Osmium−Alkenylcarbyne and −Alkenylcarbene Complexes with an

Jr,5 have also reported σ-bound ethynyl steroids. Gimeno .... (8) (a) Espuelas, J.; Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A.; Ruiz,. N. J. Am. Che...
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Organometallics 2009, 28, 5691–5696 DOI: 10.1021/om900647a

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Osmium-Alkenylcarbyne and -Alkenylcarbene Complexes with an Steroid Skeleton: Formation of a Testosterone Organometallic Derivative Containing the 7H-Amino Adenine Tautomer Marı´ a L. Buil,* Miguel A. Esteruelas,* Karin Garces, and Enrique O~ nate Departamento de Quı´mica Inorg anica, Instituto de Ciencia de Materiales de Arag on, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain Received July 22, 2009

Complex OsH2Cl2(PiPr3)2 (1) reacts with ethisterone to give the hydride-alkenylcarbyne complex OsHCl2(tCCHdC19H26O)(PiPr3)2 (2) containing the testosterone skeleton. Treatment of 2 with AgBF4 in the presence of acetonitrile leads to [OsH(tCCHdC19H26O)(CH3CN)2(PiPr3)2](BF4)2 (3), which evolves into the alkenylcarbene derivative [Os(dCHCHdC19H26O)(CH3CN)3(PiPr3)2](BF4)2 (4). The reaction of 2 with TlPF6 in a dichloromethane:acetone mixture affords [OsHCl(tCCHdC19H26O)(κ1-OCMe2)(PiPr3)2]PF6 (5), which coordinates adenine to give [OsHCl(tCCHdC19H26O)(7H-aminoadenine)(PiPr3)2]PF6 (6) containing, in addition to the androgen, a 7H-amine-adenine tautomer. The X-ray diffraction structures of 2 and 6 are also reported.

An intense amount of effort is being made to develop new ways to introduce pharmaceuticals into cancerous tissues that are rich in estrogen receptors.1 Thus, a number of transition metal complexes have been prepared using ethynyl steroids.2 One of the simplest manners to bind ethynyl steroids to transition metals is through direct attachment of the metal to the acetylene moiety.3 The groups of Bonati4 and Stockland, *To whom correspondence should be addressed. E-mail: maester@ unizar.es; [email protected]. (1) (a) Jaouen, G.; Vessieres, A.; Butler, I. S. Acc. Chem. Res. 1993, 26, 361. (b) Jaouen, G.; Top, S.; Vessieres, A.; Alberto, R. J. Organomet. Chem. 2000, 600, 23. (c) Bruijnincx, P. C. A.; Sadler, P. J. Curr. Opin. Chem. Biol. 2008, 12, 197. (2) See for example: (a) DiZio, J. P.; Fiaschi, R.; Davison, A.; Jones, A. G.; Katzenellenbogen, J. A. Bioconjugate Chem. 1991, 2, 353. (b) Top, S.; Gunn, M.; Jaouen, G.; Vaissermann, J.; Daran, J.-C.; McGlinchey, M. J. Organometallics 1992, 11, 1201. (c) Amouri, H. E.; Vessieres, A.; Vichard, D.; Top, S.; Gruselle, M.; Jaouen, G. J. Med. Chem. 1992, 35, 3130. (d) Osella, D.; Gambino, O.; Nervi, C.; Stein, E.; Jaouen, G.; Vessieres, A. Organometallics 1994, 13, 3110. (e) Vichard, D.; Gruselle, M.; Jaouen, G.; Nefedova, M. N.; Mamedyarova, I. A.; Sokolov, V. I.; Vaissermann, J. J. Organomet. Chem. 1994, 484, 1. (f) Top, S.; Hafa, H. E.; Vessieres, A.; Quivy, J.; Vaissermann, J.; Hughes, D. W.; McGlinchey, M. J.; Mornon, J.-P.; Thoreau, E.; Jaouen, G. J. Am. Chem. Soc. 1995, 117, 8372. (g) Jackson, A.; Davis, J.; Pither, R. J.; Rodger, A.; Hannon, M. J. Inorg. Chem. 2001, 40, 3964. (h) Osella, D.; Nervi, C.; Galeotti, F.; Cavigiolio, G.; Vessieres, A.; Jaouen, G. Helv. Chim. Acta 2001, 84, 3289. (i) Top, S.; Thibaudeau, C.; Vessieres, A.; Brule, E.; Bideau, F. L.; Joerger, J.-M.; Plamont, M.-A.; Samreth, S.; Edgar, A.; Marrot, J.; Herson, P.; Jaouen, G. Organometallics 2009, 28, 1414. (3) (a) Savignac, M.; Jaouen, G.; Rodger, C. A.; Perrier, R. E.; Sayer, B. G.; McGlinchey, M. J. J. Org. Chem. 1986, 51, 2328. (b) Osella, D.; Dutto, G.; Jaouen, G.; Vessieres, A.; Raithby, P. R.; De Benedetto, L.; McGlinchey, M. J. Organometallics 1993, 12, 4545. (c) Osella, D.; Galeotti, F.; Cavigiolio, G.; Nervi, C.; Hardcastle, K. I.; Vessieres, A.; Jaouen, G. Helv. Chim. Acta 2002, 85, 2918. (4) (a) Bonati, F.; Burini, A.; Pietroni, B. R.; Giorgini, E.; Bovio, B. J. Organomet. Chem. 1988, 344, 119. (5) Stockland, R. A., Jr.; Kohler, M. C.; Guzei, I. A.; Kastner, M. E.; Bawiec, J. A.; Labaree, D. C.; Hochberg, R. B. Organometallics 2006, 25, 2475. r 2009 American Chemical Society

Jr,5 have also reported σ-bound ethynyl steroids. Gimeno and co-workers6 have observed that indenyl-ruthenium complexes react with ethisterone, 17R-ethynylestradiol, and mestranol to give equilibrium mixtures of allenylidene and vinylidene tautomers, which afford σ-enynyl derivatives by deprotonation. Osmium is an attractive metal to incorporate into potential anticancer drugs due to the discovery that a number of inorganic and organometallic osmium species inhibit the growth of tumors cells.7 We have established that reactions of terminal alkynes with dihydride-, which afford dihydrogen species by coordination of electron poor Lewis bases, and dihydrogen-osmium complexes lead to stable hydridecarbyne derivatives.8 The potential of osmium compounds to act as anticancer agents prompted us to explore the reactivity of the known dihydride complex OsH2Cl2(PiPr3)2 (6) Cadierno, V.; Conejero, S.; Gamasa, M. P.; Gimeno, J.; Rodrı´ guez, M. A. Organometallics 2002, 21, 203. (7) (a) Peacock, A. F. A.; Habtemariam, A.; Fernandez, R.; Walland, V.; Fabbiani, F. P. A.; Parsons, S.; Aird, R. E.; Jodrell, D. I.; Sadler, P. J. J. Am. Chem. Soc. 2006, 128, 1739. (b) Peacock, A. F. A.; Habtemariam, A.; Moggach, S. A.; Precimone, A.; Parsons, S.; Sadler, P. J. Inorg. Chem. 2007, 46, 4049. (c) Peacock, A. F. A.; Parsons, S.; Sadler, P. J. J. Am. Chem. Soc. 2007, 129, 3348. (d) Peacock, A. F. A.; Melchart, M.; Deeth, R. J.; Habtemariam, A.; Parsons, S.; Sadler, P. J. Chem.;Eur. J. 2007, 13, 2601. (e) Kostrhunova, H.; Florian, J.; Novakova, O.; Peacock, A. F. A.; Sadler, P. J.; Brabec, V. J. Med. Chem. 2008, 51, 3635. (f) van Rijt, S. H.; Peacock, A. F. A.; Johnstone, R. D. L.; Parsons, S.; Sadler, P. J. Inorg. Chem. 2009, 48, 1753. (8) (a) Espuelas, J.; Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A.; Ruiz, N. J. Am. Chem. Soc. 1993, 115, 4683. (b) Buil, M. L.; Eisenstein, O.; Esteruelas, M. A.; García-Yebra, C.; Gutierrez-Puebla, E.; Olivan, M.; O~nate, E.; Ruiz, N.; Tajada, M. A. Organometallics 1999, 18, 4949. (c) Buil, M. L.; Esteruelas, M. A.; García- Yebra, C.; Gutierrez-Puebla, E.; Olivan, M. Organometallics 2000, 19, 2184. (d) Esteruelas, M. A.; García-Yebra, C.; Olivan, M.; O~nate, E.; Tajada, M. A. Organometallics 2000, 19, 5098. (e) Barrio, P.; Esteruelas, M. A.; O~nate, E. Organometallics 2002, 21, 2491. (f) Castro-Rodrigo, R.; Esteruelas, M. A.; Lopez, A. M.; O~nate, E. Organometallics 2008, 27, 3547. Published on Web 09/17/2009

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Figure 1. Molecular diagram of complex 2. Selected bond lengths (A˚) and angles (deg): Os-C(1) 1.734(3), C(1)-C(2) 1.414(5), C(2)-C(3) 1.342(5), P(1)-Os-P(2) 167.77(3), Cl(1)Os-Cl(2) 88.72(3), H(01)-Os-Cl(1) 164.2(16), C(1)-OsCl(2) 169.39(11), Os-C(1)-C(2) 171.1(3). Scheme 1

toward ethisterone, as a part of our work on the chemistry of osmium-hydride compounds.9 Treatment of OsH2Cl2(PiPr3)2 (1) with 1.2 equiv of ethisterone in refluxing toluene for 48 h leads to the hydridealkenylcarbyne derivative OsHCl2(tCCHdC19H26O)(PiPr3)2 (2), containing the testosterone skeleton, which is isolated as a purple solid in 66% yield according to Scheme 1. In agreement with 1-ethynyl-1-cyclohexanol,8a the formation of 2 should involve a dihydrogen-hydroxyvinylidene intermediate which could spontaneously dehydrate into a dihydrogen-alkenylvinylidene. Thus, the electrophilic transfer of Hþ from the dihydrogen to the β-carbon atom of the unsaturated chain of the androgen should afford 2. Its X-ray structure (Figure 1) proves that, from the two possible (9) (a) Esteruelas, M. A.; L opez, A. M. In Recent Advances in Hydride Chemistry; Peruzzini, M., Poli, R., Eds.; Elsevier: Amsterdam, 2001; Chapter 7, pp 189-248. (b) Esteruelas, M. A.; Oro, L. A. Adv. Organomet. Chem. 2001, 47, 1. (c) Esteruelas, M. A.; Lopez, A. M. Organometallics 2005, 24, 3584. (d) Esteruelas, M. A.; Lopez, A. M.; Olivan, M. Coord. Chem. Rev. 2007, 251, 795.

Buil et al.

isomers, with the quaternary C(sp3) atom of the five-membered ring of the steroid skeleton (C(7)) disposed cis to the alkenyl hydrogen atom is selectively formed. The coordination around the osmium atom can be rationalized as a distorted octahedron with the phosphorus atoms of the phosphine ligands occupying trans positions (P(1)Os-P(2) = 167.77(3)°). The perpendicular plane is formed by the chlorine atoms cis disposed (Cl(1)-Os-Cl(2) = 88.72(3)°, the hydride trans disposed to Cl(1) (H(01)-OsCl(1) = 164.2(16)°), and the carbyne carbon atom trans disposed to Cl(2) (C(1)-Os-Cl(2) = 169.39(11)°). The Os-C(1) bond length of 1.734(3) A˚ is fully consistent with an Os-C triple bond formulation.10 Similarly to other carbyne metal compounds11 a slight bending in the Os-C(1)-C(2) moiety is also present (Os-C(1)-C(2) = 171.1(3)°). The alkenyl carbyne proposal is supported by the bond lengths and angles within the η1-carbon donor ligand; for example C(1) and C(2) are separated by 1.414(5) A˚ and C(2) and C(3) by 1.342(5) A˚, whereas the angles around C(2) and C(3) are in the range 108°-127°. The 1H, 13C{1H}, and 31P{1H} NMR spectra in dichloromethane-d2 at room temperature are consistent with the structure shown in Figure 1. In agreement with the presence of the hydride ligand, the 1H NMR spectrum contains at -7.53 ppm a triplet with a H-P coupling constant of 17.0 Hz. In the low field region of the spectrum the C(2)H-hydrogen gives rise to a singlet at 4.33 ppm. In the 13C{1H} spectrum the OsC resonance appears at 257.4 ppm, as a triplet with a C-P coupling constant of 11.0 Hz, whereas C(2) and C(3) display singlets at 128.3 and 180.6 ppm, respectively. The 31P{1H} spectrum reveals the asymmetry of the steroid skeleton, showing an AB spin system centered at 18.9 ppm and defined by Δν = 17 Hz and JA-B = 86 Hz. Complex 2 reacts with AgBF4 in a 7:5 dichloromethane/ acetonitrile mixture to give the dicationic bis(solvento) species [OsH(tCCHdC19H26O)(CH3CN)2(PiPr3)2](BF4)2 (3), as a result of the abstraction of both chlorine atoms from the metal center and the coordination of two acetonitrile molecules. This compound is isolated as a yellow solid in 70% yield. Its 1H NMR spectrum shows the hydride resonance at -6.64 ppm, as a triplet with a H-P coupling constant of 15.8 Hz, whereas the vinylic resonance of the alkenylcarbyne moiety appears at 4.73 ppm. In the 13C{1H} spectrum the OsC resonance is observed at 280.9 ppm, as a triplet with a C-P coupling constant of 8.2 Hz. The C(sp2)carbon atoms of the alkenyl unit give rise to singlets at 194.8 and 126.4 ppm. The mutually cis disposition of the acetonitrile molecules is strongly supported by the presence of two acetonitrile resonances at 2.88 and 2.59 ppm in the 1H NMR spectrum and four acetonitrile signals at 136.2 and 131.8 (CN) and 4.6 and 4.0 (CH3) in the 13C{1H} spectrum. In agreement with 2, the 31P{1H} NMR spectrum contains an AB spin system centered at 30.2 ppm and defined by Δν = 69 Hz and JA-B = 175 Hz. (10) Jia, G. Coord. Chem. Rev. 2007, 251, 2167. (11) See for example: (a) Crochet, P.; Esteruelas, M. A.; L opez, A. M.; Martinez, M.-P.; Olivan, M.; O~ nate, E.; Ruiz, N. Organometallics 1998, 17, 4500. (b) Esteruelas, M. A.; Olivan, M.; O~nate, E.; Ruiz, N.; Tajada, M. A. Organometallics 1999, 18, 2953. (c) Bustelo, E.; Jimenez-Tenorio, M.; Mereiter, K.; Puerta, M. C.; Valerga, P. Organometallics 2002, 21, 1903. (d) Esteruelas, M. A.; Gonzalez, A. I.; Lopez, A. M.; O~nate, E. Organometallics 2003, 22, 414. (e) Wen, T. B.; Zhou, Z. Y.; Lo, M. F.; Williams, I. D.; Jia, G. Organometallics 2003, 22, 5217. (f) Barrio, P.; Esteruelas, M. A.; O~nate, E. J. Am. Chem. Soc. 2004, 126, 1946.

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Scheme 2

Figure 2. Molecular diagram of complex 6. Selected bond lengths (A˚) and angles (deg): Os(2)-C(45) 1.738(9), P(3)-Os(2)-P(4) 168.08(17), N(6)-Os(2)-H(02) 164.8, C(45)-Os(2)Cl(2) 170.6(5).

The replacement of the chloride ligands by acetonitrile molecules produces a decrease of the electron richness of the metal center, which gives rise to a decrease of the activation energy for the hydride migration from the metal center to the carbyne carbon atom.12 Thus, in contrast to 2, complex 3 is unstable in acetonitrile and evolves into [Os(dCHCHdC19H26O)(CH3CN)3(PiPr3)2](BF4)2 (4), containing the metal center and the steroid skeleton joined by an alkenylcarbene moiety. Under reflux, the transformation is quantitative after 2 h. Complex 4 is isolated as a dark green solid in 82% yield. In the 1H NMR spectrum the most noticeable resonances are those corresponding to the OsCH and CH protons of the alkenyl unit, which appear at 18.73 and 7.35 ppm as doublets with a H-H coupling constant of 14.0 Hz. In the 13C{1H} NMR spectrum the OsC resonance is observed at 265.6 ppm, as a triplet with a C-P coupling constant of 6.0 Hz, whereas the alkenyl resonances appear at 171.3 and 141.6 ppm as singlets. The 13P{1H} NMR spectrum shows an AB spin system centered at 2.6 ppm and defined by Δν = 24 Hz and JA-B = 85 Hz. Treatment of 2 with 2.2 equiv of TlPF6 in a 7:5 dichloromethane/acetone mixture, in contrast to that with AgBF4, produces the selective abstraction of the chlorine atom trans disposed to the hydride ligand. The subsequent coordination of an acetone molecule to the resulting unsaturated metal center affords [OsHCl(tCCHdC 19 H 26 O)(κ 1 -OCMe 2 )(PiPr3)2]PF6 (5), which is isolated as a pink solid in 84% yield according to Scheme 2. In dichloromethane, the coordinated acetone molecule is involved in a dissociationcoordination process, which is revealed by the presence of a broad hydride resonance at -10.5 ppm and a broad PiPr3 signal at 52.1 ppm in the 1H and 31P{1H} NMR spectra, respectively, in dichloromethane-d2 at room temperature. A triplet (JC-P = 11.1 Hz) at 269.1 ppm due to the carbyne (12) (a) Bola~ no, T.; Castarlenas, R.; Esteruelas, M. A.; Modrego, F. J.; O~ nate, E. J. Am. Chem. Soc. 2005, 127, 11184. (b) Bola~no, T.; Castarlenas, R.; Esteruelas, M. A.; O~nate, E. J. Am. Chem. Soc. 2006, 128, 3965. (c) Bola~ no, T.; Castarlenas, R.; Esteruelas, M. A.; O~nate, E. Organometallics 2007, 26, 2037. (d) Bola~no, T.; Castarlenas, R.; Esteruelas, M. A.; O~ nate, E. Organometallics 2008, 27, 6367. (e) Bola~no, T.; Castarlenas, R.; Esteruelas, M. A.; O~ nate, E. J. Am. Chem. Soc. 2009, 131, 2064.

carbon atom, in the 13C{1H} NMR spectrum, is also characteristic of this solvento species. The labile acetone molecule of 5 can be replaced by nucleobases. Treatment at room temperature of acetone solutions of 5 with 1.1 equiv of adenine for 15 min leads to [OsHCl(tCCHdC19H26O)(7H-amino-adenine)(PiPr3)2]PF6 (6) containing, in addition to the androgen, a 7H-aminoadenine tautomer. This compound is isolated as an orange solid in 88% yield. Complex 6 has been characterized by X-ray diffraction analysis, MS, elemental analysis, IR, and 1H, 13C{1H} and 31 P{1H}NMR spectroscopy. The structure13 (Figure 2) proves the 9H- to 7H-amino tautomerization of the nucleobase and its 9N-coordination. Although the 9H-amino tautomer of adenine is the most stable and hence predominant species in gas phase, in water, and in the solid state, it is well-known that metals can promote its rearrangement and stabilize the resulting tautomer by coordination.14 The distribution of ligands around the osmium atom can be described as a distorted octahedron with the phosphine ligands occupying trans positions (P(3)-Os(2)-P(4)= 168.08(17)°). The metal sphere is completed by the tautomerized adenine trans disposed to the hydride ligand (N(6)-Os(2)-H(02) = 164.8°) and the androgen trans disposed to the chlorine atom (C(45)-Os(2)-Cl(2) = 170.6(5)°). The Os(2)-C(45) distance of 1.738(9) A˚ compares well with that of 2. An extended view of the structure of 6 (Figure 3) shows that the molecules of complex are associated by means of two intermolecular hydrogen bonds between an NH-hydrogen atom of the NH2 group (N(10) in Figure 2) and N1 (N(9) in Figure 2) to form dimers. These dimers are associated with other dimers through hydrogen bonds between the oxygen atom of the androgen of a molecule of a pair and the free hydrogen atoms H7N (N(7) in Figure 2) and NH of the NH2 group of the molecule of other pair to generate infinite chains of dimer. The anions lie between the chains. The 1H, 13C{1H}, and 31P{1H} NMR spectra of 6 are consistent with Figure 2. In the 1H NMR spectrum in DMSO-d6 at room temperature, the resonances corresponding (13) The structure has two chemically equivalent but crystallographically independent molecules in the asymmetric unit. However, we only discuss one of them because the other one is disordered. (14) Lippert, B.; Gupta, D. Dalton Trans. 2009, 4619.

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Figure 3. Crystal packing of 6 showing the H-bonding pattern (blue atoms, N; red, O; green, Cl and F; orange, P; purple, Os).

to the HC-hydrogen atoms of the nucleobase appear at 9.03 (H8C) and 8.40 (H2C) ppm. The comparison of these chemical shifts with those of the free 9H-amino tautomer, 8.13 (H8C) and 8.14 (H2C) ppm, clearly indicates coordination via the 9N nitrogen (N(6) in Figure 2) since the coordination shift15 for H8C is found to be larger than that for H2C (0.90 versus 0.26). The alkenyl resonance of the alkenylcarbyne moiety of the androgen appears at 5.89 ppm as a singlet, whereas the hydride resonance is observed at -7.50 ppm as a triplet with a H-P coupling constant of 17.0 Hz. In the 13C{1H} NMR spectrum in dichloromethne-d2 the OsC resonance appears at 263.4 ppm as a triplet with a C-P coupling constant of 12.1 Hz. The alkenyl carbon atoms display singlets at 180.3 and 124.1 ppm. Although signals due to the 8C and 2C carbon atoms of the nucleobase are not observed, the HSQC spectrum indicates they should appear at 143.2 and 153.4 ppm, respectively. The 31 P{1H} NMR spectrum contains at 22.2 ppm an AB spin system defined by Δν = 17 Hz and JA-B = 84 Hz. In conclusion, steroid skeletons and transition metal fragments can be joined through alkenylcarbyne and alkenylcarbene moieties. The formation of these derivatives involves reactions between dihydride complexes, which can afford dihydrogen species,16 and ethynyl steroids. The coordination of nucleobases to the metal center gives rise to novel organometallic compounds containing, in addition to the androgen, a nucleobase.

Experimental Section All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. The starting material OsH2Cl2(PiPr3)2 (15) Beck, W. M.; Calabrese, J. C.; Kottmair, N. D. Inorg. Chem. 1979, 18, 176. (16) (a) Esteruelas, M. A.; Oro, L. A.; Ruiz, N. Inorg. Chem. 1993, 32, 3793. (b) Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A.; O~nate, E.; Ruiz, N. Inorg. Chem. 1994, 33, 787. (c) Barea, G.; Esteruelas, M. A.; Lledos, A.; L opez, A. M.; Tolosa, J. I. Inorg. Chem. 1998, 37, 5033. (d) Esteruelas, M. A.; Fernandez-Alvarez, F. J.; O~nate, E. J. Am. Chem. Soc. 2006, 128, 13044. (f) Esteruelas, M. A.; Fernandez-Alvarez, F. J.; O~nate, E. Organometallics 2008, 27, 6236.

was prepared according to the published method.17 Ethisterone and adenine were obtained from commercial sources and used without further purification. 1H, 19F, 31P{1H}, and 13C{1H} NMR spectra were recorded on a Bruker ARX 300, Bruker Avance 300, Bruker Avance 400, or a Bruker Avance 500 MHz instrument. Chemical shifts (expressed in parts per million) are referenced to residual solvent peaks (1H, 13C{1H}), external H3PO4 (31P{1H}), or CFCl3 (19F). Coupling constants, J and N, are given in hertz. Infrared spectra were run on a Perkin-Elmer 1730 spectrometer (Nujol mulls on polyethylene sheets). C, H, and N analyses were carried out in a Perkin-Elmer 2400 CHNS/ O analyzer. Preparation of OsHCl2(tCCHdC19H26O)(PiPr3)2 (2). A suspension of OsH2Cl2(PiPr3)2 (1) (600 mg, 1.028 mmol) in 35 mL of toluene was treated with 1.2 equiv of 17R-ethynyltestosterone (ethisterone) (385 mg, 1.234 mmol) for 48 h under reflux. After the mixture was cooled to room temperature, a purple precipitate was formed, which was filtered off, repeatedly washed with cold diethyl ether, and dried in vacuo. Yield: 595 mg (66%). Anal. Calcd for C39H70Cl2OOsP2: C, 53.35; H, 8.04. Found: C, 53.25; H, 8.16. IR (Nujol, cm-1): ν(OsH) 2176 (m); ν(CdO) 1668 (s); ν(CdC) 1593 (s). MS: m/z 878 (35), [M]; 843 (100), [M] - [Cl]. 1H NMR (400.13 MHz, CD2Cl2, 293 K): δ 5.67 (s, 1H, CHCO), 4.33 (s, 1H, CHdC), 2.66 (m, 6H, PCHCH3), 2.61-1.58 (m, 14H, CH2 and CH), 1.45 (dd, JH-P = 12.4, JH-H = 6.4, 9H, PCHCH3), 1.44 (dd, JH-P = 12.4, JH-H = 6.8, 9H, PCHCH3), 1.34 (dd, JH-P = 13.2, JH-H = 7.2, 9H, PCHCH3), 1.33 (dd, JH-P = 13.4, JH-H = 7.0, 9H, PCHCH3), 1.18 (s, 3H, CH3), 1.15-0.83 (m, 5H, CH2 and CH), 0.78 (s, 3H, CH3), -7.53 (t, JH-P = 17.0, 1H, OsH). 31 P{1H} NMR (162.0 MHz, CD2Cl2, 293 K): δ 18.9 (AB spin system, Δν = 17, JA-B = 86, PiPr3). 13C{1H}-APT NMR plus HMBC and HSQC (100.6 MHz, CD2Cl2, 293 K): δ 257.4 (t, JC-P = 11.0, OstC), 199.0 (s, CO), 180.6 (s, CHdC), 170.5 (s, CdCHCO), 128.3 (s, CHdC), 124.7 (s, CdCHCO), 54.5 and 53.7 (both s, CH), 47.8 and 39.4 (both s, CCH3), 36.6 (s, CH2), 36.1 (s, CH), 35.1, 34.7, 33.3, 32.5, and 32.2 (all s, CH2), 27.4 (dd, JC-P = 14.8, JC-P = 3.4, PCHCH3), 27.2 (dd, JC-P = 14.1, (17) Aracama, M.; Esteruelas, M. A.; Lahoz, F. J.; L opez, J. A.; Meyer, U.; Oro, L. A.; Werner, H. Inorg. Chem. 1991, 30, 288.

Article JC-P = 3.2, PCHCH3), 24.7 and 21.6 (both s, CH2), 20.3 and 20.2 (both s, PCHCH3), 18.0 and 17.0 (both s, CH3). Preparation of [OsH(tCCHdC19H26O)(CH3CN)2(PiPr3)2][BF4]2 (3). A purple solution of 2 (286 mg, 0.326 mmol) in a 7:5 dichloromethane/acetonitrile mixture (12 and 9 mL) was treated with 2.1 equiv of AgBF4 (133 mg, 0.684 mmol) in the absence of light. Immediately, the reaction mixture became yellow. After stirring the mixture for 1.5 h at room temperature, the suspension was filtered through Celite and the filtrate was evaporated to dryness. The crude reaction mixture was dissolved in 15 mL of dichloromethane, and the solution was filtered several times through Celite until the salt was completely eliminated and the solvent was removed in vacuo. The addition of diethyl ether (10 mL) caused the precipitation of a yellow solid, which was separated by decantation, washed with further portions of diethyl ether, and dried in vacuo. Yield: 241 mg (70%). Anal. Calcd for C43H76B2F8N2OOsP2: C, 48.60; H, 7.21; N, 2.64. Found: C, 48.35; H, 7.12; N, 2.75. IR (Nujol, cm-1): ν(CtN) 2320 (w), 2290 (w); ν(OsH) 2165 (m); ν(CdO) 1670 (s); ν(CdC) 1578 (s); ν(BF) 1059 (vs). MS: m/z 827 (100), [M] - [2CH3CN] þ [F]. 1H NMR (400.13 MHz, CD2Cl2, 293 K): δ 5.68 (s, 1H, CHCO), 4.73 (s, 1H, CHdC), 2.88 and 2.59 (both s, 6H, CH3CN), 2.52 (m, 6H, PCHCH3), 2.45-1.47 (m, 12H, CH2 and CH), 1.43 (dd, JH-P = 14.8, JH-H = 7.2, 9H, PCHCH3), 1.42 (dd, JH-P = 14.4, JH-H = 6.8, 9H, PCHCH3), 1.38 (dd, JH-P = 12.4, JH-H = 6.3, 9H, PCHCH3), 1.37 (dd, JH-P = 14.0, JH-H = 6.8, 9H, PCHCH3), 1.27-1.20 (m, 4H, CH2 and CH), 1.18 (s, 3H, CH3), 1.16-0.89 (m, 3H, CH2 and CH), 0.85 (s, 3H, CH3), -6.64 (t, JH-P = 15.8, 1H, OsH). 31P{1H} NMR (162.0 MHz, CD2Cl2, 293 K): δ 30.2 (AB spin system, Δν = 69, JA-B = 175, PiPr3). 13C{1H}-APT NMR plus HMBC and HSQC (75.5 MHz, CD2Cl2, 293 K): δ 280.9 (t, JC-P = 8.2, OstC), 199.5 (s, CO), 194.8 (s, CHdC), 170.9 (s, CdCHCO), 136.2 and 131.8 (both s, CH3CN), 126.4 (s, CHdC), 124.5 (s, CdCHCO), 53.7 and 52.7 (both s, CH), 50.0 and 39.1 (both s, CCH3), 36.2 (s, CH2), 35.7 (s, CH), 34.5, 34.2, 33.4, 33.0, and 32.0 (all s, CH2), 27.7 (d, JC-P = 16.9, JC-P = 1.1, PCHCH3), 27.6 (d, JC-P = 16.9, JC-P = 1.1, PCHCH3), 24.5 and 21.3 (both s, CH2), 19.8 and 19.6 (both s, PCHCH3), 17.7 and 17.1 (both s, CH3), 4.6 and 4.0 (both s, CH3CN). Preparation of [Os(=CHCHdC19H26O)(CH3CN)3(PiPr3)2][BF4]2 (4). A yellow solution of 3 (448 mg, 0.422 mmol) in 15 mL of acetonitrile was heated under reflux for 2 h. The solution was filtered through Celite, and the solvent was removed in vacuo. The addition of diethyl ether (12 mL) to the resulting residue led to a dark green solid, which was separated by decantation, washed with diethyl ether, and dried in vacuo. Yield: 380 mg (82%). Anal. Calcd for C45H79B2F8N3OOsP2: C, 48.96; H, 7.21; N, 3.81. Found: C, 48.78; H, 7.34; N, 3.92. IR (Nujol, cm-1): ν(CtN) 2315 (w); ν(CtN) 2274 (w); ν(CdO) 1662 (s); ν(CdC) 1580 (s); ν(BF) 1021 (vs). MS: m/z 832 (100), [M]. 1H NMR (400.13 MHz, CD2Cl2, 253 K): δ 18.73 (d, JH-H = 14.0, 1H, OsdCH), 7.35 (d, JH-H = 14.0, 1H, CHdC), 5.66 (s, 1H, CHCO), 2.96, 2.93, and 2.86 (all s, 9H, CH3CN), 2.38 (m, 6H, PCHCH3), 2.30-1.23 (m, 14H, CH2 and CH), 1.24-1.12 (m, 36H, PCHCH3), 1.17 (s, 3H, CH3, overlapped with the H of PCHCH3, assigned indirectly by HSQC), 1.07-0.91 (m, 5H, CH2 and CH), 0.78 (s, 3H, CH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 253 K): δ 2.6 (AB spin system, Δν = 24, JA-B = 85, PiPr3). 13C{1H}-APT NMR plus HMBC and HSQC (100.6 MHz, CD2Cl2, 253 K): δ 265.6 (t, JC-P = 6.0, OsdC), 200.1 (s, CO), 171.9 (s, CdCHCO), 171.3 (s, CHdC), 141.6 (s, CHdC), 135.8 and 124.0 (both s, CH3CN), 123.6 (s, CdCHCO), 123.3 (s, CH3CN), 53.3 and 52.5 (both s, CH), 47.0 and 38.6 (both s, CCH3), 35.3 (s, CH2), 34.8 (s, CH), 34.0, 33.7, 32.6, 31.5, and 31.1 (all s, CH2), 24.4 (dd, JC-P = 13.4, JC-P = 2.6, PCHCH3), 24.2 (dd, JC-P = 13.8, JC-P = 3.1, PCHCH3), 23.6 and 20.4 (both s, CH2), 18.8-18.2 (br, PCHCH3), 17.1 and 14.2 (both s, CH3), 4.5, 3.9, and 2.7 (all s, CH3CN).

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Preparation of [OsHCl(tCCHdC19H26O)(k1-OCMe2)(PiPr3)2]PF6 (5). A purple solution of 2 (305 mg, 0.347 mmol) in a 7:5 dichloromethane/acetone mixture (10 and 7 mL) was treated with 2.2 equiv of TlPF6 (267 mg, 0.764 mmol) in the absence of light at room temperature. After stirring the mixture for 2 h at room temperature, the color of the solution changed to salmonpink. The suspension was filtered through Celite, and the filtrate was evaporated to dryness. The crude reaction mixture was dissolved in 15 mL of dichloromethane, the solution was filtered through Celite several times until the salt was completely eliminated, and the solvent was removed in vacuo. The addition of diethyl ether (10 mL) caused the precipitation of a pink solid, which was separated by decantation, washed with further diethyl ether, and dried in vacuo. Yield: 305 mg (84%). Anal. Calcd for C42H76ClF6O2OsP3: C, 48.24; H, 7.33. Found: C, 47.77; H, 7.40. IR (Nujol, cm-1): ν(OsH) 2132 (m); ν((CH3)2CO) 1712 (m); ν(CdO) 1614 (s); ν(PF6) 841 (vs). 1H NMR (300.1 MHz, CD2Cl2, 293 K): δ 5.79 (s, 1H, CHCO), 4.86 (s, 1H, CHdC), 2.77 (m, 6H, PCHCH3), 2.60-2.22 (m, 6H, CH2 and CH), 2.12 (s, 6H, (CH3)2CO), 2.12-1.46 (m, 10H, CH2 and CH), 1.36 (dvt, N = 11.7, JH-H = 7.20, 18H, PCHCH3), 1.33 (dvt, N = 11.7, JH-H = 7.20, 18H, PCHCH3), 1.19 (s, 3H, CH3), 1.18-0.90 (m, 3H, CH2 and CH), 0.84 (s, 3H, CH3), -10.5 (br, 1H, OsH). 31P{1H} NMR (121.5 MHz, CD2Cl2, 293 K): δ 52.1 (br, PiPr3), -144.5 (sept, PF6). 19F{1H} NMR (282.4 MHz, CD2Cl2, 293 K): -77.3 (d, PF6). 13C{1H}-APT NMR plus HMBC and HSQC (75.5 MHz, CD2Cl2, 293 K): δ 269.1 (t, JC-P = 11.1, OstC), 202.1 (s, CO), 185.9 (s, CHdC), 173.9 (s, CdCHCO), 126.1 (s, CHdC), 124.4 (s, CdCHCO), 53.9 and 53.1 (both s, CH), 48.7 and 39.4 (both s, CCH3), 36.0 (s, CH2), 35.7 (s, CH), 34.7, 34.4, 33.3, 32.6, and 32.0 (all s, CH2), 27.2 (vt, N = 26.6, PCHCH3), 24.3 and 21.2 (both s, CH2), 20.2 and 20.1 (both s, PCHCH3), 17.7 and 17.0 (both s, CH3). Preparation of [OsHCl(tCCHdC19H26O)(7H-amino-adenine)(PiPr3)2]PF6 (6). A solution of 5 (342 mg, 0.327 mmol) in 15 mL of acetone was treated with 1.1 equiv of adenine (49 mg, 0.360 mmol) 15 min at room temperature. The resulting solution was filtered through Celite, and the solvent was removed in vacuo. The residue was dissolved in 10 mL of dichloromethane and filtered again through Celite, and the filtrate was evaporated to dryness. The residue was treated with diethyl ether (12 mL) to give an orange solid, which was separated by decantation, washed with further portions of diethyl ether, and dried in vacuo. Yield: 323 mg (88%). Anal. Calcd for C44H75N5ClF6OOsP3: C, 47.07; H, 6.73; N, 6.24. Found: C, 47.52; H, 7.09; N, 5.62. IR (Nujol, cm-1): ν(NH) þ ν(NH2) 3460 (m), 3341 (s), 3133 (s); ν(OsH) 2157 (m); ν(CdO) 1651 (s); ν(CdC) 1599 (s); ν(PF) 848 (vs). MS (MALDI-TOF): m/z 843.4 (80), [M] - [ADENINE]; 683.3 (100), [M] [ADENINE] - [PiPr3]. 1H NMR (500.1 MHz, DMSO-d6, 293 K): δ 12.94 (br, 1H, N;H7), 9.03 (s, 1H, H8), 8.40 (s, 1H, H2), 7.54 (br, 2H, NH2), 5.89 (s, 1H, CHdC), 5.64 (s, 1H, CHdCO), 2.50 (m, 6H, PCHCH3), 2.46-1.25 (m, 19H, CH2 and CH), 1.24 (dd, JH-P = 13.6, JH-H = 7.2, 9H, PCHCH3), 1.23 (dd, JH-P = 13.8, JH-H = 7.0, 9H, PCHCH3), 1.14 (s, 3H, CH3), 1.05 (dd, JH-P = 12.4, JH-H = 6.4, 9H, PCHCH3), 1.03 (dd, JH-P = 12.4, JH-H = 6.4, 9H, PCHCH3), 0.82 (s, 3H, CH3), -7.50 (t, JH-P = 17.0, 1H, OsH). 31P{1H} NMR (202.5 MHz, CD2Cl2, 293 K): δ 22.2 (AB spin system, Δν = 17, JA-B = 84, PiPr3), -144.2 (sept, PF6). 19F{1H} NMR (376.5 MHz, CD2Cl2, 293 K): -71.9 (d, PF6). 13C{1H}-APT NMR plus HMBC and HSQC (100.6 MHz, CD2Cl2, 293 K): δ 263.4 (t, JC-P = 12.1, OstC), 199.8 (s, CO), 180.3 (s, CHdC), 171.4 (s, CdCHCO), 157.8 (s, C4-A), 153.4 (no signal in 13C{1H}-APT, assigned indirectly by HSQC, C2-A), 152.6 (s, C6-A), 143.2 (no signal in 13C{1H}-APT, assigned indirectly by HSQC, C8-A), 129.5 (s, CdCHCO), 124.1 (s, CHdC), 112.2 (s, C5-A), 54.1 and 53.1 (both s, CH), 48.0 and 39.2 (both s, CCH3), 36.2 (s, CH2), 35.7 (s, CH), 34.9, 34.5, 33.1, 32.1, and 31.7 (all s, CH2), 26.4 (dd, JC-P = 12.8, JC-P = 1.5, PCHCH3), 26.4 (dd, JC-P = 11.1,

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JC-P = 1.5, PCHCH3), 24.4 and 21.3 (both s, CH2), 20.5 and 19.4 (both s, PCHCH3), 17.7 and 17.0 (both s, CH3).

Diputaci on General de Arag on (E35) is acknowledged. K.G. thanks the Spanish MEC for her grant.

Acknowledgment. Financial support from the MICINN of Spain (Project Nos. CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006) and the

Supporting Information Available: X-ray analysis and crystal structures determination, including a CIF file for 2 and 6. This material is available free of charge via the Internet at http:// pubs.acs.org.