Heterobimetallic Cr−Mn Complexes of Fused Arenes - ACS Publications

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Organometallics 2009, 28, 3004–3011

Heterobimetallic Cr-Mn Complexes of Fused Arenes: Chromium-Templated Benzannulation of a Cymanthrene-Type Metal Carbene and Haptotropic Metal Migration along a Dibenzo[c,e]indene Platform† Julien Dubarle Offner,‡ Roland Fro¨hlich,§ Olga Kataeva,§ Franc¸oise Rose-Munch,| Eric Rose,*,| and Karl Heinz Do¨tz*,‡ Kekule´-Institut fu¨r Organische Chemie and Biochemie, Rheinische Friedrich-Wilhelms-UniVersita¨t Bonn, Gerhard-Domagk-Strasse 1, D-52121 Bonn, Germany, Organisch-Chemisches Institut der UniVersita¨t, Westfa¨lische Wilhelms-UniVersita¨t Mu¨nster, Correns-Strasse 40, 48149 Mu¨nster, Germany, and Laboratoire de Chimie Organique, IPCM, UMR CNRS 7201, UniVersite´ Pierre et Marie Curie, Paris 6, Tour 44 1er e´tage, BP 181, 4, Place Jussieu, F-75252 Paris Cedex 05, France ReceiVed February 5, 2009

The chromium-templated benzannulation of the chromium cymanthrene-type carbene 3 with 3-hexyne affords the heterobimetallic chromium-manganese hydroquinoid dibenzo[c,e]indene complexes anti-4 and syn-5, in which the chromium entities are coordinated regioselectively to the hydroquinoid ring. Both diastereomers undergo a thermoinduced haptotropic migration of the chromium moiety to give their haptotropomers anti-6 and syn-7 in comparable yields, independent of the relative configuration of both metal centers, while the manganese fragment remains coordinated to the cyclopentadienyl ring. The molecular structures of all heterobimetallic complex structures were established by X-ray analysis. A kinetic NMR study of the chromium migration revealed first-order kinetics for the anti complex 4, supporting the intramolecular nature of the metal rearrangement. Introduction Arenes coordinated to transition metals represent a wellestablished class of organometallic compounds.1 For application to organic synthesis in particular, chromium2-5 and manganese6,7 complexes have been intensively investigated over the years, and their chemistry is well-known and developed. However, reports on heterobimetallic chromium-manganese complexes * To whom correspondence should be addressed. E-mail: doetz@ uni-bonn.de (K.H.D.); [email protected] (E.R.). † Dedicated to Professor Christoph Elschenbroich on the occasion of his 70th birthday. ‡ Rheinische Friedrich-Wilhelms Universita¨t Bonn. § Westfa¨lische Wilhelms-Universita¨t Mu¨nster. | Universite´ Pierre et Marie Curie. (1) For reviews, see: (a) McQuillin, F. J.; Parker, D. G.; Stephenson, G. R. Transition Metal Organometallics for Organic Synthesis; Cambridge University Press: Cambridge, U.K., 1991. (b) Morris, M. J. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Labinger, J. A., Winter, M. J., Vol. Eds.; Pergamon: Oxford, U.K., 1995; Vol. 5, Chapter 8, p 471. (c) Ku¨ndig, E. P. Topics in Organometalllic Chemistry; Springer: Berlin, Germany, 2004; Vol. 7. (2) For reviews about chromium complexes, see: (a) Rose-Munch, F.; Rose, E. In Modern Arene Chemistry; Astruc, D., Ed.; Wiley-VCH: New York, 2002; Chapter 11, p 368. (b) Rose-Munch, F.; Rose, E. Eur. J. Inorg. Chem. 2002, 1269. (c) Ku¨ndig, E. P.; Pache, S. H. Arene Organometallic Complexes of Chromium, Molybdenum and Tungsten. In Science of Synthesis; Imamoto, T., Ed.; Thieme: Stuttgart, Germany, 2002; Vol. 2, p 155. (d) McGlinchey, M. J.; Ortin, Y.; Seward, C. M. Chromium Compounds with CO or Isocyanides. In ComprehensiVe Organometallic Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier Science: Oxford, U.K., 2006; Vol. 5, p 201. (3) (a) Mahaffy, C. A. L.; Pauson, P. L. Inorg. Synth. 1979, 19, 154. (b) Desobry, V.; Ku¨ndig, E. P. HelV. Chim. Acta 1981, 64, 1288. (c) Ku¨ndig, E. P.; Grivet, C.; Spichiger, S. J. Organomet. Chem. 1987, 332, C13. (d) Zhang, S.; Shen, J. K.; Basolo, F.; Ju, T. D.; Lang, R. F.; Kiss, G.; Hoff, C. D. Organometallics 1994, 13, 3692. (e) Arrais, A.; Dana, E.; Gervasio, G.; Gobetto, R.; Marabello, D.; Stanghellini, P. L. Eur. J. Inorg. Chem. 2004, 1505. (f) Mo¨hring, D.; Nieger, M.; Lewall, B.; Do¨tz, K. H. Eur. J. Org. Chem. 2005, 2620.

are still quite rare so far,8 although heterobimetallic compounds have received considerable attention, since they allow detailed studies of a potential interaction or cooperation of both metal moieties, which may result in a tuning of individual metal properties.9 (4) For reviews about the haptotropic migration, see: (a) Do¨tz, K. H. Angew. Chem., Int. Ed. Engl. 1984, 23, 587; Angew. Chem. 1984, 96, 573. (b) Ustynyuk, N. A. Organomet. Chem. USSR 1989, 2, 20-26; Metalloorg. Khim. 1989, 2, 43-53; Chem. Abstr. 1989, 111, 115236. (c) Semmelhack, M. F. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995; Vol. 12, Chapter 9, p 979. (d) Wulff, W. D. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995; Vol. 12, pp 469-547. (e) Morris, M. J. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Labinger, J. S., Winter, M. J., Vol. Eds.; Pergamon: Oxford, U.K., 1995; Vol. 5, pp 501-504. (f) Do¨tz, K. H.; Tomuschat, P. Chem. Soc. ReV. 1999, 28, 187. (g) Oprunenko, Y. F. Russ. Chem. ReV. 2000, 69, 683-704; Usp. Khim. 2000, 69, 744-746; Chem. Abstr. 2000, 134, 178576. (h) Do¨tz, K. H.; Stendel, J., Jr. In Modern Arene Chemistry; Astruc, D., Ed.; Wiley-VCH: Weinheim, Germany, 2002; pp 250-296. (i) Do¨tz, K. H.; Jahr, H. C. Chem. Rec. 2004, 4, 61. (j) Minatti, A.; Do¨tz, K. H. Top. Organomet. Chem. 2004, 13, 123. (k) Do¨tz, K. H.; Wenzel, B.; Jahr, H. C. Top. Curr. Chem. 2004, 248, 63–103. ¨ fele, K. J. Organomet. (5) (a) Deubzer, B.; Fritz, H. P.; Kreiter, C. G.; O ¨ fele, K.; Willeford, B. J. Am. Chem. 1967, 7, 289. (b) Cunningham, S. D.; O Chem. Soc. 1983, 105, 3724. (c) Do¨tz, K. H.; Dietz, R. Chem. Ber. 1977, 110, 1555. (d) Kirss, R. U., Jr.; Treichel, P. M. J. Am. Chem. Soc. 1986, 108, 853. (e) Ku¨ndig, E. P.; Desobry, V.; Rivet, C.; Rudolph, B.; Splicher, S. Organometallics 1987, 6, 1173. (f) Oprunenko, Y. F.; Malyugina, S. G.; Ustynyuk, Y. A.; Ustynyuk, N. A.; Kravtsov, D. N. J. Organomet. Chem. 1988, 338, 357. (g) Do¨tz, K. H.; Stinner, C. Tetrahedron: Asymmetry 1997, 8, 1751. (h) Paetsch, D.; Do¨tz, K. H. Tetrahedron Lett. 1999, 40, 487. (i) Oprunenko, Y. F.; Malyugina, S.; Nesterenko, P.; Mityuk, D.; Malyshev, O. J. Organomet. Chem. 2000, 597, 42. (j) Jahr, H. C.; Nieger, M.; Do¨tz, K. H. J. Organomet. Chem. 2002, 641, 185. (k) Do¨tz, K. H.; Szesni, N.; Nieger, M.; Na¨ttinen, K. J. Organomet. Chem. 2003, 671, 58. (l) Jahr, H. C.; Do¨tz, K. H. Chem. Rec. 2004, 4, 61. (m) Jahr, H. C.; Nieger, M.; Do¨tz, K. H. Chem. Eur. J. 2005, 11, 5333. (n) Do¨tz, K. H.; Stendel, J., Jr.; Mu¨ller, S.; Nieger, M.; Ketrat, S.; Dolg, M. Organometallics 2005, 24, 3219.

10.1021/om900090q CCC: $40.75  2009 American Chemical Society Publication on Web 05/01/2009

Cr-Mn Complexes of Fused Arenes

Therefore, we decided to develop a novel type of heterobimetallic Cr-Mn complexes in which both metals are coordinated to an extended arene π system in a syn or anti configuration. We concentrated on the dibenzo[c,e]indene platform, which offers a choice of different coordination sites for the metal fragments. Due to the polyarene nature of this ligand, the π electrons are delocalized on this platform and (6) For reviews about manganese complexes, see: (a) Semmelhack, M. F. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995; Vol. 12, Chapter 9, p 979. (b) McDaniel, K. F. In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995; Vol. 6, pp 93-107. (c) Oshima, K. Organometallic Complexes of Manganese. In Science of Synthesis; Imamoto, T., Ed.; Thieme: Stuttgart, Germany, 2002; Vol. 2, p 13. (d) Sweigart, D. A.; Reingold, J. A.; Son, S. U. Manganese Compounds with CO Ligands. In ComprehensiVe Organometallic Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier Science: Oxford, U.K., 2006; Vol. 5, p 761. (7) (a) King, R. B.; Efraty, A. J. Organomet. Chem. 1970, 23, 527. (b) Treichel, P. M.; Johnson, J. W. Inorg. Chem. 1977, 16, 749. (c) Resek, M. E.; Basolo, F. Organometallics 1984, 3, 647. Ji, L.-J.; Resek, M. E.; Basolo, F. Organometallics 1984, 3, 740. (d) Biagioni, R. N.; Lorkovic, I. M.; Skelton, J.; Hartung, J. B. Organometallics 1990, 9, 547. Biagioni, R. N.; Luna, A. D.; Murphy, J. L. J. Organomet. Chem. 1994, 476, 183. (e) Jackson, J. D.; Villa, S. J.; Bacon, D. S.; Pryke, R. D.; Carpenter, G. B. Organometallics 1994, 13, 3972. (f) Sun, S.; Yeung, L. K.; Sweigart, D. A.; Lee, T.-Y.; Lee, S. S.; Chung, Y. K.; Switzer, S. R.; Pike, R. D. Organometallics 1995, 14, 2613. (g) Veiros, L. F. J. Organomet. Chem. 1999, 587, 221. Veiros, L. F. Organometallics 2000, 19, 3127. (h) Veauthier, J. M.; Chow, A.; Fraenkel, G.; Geib, S. J.; Cooper, N. J. Organometallics 2000, 19, 261. Veauthier, J. M.; Chow, A.; Fraenkel, G.; Geib, S. J.; Cooper, N. J. Organometallics 2000, 19, 3942. (i) Reginato, N.; McGlinchey, M. J. Organometallics 2001, 20, 4147. (j) Son, S. U.; Paik, S.-J.; Park, K. H.; Lee, Y.-A.; Lee, I. S.; Chung, Y. K.; Pike, D. A. Organometallics 2002, 21, 239. (k) Decken, A.; MacKay, A. J.; Brown, M. J.; Bottomley, F. Organometallics 2002, 21, 2006. (l) Rose-Munch, F.; Rose, E. Eur. J. Inorg. Chem. 2002, 1269. (m) Auffrant, A.; Prim, D.; Rose-Munch, F.; Rose, E.; Schouteeten, S.; Vaissermann, J. Organometallics 2003, 22, 1898. (n) Oh, M.; Reingold, J. A.; Carpenter, G. B.; Sweigart, D. A. Coord. Chem. ReV. 2004, 264, 561. (o) Reingold, J. A.; Virkaitis, K. L.; Carpenter, G. B.; Sun, S.; Sweigart, D. A.; Czech, P. T.; Overly, K. R. J. Am. Chem. Soc. 2005, 127, 11146. (p) Snyder, C. A.; Selegue, J. P.; Tice, N. C.; Wallace, C. E.; Blankenbuehler, M. T.; Parkin, S.; Allen, K. D. E.; Beck, R. T. J. Am. Chem. Soc. 2005, 127, 15010. (q) Jacques, B.; Chavarot, M.; Rose-Munch, F.; Rose, E. Inorg. Chem. 2005, 44, 5941. (r) Jacques, B.; Chavarot, M.; Rose-Munch, F.; Rose, E. Angew. Chem., Int. Ed. 2006, 45, 3481. (s) Pammer, F.; Sun, Y.; May, C.; Wolmersha¨user, G.; Kelm, H.; Kru¨ger, H.J.; Thiel, W. R. Angew. Chem. Int. Ed. 2007, 46, 1270. (t) Jacques, B.; Chanaewa, A.; Chavarot-Kerlidou, M.; Rose-Munch, F.; Rose, E.; Ge´rard, H. Organometallics 2008, 27, 626. (u) Cetiner, D.; Tranchier, J.-P.; RoseMunch, F.; Rose, E.; Herson, P. Organometallics 2008, 27, 784. (8) (a) Bitterwolf, T. E.; Raghuveer, K. S. Inorg. Chim. Acta 1990, 172, 59. (b) Clark, G. R.; Metzler, M. R.; Whitaker, G.; Woodgate, P. D. J. Organomet. Chem. 1996, 513, 109. (c) Lee, S. S.; Lee, T.-Y.; Lee, J. E.; Chung, Y. K.; Lah, M. S. Organometallics 1996, 15, 3664. (d) Djukic, J.-P.; Maisse, A.; Pfeffer, M.; de Cian, A.; Fischer, J. Organometallics 1997, 16, 657. Djukic, J.-P.; Maisse, A.; Pfeffer, M.; Do¨tz, K. H.; Nieger, M. Eur. J. Inorg. Chem. 1998, 1781. (e) Tamm, M.; Bannenberg, T.; Baum, K.; Fro¨hlich, R.; Steiner, T.; Meyer-Friedrichsen, T.; Heck, J. Eur. J. Inorg. Chem. 2000, 1161. (f) Schouteeten, S.; Tranchier, J.-P.; Rose-Munch, F.; Rose, E.; Auffrant, A.; Stephenson, G. R. Organometallics 2004, 23, 4308. (g) Djukic, J.-D.; Michon, C.; Berger, A.; Pfeffer, M.; de Cian, A.; Kyritsakas-Gruber, N. J. Organomet. Chem. 2006, 691, 846. (h) Dubarle Offner, J.; Schakenburg, G.; Rose-Munch, F.; Rose, E.; Do¨tz, K. H. Manuscript in preparation. (9) (a) Li, J.; Hunter, A. D.; McDonald, R.; Santarsiero, B. D.; Bott, S. G.; Atwood, J. L. Organometalllics 1992, 11, 3050. (b) Sun, S.; Dullaghan, C. A.; Carpenter, G. B.; Rieger, A. L.; Rieger, P. H.; Sweigart, D. A. Angew. Chem., Int. Ed. Engl. 1995, 34, 2540. (c) Quian, C.; Guo, J.; Sun, J.; Chen, J.; Zheng, P. Inorg. Chem. 1997, 36, 1286. (d) Prim, D.; Andrioletti, B.; Rose-Munch, F.; Rose, E.; Couty, F. Tetrahedron 2004, 60, 3325. (e) Jacques, B.; Tranchier, J.-P.; Rose-Munch, F.; Rose, E.; Stephenson, G. R.; Guyard-Duhayon, C. Organometallics 2004, 23, 184. (f) Bitta, J.; Fassbender, S.; Reiss, G.; Frank, W.; Ganter, C. Organometallics 2005, 24, 5176. (g) Bennewitz, J.; Nieger, M.; Lewall, B.; Do¨tz, K. H. J. Organomet. Chem. 2005, 690, 5892. (h) Packheiser, R.; Walfort, B.; Lang, H. Organometallics 2006, 25, 4579. (i) Li, M.; Riache, N.; Tranchier, J.P.; Rose-Munch, F.; Rose, E.; Herson, P.; Bossi, A.; Rigamonti, C.; Licandro, E. Synthesis 2007, 2, 277. (j) Djukic, J.-P.; Hijazi, A.; Flack, H. D.; Bernardinelli, G. Chem. Soc. ReV. 2008, 37, 406.

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shared with the two metal units. Following our interest in haptotropic migration reactions of a chromium fragment along one π face of extended arene skeletons,4,5 we investigated this intramolecular rearrangement of the chromium moiety in the presence of a second metal unit.

Results and Discussion Synthesis and Benzannulation of a Cymanthrene-Type Chromium Carbene. The synthesis of the heterobimetallic dibenzo[c,e]indene complexes was based on a two-step procedure, the chromium carbene functionalization10 of a cymanthrene-type precursor bearing the Mn(CO)3 fragment and its chromium-templated benzannulation,11 which allows for the regioselective labeling of the newly formed hydroquinoid ring. The starting material 1e for the cymanthrene-type complex 2, 8-bromobenzo[e]-1H-indene, was prepared from 1,4-dibromonaphthalene in a five-step sequence (Scheme 1).12 A lithium-bromide exchange of one bromide followed by silylation gave bromo(trimethylsilyl)naphthalene (1a). Subsequent inter- and intramolecular Friedel-Crafts reactions with 3-chloropropionyl chloride afforded 5-bromo-2,3-dihydrobenzo[e]inden-1-one (1c). Reduction of the ketone to the secondary alcohol and its dehydration, performed under mild conditions in order to avoid formation of a dimeric byproduct, afforded 8-bromobenzo[e]-1H-indene (1e), which was accessible from 1,4dibromonaphthalene in an overall isolated yield of 57%. Scheme 1. Synthesis of 8-Bromobenzo[e]-1H-indene (1e)a

a (a) (1) n-BuLi, Et O, -20 °C, 2 h, (2) TMSCl, room temperature, 2 15 min, 99%; (b) AlCl3, ClCH2CH2(O)Cl, DCM, -78 °C to room temperature, 100 min, 96%; (c) AlCl3/H2SO4, 70 to 98 °C, 3 h, 83%; (d) NaBH4, toluene/ethanol 5:3, room temperature, overnight, 99%; (e) p-TSOH, toluene, 50 °C, 15 min, 73%.

Reflecting the presence of the bromo substituent susceptible to halide-metal exchange, we modified the experimental procedures reported for the complexation of indene to the manganese tricarbonyl unit.7a,k We favored the desired deprotonation by choosing a weaker base, potassium hydride, at room temperature in absolute THF, which resulted in the isolation of tricarbonyl{η5-1,2,3,3a,9a-(8-bromobenzo[e]indenyl)}manganese (2) as a yellow powder in 40% yield (Scheme 2). In comparison to 8-bromobenzo[e]-1H-indene (1e) the η5 coordination of the terminal ring is indicated by upfield shifts of 1.4-2.3 ppm for hydrogen atoms H2-H3 and a downfield shift (10) (a) Fischer, E. O.; Maasbo¨l, A. Angew. Chem. Int. Ed. Engl. 1964, 3, 580. (b) Fischer, E. O. Auf dem Weg zu Carben- und Carbin-Komplexen (Nobel Lecture). Angew. Chem. 1974, 86, 651–663. (11) (a) Do¨tz, K. H. Angew. Chem. Int. Ed. Engl. 1975, 14, 644. (b) Do¨tz, K. H.; Dietz, R.; Neugebauer, D. Chem. Ber. 1979, 112, 1486. (12) Bennewitz, J. Dissertation, University of Bonn, July 2007.

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Dubarle Offner et al.

of 1.3-1.4 ppm for H1. The cyclopentadiene carbon atom C1 is deshielded by 40 ppm, whereas the carbon atoms C2/C3 and C3a/C9b are shielded by 42-62 and 40-42 ppm, respectively. Moreover, the incorporation of the Mn(CO)3 fragment is supported by an additional 13C NMR signal at 224.9 ppm and typical IR bands at 2025 (s) and 1946 (vs) cm-1, as expected for local C3V symmetry. Scheme 2. Synthesis of {8-Bromobenzo[e]indenyl}manganese Complex 2

Lithiation of manganese complex 2 with n-butyllithium and addition of hexacarbonylchromium followed by O-alkylation of the resulting acyl chromate by methyl triflate afforded bimetallic tricarbonyl{pentacarbonyl[8-benzo[e]indenyl-(methoxy)carbene]chromium[η5-1,2,3,3a,9a]}manganese (3) as a dark red solid in 50% isolated yield (Scheme 3). The reaction was monitored by IR spectroscopy, which demonstrated that under these conditions the desired bromide-lithium exchange was faster than any competing nucleophilic addition of organolithium reagents to the manganese-coordinated carbonyl ligands. Scheme

3.

Synthesis of {(Benzo[e]indenyl)manganese}chromium Carbene 3

Dark red crystals have been grown in dichloromethane at 4 °C by slow evaporation. Complex 3 crystallizes in the triclinic system, and the lattice belongs to the symmetry space group P1j. The benz[e]indene establishes almost a plane with a torsion angle φ(C1-C13-C12-C9) ) 2.0(7)°. The manganese is centered over the cyclopentadienyl ring with a mean distance of 2.155(4) Å to the five sp2 carbon atoms. The syn orientation of the chromium carbonyl fragment relative to the Mn(CO)3 moiety may be caused by packing effects; IR studies in solution indicate a free rotation of the chromium carbene unit around the C5-C14 bond (Figure 1 and Table 1). The cymanthrene-type Fischer carbene complex 3 undergoes a clean benzannulation with 3-hexyne upon warming in refluxing tert-butyl methyl ether. The two diastereomers anti-4 and syn-5 could be isolated after in situ O-protection by tert-butyldimethylsilyl chloride in 51% and 21% yield (Scheme 4). Scheme

4. Chromium-Templated Benzannulation Cymanthrene-Type Chromium Carbene 3

of

Although both diastereomeric complexes clearly differ in their structure, they reveal nearly similar 1H and 13C NMR spectra and furthermore show indistinguishable ν(CO) IR absorption

Figure 1. Molecular structure of cymanthrene-type chromium carbene 3. The numbering of atoms differs from that used in the NMR characterization. Hydrogen atoms are omitted for clarity. Torsion angle φ(C1-C13-C12-C9) ) 2.0(7)°. Selected bond lengths (Å): Mn-C1 ) 2.141(4), Mn-C2 ) 2.120(4), Mn-C3 ) 2.130(4), Mn-C10 ) 2.186(4), Mn-C13 ) 2.198(4).

bands, which suggests the absence of any significant communication of both metal centers. The elucidation of the molecular structures of heterobimetallic complexes 4 and 5 was based on X-ray crystallography. Suitable dark red single crystals of both diastereomers were grown from dichloromethane at 4 °C and analyzed as monoclinic with the symmetry space group P21/c for 4 (Figure 2 and Table 1) and P21/n for 5 (Figure 3 and Table 1). The manganese-Cp entity is unaffected by the additional hydroquinone-Cr(CO)3 fragment. The mean bond length between the manganese atom and the five carbon atoms of the cyclopentadienyl ring is identical with that observed for the chromium carbene precursor 3, all around 2.155(4) Å. This indicates that the electronic environment of the manganese moiety does not respond either to the extension of the arene platform and the additional chromium functionality or to the distances of both metal fragments, which distinctly differ in the anti and syn diastereomeric complexes 4 and 5. The mean bond length between the chromium atom and five carbon atoms (C4, C5, C6, C7, C7A) of the hydroquinoid ring in complex 4 (2.246(3) Å) is similar to Cr-C bond distances typically observed in (arene)Cr(CO)3 complexes.13 However, the Cr-C4A bond is distinctly longer (2.329 Å), which mainly results from the nonplanarity of the tetracyclic arene platform, as illustrated by the peripheral torsion angles. In the literature the distances between the Cr atom and the carbon atoms of aromatic rings have been studied. Indeed, a (13) (a) Kunz, V.; Nowacki, W. HelV. Chim. Acta 1967, 50, 1052. (b) van Meurs, F.; van der Toorn, J. M.; van Bekkum, H. J. Organomet. Chem. 1976, 113, 341. (c) van Meurs, F.; van Koningsveld, H. J. Organomet. Chem. 1976, 118, 295. (d) Boutonnet, J. C.; Le Martret, O.; Mordenti, L.; Rose, E.; Precigoux, G. J. Organomet. Chem. 1981, 221, 147. (e) Boutonnet, J. C.; Levisalles, J.; Rose, E.; Precigoux, G.; Courseille, C.; Platzer, N. J. Organomet. Chem. 1983, 255, 317. (f) Boutonnet, J. C.; Levisalles, J.; RoseMunch, F.; Rose, E. J. Organomet. Chem. 1985, 290, 153. (g) Boutonnet, J. C.; Rose-Munch, F.; Rose, E.; Jeannin, Y.; Robert, F. J. Organomet. Chem. 1985, 297, 185. (h) Rose-Munch, F.; Rose, E.; Semra, A.; PhilocheLevisalles, M. J. Organomet. Chem. 1989, 363, 297. (i) Onlsson, B.; Ullenius, C.; Jaguer, S.; Grivet, C.; Wenger, E.; Ku¨ndig, E. P. J. Organomet. Chem. 1989, 365, 243. (j) Rose-Munch, F.; Aniss, K.; Rose, E.; Vaissermann, J. J. Organomet. Chem. 1991, 415, 223. (k) Schmalz, H.-G.; Millies, B.; Bats, J. W.; Du¨rner, G. Angew. Chem., Int. Ed. Engl. 1992, 31, 631. (l) Rose-Munch, F.; Rose, E.; Djukic, J.-P.; Vaissermann, J. Eur. J. Inorg. Chem. 2000, 1295. (m) Cumming, G. R.; Bernardinelli, G.; Ku¨ndig, E. P. Chem. Asian J. 2006, 1, 459.

Cr-Mn Complexes of Fused Arenes

Organometallics, Vol. 28, No. 10, 2009 3007

Table 1. Crystal Data and Structure Refinement Parameters for Heterobimetallic Cr-Mn Complexes 3-7 3 empirical formula formula wt temp (K) wavelength (Å) cryst syst Space group unit cell dimens a (Å) b (Å) c (Å) R (deg) β (deg) γ (deg) V (Å3) Z Dcalcd (Mg/m3) µ (mm-1) F(000) cryst size (mm) diffractometer θ range (deg) limiting indices

no. or rflns collected/unique refinement method no. of data/restraints/params goodness of fit on F2 final R indices (I > 2σ(I)) R indices (all data) largest diff peak and hole (e Å-3)

4

5

C23H11CrMnO9 538.26 223(2)

C34H35CrMnO8Si · CH2Cl2 706.65-84.93 198(2)

triclinic P1j (No. 2)

monoclinic P21/c (No. 14)

C34H35CrMnO8Si · CH2Cl2 706.65-84.93 223(2) 0.710 73 monoclinic P21/c (No. 14)

6.760(1) 7.520(1) 21.444(1) 85.86(1) 183.38(1) 88.90(1) 1080.0(2) 2 1.655 1.142 540 0.35 × 0.20 × 0.10

14.3645(2) 14.1696(2) 19.2953(5) 90 111.194(1) 90 3661.71(11) 4 1.436 0.869 1632 0.15 × 0.15 × 0.10

0.96-28.54 0ehe8 -9 e k e 9 -28 e l e 28 10 176/5235 (R(int) ) 0.052)

1.83-26.30 -17 e h e 17 -16 e k e 17 -24 e l e 20 24 362/7414 (R(int) ) 0.0683)

3272/3/316 1.040 R1 ) 0.066 wR2 ) 0.129 R1 ) 0.120 wR2 ) 0.155 0.80 and -0.65

7414/0/441 1.019 R1 ) 0.059 wR2 ) 0.106 R1 ) 0.093 wR2 ) 0.121 0.69 and -0.67

11.512(1) 15.537(1) 21.125(1) 90 96.81(1) 90 3655.2(4) 4 1.438 0.870 1632 0.45 × 0.30 × 0.10 Nonius KappaCCD 1.66-27.86 -15 e h e 14 -18 e k e 19 -27 e l e 24 22 824/8620 (R(int) ) 0.0752) full-matrix least squares on F2 5546/1/441 1.033 R1 ) 0.058 wR2 ) 0.135 R1 ) 0.106 wR2 ) 0.155 1.18 and -0.97

6

7

C34H35CrMnO8Si 706.65 223(2)

C34H35CrMnO8Si 706.65 223(2)

monoclinic C2/c (No. 15)

triclinic P1j (No. 2)

28.566(1) 17.145(1) 14.458(1) 90 102.08(1) 90 6924.2(7) 8 1.356 0.761 2928 0.30 × 0.06 × 0.03

7.372(1) 14.481(1) 15.609(1) 96.46(1) 91.20(1) 98.64(1) 1635.7(3) 2 1.435 0.805 732 0.54 × 0.45 × 0.40

1.46-27.93 -37 e h e 30 -22 e k e 20 -15 e l e 18 27 349/8100 (R(int) ) 0.1110)

2.63-30.89 0 e h e 10 -20 e k e 20 -22 e l e 21 19 093/9994 (R(int) ) 0.042)

4779/0/414 1.057 R1 ) 0.072 wR2 ) 0.093 R1 ) 0.155 wR2 ) 0.111 0.40 and -0.54

7795/0/414 1.049 R1 ) 0.045 wR2 ) 0.113 R1 ) 0.063 wR2 ) 0.122 0.40 and -0.61

specific geometry constraint imposed by the electronic properties of a given substituent connected to the arene ligand was shown for different (arene)tricarbonylchromium complexes.14 Thus, an electron-accepting substituent (complex A) would induce a bending of the aromatic ipso carbon toward the Cr(CO)3 moiety, while the opposite effect would be observed with an electrondonating substituent (complex D) (Scheme 5).15 This means that

Figure 2. Molecular structure of kinetic anti-Cr-Mn arene complex 4. The numbering of atoms differs from that used in the NMR characterization. Hydrogen atoms are omitted for clarity. Dihedral angles: R1 (C7-Crproj-Cr-C121) ) -22.0°, R2 (C4ACrproj-Cr-C122) ) -22.1°, and R3 (C5-Crproj-Cr-C123) ) -23.0°. Peripheral torsion angles: φ (C1-C1a-C11a-C11) ) -11.6(5)°, φ1 (C7-C7a-C8a-C8) ) 21.9(4)° and φ2 (C3-C3aC4a-C4) ) 7.8(5)°. Selected bond lengths (Å): Mn-C1 ) 2.149(3), Mn-C2 ) 2.127(3), Mn-C3 ) 2.125(3), Mn-C1A ) 2.164(3), Mn-C3A ) 2.157(3), Cr-C4 ) 2.264(3), Cr-C5 ) 2.240(3), Cr-C6 ) 2.258(3), Cr-C7 ) 2.238(3), Cr-C4A ) 2.329(3), Cr-C7A ) 2.229(3).

Figure 3. Molecular structure of kinetic syn-Cr-Mn arene complex 5. The numbering of atoms differs from that used in the NMR characterization. Hydrogen atoms are omitted for clarity. Dihedral angles: R1 (C4- Crproj-Cr- C38) ) -8.4°, R2 (C6-CrprojCr-C40) ) -7.2°, and R3 (C14-Crproj-Cr-C42) ) -6.8°. Peripheral torsion angles: φ (C1-C17-C16-C11) ) -3.5(5)°, φ1 (C7-C14-C15-C8) ) -4.0(5)°, and φ2 (C3-C12-C13-C4) ) -9.0(5)°. Selected bond lengths (Å): Mn-C1 ) 2.129(3), Mn-C2 ) 2.116(3), Mn-C3 ) 2.140(3), Mn-C12 ) 2.236(3), Mn-C17 ) 2.179(3), Cr-C4 ) 2.270(3), Cr-C5 ) 2.239(3), Cr-C6 ) 2.205(3), Cr-C7 ) 2.228(3), Cr-C14 ) 2.303(3), Cr-C13 ) 2.221(3).

3008 Organometallics, Vol. 28, No. 10, 2009

the CpMn(CO)3 group plays an overall role similar to that of a donor substituent. This kind of structure was observed in the case of the (2-(triisopropylsilyl)-6-phenylanisole)tricarbonylchromium complex, where the bulky trimethylsilyl group is antieclipsed by a Cr-CO bond, as well as in the (2-methoxy-3(triisopropylsilyl)-6-phenylanisole)tricarbonylchromium complex.13e The torsion angles R1 (C7-Crproj-Cr-C121), R2 (C4A-Crproj-Cr-C122), and R3 (C5-Crproj-Cr-C123) are about -22.0, -22.1, and -23.0°, respectively, Crproj being the projection of the chromium atom on the plane of the arene (C4A, C4, C5, C6, C7, and C7A), and these data indicate an almost staggered conformation of the Cr(CO)3 entity.

Dubarle Offner et al. Scheme 6. Haptotropic Chromium Migration in Anti and Syn Heterobimetallic Cr-Mn Arene Complexes 4 and 5

Scheme 5. Substituent-Dependent Distortion of the Arene Ligand in (η6-arene)Cr(CO)3 Complexes

For complex 5, the two metallic moieties present a syn orientation, meaning that the sterically demanding Mn(CO)3 fragment inhibits the carbon C13 to be eclipsed with respect to the Cr(CO)3 tripod. Indeed, the carbon C13 is anti-eclipsed and carbon atoms C4, C6, and C14 are totally eclipsed by the CO ligands. The longest Cr-C distance corresponds to the Cr-C14 bond with 2.303(1) Å bond length, in good agreement with an overall -OTBDMS electron-donating group. The anti and syn diastereomers 4 and 5 differ considerably in the helical twists of their tetracyclic aromatic skeletons. The pronounced deviation from planarity in the anti diastereomer 4 culminates in the large peripheral torsion angle (21.9°); in contrast, the syn diastereomer 5 reveals a more flattened arene platform with a major torsion angle at the hydroquinone/Cp bay. Haptotropic Metal Migration. Upon warming in a polar high-boiling solvent such as di-n-butyl ether, the kinetic diastereoisomeric anti- and syn-heterobimetallic Cr-Mn polyarene complexes 4 and 5 underwent a haptotropic migration of the chromium fragment along the phenanthrene part of the aromatic platform to give the thermodynamic isomers syn-6 and anti-7. The haptotropomers 4/6 and 5/7, respectively, differ significantly in their ν(CO) absorption bands, which reveal a characteristic hypsochromic shift (4 and 12 cm-1 for the A1 bands, respectively) for the thermodynamic rearrangement products 6 and 7, and which allows for an IR spectroscopic monitoring of the metal shift. At 105 °C the metal migration was completed after 3 h; chromatographic workup afforded the anti isomer 6 and the syn isomer 7 in comparable yields of 59% and 63%, respectively, indicating that s independent of the relative configuration s the manganese fragment reveals neither an electronic nor a steric effect on the haptotropic migration of the chromium moiety (Scheme 6). (14) Rose-Munch, F.; Rose, E.; Djukic, J.-P.; Vaissermann, J. Eur. J. Inorg. Chem. 2000, 1295. (15) (a) Hunter, A. D.; Shilliday, L.; Furey, W. S.; Zaworotko, M. J. Organometallics 1992, 11, 1550. (b) Hunter, A. D.; Mozol, V.; Tsai, S. D. Organometallics 1992, 11, 2251.

The haptotropic migration of the chromium fragment is evident from a comparison of NMR data of the pairs of haptotropomers 4/6 and 5/7. Due to the coordination of the terminal unsubstituted benzene ring in the thermodynamic isomers 6 and 7 their hydrogen atoms H4-H7 are distinctly shielded by approximately 1.4-2.1 ppm. This coordination shift is most pronounced for the central hydrogen atoms H5 and H6 (Table 2, entries 3 and 6), as has been observed for hydroquinoid phenanthrene Cr(CO)3 complexes.13 In general, in (arene)Cr(CO)3 complexes the relative downfield shift of hydrogen atoms next to ring-bridging (e.g., H5, H6 in indane derivatives13d and N-methylindole13e) or 1,2-substituted carbon atoms (such as in veratrole13f and other polysubstituted complexes13b,c,f-l) is welldocumented. Table 2. Selected 1H NMR and Coordination Shifts of Pairs of Haptotropomers 4/6 and 5/7a entry

complexes and ∆δ

H4

H5

H6

H7

1 2 3 4 5 6

kinetic anti complex 4 thermodynamic anti complex 6 ∆δ (δ(Hi)complex 4 - δ(Hi)complex 6) kinetic syn complex 5 thermodynamic syn complex 7 ∆δ (δ(Hi)complex 5 - δ(Hi)complex 7)

9.01 7.46 1.55 8.96 7.54 1.42

7.60 5.60 2.00 7.61 5.75 1.86

7.51 5.37 2.14 7.58 5.58 2.00

7.83 6.05 1.78 7.80 6.35 1.45

a The numbering of atoms differs from that used in the X-ray analyses.

To elucidate structural details of the haptotropic rearrangement single crystals of anti diastereomer 6 (monoclinic, symmetry space group C2/c, Figure 4 and Table 1) and syn diastereomer 7 (triclinic, symmetry space group P1j, Figure 5 and Table 1) were characterized by X-ray analysis. As observed for the kinetic benzannulation products, the aromatic skeleton reveals a helical twist, which is more important for the anti isomer 6 than for syn-7 and is most pronounced for the inner phenanthrene bay area (φ2 (C7-C14-C15-C8) ) -17.31 and 14.54°). The mean distance between the manganese atom and the five cyclopentadienyl carbon atoms does not differ from one haptotropomer to the other, whereas the averaged Cr-Carene bond lengths are significantly smaller in the thermodynamic complexes 6 and 7 compared to their kinetic haptotropomers 4 and 5. In both rearranged haptotropomers the Cr(CO)3 tripod adopts a staggered outward conformation; the syn configuration in diastereomer 7 results in a chromium shift toward the periphery of the arene platform, indicated by distinctly elongated bonds (by 0.08-0.10 Å) to the bridging carbon atoms C15 and C16.

Cr-Mn Complexes of Fused Arenes

Figure 4. Molecular structure of thermodynamic anti-Cr-Mn arene complex 6. The numbering of atoms differs from that used in the NMR characterization. Hydrogen atoms are omitted for clarity. Dihedral angles: R1(C8-Crproj-Cr-C38) ) -19.3°, R2(C10-CrprojCr-C40) ) -16.3°, and R3(C16-Crproj-Cr-C42) ) -15.9°. Peripheral torsion angles: φ(C1-C17-C16-C11) ) 8.4(5)°, φ1(C7-C14-C15-C8) ) -17.3(5)°, and φ2(C3-C12-C13-C4) ) -7.5(6)°. Selected bond lengths (Å): Mn-C1 ) 2.138(4), Mn-C2 ) 2.126(4), Mn-C3 ) 2.128(3), Mn-C12 ) 2.171(3), Mn-C17 ) 2.146(3), Cr-C8 ) 2.190(3), Cr-C9 ) 2.212(3), Cr-C10 ) 2.218(4), Cr-C11 ) 2.211(4), Cr-C16 ) 2.213(3), Cr-C15 ) 2.257(3).

Organometallics, Vol. 28, No. 10, 2009 3009

Figure 6. Kinetic plots for the haptotropic metal migration of the kinetic anti-Cr-Mn arene complex 4 at 363 K in hexafluorobenzene.

This excludes an intermolecular decomplexation-recomplexation process and demonstrates a first-order reaction, as expected for an intramolecular haptotropic migration of the chromium fragment along the same π face of the extended arene platform (Figure 6). In comparison with haptotropic metal shifts in hydroquinoid phenanthrene16 and structurally related chromium complexes,12 the rate constant observed for the bimetallic Cr-Mn complex 4 (k ) (3.7 ( 0.1) × 10-5 s-1) is decreased by 2 orders of magnitude, and the free activation enthalpy ∆Gq (120.3 ( 0.2 kJ mol-1) is increased by 10-20%. Ongoing studies are expected to clarify whether the manganese acceptor fragment and/or the extended π system are responsible for slowing down the chromium migration.

Conclusion

Figure 5. Molecular structure of thermodynamic syn-Cr-Mn arene complex 7. The numbering of atoms differs from that used in the NMR characterization. Hydrogen atoms are omitted for clarity. Dihedral angles: R1(C15-Crproj-Cr-C38) ) 25.4°, R2(C9-CrprojCr-C40) ) 25.81°, and R3(C11-Crproj-Cr-C42) ) 24.2°. Peripheral torsion angles: φ(C1-C17-C16-C11) ) -0.1(3)°, φ1(C7-C14-C15-C8) ) 14.5(3)°, and φ2(C3-C12-C13-C4) ) -7.0(3)°. Selected bond lengths (Å): Mn-C1 ) 2.145(2), Mn-C2 ) 2.133(2), Mn-C3 ) 2.131(2), Mn-C12 ) 2.179(2), Mn-C17 ) 2.172(2), Cr-C8 ) 2.197(2), Cr-C9 ) 2.199(2), Cr-C10 ) 2.214(2), Cr-C11 ) 2.204(2), Cr-C16 ) 2.287(2), Cr-C15 ) 2.298(2).

In order to demonstrate a potential influence of the manganese fragment on the intramolecular nature of the chromium migration, we undertook a kinetic study of the thermoinduced rearrangement of anti diastereomer 4 into its haptotropomer 6. An NMR experiment carried out at 363 K in hexafluorobenzene, which is inert toward metal coordination, resulted in a linear plot of the ln([c]/[c]0) vs time correlation over several hours.

In summary, a novel type of polyarene heterobimetallic Cr-Mn complex has been synthesized from a cymanthrenetype Fischer carbene complex via chromium-templated benzannulation to give syn and anti diastereomers bearing Mn(CO)3 and Cr(CO)3 fragments coordinated to the cyclopentadienyl ring and to the hydroquinoid ring of a dibenzo[c,e]indene skeleton, respectively. Both heterobimetallic diastereomers undergo a thermoinduced chromium migration within the phenanthrene part, affording the thermodynamic haptotropomers in which the chromium fragment is coordinated to the unsubstituted benzene ring, while the manganese moiety remains coordinated to the Cp ring. A kinetic study carried out for the kinetic anti diastereomer reveals a first-order metal rearrangement in line with an intramolecular chromium migration along the π face of the dibenzo[c,e]indene platform. A comparison with phenanthrene Cr(CO)3 complex analogues indicates that cyclopentannulation of the arene platform by a cymanthrene unit slows down the rate of the chromium shift in the heterobimetallic Cr-Mn complex by 2 orders of magnitude.

Experimental Section General Considerations. All experiments involving organometallic compounds were carried out under an inert argon atmosphere by using standard Schlenk techniques. Solvents were distilled, dried using standard methods, saturated, and stored under argon. Chromatographic columns were performed with degassed Macherey (16) (a) Do¨tz, K. H.; Stendel, J.; Nieger, M. Z. Anorg. Allg. Chem. 2009, 635, 221. (b) Stendel, J., Jr. Dissertation, University of Bonn, 2004.

3010 Organometallics, Vol. 28, No. 10, 2009 Nagel silica gel MN 60 (0.015-0.025 mm). 1H and 13C NMR spectra were recorded on a Bruker DRX 500 spectrometer at room temperature. The solvent used for the NMR monitoring of the haptotropic migration was carefully degassed using the pumpfreeze-thaw method (three cycles), saturated, and stored under argon. IR spectra were measured with a Nicolet Magna 550 FT spectrometer in petroleum ether. Mass spectra (FAB+ and EI) were recorded on a Kratos MS 50 instrument. Melting points were determined with a Reichert Austria apparatus. Data sets for X-ray structure analyses were collected with a Nonius KappaCCD diffractometer, equipped with a rotating anode generator. Programs used: data collection COLLECT (Nonius BV, 1998), data reduction Denzo-SMN,17 absorption correction SORTAV18 and Denzo,19 structure solution SHELXS-97,20 structure refinement SHELXL-97 (G. M. Sheldrick, Universita¨t Go¨ttingen, 1997), and Diamond 3.0 for figures. 8-Bromobenzo[e]-1H-indene (1e). 1H NMR (300 MHz, CDCl3): δ (ppm) 3.52 (2H, pt, 3J ) 1.7 Hz, H1), 6.57 (1H, dt, 3J ) 1.7 Hz, 3 J ) 5.5 Hz, H2), 7.44 (1H, dtd, 5J ) 0.7 Hz, 4J ) 1.8 Hz, 3J ) 5.5 Hz, H3), 7.54-7.63 (2H, m, ArH), 7.95 (1H, s, H9), 8.10 (1H, m, ArH), 8.29 (1H, m, ArH). 13C NMR (75 MHz, CDCl3): δ (ppm) 40.2 (C1), 119.3 (C9), 124.2, 126.2, 126.3, 126.6, 127.6 (4 ArCH), 128.5 (ArC), 129.2 (ArCH), 130.6 (ArC), 134.7 (ArCH), 141.1, 141.5 (2 ArC). MS (EI): m/z 246.0 [M+, 39], 165.1 [M+ - Br, 100]. Tricarbonyl{η5-1,2,3,3a,9a-(8-bromobenzo[e]indenyl)}manganese (2). KH (1.32 g, 33.0 mmol) was added to a solution of 8-bromobenz[e]-1H-indene (7.8 g, 31.8 mmol) in 50 mL of freshly distilled absolute THF and the mixture stirred for 1 h at room temperature under argon. Then BrMn(CO)5 (9.07 g, 33.0 mmol) was charged in the Schlenk tube and the reaction mixture was stirred overnight. Chromatography on fine silica gel at 5 °C with petroleum ether/dichloromethane (3:1) afforded 4.87 g of complex 2 (40%) as an air-sensitive yellow powder. Mp: 144 °C. IR (petroleum ether): ν(CO) 2025 (s), 1946 (vs) cm-1. 1H NMR (500 MHz, CD2Cl2): δ (ppm) 5.09 (1H, pt, 3J ) 2.8 Hz, CpH), 5.22 (1H, dd, 3J ) 2.8 Hz, 3 J ) 2.8 Hz, CpH), 5.61 (1H, pt, 3J ) 2.8 Hz, CpH), 7.66-7.73 (2H, m, ArH), 7.71 (1H, sbr, ArH), 8.02 (1H, m, ArH), 8.25 (1H, m, ArH). 13C NMR (125 MHz, CD2Cl2): δ (ppm) 72.1, 73.8, 86.9 (C1-C3), 99.0, 101.1 (C3a, C9a), 122.9 (ArC), 123.9, 125.6, 128.3, 129.2, 129.4 (C4-C7, C9), 130.0, 130.1 (2 ArC), 224.9 (Mn(CO)3). MS (FAB): m/z 382 [M+, 25], 325.9 [M+ - 2CO, 59], 297.9 [M+ - 3CO, 52], 245 [M+ - Mn - 3CO, 42]. Tricarbonyl{pentacarbonyl[8-benzo[e]indenyl(methoxy)carbene]chromium[η5-1,2,3,3a,9a]}manganese (3). Tricarbonyl{η51,2,3,3a,9a-(8-bromobenzo[e]indenyl)}manganese (2; 3.97 g, 10.36 mmol) was dissolved in 80 mL of freshly distilled absolute THF to give a yellow solution. At -78 °C was added dropwise a 2.5 M solution of n-BuLi in hexanes (4.4 mL, 11.0 mmol); the solution immediately became brown, and 5 min later Cr(CO)6 (2.64 g, 12.0 mmol) was added. The solution was warmed to 20 °C within 1 h, and then the solvent was evaporated via a vacuum pump. The resulting brown oil was then dissolved in 100 mL of absolute DCM and cooled down to -50 °C. Methyl triflate (3.28 g, 20.0 mmol) was added dropwise to the solution, which was then warmed to room temperature within 1/2 h and stirred an extra 1 h. The solution became deep dark red. Chromatography on fine silica gel at 5 °C with petroleum ether/dichloromethane (3:1) afforded 2.83 g of complex 3 (50%) as an air-sensitive dark red powder. Mp: decomposition over 150 °C. IR (petroleum ether): ν(CO) 2067 (A1, (17) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307– 326. (18) Blessing, R. H. Acta Crystallogr. 1995, A51, 33–37. (a) Blessing, R. H. J. Appl. Crystallogr. 1997, 30, 421–426. (19) Otwinowski, Z.; Borek, D.; Majewski, W.; Minor, W. Acta Crystallogr. 2003, A59, 228–234. (20) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467–473.

Dubarle Offner et al. m), 2025 (s), 1957 (E, vs), 1944 (s) cm-1. 1H NMR (500 MHz, acetone): δ (ppm) 4.34 (3H, s, OCH3), 5.39 (1H, dd, 3J ) 2.7 Hz, 3 J ) 2.9 Hz, CpH), 5.63 (1H, sbr, CpH), 6.00 (1H, sbr, CpH), 7.15 (1H, sbr, ArH), 7.45 (1H, d, 3J ) 8.0 Hz, ArH), 7.66 (1H, m, ArH), 7.73 (1H, m, ArH), 8.32 (1H, d, 3J ) 8.0 Hz, ArH). 13C NMR (125 MHz, CH2Cl2): δ (ppm) 66.6 (OCH3), 75.4 (C1 and C3), 87.8 (C2), 98.7 (ArC), 114.6, 124.8 (2 ArCH), 125.0 (ArC), 126.3, 128.3, 129.0 (3 ArCH), 129.4 (ArC), 216.2 (Cr(CO)5), 224.9 (Cr(CO)5 and Mn(CO)3), 356.7 (C10). MS (EI): m/z 537.8 [M+, 2], 481.9 [M+ - 2CO, 13], 453.9 [M+ - 3CO, 3], 425.9 [M+ - 4CO, 18], 397.9 [M+ - 5CO, 82], 369.9 [M+ - 6CO, 8], 341.9 [M+ - 7CO, 28], 313.9 [M+ - 8CO, 53]. HRMS (ESI): m/z [M + Na]+ calcd 590.9086, found 560.9081. anti-Tricarbonyl{tricarbonyl(η6-7b,8,9,10,11,11a-(9,10-diethyl-8methoxy-11-[(tert-butyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η5-1,2,3,3a,11b]}manganese (4) and syn-Tricarbonyl{tricarbonyl(η67b,8,9,10,11,11a-(9,10-diethyl-8-methoxy-11-[(tert-butyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η5-1,2,3,3a,11b]}manganese (5). A solution of tricarbonyl{pentacarbonyl[8-benzo[e]indenyl(methoxy)carbene]chromium[η5-1,2,3,3a,9a]}manganese (3; 2.45 g, 4.55 mmol) and 3-hexyne (1.50 g, 18.2 mmol) in 50 mL of tertbutyl methyl ether was warmed to 65 °C (oil bath temperature) for 2 h. Then the phenolic group was protected at room temperature by addition of triethylamine (1.18 g, 18.2 mmol) and tertbutyldimethylsilyl triflate (4.81 g, 18.2 mmol). After the mixture was stirred for 2 h, chromatography on fine silica gel at 5 °C with petroleum ether/dichloromethane (3:2) afforded first 1.65 g of the anti complex 4 (51%) followed by 0.68 g of the syn complex 5 (21%) as air-sensitive red powders. Recrystallization of both isomers from dichloromethane at 4 °C gave crystals suitable for X-ray analysis. Data for the major isomer 4 are as follows: Mp: 92 °C. IR (petroleum ether): ν(CO) 2025 (s), 1963 (A1, vs), 1948 (s), 1903 (E, s), 1888 (E, s) cm-1. 1H NMR (500 MHz, CD2Cl2): δ (ppm) 0.40 (3H, s, SiCH3), 0.63 (3H, s, SiCH3), 1.17 (9H, s, SiC(CH3)3), 1.30-1.36 (6H, m, CH2CH3, CH2CH3), 2.52 (2H, q, 3J ) 7.4 Hz, CH2CH3), 2.64 (1H, m, CH2CH3), 3.02 (1H, m, CH2CH3), 3.57 (3H, s, OCH3), 5.04 (1H, sbr, H1 or H3), 5.60 (1H, sbr, H2), 6.19 (1H, sbr, H1 or H3), 7.51 (1H, pt, 3J ) 7.5 Hz, H6), 7.60 (1H, pt, 3 J ) 8.3 Hz, H5), 7.83 (1H, d, 3J ) 7.5 Hz, H7), 9.01 (1H, d, 3J ) 8.3 Hz, H4). 13C NMR (125 MHz, CD2Cl2): δ (ppm) -2.1 (SiCH3), -0.2 (SiCH3), 15.2 (CH2CH3), 18.1 (CH2CH3), 19.4 (SiC(CH3)3), 20.2 (CH2CH3), 21.2 (CH2CH3), 26.3 (SiC(CH3)3), 61.7 (OCH3), 73.8 (C2), 83.9, 84.0 (C1, C3), 86.1, 89.5 (C3a, C11b), 104.3, 105.1, 106.1, 111.7, 120.2 (5 ArC), 123.9 (C7), 126.5 (1 ArC), 128.2 (C6), 128.3 (C4), 129.5 (C5), 130.3 (C3b), 140.7 (1 ArC), 224.4 (Mn(CO3)), 234.1 (Cr(CO3)). MS (EI): m/z 706.1 [M+, 24], 622.1 [M+ - 3CO, 60], 566.1 [M+ - 5CO, 39], 538.1 [M+ - 6CO, 79], 486.2 [M+ - 6CO - Cr, 64], 425.1 [M+ - 6CO - Cr - Mn, 96]. HRMS (ESI): m/z [M + Na]+ calcd 729.0785, found 729.0779. Data for the minor isomer 5 are as follows: Mp: 92 °C. IR (petroleum ether): ν(CO) 2030 (vs), 1967 (A1, s), 1943 (s), 1898 (E, s), 1888 (E, s) cm-1. 1H NMR (500 MHz, CD2Cl2): δ (ppm) 0.24 (3H, s, SiCH3), 0.31 (3H, s, SiCH3), 1.03 (9H, s, SiC(CH3)3), 1.27 (3H, t, 3J ) 7.5 Hz, CH2CH3),1.42 (3H, t, 3J ) 7.4 Hz, CH2CH3), 2.40 (1H, dt, 2J ) 14.8 Hz, 3J ) 7.4 Hz, CH2CH3), 2.62 (1H, dt, 2J ) 14.8 Hz, 3J ) 7.4 Hz, CH2CH3), 2.75 (1H, dt, 2J ) 15.0 Hz, 3J ) 7.5 Hz, CH2CH3), 3.06 (1H, dt, 2J ) 15.0 Hz, 3J ) 7.5 Hz, CH2CH3), 3.61 (3H, s, OCH3), 4.89 (1H, m, CpH), 5.42 (1H, m, CpH), 6.15 (1H, m, CpH), 7.56-7.63 (2H, m, ArH), 7.80 (1H, dd, 3J ) 7.5 Hz, 3J ) 7.8 Hz, ArH), 8.96 (1H, dd, 3 J ) 8.0 Hz, 3J ) 7.8 Hz, ArH). 13C NMR (125 MHz, CD2Cl2): δ (ppm) -1.3 (SiCH3), -0.3 (SiCH3), 15.2 (CH2CH3), 19.2 (CH2CH3), 19.4 (SiC(CH3)3), 20.5 (CH2CH3), 21.7 (CH2CH3), 26.3 (SiC(CH3)3), 64.1 (OCH3), 71.5 (C2), 81.6, 83.2 (C1, C3), 87.3, 100.4, 100.8, 102.4, 112.9 (5 ArC), 123.6, 128.5 (2 ArCH), 128.6, 129.5 (2 ArC), 129.8 (ArCH), 130.2 (ArC), 130.4 (ArCH), 140.6 (ArC), 224.3 (Mn(CO3)), 233.8 (Cr(CO3)). MS (EI): m/z 706.1 [M+,

Cr-Mn Complexes of Fused Arenes 2], 622.1 [M+ - 3CO, 5], 570.2 [M+ - 3CO - Cr, 8], 538.1 [M+ - 6CO, 10], 486.2 [M+ - 6CO - Cr, 95], 425.1 [M+ - 6CO Cr - Mn, 10]. HRMS (ESI): m/z [M + Na]+ calcd 729.0785, found 729.0779. anti-Tricarbonyl{tricarbonyl(η6 -3b,4,5,6,7,7a-(9,10-diethyl-8methoxy-11-[(tert-butyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η5-1,2,3,3a,11b]}manganese (6). A solution of anti-tricarbonyl{tricarbonyl(η6 -7b,8,9,10,11,11a-(9,10-diethyl-8-methoxy-11-[(tertbutyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η 5 1,2,3,3a,11b]}manganese (4; 0.72 g, 1.01 mmol) in 100 mL of din-butyl ether was warmed to 105 °C and stirred for 3 h under an argon atmosphere. Chromatography on fine silica gel at 5 °C in petroleum ether/dichloromethane (3:2) afforded 0.42 g (59%) of complex 6 as an air-sensitive red-orange powder. Mp: 149 °C. IR (petroleum ether): ν(CO) 2023 (s), 1975 (vs), 1948 (s) 1944 (sh), 1913 (s) cm-1. 1H NMR (500 MHz, CD2Cl2): δ (ppm) -0.09 (3H, s, SiCH3), -0.05 (3H, s, SiCH3), 1.12 (9H, s, SiC(CH3)3), 1.17-1.23 (6H, m, CH2CH3, CH2CH3), 2.57 (1H, dt, 2J ) 13.4 Hz, 3J ) 7.3 Hz, CH2CH3), 2.68 (1H, dt, 2J ) 13.4 Hz, 3J ) 7.3 Hz, CH2CH3), 2.84 (1H, dt, 2J ) 13.3 Hz, 3J ) 7.4 Hz, CH2CH3), 2.93 (1H, dt, 2J ) 13.3 Hz, 3J ) 7.4 Hz, CH2CH3), 3.66 (3H, s, OCH3), 5.01 (1H, m, CpH), 5.37 (1H, sbr, ArH), 5.60 (2H, m, CpH and ArH), 6.05 (2H, m, CpH and ArH), 7.46 (1H, m, ArH). 13C NMR (125 MHz, CD2Cl2): δ (ppm) -5.0 (SiCH3), -2.7 (SiCH3), 14.9 (CH2CH3), 15.8 (CH2CH3), 18.6 (SiC(CH3)3), 20.6 (CH2CH3), 21.2 (CH2CH3), 26.2 (SiC(CH3)3), 62.1 (OCH3), 72.3 (C2), 81.0, 84.2 (C1, C3), 88.1, 91.8, 92.7, 93.0 (C4-C7), 96.3, 98.0, 98.8, 103.1, 120.2, 120.5, 128.3, 138.5, 146.9, 153.3 (10 ArC), 224.9 (Mn(CO3)), 233.1 (Cr(CO3)). MS (EI): m/z 706.1 [M+, 4], 622.1 [M+ - 3CO, 10], 570.1 [M+ - 3CO - Cr, 11], 538.1 [M+ - 6CO, 14], 486.1 [M+ - 6CO - Cr, 99], 425.1 [M+ - 6CO - Cr - Mn, 11]. HRMS (ESI): m/z [M + Na]+ calcd 729.0785, found 729.0779. syn-Tricarbonyl{tricarbonyl(η6 -3b,4,5,6,7,7a-(9,10-diethyl-8methoxy-11-[(tert-butyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η5-1,2,3,3a,11b]}manganese (7). A solution of syn-tricarbonyl{tricarbonyl(η6 -7b,8,9,10,11,11a-(9,10-diethyl-8-methoxy-11-[(tert-

Organometallics, Vol. 28, No. 10, 2009 3011 butyl)dimethylsilyloxy]dibenzo[c,e]indenyl)chromium[η 5 1,2,3,3a,11b]}manganese (5; 0.60 g, 0.85 mmol) in 100 mL of din-butyl ether was warmed to 105 °C and stirred for 3 h under an argon atmosphere. Chromatography on fine silica gel at 5 °C in petroleum ether/dichloromethane (3:2) afforded 0.38 g (63%) of complex 7 as an air-sensitive red-orange powder. Mp: 149 °C. IR (petroleum ether): ν(CO) 2029 (s), 1971 (A1, vs), 1957 (s), 1946 (m), 1903 (E, s) cm-1. 1H NMR (500 MHz, CD2Cl2): δ (ppm) -0.05 (3H, s, SiCH3), 0.02 (3H, s, SiCH3), 1.12 (3H, t, 3J ) 7.45 Hz, CH2CH3), 1.15 (9H, s, SiC(CH3)3), 1.20 (3H, t, 3J ) 6.9 Hz, CH2CH3), 2.57 (1H, m, CH2CH3), 2.70 (1H, m, CH2CH3), 2.90 (1H, m, CH2CH3), 2.98 (1H, m, CH2CH3), 4.05 (3H, s, OCH3), 4.96 (1H, s, CpH), 5.32 (1H, sbr, CpH), 5.40 (1H, sbr, CpH), 5.58 (1H, m, ArH), 5.75 (1H, sbr, ArH), 6.35 (1H, d, 3J ) 6.0 Hz, ArH), 7.54 (1H, d, 3J ) 6.7 Hz, ArH). 13C NMR (125 MHz, CD2Cl2): δ (ppm) -4.5 (SiCH3), -2.5 (SiCH3), 14.9 (CH2CH3), 15.6 (CH2CH3), 18.6 (SiC(CH3)3), 20.6 (CH2CH3), 21.3 (CH2CH3), 26.0 (SiC(CH3)3), 61.9 (OCH3), 75.7 (C2), 75.9, 84.3 (C1, C3), 87.7, 90.7, 92.2, 95.7 (C4-C7), 94.4, 101.6, 104.1, 104.8, 120.5, 121.7, 139.2, 139.3, 147.6, 153.4 (10 ArC), 224.6 (Mn(CO3)), 233.9 (Cr(CO3)). MS (EI): m/z 706.1 [M+, 2], 622.1 [M+ - 3CO, 6], 570.1 [M+ - 3CO - Cr, 13], 538.1 [M+ - 6CO, 7], 486.1 [M+ 6CO - Cr, 99], 425.1 [M+ - 6CO - Cr - Mn, 7]. HRMS (ESI): m/z [M + Na]+ calcd 729.0785, found 729.0779.

Acknowledgment. We are grateful to the Deutsche Forschungsgemeinschaft (DFG) for financial support granted within the Sonderforschungsbereich 624 (“Templates”). Supporting Information Available: CIF files giving X-ray structural information and figures giving NMR spectra for complexes 3-7. This material is available free of charge via the Internet at http://pubs.acs.org. OM900090Q