. The 1H NMR spectra of 2a and 2b show that the two mesityl groups of the SDmp ligand are inequivalent, where a pair of signals were observed for the ortho- as well as the para-methyls with the intensity ratio 6H(ortho):6H(ortho): 3H( para):3H( para). These signals did not show notable linebroadning even at 80 °C. Thus the M-C(ipso) interaction is likely retained in solution on the NMR time scale. The three protons of the central phenyl group in the SDmp were also found to be inequivalent, and one of the meta-protons shifts to higher field at 6.41 ppm (2a) and 6.50 ppm (2b), respectively. This upfield shift may be due to the ring-current effect of the metal-bound mesityl group, since bending of the mesityl ring makes it more facing toward one of the metaH of the central phenyl group. Reactions of 2a and 2b with Small Molecules. The MC(ipso) interaction in 2a and 2b provides stability for the coordinatively unsaturated metal center by blocking a potential reaction site. On the other hand, dissociation of the ipso-carbon from the coordination sphere apparently occurs, allowing the following reactions with organic substrates. Lability of the M-C(ipso) interaction also has been suggested to be important for the high catalytic performance of the palladium complexes bearing ortho-biaryl phosphines PR2(C6H4-2-Ar).11 A. 2,20 -Bipyridine and 1,10-Phenanthroline. The reactions of 2a and 2b with 1 equiv of 2,20 -bipyridine (bpy) gave rise to (14) (a) Jones, W. D.; Chandler, V. L.; Feher, F. J. Organometallics 1990, 9, 164–174. (b) Jones, W. D.; Kuykendall, V. L. Inorg. Chem. 1991, 30, 2615–2622. (c) Selmeczy, A. D.; Jones, W. D.; Partridge, M. G.; Perutz, R. N. Organometallics 1994, 13, 522–532. (d) Edelbach, B. L.; Jones, W. D. J. Am. Chem. Soc. 1997, 119, 7734–7742. (e) Hughes, R. P.; Laritchev, R. B.; Williamson, A.; Incarvito, C. D.; Zakharov, L. N.; Rheingold, A. L. Organometallics 2003, 22, 2134–2141. (f) Corkey, B. K.; Taw, F. L.; Bergman, R. G.; Brookhart, M. Polyhedron 2004, 23, 2943–2954. (15) (a) Woerpel, K. A.; Bergman, R. G. J. Am. Chem. Soc. 1993, 115, 7888–7889. (b) Alaimo, P. J.; Ardtsen, B. A.; Bergman, R. G. J. Am. Chem. Soc. 1997, 119, 5269–5270. (c) Kaplan, A. W.; Ritter, J. C. M.; Bergman, R. G. J. Am. Chem. Soc. 1998, 120, 6828–6829. (d) Tellers, D. M.; Ritter, J. C.; Bergman, R. G. Inorg. Chem. 1999, 38, 4810–4818. (e) Hughes R. P.; Laritchev, R. B.; Williamson, A.; Incarvito, C. D.; Zakharov, L. N.; Rheingold, A. L. Organometallics 2002, 21, 4873–4885. (f) Rais, D.; Bergman, R. G. Chem.;Eur. J. 2004, 10, 3970–3978. (16) (a) Block, E.; Ofori-Okai, G. Inorg. Chim. Acta 1991, 190, 97– 102. (b) Kettler, P. B.; Chang, Y.; Rose, D.; Zubieta, J.; Abrams, M. J. Inorg, Chim. Acta 1996, 244, 199–205. (c) Myers, A. W.; Jones, W. D. Organometallics 1996, 15, 2905–2917. (d) Jung, O.-S.; Lee, Y.-A.; Kim, Y. T.; Chae, H. K. Inorg. Chim. Acta 2000, 299, 100–103. (e) Handerson, W.; Nicholson, B. K.; Dinger, M. B.; Bennett, R. L. Inorg. Chim. Acta 2002, 338, 210–218. (f) Wang, X.; Jin, G.-X. Chem.;Eur. J. 2005, 11, 5758–5764. (17) (a) Hughes, R. P.; Smith, J. M.; Incarvito, C. D.; Lam., K.-C.; Rhatigan, B.; Rheingold, A. L. Organometallics 2000, 21, 2136–2144. (b) Nomura, M.; Kusui, A.; Kajitani, M. Organometallics 2005, 24, 2811–2818. (c) Saito, A.; Seino, H.; Kajitani, H.; Takagi, F.; Yashiro, A.; Ohnishi, T.; Mizobe, Y. J. Organomet. Chem. 2006, 691, 5746–5752. (d) Sekioka, Y.; Suzuki, T. Bull. Chem. Soc. Jpn. 2006, 79, 1897–1899.


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Scheme 2. Reactions of 2a and 2b with 2,20 -Bipyridine and 1,10-Phenanthroline

the 18-electron complexes [Cp*M(SDmp)(bpy)](BArF4) (3a, M = Rh; 3b, M = Ir), in which the SDmp ligand has no metal-arene interaction (Scheme 2). In a similar manner, the reactions with 1,10-phenanthroline (phen) afforded [Cp*M(SDmp)(phen)](BArF4) (4a, M = Rh; 4b, M = Ir). These complexes were isolated as brown crystals in 80-90% yields. In the 1H NMR spectra of these complexes, the two mesityl groups of the SDmp ligand are equivalent, exhibiting single ortho- and para-methyl signals with a 12H(ortho):6H( para) intensity ratio. The X-ray analysis reveals a typical three-legged piano stool geometry of 3 and 4, as shown in Figure 2. The M-S bond distances listed in Table 2 (2.3659(4)-2.3792(7) A˚) are evidently longer than those of coordinatively unsaturated complexes 2a and 2b, while they are comparable to those of known 18-electron thiolate complexes of rhodium and iridium.16,17 In the known [Cp*MX(bpy)]þ and [Cp*ML(bpy)]2þ complexes of Rh(III) and Ir(III), bpy coordinates with a planar five-membered-ring geometry.18 In contrast, the bpy ligand in 3a,b is bent toward the Cp* ligand, distorting the ring from planarity. The dihedral angles between the N1-M-N2 plane and the least-squared plane of N1-C4-C5-N2 are 21.1(1)° (3a) and 20.2(2)° (3b). The phen ligand in 4a,b is also bent, but to a lesser extent, with the corresponding dihedral angles being 18.6(1)° for 4a and 8.7(4)° for 4b. Steric hindrance between the bpy/phen and the SDmp ligands may contribute to the bending of these chelating ligands. Interestingly, the bpy/phen aromatic rings in 3a-4b are nearly parallel to one of the mesityl rings of SDmp. The interplane angles are 11.1(1)° (3a), 12.4(2)° (3b), 4.7(1)° (4a), and 16.1(3)° (4b), and the shortest C-C contacts between the bpy/phen and mesityl carbons are 3.329(5) A˚ (3a), 3.327(5) A˚ (3b), 3.389(5) A˚ (4a), and 3.149(2) A˚ (4b). This π-π stacking may also contribute to the bending of the bpy and phen ligands. (18) (a) Youinou, M.-T.; Ziessel, R. J. Organomet. Chem. 1989, 363, 197–208. (b) Dadci, L.; Elias, H.; Frey, U.; H€ornig, A.; Koelle, U.; Merbach, A. E.; Paulus, H.; Schneider, J. S. Inorg. Chem. 1995, 34, 306–315. (c) Lo, H. C.; Leiva, C.; Buriez, O.; Kerr, J. B.; Olmstead, M. M.; Fish, R. H. Inorg. Chem. 2001, 40, 6705–6716. (d) Ogo, S.; Makihara, N.; Kaneko, Y.; Watanabe, Y. Organometallics 2001, 20, 4903–4910. (e) Abura, T.; Ogo, S.; Watanabe, Y.; Fukuzumi, S. J. Am. Chem. Soc. 2003, 125, 4149–4154. (f) Ogo, S.; Uehara, K.; Abura, T.; Watanabe, Y.; Fukuzumi, S. J. Am. Chem. Soc. 2004, 126, 16520–16527. (g) Ogo, S.; Hayashi, H.; Uehara, K.; Fukuzumi, S. Appl. Organomet. Chem. 2005, 19, 639–643.

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Figure 2. Structures of the cations of 3a (left) and 4a (light) with thermal ellipsoids at the 50% probability level. Table 2. Selected Bond Distances (A˚) and Angles (deg) for Complexes 3a, 3b, 4a, 4b, 5b, and 6b

M-S M-X1a M-X2b C2-Y1c C3-Y2c S-C1 M-S-C1 S-M-X1a S-M-X2b X1-M-X2a,b (N1-M-N2)-(N1-C4-C5-N2)d M-C2-Y1c M-C3-Y2c d

3a

3b

4a

4b

5b

6b

2.3765(7) 2.099(3) 2.103(3)

2.3792(7) 2.091(3) 2.087(3)

2.3659(4) 2.1064(18) 2.121(2)

2.3773(18) 2.099(6) 2.108(6)

1.786(3) 118.93(11) 90.79(7) 101.07(7) 76.08(13) 21.1(1)

1.793(3) 118.78(12) 99.98(8) 89.51(8) 75.60(14) 20.2(2)

1.773(2) 125.30(8) 89.44(5) 104.22(5) 77.50(9) 18.6(1)

1.784(6) 126.6(2) 87.43(18) 102.29(16) 77.4(2) 8.7(4)

2.4008(12) 1.950(6) 1.967(4) 1.134(8) 1.149(6) 1.780(3) 113.06(17) 88.86(14) 95.31(14) 94.9(2)

2.389(2) 1.905(8) 1.919(9) 1.123(10) 1.126(12) 1.778(7) 114.4(3) 93.0(2) 88.3(2) 95.6(3)

171.7(3) 172.7(5)

177.2(8) 173.0(7)

a X1 = N1 (3a, 3b, 4a, 4b), C2 (5b, 6b). b X2 = N2 (3a, 3b, 4a, 4b), C3 (5b, 6b). c For 5b and 6b: Y1 = C2 (5b), O1 (6b); Y2 = C3 (5b), O2 (6b). Interplane angles.

Scheme 3. Reactions of 2a and 2b with tert-Butyl Isocyanide and Carbon Monoxide

B. tert-Butyl Isocyanide and Carbon Monoxide. The reactions of 2a,b with two-electron donors (L) such as CNtBu and CO resulted in the formation of a series of bis-adducts [Cp*M(SDmp)(L)2](BArF4) (5a, M = Rh, L = CNtBu; 5b, M = Ir, L = CNtBu; 6a, M = Rh, L = CO; 6b, M = Ir, L = CO), as shown in Scheme 3. Whereas the rhodium complexes 5a and 6a were formed in >90% yield according to the NMR measurements, their isolation has been unsuccessful due to instability in solution. The isocyanide complex 5a is generated cleanly at -40 °C, but it gradually decomposes at room temperature. The carbonyl complex 6a is also labile, and evaporation of the solution of 6a under reduced pressure resulted in the dissociation of CO to reproduce 2a. In contrast, the iridium congeners, 5b and 6b, are both stable,

and they were isolated as crystals. Their structures determined by X-ray diffraction studies are shown in Figure 3. The Ir-S bond distances of 5b (2.4008(12) A˚) and 6b (2.389(2) A˚) are slightly longer than those of bpy/phen complexes 3b (2.3792(7) A˚) and 4b (2.3773(18) A˚), while the coordination geometries are similar. In the 13C{1H} NMR spectra, the coordinated carbon atoms of CNtBu and CO were observed at 149.8 (5a), 149.9 (5b), 179.2 (6a), and 184.2 (6b) ppm, respectively. The CtN or CtO bands in the IR spectra appeared at 2202, 2185 cm-1 (5a), 2198, 2173 cm-1 (5b), 2125, 2100 cm-1 (6a), and 2116, 2083 cm-1 (6b). C. 1-Pentyne and Phenylacetylene. When 2a or 2b was treated with an excess of 1-pentylne or phenylacetylene, the coupling of two alkynes and the SDmp ligand occurred in

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Figure 3. Structures of the cations of 5b (left) and 6b (right) with thermal ellipsoids at the 50% probability level. Scheme 4. Reactions of 2a and 2b with Terminal Alkynes

either case to give the S-arylated thiophene complexes [Cp*M(η4-2,4-R2C4H2SDmp)](BArF4) (7a, M = Rh, R = n Pr; 7b, M = Ir, R = nPr; 7c, M = Rh, R = Ph; 7d, M = Ir, R = Ph) (Scheme 4). S-Alkyl thiophene complexes of Cp*Ir are known, which were formed by the alkylation of the preformed η4-thiophene ligand by (R3O)BF4 (R = Me, Et).19 To our knowledge, the formation of a thiophene moiety from alkynes and a thiolate ligand is unprecedented. NMR monitoring of the reaction mixtures revealed no isomers or byproducts, indicating that the coupling of the SDmp ligand with two alkyne molecules occurs regioselectively, providing the 2,4-substituted S-aryl thiophene ligands. Complexes 7a-d were isolated as yellow crystals in 70-80% yields, and they were characterized by the NMR spectra, elemental analysis, and X-ray crystallography. In the 1H NMR, the η4-thiophene ring of 7a-d gave rise to two singlets found between 2.9-3.9 ppm and 4.3-5.4 ppm. The 13C{1H} NMR of 7a-d exhibited four signals for the η4-thiophene ring. The structures of 7a and 7b, determined by X-ray diffraction studies, include the unique metal-bound η4-S-arylated thiophene ligand, as shown in Figure 4. Selected bond (19) Chen, J.; Angelici, R. J. Organometallics 1990, 9, 849–852. (20) (a) Ogilvy, A. E.; Skaugset, A. E.; Rauchfuss, T. B. Organometallics 1989, 8, 2739–2741. (b) Skaugset, A. E.; Rauchfuss, T. B.; Stern, C. L. J. Am. Chem. Soc. 1990, 112, 2432–2433. (c) Luo, S.; Ogilvy, A. E.; Rauchfuss, T. B.; Rheingold, A. L.; Wilson, S. R. Organometallics 1991, 10, 1002–1009. (21) (a) Chen, J.; Angelici, R. J. Organometallics 1989, 8, 2277–2279. (b) Chen, J.; Daniels, L. M.; Angelici, R. J. J. Am. Chem. Soc. 1990, 112, 199–204. (c) Chen, J.; Angelici, R. J. Organometallics 1990, 9, 879–880. (d) Chen, J.; Daniels, L. M.; Angelici, R. J. J. Am. Chem. Soc. 1991, 113, 2544– 2552. (e) Chen, J.; Young, V. G.; Angelici, R. J. Organometallics 1996, 15, 2727–2734. (f) Chen, J.; Angelici, R. J. J. Organomet. Chem. 2001, 621, 55– 65.

Figure 4. Structure of the cation of 7b with thermal ellipsoids at the 50% probability level. Table 3. Selected Bond Distances (A˚) and Angles (deg) for Complexes 7a and 7b

M-S S-C1 S-C4 C1-C2 C2-C3 C3-C4 S-C5 C1-S-C4 S-C1-C2 C1-C2-C3 C2-C3-C4 C3-C4-S (C1-C2-C3-C4)-Sa (C1-C2-C3-C4)-(C1-S-C4)b

7a

7b

2.7514(11) 1.803(5) 1.757(5) 1.422(7) 1.404(9) 1.425(10) 1.839(5) 85.4(2) 109.7(3) 112.4(5) 109.2(5) 112.6(4) 0.631(9) 28.8(3)

2.8134(10) 1.814(5) 1.763(5) 1.443(7) 1.429(8) 1.426(9) 1.833(4) 84.8(2) 109.3(3) 110.5(5) 109.6(4) 112.0(4) 0.712(8) 32.6(2)

a Distances between the C1-C4 plane and the sulfur atom. b Interplane angles.

distances and angles are summarized in Table 3. The bond lengths and angles of the thiophene ligands are comparable to those of previously reported η4-thiophene complexes,19-21 and the long M-S distances (2.7514(11) A˚ (7a), 2.8134(10) A˚ (7b)) indicate the absence of a direct M-S bonding interaction. The sulfur atom bends away from the metal atom and is

Sakamoto et al.

Scheme 5. Possible Pathway for the Formation of 7


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relevant to C, Cp*Ir{SC(Me)dCH-CHd C(Me)}, forms an S-bound BH3 adduct, promoting ring closure to generate an η4-thiophene complex.19 An alternative pathway to 7 may be the initial formation of a metallacyclopentadiene intermediate via cycloaddition of two alkynes at the metal center, followed by successive formation of two S-C bonds. However, we assume this latter pathway is less likely, because a metallacyclopentadiene intermediate would be a relatively uncommon Rh(V)/Ir(V) species.

Conclusions

displaced from the plane of thiophene carbons by 0.631(9) A˚ (7a) and 0.712(8) A˚ (7b). The angles between the planes defined by C1-C2-C3-C4 and C1-S-C4 are 28.8(3)° (7a) and 32.6(2)° (7b). The S-arylated-thiphene sulfur is substantially pyramidalized, and it may have some character of sulfonium cation. If the cation center of 7a and 7b resides in the sulfur atom, the oxidation state of rhodium and iridium is regarded as þI. The S-C bond length varies from the long S-C5(Dmp) distances (1.839(5) A˚ (7a), 1.833(4) A˚ (7b)), to the intermediary S-C1 distances (1.803(5) A˚ (7a), 1.814(5) A˚ (7b)), to the short S-C4 distances (1.757(5) A˚ (7a), 1.763(5) A˚ (7b)). A similar long S-C distance is found in the analogous S-methylated thiophene complex of iridium, [Cp*Ir(η4-2,5-Me2C4H2SCH3)]þ (S-CH3; 1.83(1) A˚).21f A reaction pathway for the formation of 7 is proposed in Scheme 5. The reaction is initiated by coordination of an alkyne at the coordinatively unsaturated metal center (A). The insertion of the η2-alkyne into the M-S bond follows, where the substituent R of alkyne orients away from the bulky Dmp group of thiolate, generating B selectively. Another alkyne molecule is inserted into the M-C bond of B, and a six-membered metallacycle is formed (C). This reaction occurs regioselectively, in such a way that two alkynes couple in a head-to-tail manner to avoid the steric repulsion between two R groups of the alkynes. Attempts to observe the intermediary species such as B or C have been unsuccessful. The 1H NMR monitoring of the reaction mixtures of 2a,b and 1-2 equiv of alkynes gave the signals of only 7a-d other than those of 2a,b, probably because of the relatively slow dissociation of the M-C(ipso) interaction in 2a,b rather than the following steps. Formation of a sixmembered metallacycle analogous to C was observed for a half-sandwich rhodium complex of 1,2-dicarba-closo-dodecaborane-1,2-dithiolate, via the regioselective insertion of two alkyne molecules into the Rh-S(thiolate) bond.22 At the final step, the thioether sulfur of C forms a bond with the metal-bound carbon atom, resulting in generation of 7. Although the driving force for the C-S coupling is unclear, it is interesting to note that a metallacycle complex of iridium

(22) Herberhold, M.; Yan, H.; Milius, W.; Wrackmeyer, B. Chem.; Eur. J. 2000, 6, 3026–3032.

Coordinatively unsaturated half-sandwich rhodium(III) and iridium(III) complexes 2a and 2b carrying a bulky thiolate ligand SDmp have been successfully synthesized. These complexes feature the M-C(ipso) interaction, which provides stability for the metal center by occupying the reactive sites and by the relief of electron deficiency. These complexes react with Lewis bases via dissociation of the ipsocarbon from the metal centers, as demonstrated by the facile formation of a series of 18-electron complexes with 2,20 bipyridine, 1,10-phenanthroline, tert-butylisocyanide, and carbon monoxide. The reactions of 2a and 2b with 1-pentyne or phenylacetylene, which result in the formation of Sarylated thiophenes, are a new class of coupling reactions between metal-thiolates and alkynes. Interestingly, the reactivity of 2a,b toward alkynes is different from that of isostructural complex Cp*Ru(SDmp). A possible reason for the difference is the cationic charge of the rhodium and iridium complexes, and the cationic charge probably prevents the dissociation of the SDmp anion that is required for the cyclotrimerization of alkynes mediated by Cp*Ru(SDmp). This cationic charge also results in the less efficient RhfCO π-back-donation, facilitating the dissociation of CO from 6a under reduced pressure.

Experimental Section General Procedures. All reactions were carried out under a nitrogen or argon atmosphere using standard Schlenk techniques. THF, toluene, Et2O, dichloromethane, and hexane were purified by the method of Grubbs,23 where the solvents were passed over columns of activated alumina and a supported copper catalyst supplied by Hansen & Co. Ltd. CDCl3 was dried over CaH2 and distilled prior to use. 1H and 13C{1H} NMR spectra were acquired on a JEOL ECA-600 or Varian INOVA-500. 1H NMR signals were referenced to the residual proton peak of the deuterated solvent. The 13C chemical shifts were relative to the carbon signals for the deuterated solvents. Infrared spectra were recorded on a JASCO FT/IR-410 spectrometer. Elemental analyses were performed on a LECO-CHNS932 elemental analyzer where the crystalline samples were sealed in silver capsules under nitrogen. X-ray diffraction data were collected on a Rigaku AFC8 equipped with a CCD area detector using graphite-monochromatized Mo KR radiation. Complexes 1a and 1b2b and NaBArF410 were prepared according to the literature procedures. Synthesis of [Cp*Rh(SDmp)](BArF4) (2a). Complex 1a (85.1 mg, 0.138 mmol), NaBArF4 (122.1 mg, 0.138 mmol), and dichloromethane (40 mL) were charged into a Schlenk tube, and the mixture was stirred at room temperature for 2 h. The solution was centrifuged to remove NaCl, and then the solvent was removed under reduced pressure to afford a green solid. After washing with hexane (3 mL), the product (23) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.; Timmers, F. J. Organometallics 1996, 15, 1518–1520.

Article was dissolved in Et2O and the solution was stored at -30 °C. [Cp*Rh(SDmp)](BArF4) (2a) (183.8 mg, 0.123 mmol, 89% yield) was obtained as green crystals. 1H NMR (CDCl3): δ 7.70 (bs, 8H, o-H of ArF), 7.53 (bs, 4H, p-H of ArF), 7.31 (t, J = 7.5 Hz, 1H, p-H of SC6H3Mes2), 7.52, 7.00 (s, 2H, m-H of Mes), 7.14, 6.41 (d, J = 7.5 Hz, 1H, m-H of SC6H3Mes2), 2.62, 2.38 (s, 3H, p-CH3 of Mes), 1.94, 1.73 (s, 6H, o-CH3 of Mes), 1.28 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.2 Hz, ipso-C of ArF), 149.1, 145.2, 140.7, 137.7, 137.5, 136.0 (s, Ar), 135.5, 135.4 (s, m-C of Mes), 134.8 (s, o-C of ArF), 130.1 (s, p-C of SC6H3Mes2), 129.0 (q, JFC = 30.9 Hz, m-C of ArF), 128.3, 126.0 (s, m-C of SC6H3Mes2), 124.5 (q, JFC = 271.4 Hz, CF3), 117.5 (s, p-C of ArF), 100.6 (d, JRhC = 8.0 Hz, C5(CH3)5), 21.8, 21.1 (s, p-CH3 of Mes), 20.4, 20.2 (s, o-CH3 of Mes), 9.3 (d, JRhC = 2.4 Hz, C5(CH3)5). Anal. Calcd for C66H52SF24BRh: C, 54.79; H, 3.62; S, 2.22. Found: C, 54.43; H, 3.62; S, 2.25. Synthesis of [Cp*Ir(SDmp)](BArF4) (2b). The procedure is similar to the one used for the synthesis of 2a. The reaction of 1b (65.1 mg, 0.092 mmol) with NaBArF4 (83.3 mg, 0.094 mmol) in dichloromethane (40 mL) at room temperature afforded a dark green solid. Dark green crystals of [Cp*Ir(SDmp)](BArF4) (2b) (125.8 mg, 0.082 mmol, 89% yield) were grown from its Et2O solution at -30 °C. 1H NMR (CDCl3): δ 7.67 (bs, 8H, o-H of ArF), 7.51 (bs, 4H, p-H of ArF), 7.31 (t, J = 7.5 Hz, 1H, p-H of SC6H3Mes2), 7.45, 6.98 (s, 2H, m-H of Mes), 7.10, 6.50 (d, J = 7.5 Hz, 1H, m-H of SC6H3Mes2), 2.76, 2.38 (s, 3H, p-CH3 of Mes), 1.92, 1.64 (s, 6H, o-CH3 of Mes), 1.26 (s, 15H, Cp*). 13 C{1H} NMR (CDCl3): δ 161.6 (q, JBC = 49.0 Hz, ipso-C of ArF), 153.9, 148.5, 144.7, 142.4, 140.4, 137.7, 135.9 (s, Ar), 134.8 (s, o-C of ArF), 134.1, 128.3 (s, m-C of Mes), 130.6 (s, p-C of SC6H3Mes2), 128.9 (q, JFC = 33.2 Hz, m-C of ArF), 128.5, 128.3 (s, m-C of SC6H3Mes2), 124.5 (q, JFC = 272.4 Hz, CF3), 117.4 (s, p-C of ArF), 94.3 (s, C5(CH3)5), 21.6, 21.2 (s, p-CH3 of Mes), 21.0, 20.2 (s, o-CH3 of Mes), 9.1 (s, C5(CH3)5). Anal. Calcd for C66H52SF24BIr: C, 51.60; H, 3.41; S, 2.09. Found: C, 51.26; H, 3.38; S, 2.19. Synthesis of [Cp*Rh(SDmp)(bpy)](BArF4) (3a). Complex 2a (481.4 mg, 0.322 mmol), 2,20 -bipyridine (50.2 mg, 0.321 mmol), and toluene (30 mL) were charged into a Schlenk tube, and the mixture was stirred at room temperature for 3 h. The solvent was removed under reduced pressure, and the residue was washed with hexane (3 mL) to give a brown solid. Brown crystals of [Cp*Rh(SDmp)(bpy)](BArF4) (3a) (438.8 mg, 0.274 mmol, 85% yield) were grown at room temperature from a toluene solution layered with hexane. 1H NMR (CDCl3): δ 8.13 (d, J = 4.8 Hz, 2H, bpy), 7.91 (d, J = 7.9 Hz, 2H, bpy), 7.86 (dt, J = 7.9, 1.4 Hz, 2H, bpy), 7.71 (bs, 8H, o-H of ArF), 7.50 (bs, 4H, p-H of ArF), 7.35 (dt, J = 7.6, 1.7 Hz, 2H, bpy), 7.02 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 6.69 (d, J = 7.3 Hz, 2H, m-H of SC6H3Mes2), 6.63 (s, 4H, m-H of Mes), 2.25 (s, 6H, p-CH3 of Mes), 1.78 (s, 12H, o-CH3 of Mes), 0.89 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.6 (q, JBC = 50.0 Hz, ipso-C of ArF), 153.4, 148.1, 140.8, 139.1, 135.4 (s, Ar), 152.3, 152.2, 138.8, 122.3 (s, bpy), 134.7 (s, o-C of ArF), 129.7 (s, p-C of SC6H3Mes2), 128.9 (q, JFC =30.7 Hz, m-C of ArF), 128.0 (s, m-C of Mes), 127.5 (s, m-C of SC6H3Mes2), 124.5 (q, JFC = 272.7 Hz, CF3), 117.4 (s, pC of ArF), 97.4 (d, JRhC =4.8 Hz, C5(CH3)5), 21.4 (s, o-CH3 of Mes), 20.9 (s, p-CH3 of Mes), 7.1 (s, C5(CH3)5). Anal. Calcd for C76H60SN2F24BRh: C, 56.94; H, 3.77; N, 2.00; S, 1.75. Found: C, 56.61; H, 3.61; N, 1.92; S, 1.82. Synthesis of [Cp*Ir(SDmp)(bpy)](BArF4) (3b). The synthetic procedure is analogous to that of 3a. The reaction of 2b (198.2 mg, 0.114 mmol) with 2,20 -bipyridine (19.8 mg, 0.127 mmol) in toluene (20 mL) afforded a greenish-brown solid, from which [Cp*Ir(SDmp)(bpy)](BArF4) (3b) (175.6 mg, 0.104 mmol, 91% yield) was obtained as brown crystals. 1H NMR (CDCl3): δ 8.21 (d, J = 5.0 Hz, 2H, bpy), 7.90 (d, J = 7.9 Hz, 2H, bpy), 7.78 (t, J = 7.7 Hz, 2H, bpy), 7.69 (bs, 8H, o-H of ArF), 7.50 (bs, 4H, p-H of ArF), 7.32 (t, J = 5.6 Hz, 2H, bpy), 7.00 (t, J = 7.4 Hz, 1H, p-H of SC6H3Mes2), 6.68 (d, J = 7.4 Hz, 2H, m-H of


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SC6H3Mes2), 6.64 (s, 4H, m-H of Mes), 2.26 (s, 6H, p-CH3 of Mes), 1.80 (s, 12H, o-CH3 of Mes), 0.92 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.8 Hz, ipso-C of ArF), 154.5, 148.4, 140.8, 136.7, 135.5, 135.4 (s, Ar), 151.8, 138.6, 125.8, 122.3 (s, bpy), 134.7 (s, o-C of ArF), 130.0 (s, m-C of SC6H3Mes2), 128.9 (q, JFC = 31.1 Hz, m-C of ArF), 128.1 (s, m-C of Mes), 127.5 (s, p-C of SC6H3Mes2), 124.5 (q, JFC = 272.7 Hz, CF3), 117.5 (s, p-C of ArF), 90.9 (s, C5(CH3)5), 21.6 (s, oCH3 of Mes), 20.9 (s, p-CH3 of Mes), 6.7 (s, C5(CH3)5). Anal. Calcd for C76H60SN2F24BIr: C, 53.94; H, 3.57; N, 1.66; S, 1.89. Found: C, 53.52; H, 3.59; N, 1.86; S, 1.92. Synthesis of [Cp*Rh(SDmp)(phen)](BArF4) (4a). The synthetic procedure is analogous to that of 3a. The reaction of 2a (113.6 mg, 0.076 mmol) with 1,10-phenanthroline (13.3 mg, 0.074 mmol) in toluene (30 mL) gave a brown solid, from which brown crystals of [Cp*Rh(SDmp)(phen)](BArF4) (4a) (110.6 mg, 0.068 mmol, 89% yield) were obtained. 1H NMR (CDCl3): δ 8.46 (d, J=5.5 Hz, 2H, phen), 8.33 (d, J = 8.3 Hz, 2H, phen), 7.84 (s, 2H, phen), 7.66 (m, 15H, phen þ o-H of ArF), 7.46 (bs, 4H, p-H of ArF), 6.94 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 6.59 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes2), 6.48 (s, 4H, m-H of Mes), 2.23 (s, 6H, p-CH3 of Mes), 1.55 (s, 12H, oCH3 of Mes), 0.88 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.3 Hz, ipso-C of ArF), 154.5, 151.8, 137.7, 126.3, 125.9, 125.3 (s, phen), 148.1, 145.4, 140.9, 139.2, 135.3, 130.2 (s, Ar), 134.8 (s, o-C of ArF), 129.6 (s, m-C of SC6H3Mes2), 128.9 (q, JFC =28.6 Hz, m-C of ArF), 128.2 (s, p-C of SC6H3Mes2), 127.8 (s, m-C of Mes), 124.5 (q, JFC = 264.3 Hz, CF3), 117.4 (s, p-C of ArF), 97.3 (d, JRhC=7.5 Hz, C5(CH3)5), 20.9 (s, o-CH3 of Mes), 20.8 (s, p-CH3 of Mes), 7.2 (s, C5(CH3)5). Anal. Calcd for C78H60SN2F24BRh: C, 57.58; H, 3.72; N, 1.72; S, 1.97. Found: C, 57.57; H, 4.06; N, 1.80; S, 1.84. Synthesis of [Cp*Ir(SDmp)(phen)](BArF4) (4b). The synthetic procedure is analogous to that of 3a. The reaction of 2b (101.5 mg, 0.066 mmol) with 1,10-phenanthroline (11.8 mg, 0.066 mmol) in toluene (20 mL) afforded a brown solid, from which brown crystals of [Cp*Ir(SDmp)(phen)](BArF4) 3 1/2C6H14 (4b 3 1/2C6H14) (104.2 mg, 0.059 mmol, 90% yield) were obtained. 1H NMR (CDCl3): δ 8.52 (d, J = 5.0 Hz, 2H, phen), 8.26 (d, J = 8.1 Hz, 2H, phen), 7.85 (s, 2H, phen), 7.69 (m, 10H, phen þ o-H of ArF), 7.48 (bs, 4H, p-H of ArF), 6.93 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 6.59 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes2), 6.51 (s, 4H, m-H of Mes), 2.25 (s, 6H, p-CH3 of Mes), 1.57 (s, 12H, o-CH3 of Mes), 0.92 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.8 Hz, ipso-C of ArF), 151.0, 137.8, 136.9, 135.2, 126.3, 125.7 (s, phen), 148.3, 147.0, 140.8, 135.3, 130.4 (s, Ar), 134.8 (s, o-C of ArF), 129.8 (s, p-C of SC6H3Mes2), 129.0 (q, JFC = 31.1 Hz, m-C of ArF), 127.9 (s, mC of Mes), 127.6 (s, m-C of SC6H3Mes2), 124.9 (q, JFC =272.8 Hz, CF3), 117.5 (s, p-C of ArF), 90.9 (s, C5(CH3)5), 21.1 (s, oCH3 of Mes), 20.9 (s, p-CH3 of Mes), 6.8 (s, C5(CH3)5). Anal. Calcd for C78H60SN2F24BIr: C, 54.58; H, 3.52; N, 1.63; S, 1.83. Found: C, 54.57; H, 3.82; N, 1.72; S, 2.21. Formation of [Cp*Rh(SDmp)(CNtBu)2](BArF4) (5a). (A) NMR experiment: A 1.0 M CDCl3 solution of tert-butyl isocyanide (20.7 μL, 0.021 mmol) was added to a CDCl3 (0.6 mL, with 1% Si(SiMe3)4 as the internal standard) solution of 2a (15.5 mg, 0.010 mmol) at -40 °C, and the mixture was left at this temperature for 3 h. The 1H NMR spectrum of the resultant yellowish-brown solution revealed the disappearance of 2a and the formation of [Cp*Rh(SDmp)(CNtBu)2](BArF4) (5a; 93% yield based on the internal standard) together with a small amount of unidentified products. (B) Preparative scale: A 1.0 M toluene solution of tert-butyl isocyanide (156.0 μL, 0.156 mmol) was added to a toluene (20 mL) solution of 2a (117.0 mg, 0.078 mmol) at -40 °C, and the mixture was stirred for 1 h. The volatile materials were removed under vacuum at -40 °C, and the residue was washed with hexane (3 mL) to give a yellow solid (114.0 mg) of [Cp*Rh(SDmp)(CNtBu)2](BArF4) (5a) with some impurities. We have been unable to obtain

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satisfactory elemental analysis on this compound. 1H NMR (CDCl3, -40 °C): δ 7.66 (bs, 8H, ArF), 7.50 (bs, 4H, ArF), 7.17 (t, J = 7.4 Hz, 1H, p-H of SC6H3Mes2), 6.95 (m, 6H, m-H of SC6H3Mes2 þ m-H of Mes), 2.31, 2.21 (bs, 6H, o-CH3 of Mes), 2.00 (br, 6H, p-CH3 of Mes), 1.37 (s, 15H, Cp*), 1.21 (bs, 18H, CNtBu). 13C{1H} NMR (CDCl3, -40 °C): δ 161.4 (q, JBC = 48.7 Hz, ipso-C of ArF), 149.8 (br, CNC(CH3)3), 141.1, 140.9, 137.6 (s, Ar), 134.5 (s, o-C of ArF), 130.0 (s, m-C of SC6H3Mes2), 128.5 (q, JFC = 28.4 Hz, m-C of ArF), 128.3 (s, m-C of Mes), 127.1 (s, p-C of SC6H3Mes2), 124.3 (q, JFC = 273.9 Hz, CF3), 117.3 (s, p-C of ArF), 104.3 (s, C5(CH3)5), 59.4 (s, CNC(CH3)3), 30.2 (s, CNC(CH3)3), 21.3 (bs, p-CH3 of Mes), 21.0 (s, o-CH3 of Mes), 8.5 (s, C5(CH3)5). IR (KBr, cm-1): νCN = 2202, 2185. Synthesis of [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b). A 1.0 M toluene solution of tert-butyl isocyanide (143.8 μL, 0.144 mmol) was added to a toluene (20 mL) solution of 2b (100.4 mg, 0.065 mmol), and the mixture was stirred for 3 h at room temperature. The volatile materials were removed under reduced pressure, and the residue was washed with hexane (3 mL) to give a yellow solid. Yellow crystals of [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b) (83.1 mg, 0.049 mmol, 75% yield) were obtained from a CH2Cl2 solution layered with hexane at room temperature. 1H NMR (CDCl3): δ 7.68 (bs, 8H, ArF), 7.52 (bs, 4H, ArF), 7.18 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 6.92 (s, 4H, m-H of Mes), 6.87 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes3), 2.32 (s, 6H, p-CH3 of Mes), 2.16 (bs, 12H, o-CH3 of Mes), 1.49 (s, 15H, Cp*), 1.26 (s, 18H, CNtBu). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.8 Hz, ipso-C of ArF), 149.9 (s, CNC(CH3)3), 141.3, 138.9, 136.2 (s, Ar), 134.8 (s, o-C of ArF), 130.5 (s, m-C of SC6H3Mes2), 129.0 (q, JFC = 31.1 Hz, m-C of ArF), 128.8 (s, m-C of Mes), 127.3 (s, p-C of SC6H3Mes2), 124.5 (q, JFC = 272.8 Hz, CF3), 117.4 (s, p-C of ArF), 100.3 (s, C5(CH3)5), 59.8 (s, CNC(CH3)3), 30.0 (s, CNC(CH3)3), 22.2 (bs, p-CH3 of Mes), 20.9 (s, o-CH3 of Mes), 7.9 (s, C5(CH3)5). IR (KBr, cm-1): νCN = 2198, 2173. Anal. Calcd for C76H70BF24N2SIr: C, 53.62; H, 4.14; N, 1.65; S, 1.88. Found: C, 53.53; H, 4.32; N, 1.79; S, 1.70. Formation of [Cp*Rh(SDmp)(CO)2](BArF4) (6a). An NMR tube equipped with a J-Young valve was charged with 2a (10.0 mg, 0.007 mmol) and CDCl3 (0.6 mL, with 1% Si(SiMe3)4 as the internal standard). After freeze-pump-thaw cycles, 1 atm of CO was charged into the tube at room temperature. The color of the solution immediately became lighter. The 1H NMR spectrum revealed the quantitative formation of [Cp*Rh(SDmp)(CO)2](BArF4) (6a). Removal of CO from the reaction mixture by three freeze-pump-thaw cycles followed by purging with N2 resulted in the regeneration of 2a (94%), leaving a small amount of 6a (6%). Isolation of 6a has not been successful. 1H NMR (CDCl3): δ 7.67 (bs, 8H, ArF), 7.51 (bs, 4H, ArF), 7.45 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 7.11 (d, J = 7.6 Hz, 2H, mH of SC6H3Mes2), 6.95 (s, 4H, m-H of Mes), 2.29 (s, 6H, p-CH3 of Mes), 2.06 (s, 12H, o-CH3 of Mes), 1.54 (s, 15H, Cp*). 13 C{1H} NMR (CDCl3): δ 179.2 (d, JRhC = 63.3 Hz, CO), 160.9 (q, JBC = 49.8 Hz, ipso-C of ArF), 148.4, 138.0, 136.8, 134.7 (s, Ar), 134.0 (s, o-C of ArF), 130.1 (s, m-C of SC6H3Mes2), 129.6 (s, p-C of SC6H3Mes2), 128.1 (q, JFC =32.1 Hz, m-C of ArF), 128.0 (s, m-C of Mes), 123.7 (q, JFC = 272.8 Hz, CF3), 116.7 (s, p-C of ArF), 110.7 (d, JRhC = 3.0 Hz, C5(CH3)5), 20.1 (s, o-CH3 of Mes), 20.0 (s, p-CH3 of Mes), 8.0 (s, C5(CH3)5). IR (CDCl3, cm-1): νCO = 2125, 2100. Synthesis of [Cp*Ir(SDmp)(CO)2](BArF4) (6b). (A) NMR experiment: An NMR tube equipped with a J-Young valve was charged with 2b (10.3 mg, 0.007 mmol) and CDCl3 (0.60 mL, with 1% Si(SiMe3)4 as the internal standard). After freezepump-thaw cycles, 1 atm of CO was charged into the tube at room temperature. The color of the solution immediately turned pink. The 1H NMR spectrum revealed the quantitative formation of [Cp*Ir(SDmp)(CO)2](BArF4) (6b). The NMR signals of 6b were retained after three freeze-pump-thaw cycles followed by purging with N2. (B) Preparative scale: A toluene (20 mL) solution of 2b (101.9 mg, 0.066 mmol) was exposed to 1 atm of

Sakamoto et al. CO via freeze-pump-thaw cycles, and the mixture was stirred for 3 h at room temperature. Slow evaporation of the solvent under reduced pressure gave pink crystals of [Cp*Ir(SDmp)(CO)2](BArF4) 3 (C7H8) (6b 3 C7H8) (108.2 mg, 0.064 mmol, 97% yield). 1H NMR (CDCl3): δ 7.66 (bs, 8H, ArF), 7.51 (bs, 4H, ArF), 7.41 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2), 7.11 (d, J=7.6 Hz, 2H, m-H of SC6H3Mes2), 6.95 (s, 4H, m-H of Mes), 2.29 (s, 6H, p-CH3 of Mes), 2.07 (s, 12H, o-CH3 of Mes), 1.67 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 184.2 (s, CO), 161.6 (q, JBC = 49.8 Hz, ipso-C of ArF), 158.7, 149.0, 138.6, 137.6, 135.5, 133.8 (s, Ar), 134.7 (s, o-C of ArF), 131.0 (s, m-C of SC6H3Mes2), 130.0 (s, p-C of SC6H3Mes2), 128.9 (q, JFC=31.1 Hz, m-C of ArF), 128.9 (s, m-C of Mes), 124.5 (q, JFC=272.8 Hz, CF3), 117.5 (s, p-C of ArF), 107.7 (s, C5(CH3)5), 20.8 (s, o-CH3 of Mes), 15.3 (s, p-CH3 of Mes), 8.1 (s, C5(CH3)5). IR (KBr, cm-1): νCO = 2119, 2084. IR (CDCl3, cm-1): νCO=2116, 2083. Anal. Calcd for C68H52BF24O2SIr 3 C7H8: C, 53.48; H, 3.59; S, 1.90. Found: C, 53.01; H, 3.60; S, 1.84. Synthesis of [Cp*Rh(η4-2,4-nPr2C4H2SDmp)](BArF4) (7a). Complex 2a (101.8 mg, 0.070 mmol), 20 equiv of 1-pentyne (138.7 μL, 0.141 mmol), and dichloromethane (20 mL) were charged into a Schlenk tube, and the mixture was stirred at room temperature for 3 h. The volatile materials were removed under vacuum, and the residue was washed with hexane (3 mL) to give a yellow solid. Yellow crystals of [Cp*Rh(η4-2,4-nPr2C4H2SDmp)](BArF4) (7a) (83.7 mg, 0.053 mmol, 75% yield) were obtained from a CH2Cl2 solution layered with hexane at room temperature. Carbon atoms of η4-2,4-R2C4H2SDmp are numbered as shown below. 1H NMR (CDCl3): δ 7.89 (bs, 8H, ArF), 7.59 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H, ArF), 7.09 (d, J=7.6 Hz, 2H, m-H of SC6H3Mes2), 7.02 (s, 4H, m-H of Mes), 4.43 (s, 1H, H-C2 in SC4H2(C2H4CH3)2), 2.88 (s, 1H, H-C4 in SC4H2(C2H4CH3)2), 2.37 (s, 6H, p-CH3 of Mes), 1.98, 1.93 (s, 6H, o-CH3 of Mes), 1.56 (s, 15H, Cp*), 2.13, 1.68, 1.43, 1.20 (m, 2H, SC4H2(C2H4CH3)2), 1.48, 0.87 (t, J=5.5 Hz, 3H, SC4H2(C2H4CH3)2). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 50.4 Hz, ipso-C of ArF), 141.0, 139.0, 136.1, 134.3 (s, Ar), 134.8 (s, o-C of ArF), 133.5 (s, p-C of SC6H3Mes2), 131.6 (s, m-C of SC6H3Mes2), 128.9 (q, JFC = 30.3 Hz, m-C of ArF), 128.7, 128.6 (s, m-C of Mes), 124.5 (q, JFC=271.5 Hz, CF3), 117.4 (s, p-C of ArF), 99.0 (C3 in SC4H2(C2H4CH3)2), 98.1 (d, JRhC = 5.8 Hz, C5(CH3)5), 75.3 (d, JRhC = 5.8 Hz, C2 in SC4H2(C2H4CH3)2), 65.7 (d, JRhC = 13.0 Hz, C1 in SC4H2(C2H4CH3)2), 43.2 (d, JRhC = 14.4 Hz, C4 in SC4H2(C2H4CH3)2), 29.4, 28.8, 21.3, 20.6 (s, SC4H2(C2H4CH3)2), 21.2 (s, p-CH3 of Mes), 20.9, 20.8 (s, o-CH3 of Mes), 13.9, 13.5 (s, SC4H2(C2H4(CH3)2), 9.3 (s, C5(CH3)5). Anal. Calcd for C78H76SF24BRh: C, 58.00; H, 4.74; S, 1.99. Found: C, 57.80; H, 4.41; S, 1.81.

Synthesis of [Cp*Ir(η4-2,4-nPr2C4H2SDmp)](BArF4) (7b). The synthetic procedure is analogous to that of 7a. The reaction of 2b (109.0 mg, 0.080 mmol) with 1-pentyne (139.9 μL, 1.42 mmol) in dichloromethane (20 mL) afforded a yellow solid, from which [Cp*Ir(η4-2,4-nPr2C4H2SDmp)](BArF4) (7b) (96.4 mg, 0.058 mmol, 72% yield) was obtained as yellow crystals (an Et2O/ hexane solution was used). See above for the numbering of the η4-2,4-R2C4H2S-Dmp ligand. 1H NMR (CDCl3): δ 7.69 (bs, 8H, ArF), 7.61 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H, ArF), 7.03, 7.01 (s, 2H, m-H of Mes) 7.01 (d, J=7.6 Hz, 1H, m-H of SC6H3Mes2), 4.32 (s, 1H, H-C2 in SC4H2(C2H4CH3)2), 3.05 (s, 1H, H-C4 in SC4H2(C2H4CH3)2), 2.36, 1.92 (s, 6H, o-CH3 of Mes), 2.02 (s, 6H, p-CH3 of Mes), 1.66 (s, 15H,

Article


1769

Table 4. Crystal Data for [Cp*M(SDmp)](BArF4) (2a, M = Rh; 2b, M = Ir), [Cp*M(SDmp)(bpy)](BArF4) (3a, M = Rh; 3b, M = Ir), [Cp*M(SDmp)(phen)](BArF4) (4a, M = Rh; 4b, M = Ir), [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b), [Cp*M(η4-2,4-nPr2C4H2SDmp)](BArF4) (7a, M = Rh; 7b, M = Ir), and [Cp*M(η4-2,4-Ph2C4H2SDmp)](BArF4) (8a, M = Rh; 8b, M = Ir)

empirical formula fw cryst color, habit cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z value Dcalcd (g cm-3) μ(Mo KR) (cm-1) max 2θ (deg) no. of reflns measd no. observations (all reflns) no. variables refln/param ratio R1 (I > 2.00σ(I))a wR2 (all reflections)b GOFc on F2

empirical formula fw cryst color, habit cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z value Dcalcd (g cm-3) μ(Mo KR) (cm-1) max 2θ (deg) no. of reflns measd no. observations (all reflns) no variables refln/param ratio R1 (I > 2.00σ(I))a wR2 (all reflections)b GOFc on F2 empirical formula fw cryst color, habit cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z value Dcalcd (g cm-3) μ(Mo KR) (cm-1) max 2θ (deg) no. of reflns measd

2a

2b

3a

C66H52RhSF24B 1446.87 green, block triclinic P1 (No. 2) 13.2119(16) 14.4067(17) 17.253(2) 89.116(4) 87.236(4) 75.225(3) 3171.6(7) 2 1.515 4.127 55 total: 26 045 unique: 13 941 (Rint = 0.032) 13 941 833 16.74 0.0486 0.1394 1.059 3b

C66H52IrSF24B 1536.19 green, block triclinic P1 (No. 2) 13.265(3) 14.381(3) 17.235(3) 89.267(7) 87.527(7) 75.296(4) 3177.1(11) 2 1.606 22.509 55 total: 25 274 unique: 13 941 (Rint = 0.086) 13 941 830 16.80 0.0631 0.1488 0.916 4a

C76H60N2RhSF24B 1603.06 brown, block triclinic P1 (No. 2) 14.345(4) 15.473(4) 17.581(5) 102.956(2) 110.459(4) 91.609(3) 3538.7(18) 2 1.504 3.789 55 total: 27 948 unique: 15 475 (Rint = 0.036) 15 475 977 15.84 0.0627 0.1732 1.058 4b 3 1/2C6H14

C78H60N2RhF24SB 1627.08 brown, block triclinic P1 (No. 2) 14.0447(18) 16.641(2) 17.788(2) 70.042(9) 67.269(8) 77.022(11) 3583.7(8) 2 1.508 3.754 55 total: 28163 unique: 15655 (Rint = 0.017) 15 655 962 16.27 0.0461 0.1293 1.027

C81H67N2IrF24SB 1759.49 brown, block triclinic P1 (No. 2) 12.803(3) 14.759(3) 21.882(5) 75.953(6) 82.947(8) 72.827(7) 3826.6(14) 2 1.527 18.804 55 total: 30187 unique: 16745 (Rint = 0.056) 16 745 959 17.46 0.0677 0.1726 1.063 7b

C76H60N2IrSF24B 1692.37 brown, block triclinic P1 (No. 2) 14.362(3) 15.485(3) 17.547(3) 103.1680(19) 110.4260(17) 91.3870(15) 3537.8(11) 2 1.589 20.304 55 total: 27818 unique: 15434 (Rint = 0.034) 15 434 941 16.40 0.0402 0.1043 1.030 5b C76H74N2IrSF24B 1706.49 yellow, block triclinic P1 (No. 2) 14.072(4) 14.753(4) 20.935(5) 98.802(2) 100.479(2) 113.803(3) 3784.3(16) 2 1.497 18.986 55 total: 31 073 unique: 16 636

6b 3 C6H5CH3

7a

C75H60O2IrF24SB 1684.35 pink, block triclinic P1 (No. 2) 12.391(4) 14.593(4) 20.903(6) 92.797(5) 102.433(7) 97.229(3) 3650.6(19) 2 1.532 19.684 55 total: 29 442 unique: 16 081

C76H68RhF24SB 1583.11 yellow, block triclinic P1 (No. 2) 12.497(4) 15.449(4) 20.125(6) 81.748(9) 77.176(9) 86.299(10) 3747.2(18) 2 1.403 3.560 55 total: 30 825 unique: 16 482

C76H68IrF24SB 1672.42 yellow, block triclinic P1 (No. 2) 12.5495(18) 15.480(2) 20.139(2) 81.869(4) 77.328(4) 86.001(4) 3775.6(9) 2 1.471 19.007 55 total: 30 852 unique: 16 610

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Sakamoto et al. Table 4. Continued

empirical formula fw cryst color, habit cryst syst space group a (A˚) b (A˚) c (A˚)

5b

6b 3 C6H5CH3

7a

7b

C76H74N2IrSF24B 1706.49 yellow, block triclinic P1 (No. 2) 14.072(4) 14.753(4) 20.935(5)

C75H60O2IrF24SB 1684.35 pink, block triclinic P1 (No. 2) 12.391(4) 14.593(4) 20.903(6)

C76H68RhF24SB 1583.11 yellow, block triclinic P1 (No. 2) 12.497(4) 15.449(4) 20.125(6)

C76H68IrF24SB 1672.42 yellow, block triclinic P1 (No. 2) 12.5495(18) 15.480(2) 20.139(2)

Cp*), 1.26, 1.10 (m, 2H, SC4H2(C2H4CH3)2), 1.20, 0.90 (t, J = 7.0 Hz, 2H, SC4H2(C2H4CH3)2), 0.95, 0.81 (t, J = 7.2 Hz, 3H, SC4H2(C2H4CH3)2). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.7 Hz, ipso-C of ArF), 146.5, 140.2, 139.1, 136.3, 136.2, 134.3 (s, Ar), 134.8 (s, o-C of ArF), 133.1 (s, p-C of SC6H3Mes2), 131.7 (s, m-C of SC6H3Mes2), 128.8 (q, JFC =31.5 Hz, m-C of ArF), 128.7, 128.6 (s, m-C of Mes), 124.5 (q, JFC = 271.9 Hz, CF3), 117.4 (s, p-C of ArF), 92.9 (s, C5(CH3)5), 89.3 (s, C3 in SC4H2(C2H4CH3)2), 77.0 (s, C2 in SC4H2(C2H4CH3)2), 66.8 (s, C4 in SC4H2(C2H4CH3)2), 57.0 (s, C1 in SC4H2(C2H4CH3)2), 29.5, 29.2, 21.9, 20.7 (s, SC4H2(C2H4CH3)2), 21.3 (s, p-CH3 of Mes), 21.0, 20.9 (s, o-CH3 of Mes), 13.9, 13.4 (s, SC4H2(C2H4(CH3)2), 9.2 (s, C5(CH3)5). Anal. Calcd for C78H76SF24BIr: C, 54.58; H, 4.10; S, 1.92. Found: C, 54.96; H, 4.15; S, 1.92. Synthesis of [Cp*Rh(η4-2,4-Ph2C4H2SDmp)](BArF4) (7c). The synthetic procedure is analogous to that of 7a. The reaction of 2a (101.6 mg, 0.070 mmol) with phenylacetylene (154.2 μL, 0.140 mmol) in dichloromethane (20 mL) gave a yellow solid, from which [Cp*Rh(η4-2,4-Ph2C4H2SDmp)](BArF4) (7c) (96.4 mg, 0.057 mmol, 82% yield) was obtained as yellow crystals. See above for the numbering of the η4-2,4-R2C4H2SDmp ligand. 1H NMR (CDCl3): δ 7.70 (bs, 8H, ArF), 7.60 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H, ArF), 7.41, 7.28 (t, J = 7.7 Hz, 2H, m-H of Ph), 7.36, 7.22 (m, 1H, p-H of Ph), 7.11 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes2), 7.08, 6.79 (d, J = 7.7 Hz, 2H, o-H of Ph), 6.91, 6.81 (s, 2H, m-H of Mes), 5.36 (s, 1H, H-C2 in SC4H2Ph2), 3.67 (s, 1H, H-C4 in SC4H2Ph2), 2.36 (s, 6H, p-CH3 of Mes), 1.92, 1.62 (s, 6H, o-CH3 of Mes), 1.11 (s, 15H, Cp*). 13 C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 50.0 Hz, ipso-C of ArF), 142.2, 139.7, 138.8, 136.4, 135.9 (s, Ar), 134.8 (s, o-C of ArF), 134.1 (s, p-C of SC6H3Mes2), 131.5 (s, m-C of SC6H3Mes2), 130.1, 129.9 (s, ipso-C of Ph), 129.7, 128.0 (s, p-C of Ph), 129.4, 129.3 (s, o-C of Ph), 129.0, 128.6 (s, m-C of Mes), 128.8 (q, JFC = 33.3 Hz, m-C of ArF), 124.6, 124.4 (s, m-C of Ph), 124.5 (q, JFC = 272.7 Hz, CF3), 117.4 (s, p-C of ArF), 98.7 (d, JRhC = 5.8 Hz, C5(CH3)5), 95.3 (d, JRhC = 6.4 Hz, C3 in SC4H2Ph2), 71.1 (d, JRhC = 6.4 Hz, C2 in SC4H2Ph2), 63.0 (d, JRhC = 13.0 Hz, C1 in SC4H2Ph2), 40.0 (d, JRhC = 14.5 Hz, C4 in SC4H2Ph2), 21.4, 21.0 (s, o-CH3 of Mes), 20.8 (s, p-CH3 of Mes), 8.2 (s, C5(CH3)5). Anal. Calcd for C84H72SF24BRh: C, 59.94; H, 4.31; S, 1.90. Found: C, 59.91; H, 3.93; S, 1.97. Synthesis of [Cp*Ir(η4-2,4-Ph2C4H2SDmp)](BArF4) (7d). The synthetic procedure is analogous to that of 7a. The reaction of 2b (115.5 mg, 0.075 mmol) with phenylacetylene (165.2 μL, 1.50 mmol) in dichloromethane (20 mL) afforded a yellow solid, from which [Cp*Ir(η4-2,4-Ph2C4H2SDmp)](BArF4) (7d) (105.9 mg, 0.060 mmol, 79% yield) was obtained as yellow crystals (a THF/hexane solution was used). See above for the numbering of the η4-2,4-R2C4H2SDmp ligand. 1H NMR (CDCl3): δ 7.69 (bs, 8H, ArF), 7.63 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H, ArF), 7.39, 7.26 (t, J = 8.1 Hz, 2H, m-H of Ph), 7.34, 7.21 (m, 1H, p-H of Ph), 7.13 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes2), 7.05, 6.75 (d, J = 8.0 Hz, 2H, o-H of Ph), 6.89, 6.86 (s, 2H, m-H of Mes), 5.23 (s, 1H, H-C2 in SC4H2Ph2), 3.93 (s, 1H, H-C4 in SC4H2Ph2), 2.36 (s, 6H, p-CH3 of Mes), 1.92, 1.62 (s, 6H, o-CH3 of Mes), 1.21 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 50.7 Hz, ipso-C of ArF), 143.8, 142.1, 138.9, 136.4, 136.0 (s, Ar), 134.8 (s, o-C of ArF), 133.9 (s, p-C of SC6H3Mes2), 131.7 (s, m-C of SC6H3Mes2), 131.2, 130.5

(s, ipso-C of Ph), 129.4, 127.9 (s, p-C of Ph), 129.3, 129.2 (s, o-C of Ph), 128.9, 128.7 (s, m-C of Mes), 128.9 (q, JFC=32.4 Hz, m-C of ArF), 124.6, 124.4 (s, m-C of Ph), 124.5 (q, JFC = 287.9 Hz, CF3), 117.4 (s, p-C of ArF), 93.5 (s, C5(CH3)5), 85.4 (s, C3 in SC4H2Ph2), 77.2 (s, C2 in SC4H2Ph2), 62.8 (s, C4 in SC4H2Ph2), 52.2 (s, C1 in SC4H2Ph2), 25.4, 20.8 (s, o-CH3 of Mes), 21.1 (s, pCH3 of Mes), 8.1 (s, C5(CH3)5). Anal. Calcd for C84H72SF24BIr: C, 56.59; H, 3.71; S, 1.84. Found: C, 56.69; H, 3.90; S, 1.75. X-ray Structural Determination. Crystal data and refinement parameters for complexes 2a, 2b, 3a, 3b, 4a, 4b, 5b, 6b, 7a, and 7b are summarized in Table 4. Single crystals were coated with oil (immersion oil, type B: code 1248, Cargille Laboratories, Inc.) and mounted on loops. Diffraction data were collected at -100 °C under a cold nitrogen stream on a Rigaku AFC8 equipped with a Saturn CCD detector (2a, 5b, 6b, 7a, 7b) or a Rigaku AFC8 equipped with a Mercury CCD detector (2b, 3a, 3b, 4a, 4b) equipped with a graphite-monochromatized Mo KR source (λ = 0.71070 A˚). Six preliminary data frames were measured at 0.5° ω increments, to assess the crystal quality and preliminary unit cell parameters. The intensity images were also measured at 0.5° intervals of ω. The frame data were integrated using the CrystalClear program package, and the data sets were corrected for absorption using the REQAB program. The calculations were performed with the CrystalStructure program package. Structures were solved by Patterson methods (2a, 2b, 4a, 4b, 5b, 6b, 7a, 7b) or direct methods (3a, 3b) and refined by full-matrix least-squares procedures on F2. Anisotropic refinement was applied to all non-hydrogen atoms except for disordered CF3 groups of BArF4 anions and crystal solvents. All of the hydrogen atoms except for the 2,4-nPr2C4H2SDmp group in 7a and 7b were placed at calculated positions. The hydrogen atoms in the 2,4-nPr2C4H2SDmp group in 7a and 7b were located in each Fourier map and were refined isotropically. The R value for 7a is relatively high (R1 = 9.20%) owing to the disorders found for the propyl groups of the 2,4-nPr2C4H2SDmp ligand and the CF3 groups of the BArF4 anion. The propyl groups of the 2,4-nPr2C4H2SDmp ligand in 7a and 7b were disordered over two positions with occupancy factors of 50:50. Two CF3 groups in 2a, 3a, 3b, 5b, and 7b, three CF3 groups in 2b, one CF3 group in 4a and 7a, and five CF3 groups in 4b and 6b were disordered over two positions with occupancy factors of 50:50. One of the CF3 groups in 4b and 7b and three CF3 groups in 7a were disordered over two positions with occupancy factors of 70:30. One of the CF3 groups in 5b, two CF3 groups in 6b and 7a, and three CF3 groups in 7b were disordered over three positions. The atomic coordinates are available as a CIF file. Supporting Information Available: An X-ray crystallographic information file (CIF) is available free of charge via the Internet at http://pubs.acs.org.

Acknowledgment. This research was financially supported by a Grant-in-Aid for Scientific Research (Nos. 18GS0207, 18064009, and 20613004) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. We thank Prof. Roger E. Cramer at the University of Hawaii for fruitful discussions and for careful reading of the manuscript.

Synthesis and Reactions of Coordinatively Unsaturated Half

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