Reactivity of Dihydrides MH2P4 (M = Fe, Ru, Os) with SnCl2

Aug 10, 2010 - Synopsis. The preparation of iron triad hydride-trihydridestannyl MH(SnH3)P4 and bis(trihydridestannyl) complexes M(SnH3)2P4 is describ...
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Organometallics 2010, 29, 3808–3816 DOI: 10.1021/om1004308

Reactivity of Dihydrides MH2P4 (M = Fe, Ru, Os) with SnCl2: Preparation of Bis(trihydridestannyl) Derivatives Gabriele Albertin,*,† Stefano Antoniutti,† and Jes us Castro‡ †

‡

Dipartimento di Chimica, Universit a Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia, Italy, and Departamento de Quı´mica Inorg anica, Universidade de Vigo, Facultade de Quı´mica, Edificio de Ciencias Experimentais, 36310 Vigo (Galicia), Spain Received May 6, 2010

Depending on the nature of the central metal and experimental conditions, the reaction of dihydride MH2P4 [M = Fe, Ru, Os; P = P(OEt)3, PPh(OEt)2] with SnCl2 gives both hydride-trichlorostannyl- MH(SnCl3)P4 (1, 2) and bis(trichlorostannyl) complexes M(SnCl3)2P4 (3, 4). Treatment of compounds 1-4 with NaBH4 in ethanol yielded both mono(trihydridestannyl) MH(SnH3)P4 (5, 6) and bis(trihydridestannyl) derivatives M(SnH3)2P4 (7, 8). Reaction of the hydride-trihydridestannyl complexes MH(SnH3)P4 with CO2 (1 atm) led to hydroxobis(formate)stannyl derivatives MH[Sn(OH){OC(H)dO}2]P4 (9, 10). The complexes were characterized by spectroscopy (IR and 1H, 31P, 13 C, 119Sn NMR) and by X-ray crystal structure determination of OsH[Sn(OH){OC(H)dO}2][PPh(OEt)2]4 (10b).

Introduction Transition metal complexes containing either a halogenostannyl [M]-SnX3 or an organostannyl [M]-SnR3 group as ligands have been extensively studied in recent years,1-5 both from a fundamental viewpoint and because the introduction of a stannyl ligand often changes the properties of complexes and may modify the activity of noble metal catalysts.6 In addition, coordinate stannyl groups may undergo a variety of reactions, including ligand substitution at the tin center, thus allowing the synthesis of stannyl complexes with novel functionalities.2,3 *Corresponding author. Fax: þ39 041 234 8917. E-mail: albertin@ unive.it. (1) (a) Mackay, K. M.; Nicholson, B. K. Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon Press: New York, 1982; Vol. 2, pp 1043-1114. (b) Holt, M. S.; Wilson, W. L.; Nelson, J. H. Chem. Rev. 1989, 89, 11–49. (c) Lappert, M. F.; Rowe, R. S. Coord. Chem. Rev. 1990, 100, 267–292. (d) Davies, A. G. Comprehensive Organometallic Chemistry; Stone, F. G. A.; Abel, E. W.; Wilkinson, G., Eds.; Pergamon Press: New York, 1995; Vol. 2, pp 218-297. (e) Davies, A. G. Organotin Chemistry; Wiley-VCH: Weinheim, Germany, 2004. (f ) Roper, W. R.; Wright, L. J. Organometallics 2006, 25, 4704–4718. (2) (a) Buil, M. L.; Esteruelas, M. A.; Lahoz, F. J.; O~ nate, E.; Oro, L. A. J. Am. Chem. Soc. 1995, 117, 3619–3620. (b) Nakazawa, H.; Yamaguchi, Y.; Miyoshi, K. Organometallics 1996, 15, 1337–1339. (c) Schubert, U.; Grubert, S. Organometallics 1996, 15, 4707–4713. (d) Akita, M.; Hua, R.; Nakanishi, S.; Tanaka, M.; Moro-oka, Y. Organometallics 1997, 16, 5572–5584. (e) Djukic, J.-P.; D€otz, K. H.; Pfeffer, M.; De Cian, A.; Fischer, J. Organometallics 1997, 16, 5171–5182. (f ) Nakazawa, H.; Yamaguchi, Y.; Kawamura, K.; Miyoshi, K. Organometallics 1997, 16, 4626–4635. (g) Biswas, B.; Sugimoto, M.; Sakaki, S. Organometallics 1999, 18, 4015–4026. (h) Baya, M.; Crochet, P.; Esteruelas, M. A.; Gutierrez-Puebla, E.; Ruiz, N. Organometallics 1999, 18, 5034–5043. (i) Rickard, C. E. F.; Roper, W. R.; Woodman, T. J.; Wright, L. J. Chem. Commun. 1999, 837–838. ( j) Adams, H.; Broughton, S. G.; Walters, S. J.; Winter, M. J. Chem. Commun. 1999, 1231–1232. (k) Clark, A. M.; Rickard, C. E. F.; Roper, W. R.; Woodman, T. J.; Wright, L. J. Organometallics 2000, 19, 1766–1774. (l) Hermans, S.; Johnson, B. F. G. Chem. Commun. 2000, 1955–1956. (m) Turki, M.; Daniel, C.; Zalis, S.; Vlcek, A., Jr.; van Slageren, J.; Stufkens, D. J. J. Am. Chem. Soc. 2001, 123, 11431–11440. pubs.acs.org/Organometallics

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We are interested in the chemistry of stannyl complexes of both manganese and iron triads and have reported7,8 on the reaction of halogeno complexes [M]-Cl with SnCl2 3 H2O, giving trichlorostannyl derivatives [M]-SnCl3, and the subsequent reaction with nucleophiles, which allowed the synthesis of both trihydridestannyl [M]-SnH3 complexes and novel organostannyl derivatives of the type M(SnH3)(CO)nP5-n, [M{Sn[OC(H)dO]2(μ-OH)}(CO)nP5-n]2, M[Sn{C(COOR)dCH2}3](CO)nP5-n (M = Mn, Re; n = 2, 3), M(SnH3)(Tp)(P)(PPh3), M(SnH3)(Cp)(P)(PPh3), M[Sn(Ct CR)3](Tp)(P)(PPh3) (M = Ru, Os; P = phosphite), etc. The (3) (a) Neale, N. R.; Tilley, T. D. J. Am. Chem. Soc. 2002, 124, 3802– 3803. (b) Esteruelas, M. A.; Lledos, A.; Maseras, F.; Olivan, M.; O~nate, E.; Tajada, M. A.; Tomas, J. Organometallics 2003, 22, 2087–2096. (c) Adams, R. D.; Captain, B.; Smith, J. L., Jr.; Hall, M. B.; Beddie, C. L.; Webster, C. E. Inorg. Chem. 2004, 43, 7576–7578. (d) Neale, N. R.; Tilley, T. D. J. Am. Chem. Soc. 2005, 127, 14745–14755. (e) Adams, R. D.; Captain, B.; Herber, R. H.; Johansson, M.; Nowik, I.; Smith, J. L.; Smith, M. D. Inorg. Chem. 2005, 44, 6346–6358. (f ) Eguillor, B.; Esteruelas, M. A.; Olivan, M.; O~nate, E. Organometallics 2005, 24, 1428–1438. (g) Sagawa, T.; Ohtsuki, K.; Ishiyama, T.; Ozawa, F. Organometallics 2005, 24, 1670–1677. (h) Adams, R. D.; Captain, B.; Hollandsworth, C. B.; Johansson, M.; Smith, J. L., Jr. Organometallics 2006, 25, 3848–3855. (i) Alvarez, M. A.; Garcia, M. E.; Ramos, A.; Ruiz, M. A. Organometallics 2006, 25, 5374–5380. ( j) Braunschweig, H.; Bera, H.; Geibel, B.; D€orfler, R.; G€otz, D.; Seeler, F.; Kupfer, T.; Radacki, K. Eur. J. Inorg. Chem. 2007, 3416–3424. (k) Albertin, G.; Antoniutti, S.; Castro, J.; García-Fontan, S.; Noe, M. Dalton Trans. 2007, 5441–5452. (l) Carlton, L.; Fernandes, M. A.; Sitabule, E. Proc. Natl. Acad. Sci. 2007, 104, 6969–6973. (m) Kabir, S. E.; Raha, A. K.; Hassan, M. R.; Nicholson, B. K.; Rosenberg, E.; Sharmin, A.; Salassa, L. Dalton Trans. 2008, 4212–4219. (4) (a) Chipperfield, J. R.; Hayter, A. C.; Webster, D. E. J. Chem. Soc., Dalton Trans. 1977, 485–490. (b) McCullen, S. B.; Brown, T. L. J. Am. Chem. Soc. 1982, 104, 7496–7500. (c) Foster, S. P.; Mackay, K. M. J. Organomet. Chem. 1983, 247, 21–26. (d) Bullock, J. P.; Palazzotto, M. C.; Mann, K. R. Inorg. Chem. 1990, 29, 4413–4421. (e) Sullivan, R. J.; Brown, T. L. J. Am. Chem. Soc. 1991, 113, 9155–9161. (f ) Utz, T. L.; Leach, P. A.; Geib, S. J.; Cooper, N. J. Chem. Commun. 1997, 847–848. (g) Chen, Y.-S.; Ellis, J. E. Inorg. Chim. Acta 2000, 300-302, 675–682. (h) Christendat, D.; Wharf, I.; Lebuis, A.-M.; Butler, I. S.; Gilson, D. F. G. Inorg. Chim. Acta 2002, 329, 36–44. r 2010 American Chemical Society

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interesting properties shown by the trihydride ligand SnH3 in these complexes7,8 prompted us to extend our study to dihydrides MH2P4 [M = Fe, Ru, Os; P = P(OEt)3, PPh(OEt)2] with the aim of testing whether bis(trihydridestannyl) complexes could be prepared. The results, which include the synthesis and some reactivity of hydride-trihydridestannyl and of the first example of a bis(trihydridestannyl) complex, are reported here.

Experimental Section General Comments. All synthetic work was carried out in an appropriate atmosphere (Ar, N2) using standard Schlenk techniques or an inert atmosphere drybox. Once isolated, the complexes were found to be relatively stable in air, but were stored under nitrogen at -25 °C. All solvents were dried over appropriate drying agents, degassed on a vacuum line, and distilled into vacuum-tight storage flasks. RuCl3 3 3H2O and OsO4 were Pressure Chemical Co. (USA) products, used as received. Phosphite PPh(OEt)2 was prepared by the method of Rabinowitz and Pellon,9 while P(OEt)3 was an Aldrich product, purified by distillation under nitrogen. Other reagents were purchased from commercial sources in the highest available purity and used as received. Infrared spectra were recorded on a Perkin-Elmer Spectrum-One FT-IR spectrophotometer. NMR spectra (1H, 31 P, 13C, 119Sn) were obtained on AC200 or AVANCE 300 Bruker spectrometers at temperatures between -90 and þ30 °C, unless otherwise noted. 1H and 13C spectra are referenced to internal tetramethylsilane; 31P{1H} chemical shifts are reported with respect to 85% H3PO4, and those of 119Sn with respect to Sn(CH3)4, and in both cases downfield shifts are considered positive. COSY, HMQC, and HMBC NMR experiments were performed with standard programs. The SwaN-MR and iNMR software packages10 were used to treat NMR data. The conductivity of 10-3 mol dm-3 solutions of the complexes in CH3NO2 at 25 °C was measured on a Radiometer CDM 83. Elemental analyses were determined in the Microanalytical Laboratory of the Dipartimento di Scienze Farmaceutiche, University of Padova (Italy). Synthesis of Complexes. Hydride complexes MH2P4 [M = Fe, Ru. Os; P = P(OEt)3, PPh(OEt)2] and dihydrogen derivatives (5) (a) Luong, J. C.; Faltynek, R. A.; Wrighton, M. S. J. Am. Chem. Soc. 1980, 102, 7892–7900. (b) Huie, B. T.; Kirtley, S. W.; Knobler, C. B.; Kaesz, H. D. J. Organomet. Chem. 1981, 213, 45–62. (c) Narayanan, B. A.; Kochi, J. K. Inorg. Chim. Acta 1986, 122, 85–90. (d) Westerberg, D. E.; Sutherland, B. E.; Huffman, J. C.; Caulton, K. G. J. Am. Chem. Soc. 1988, 110, 1642–1643. (e) Warnock, G. F. P.; Moodie, L. C.; Ellis, J. E. J. Am. Chem. Soc. 1989, 111, 2131–2141. (f ) Loza, M. L.; Crabtree, R. H. Inorg. Chim. Acta 1995, 236, 63–66. (6) (a) Coupe, J. N.; Jord~ao, E.; Fraga, M. A.; Mendes, M. J. Appl. Catal. A 2000, 199, 45. (b) Hermans, S.; Raja, R.; Thomas, J. M.; Johnson, B. F. G.; Sankar, G.; Gleeson, D. Angew. Chem., Int. Ed. 2001, 40, 1211. (c) Huber, G. W.; Shabaker, J. W.; Dumesic, J. A. Science 2003, 300, 2075. (d) Adams, R. D.; Captain, B.; Johansson, M.; Smith, J. L., Jr. J. Am. Chem. Soc. 2005, 127, 488–489. (7) (a) Albertin, G.; Antoniutti, S.; Bacchi, A.; Bortoluzzi, M.; Pelizzi, G.; Zanardo, G. Organometallics 2006, 25, 4235–4237. (b) Albertin, G.; Antoniutti, S.; Castro, J.; García-Fontan, S.; Zanardo, G. Organometallics 2007, 26, 2918–2930. (c) Albertin, G.; Antoniutti, S.; Bacchi, A.; Pelizzi, G.; Zanardo, G. Organometallics 2008, 27, 4407–4418. (8) (a) Albertin, G.; Antoniutti, S.; Castro, J.; Garcı´ a-Fontan, S.; Zanardo, G. Organometallics 2008, 27, 2789–2794. (b) Albertin, G.; Antoniutti, S.; Castro, J.; Zanardo, G. Organometallics 2009, 28, 1270– 1273. (9) Rabinowitz, R.; Pellon, J. J. Org. Chem. 1961, 26, 4623–4626. (10) Balacco, G. J. Chem. Inf. Comput. Sci. 1994, 34, 1235–1241http:// www.inmr.net/. (11) (a) Tebbe., F. N.; Meakin, P.; Jesson, J. P.; Muetterties, E. L. J. Am. Chem. Soc. 1970, 92, 1068–1070. (b) Titus, D.; Orio, A. A.; Gray, H. B. Inorg. Synth. 1972, 13, 117. (c) Gerlach, D. H.; Peet, W. G.; Muetterties, E. L. J. Am. Chem. Soc. 1972, 94, 4545–4549. (d) Albertin, G.; Antoniutti, S.; Bordignon, E. J. Chem. Soc., Dalton Trans. 1989, 2353– 2358.

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[FeH(η2-H2)P4]BPh4 and [OsH(η2-H2)P4]BF4 were prepared following the methods previously described.11,12 FeH(SnCl3)P4 (1) [P=P(OEt)3 (a), PPh(OEt)2 (b)]. Method 1. In a 100 mL three-necked round-bottomed flask were placed 3.7 mmol of the appropriate hydride FeH2P4, an excess of anhydrous SnCl2 (37 mmol, 7.0 g), and 40 mL of dichloromethane. The reaction mixture was stirred for 24 h and then filtered to remove the unreacted tin chloride. The resulting solution was evaporated to dryness under reduced pressure to give an oil, which was triturated with ethanol (8 mL). A yellow solid slowly separated out, which was filtered and crystallized from CH2Cl2 and ethanol. Yield: 2.31 g (66%) for 1a; 2.55 g (64%) for 1b. Method 2. An excess of SnCl2 3 2H2O (2.0 g, 8.9 mmol) in 10 mL of ethanol was added to a suspension of the appropriate complex [FeH(η2-H2)P4]BPh4 (0.89 mmol) in ethanol (20 mL) and the reaction mixture stirred for 24 h. The resulting solution was concentrated to about 5 mL by evaporation of the solvent under reduced pressure and allowed to stand at -25 °C. A yellow solid slowly separated out within 2-3 days, which was filtered and crystallized from CH2Cl2 and ethanol. Yield: 0.63 g (75%) for 1a; 0.75 g (78%) for 1b. 1a: IR (KBr) cm-1: νFeH 1902 (m). 1H NMR (CD3C6D5, 25 °C) δ: 4.09 (m, 24H, CH2), 1.30, 1.22 (t, 36H, CH3), ABC2X spin system (X=1H), δX -11.73, J31PA1H = 26.3, J31PB1H = 94.4, J31PC1H = 40.2 Hz (1H, FeH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: ABC2, δA 174.4, δB 167.4, δC 166.4, J31PA31PB=112.6, J31PA31PC = 127.5, J31PB31PC = 49.1 (J31PA117Sn = 812.9, J31PB117Sn = 850.9, J31PC117Sn=865.7). 119Sn{1H} NMR (CD3C6D5, 25 °C) δ: ABC2M, δM -163.1, J31PA119Sn = 851.5, J31PB119Sn = 892.9, J31PC119Sn = 908.1. Anal. Calcd for C24H61Cl3FeO12P4Sn: C, 30.45; H, 6.50; Cl, 11.24. Found: C, 30.64; H, 6.43; Cl, 11.05. 1b: IR (KBr) cm-1: νFeH 1728 (m). 1H NMR (CD3C6D5, 25 °C) δ: 7.81-7.18 (m, 20H, Ph), 3.97, 3.55, 3.25, 2.90 (m, 16H, CH2), 1.29, 1.26, 1.15, 0.86 (t, 24H, CH3), ABC2X, δX -11.40, J31PA1H =21.5, J31PB1H =82.7, J31PC1H = 40.5 (1H, FeH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: ABC2, δA 195.5, δB 190.5, δC 189.5, J31PA31PB = 80.5, J31PA31PC = 95.4, J31PB31PC = 30.3 (J31PA117Sn = 588.2, J31PB117Sn = 592.2, J31PC117Sn = 718.7). 119Sn{1H} NMR (CD3C6D5, 25 °C) δ: ABC2M, δM -220.0, J31PA119Sn = 613.0, J31PB119Sn=610.0, J31PC119Sn=754.0. Anal. Calcd for C40H61Cl3FeO8P4Sn: C, 44.70; H, 5.72; Cl, 9.90. Found: C, 44.87; H, 5.80; Cl, 9.69. OsH(SnCl3)P4 (2) [P=P(OEt)3 (a), PPh(OEt)2 (b)]. Method 1. In a 50 mL three-necked round-bottomed flask were placed 0.6 mmol of the appropriate hydride OsH2P4, an excess of SnCl2 3 2H2O (1.8 mmol, 0.41 g), and 20 mL of ethanol, and the reaction mixture was refluxed for 3 h. The solvent was removed under reduced pressure to give a solid, from which the trichlorostannyl complex was extracted with three 10 mL portions of acetone. The extracts were evaporated to dryness under reduced pressure to give an oil, which was triturated with ethanol (5 mL). A white solid slowly separated out, which was filtered and dried under vacuum. Yield: 0.50 g (77%) for 2a; 0.57 g (78%) for 2b. Method 2. In a 50 mL three-necked round-bottomed flask were placed 0.6 mmol of the appropriate complex [OsH(η2-H2)P4]BF4, an excess of SnCl2 3 2H2O (1.5 mmol, 0.34 g), and 20 mL of ethanol. The reaction mixture was refluxed for 2 h, and then the solvent was removed under reduced pressure. The solid obtained was extracted with three 10 mL portions of acetone, and the extracts were evaporated to dryness. The addition of ethanol (5 mL) to the oil obtained caused the slow separation of a white solid, which was filtered and dried under vacuum. Yield: 0.42 g (65%) for 2a; 0.49 g (67%) for 2b. 2a: IR (KBr) cm-1: νOsH 1974 (m). 1H NMR [(CD3)2CO, 25 °C] δ: 4.08, 3.96 (m, 24H, CH2), 1.33, 1.30, 1.27 (t, 36H, CH3), AB2CX, δX -11.14, J31PA1H = 71.0, J31PB1H=24.0, J31PC1H=17.6 (1H, OsH) (J1H119Sn = 153.7, J1H117Sn = 147.3). 31P{1H} NMR (12) (a) Albertin, G.; Antoniutti, S.; Bordignon, E. J. Am. Chem. Soc. 1989, 111, 2072–2077. (b) Amendola, P.; Antoniutti, S.; Albertin, G.; Bordignon, E. Inorg. Chem. 1990, 29, 318–324.

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[(CD3)2CO, 25 °C] δ: AB2C, δA 108.9, δB 105.2, δC 98.0, J31PA31PB =30.4, J31PA31PC = 28.9, J31PB31PC = 43.6 (J31PA117Sn = 281.0, J31PB117Sn = 343.0, J31PC117Sn = 2789.0). 119Sn{1H} NMR [(CD3)2CO, 25 °C] δ: AB2CM, δM -435.9, J31PA119Sn = 298.0, J31PB119Sn = 360.5, J31PC119Sn = 2916.5. Anal. Calcd for C24H61Cl3O12OsP4Sn: C, 26.67; H, 5.69; Cl, 9.84. Found: C, 26.49; H, 5.77; Cl, 9.70. 2b: IR (KBr) cm-1: νOsH 1975 (w). 1H NMR [(CD3)2CO, 25 °C] δ: 7.98-7.25 (m, 20H, Ph), 3.74, 3.57, 3.23, 3.15 (m, 16H, CH2), 1.26, 1.21, 1.14, 0.89 (t, 24H, CH3), AB2CX, δX -10.33, J31PA1H=62.5, J31PB1H=23.9, J31PC1H=16.7 (1H, OsH) (J1H119Sn = 145.2, J1H117Sn = 139.6). 31P{1H} NMR [(CD3)2CO, 25 °C] δ: AB2C, δA 128.0, δB 124.9, δC 116.0, J31PA31PB = 18.7, J31PA31PC = 18.9, J31PB31PC=30.3 (J31PA117Sn=285.0, J31PB117Sn=310.2, J31PC117Sn= 2275.5). 119Sn{1H} NMR [(CD3)2CO, 25 °C] δ: AB2CM, δM -456.6, J31PA119Sn = 296.2, J31PB119Sn = 322.0, J31PC119Sn = 2380.0. Anal. Calcd for C40H61Cl3O8OsP4Sn: C, 39.73; H, 5.09; Cl, 8.80. Found: C, 39.92; H, 5.22; Cl, 8.63. Ru(SnCl3)2[P(OEt)3]4 (3a). In a 50-mL three-necked roundbottomed flask were placed 1.0 mmol (0.77 g) of RuH2[P(OEt)3]4, an excess of anhydrous SnCl2 (10 mmol, 1.9 g), and 20 mL of dichloromethane. The reaction mixture was stirred for 24 h, and then the solvent was removed under reduced pressure. The oil obtained was treated with ethanol (5 mL), and the resulting solution was stirred until a white solid separated out, which was filtered and crystallized from CH2Cl2 and ethanol; yield 1.00 g (82%). 1H NMR (CD2Cl2, 25 °C) δ: 4.19 (m, 24H, CH2), 1.39, 1.37 (t, 36H, CH3). 31P{1H} NMR (CD2Cl2, 25 °C) δ: AA0 B2, δA = δA0 128.9, δB 128.3, J31PA31PB = J31PA0 31PB = 52.4 (J31PA117Sn = 2954.5, J31PA0 117Sn = 350.9, J31PB117Sn = 408.1). 119Sn NMR (CD2Cl2, 25 °C) δ: AA0 B2MM0 , δM = δM0 -349.7, J31PA119Sn = J31PA0 119Sn0 = 3092.0, J31PA0 119Sn = J31PA119Sn0 = 371.0, J31PB119Sn = J31PB119Sn0 = 423.5. Anal. Calcd for C24H60Cl6O12P4RuSn2: C, 23.71; H, 4.97; Cl, 17.50. Found: C, 23.53; H, 4.81; Cl, 17.38. Os(SnCl3)2P4 (4) [P = P(OEt)3 (a), PPh(OEt)2 (b)]. In a 50-mL three-necked round-bottomed flask were placed 1.0 mmol of the appropriate trichlorostannyl complex OsH(SnCl3)P4, an excess of SnCl2 3 H2O (4 mmol, 0.9 g), and 20 mL of ethanol. The reaction mixture was refluxed for 10 h, and then the volume was reduced to about 5 mL by evaporation of the solvent under reduced pressure. By cooling the resulting solution to -25 °C, a white solid slowly separated out, which was filtered and crystallized from CH2Cl2 and ethanol. Yield: 1.02 g (78%) for 4a; 1.16 g (81%) for 4b. 4a: 1H NMR (CD2Cl2, 25 °C) δ: 4.18 (m, 24H, CH2), 1.39, 1.37 (t, 36H, CH3). 31P{1H} NMR (CD2Cl2, 25 °C) δ: AA0 B2, δA = δA0 89.7, δB 81.3, J31PA31PB = J31PA0 31PB = 38.4 (J31PA117Sn = 334.0, J31PA0 117Sn = 272.2, J31PB117Sn = 2575.4). 119Sn NMR (CD2Cl2, 25 °C) δ: AA0 B2MM0 , δM =δM0 -372.2, J31PA119Sn = J31PA0 119Sn0 = 344.2, J31PA0 119Sn = J31PA119Sn0 = 286.4, J31PB119Sn = J31PB119Sn0 = 2717.8. Anal. Calcd for C24H60Cl6O12OsP4Sn2: C, 22.09; H, 4.63; Cl, 16.30. Found: C, 21.88; H, 4.69; Cl, 16.12. 4b: 1H NMR [(CD3)2CO, 25 °C] δ: 7.90-7.10 (m, 20H, Ph), 3.90-3.55, 3.10-2.93 (m, 16H, CH2), 1.45, 1.41, 1.25, 1.40, 1.38, 1.22 (t, 24H, CH3). 31P{1H} NMR [(CD3)2CO, 25 °C] δ: A2BB0 , δA 113.5, δB=δB0 110.2, J31PA31PB=J31PA31PB0 =25.6 (J31PA117Sn = 311.1, J31PB117Sn=2188.6, J31PB0 117Sn=269.3). 119Sn NMR [(CD3)2CO, 25 °C] δ: A2BB0 MM0 , δM = δM0 -423.0, J31PA119Sn = J31PA119Sn0 =323.9, J31PB119Sn = J31PB0 119Sn0 = 2283.3, J31PB0 119Sn = J31PB119Sn0 = 281.2. Anal. Calcd for C40H60Cl6O8OsP4Sn2: C, 33.52; H, 4.22; Cl, 14.84. Found: C, 33.68; H, 4.15; Cl, 14.63. FeH(SnH3)P4 (5) [P = P(OEt)3 (a), PPh(OEt)2 (b)]. In a 50 mL three-necked round-bottomed flask were placed 0.6 mmol of the appropriate complex FeH(SnCl3)P4 and an excess of NaBH4 (6 mmol, 0.23 g), and the flask was cooled to -196 °C. Ethanol (15 mL) was added, and the reaction mixture was left to reach 0 °C and stirred for 5 min. The solvent was removed at 0 °C under reduced pressure to leave an oil, which was extracted with three 5 mL portions of toluene. The extracts were evaporated to

Albertin et al. dryness under reduced pressure, and the resulting oil was triturated with pentane (10 mL). A white (5a) or pale yellow (5b) solid slowly separated out, which was filtered and dried under vacuum. Yield: 0.28 g (55%) for 5a; 0.34 g (59%) for 5b. 5a: IR (KBr) cm-1: νFeH 1901 (m); νSnH 1762, 1735 (s). 1H NMR (CD3C6D5, 25 °C) δ: 4.25-3.88 (m, 24H, CH2), ABC2XY3 (X, Y=1H), δY 3.60, J31PA1H = 5.9, J31PB1H = 0.7, J31PC1H = 0.4, J1H1H = 0.1 (J1H119Sn = 1250.0, J1H117Sn=1194.5) (3H, SnH3), 1.27, 1.25, 1.22 (t, 36H, CH3), -13.40 to -13.90 (m, 1H, FeH); 1 H{31P}: δH -13.7, J1H119Sn=164.5, J1H117Sn = 157.0 (1H, FeH). 31 P{1H} NMR (CD3C6D5, 25 °C) δ: ABC2, δA 182.0, δB 175.1, δC 174.4, J31PA31PB = 86.0, J31PA31PC = 87.8, J31PB31PC = 59.1 (J31PA117Sn = 341.0, J31PB117Sn = 474.0, J31PC117Sn = 628.0). 119Sn NMR (CD3C6D5, 25 °C) δ: ABC2XMY3, δM -333 (m); 119Sn{1H}: ABC2M, δM -332.8, J31PA119Sn = 353.7, J31PB119Sn = 492.0, J31PC119Sn = 653.0. Anal. Calcd for C24H64FeO12P4Sn: C, 34.19; H, 7.65. Found: C, 34.36; H, 7.72%. 5b: IR (KBr) cm-1: νSnH 1755 (m, br). 1H NMR (CD3C6D5, 25 °C) δ: 8.20-6.96 (m, 20H, Ph), 4.12-3.10 (m, 16H, CH2), AB2CXY3, δY 3.84, J31PA1H = 3.8, J31PB1H = 1.1, J31PC1H = 0.5, J1H1H = 0.1 (J1H119Sn = 1263.3, J1H117Sn = 1208.0) (3H, SnH3), 1.25, 1.22, 1.06, 1.04 (t, 24H, CH3), AB2CXY3, δX -12.85, J31PA1H = 36.0, J31PB1H = 63.8, J31PC1H = 23.5, J1H1H = 0.1 (J1H119Sn = 164.5, J1H117Sn = 157.0) (1H, FeH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: AB2C, δA 199.1, δB 192.7, δC 186.9, J31PA31PB = 66.1, J31PA31PC = 59.4, J31PB31PC = 30.8 (J31PA117Sn = 208.8, J31PB117Sn = 528.8, J31PC117Sn =460.5). 119Sn NMR (CD3C6D5, 25 °C) δ: AB2CXMY3, δM -310 (m). 119Sn{1H}: AB2CM, δM -309.4, J31PA119Sn = 216.5, J31PB119Sn=553.3, J31PC119Sn = 485.5. Anal. Calcd for C40H64FeO8P4Sn: C, 49.46; H, 6.64. Found: C, 49.59; H, 6.51. OsH(SnH3)P4 (6) [P = P(OEt)3 (a), PPh(OEt)2 (b)]. These complexes were prepared following the method used for the related iron derivatives 5. Yield: 0.33 g (56%) for 6a; 0.38 g (57%) for 6b. 6a: IR (KBr) cm-1: νOsH 1976 (m); νSnH 1754, 1735 (s). 1H NMR (CD3C6D5, 25 °C) δ: 4.01 (m, 24H, CH2), AB2CY3X (Y, X = 1H), δY 3.03, J31PA1H = 11.2, J31PB1H = 3.75, J31PC1H = 3.65, J1H1H = 1.70 (J1H119Sn = 1228.7, J1H117Sn = 1166.5) (3H, SnH3), 1.23, 1.20, 1.19 (t, 36H, CH3), AB2CY3X, δX -12.07, J31PA1H = 25.6, J31PB1H = 19.0, J31PC1H = 74.0 (J1H119Sn =133.8, J1H117Sn = 126.0) (1H, OsH). 31P{1H} NMR (CD3C6D5, -40 °C) δ: AB2C, δA 114.9, δB 112.8, δC 112.3, J31PA31PB = 37.0, J31PA31PC = 21.6, J31PB31PC = 31.8 (J31PA117Sn=1161.0, J31PB117Sn=259.8, J31PC117Sn = 169.8). 119Sn NMR (CD3C6D5, 25 °C) δ: AB2CXMY3, δM -570 (m). 119Sn{1H}: AB2CM, δM -568.6, J31PA119Sn = 1128.7, J31PB119Sn = 273.7, J31PC119Sn = 178.0. Anal. Calcd for C24H64O12OsP4Sn: C, 29.49; H, 6.60. Found: C, 29.30; H, 6.75. 6b: IR (KBr) cm-1: νOsH 1990 (w); νSnH 1758, 1732 (s). 1H NMR [(CD3)2CO, 25 °C] δ: 7.89-7.13 (m, 20H, Ph), 3.80-3.21 (m, 16H, CH2), AB2CY3X, δY 2.55, J31PA1H = 8.7, J31PB1H = 2.5, J31PC1H = 3.4, J1H1H = 1.2 (J1H117Sn =1153.6) (3H, SnH3), 1.22, 1.16, 1.14, 1.10 (t, 24H, CH3), AB2CY3X, δX -11.39, J31PA1H = 63.3, J31PB1H = 24.2, J31PC1H = 15.9 (J1H117Sn = 75.0) (1H, OsH). 31 P{1H} NMR [(CD3)2CO, 25 °C] δ: AB2C, δA 126.2, δB 124.4, δC 121.6, J31PA31PB = 26.8, J31PA31PC = 17.7, J31PB31PC = 16.7 (J31PA117Sn = 956.0, J31PB117Sn = 223.0, J31PC117Sn = 181.0). 119Sn NMR (CD3C6D5, 25 °C) δ: AB2CXMY3, δM -524.5, J31PA119Sn = 1002.5, J31PB119Sn = 233.8, J31PC119Sn = 190.1, J119Sn1HX = 81.4, J119Sn1HY = 1210.5. Anal. Calcd for C40H64O8OsP4Sn: C, 43.45; H, 5.83. Found: C, 43.27; H, 5.71. M(SnH3)2P4 (7, 8) [M = Ru (7), Os (8); P = P(OEt)3 (a), PPh(OEt)2 (b)]. In a 50 mL three-necked round-bottomed flask were placed 0.35 mmol of the appropriate bis(trichlorostannyl) complex M(SnCl3)2P4 and 5 mL of ethanol. The flask was cooled to -196 °C, and an excess of NaBH4 (7.0 mmol, 0.26 g) in ethanol (15 mL) was slowly added. The reaction mixture was left to reach 0 °C and stirred for 20 min, and then the solvent was removed at 0 °C under reduced pressure. The oil obtained was extracted with three 5 mL portions of toluene, and the extracts were evaporated to dryness by evaporation under reduced pressure. The oil obtained

Article was triturated with pentane (15 mL) until a white solid separated out, which was filtered and crystallized from toluene and pentane. Yield: 0.12 g (35%) for 7a; 0.14 g (37%) for 8a; 0.16 g (38%) for 8b. 7a: IR (KBr) cm-1: νSnH 1759, 1721 (s). 1H NMR [(CD3)2CO, 25 °C] δ: 4.08, 3.98 (m, 24H, CH2), AA0 B2Y3Y0 3 (Y, Y0 = 1H), δY, δY0 3.30, J31PA1H = 3.75, J31PA1H0 =J31PA0 1H = 14.7, J31PA0 1H0 = 2.3, J31PB1H = J31PB1H0 = 3.26 (J1H117Sn = 1170.0) (6H, SnH3), 1.24, 1.22 (t, 36H, CH3). 31P{1H} NMR [(CD3)2CO, 25 °C] δ: AA0 B2, δA, δA0 146.2, δB 145.0, J31PA31PB = J31PA0 31PB = 49.8 (J31PA117Sn = 198.0, J31PA0 117Sn = 1476.0, J31PB117Sn = 271.5). 119Sn NMR [(CD3)2CO, 25 °C] δ: AA0 B2MY3M0 Y0 3, δM = δM0 -312.2, J31PA119Sn = J31PA0 119Sn0 = 206.5, J31PA0 119Sn = J31PA119Sn0 = 1543.0, J31PB119Sn = J31PB119Sn0 = 281.0, J119Sn1H = J119Sn0 1H0 = 1225.6. Anal. Calcd for C24H66O12P4RuSn2: C, 28.56; H, 6.59. Found: C, 28.76; H, 6.43. 8a: IR (KBr) cm-1: νSnH 1748, 1730 (s). 1H NMR (CD3C6D5, 25 °C) δ: 3.98 (m, 24H, CH2), AA0 B2Y3Y0 3, δY, δY0 3.64, J31PA1H = J31PA0 1H0 =11.35, J31PA1H0 =J31PA0 1H = 4.0, J31PB1H = J31PB1H0 = 2.85, J1H1H0 = 0.25 (J1H117Sn = 1244.5, J1H117Sn = 46.5) (6H, SnH3), 1.24, 1.22 (t, 36H, CH3). 31P{1H} NMR (CD3C6D5, 25 °C) δ: AA0 B2, δA, δA0 100.2, δB 97.2, J31PA31PB = J31PA0 31PB = 35.5 (J31PA117Sn = 171.2, J31PA0 117Sn = 1178.6, J31PB117Sn = 233.2). 119 Sn NMR (CD3C6D5, 25 °C) δ: AA0 B2MY3M0 Y0 3, δM = δM0 -463.8, J31PA119Sn=J31PA0 119Sn0 = 1234.9, J31PA0 119Sn = J31PA119Sn0 = 178.9, J31PB119Sn = J31PB119Sn0 = 244.2, J119Sn1H = J119Sn0 1H0 = 1302.7, J119Sn0 1H = J119Sn1H0 = 51.0. Anal. Calcd for C24H66O12OsP4Sn2: C, 26.25; H, 6.06. Found: C, 26.40; H, 6.01. 8b: IR (KBr) cm-1: νSnH 1743, 1733 (s). 1H NMR (CD3C6D5, 25 °C) δ: 7.89-6.97 (m, 20H, Ph), 3.42 (m, 16H, CH2), AA0 B2Y3Y0 3, δY, δY0 3.20, J31PA1H = J31PA0 1H0 = 10.75, J31PA0 1H = J31PA1H0 = 2.5, J31PB1H = J31PB1H0 = 3.0, J1H1H0 = 0.3 (J1H117Sn = 1398.0, J1H117Sn = 14.0) (6H, SnH3), 1.16, 1.14 (t, 24H, CH3). 31 P{1H} NMR (CD3C6D5, 25 °C) δ: AA0 B2, δA, δA0 116.7, δB 113.0, J31PA31PB=J31PA0 31PB = 23.1 (J31PA117Sn=993.3, J31PA0 117Sn = 155.4, J31PB117Sn = 201.3). 119Sn NMR (CD3C6D5, 25 °C) δ: AA0 B2MY3M0 Y0 3, δM = δM0 -419.2, J31PA119Sn = J31PA0 119Sn0 = 1039.2, J31PA0 119Sn = J31PA119Sn0 = 163.0, J31PB119Sn = J31PB119Sn0 = 212.1, J119Sn1H = J119Sn0 1H0 = 1456.5, J119Sn0 1H = J119Sn1H0 = 15.0. Anal. Calcd for C40H66O8OsP4Sn2: C, 39.17; H, 5.42. Found: C, 39.01; H, 5.54%. FeH[Sn(OH){OC(H)dO}2]P4 (9) [P = P(OEt)3 (a), PPh(OEt)2 (b)]. A solution of the appropriate trihydridestannyl complex FeH(SnH3)P4 (0.5 mmol) in toluene (15 mL) was allowed to stand under a CO2 atmosphere (1 atm) for 4 h. The solvent was removed under reduced pressure to give an oil, which was triturated with pentane (15 mL). A white (9a) or pale yellow (9b) solid slowly separated out, which was filtered and crystallized from toluene and pentane. Yield: 0.27 g (56%) for 9a; 0.31 g (58%) for 9b. 9a: IR (KBr) cm-1: νOCO 1662, 1614 (s). 1H NMR (CD3C6D5, 25 °C) δ: 8.89 (s, br, 2H, HCdO), 4.06, 3.80 (m, 24H, CH2), 1.25, 1.17, 1,08 (t, 36H, CH3), -13.65 to -14.10 (m, 1H, FeH). 31 1 P{ H} NMR (CD3C6D5, 25 °C) δ: AB2C, δA = 173.1, δB 170.3, δC 169.3, J31PA31PB = 130.0, J31PA31PC = 95.7, J31PB31PC = 60.0. 119Sn NMR (CD3C6D5, -50 °C) δ: -292 (m, br). Anal. Calcd for C26H64FeO17P4Sn: C, 32.97; H, 6.81. Found: C, 32.78; H, 6.69. 9b: IR (KBr) cm-1: νOCO 1667, 1635 (s). 1H NMR (CD3C6D5, 25 °C) δ: 9.30 (s, br, 2H, HCdO), 8.20-6.96 (m, 20H, Ph), 4.10-3.09 (m, 16H, CH2), 1.89, 1.15 (m, 24H, CH3), -11.20 to -11.65 (m, 1H, FeH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: AB2C, δA =196.2, δB 192.3, δC 191.6, J31PA31PB =109.0, J31PA31PC = 91.2, J31PB31PC = 91.5. 119Sn NMR (CD3C6D5, -70 °C) δ: -275 (m, br). Anal. Calcd for C42H64FeO13P4Sn: C, 46.91; H, 6.00. Found: C, 46.75; H, 5.90. OsH[Sn(OH){OC(H)dO}2]P4 (10) [P = P(OEt)3 (a), PPh(OEt)2 (b)]. These complexes were prepared like the related iron derivatives 9, but using a reaction time of 6 h. Yield: 0.35 g (65%) for 10a; 0.41 g (68%) for 10b. 10a: IR (KBr) cm-1: νOCO 1668, 1627 (s). 1H NMR (CD3C6D5, 25 °C) δ: 8.78 (s, 2H, HCdO), 3.99 (m), 3.83 (qnt) (24H, CH2), 1.20 (m), 1.12 (t) (36H, CH3), AB2CX, δX -11.49,

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Table 1. Crystal Data and Structure Refinement for 10b empirical formula fw temperature wavelength cryst syst space group unit cell dimens

volume Z density (calcd) absorp coeff F(000) cryst size θ range for data collection index ranges reflns collected indep reflns reflns obsd (>2σ) data completeness absorp corr max. and min transmn refinement method data/restraints/params goodness-of-fit on F2 final R indices [I > 2σ(I )] R indices (all data) largest diff peak and hole

C42H64O13P4SnOs 1209.70 293(2) K 0.71073 A˚ monoclinic P21/n a = 12.4488(8) A˚ b = 24.8116(15) A˚ c = 16.4851(10) A˚ β = 91.0810(10)° 5090.9(5) A˚3 4 1.578 Mg/m3 3.166 mm-1 2424 0.44  0.28  0.13 mm 1.64-25.00° -10 e h e 14; -29 e k e 29; -19 e l e 19 26 869 8926 [R(int) = 0.0631] 6161 0.995 semiempirical from equivalents 1.000 and 0.736 full-matrix least-squares on F2 8926/0/564 0.993 R1 = 0.0387, wR2 = 0.0742 R1 = 0.0718, wR2 = 0.0868 0.695 and -0.686 e A˚-3

J31PA1H = 63.4, J31PB1H = 19.7, J31PC1H = 19.7 (J1H117Sn = 121.0) (1H, OsH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: AB2C, δA = 108.6, δB 106.8, δC 101.7, J31PA31PB = 35.1, J31PA31PC = 26.1, J31PB31PC = 43.4 (J31PA117Sn = 241.5, J31PB117Sn = 348.5, J31PC117Sn = 2550.2). 13C NMR (CD3C6D5, 25 °C) δ: 165.5 (s, OCdO), 62.0 (br), 60.8 (t) (CH2), 16.19 (d), 15.97 (m) (CH3). 119Sn NMR (CD3C6D5, 25 °C) δ: AB2CXM, δM -436.0, J31PA119Sn = 253.5, J31PB119Sn = 362.0, J31PC119Sn = 2550.2, J119Sn1H = 133.5. Anal. Calcd for C26H64O17OsP4Sn: C, 28.87; H, 5.96. Found: C, 29.06; H, 6.10. 10b: IR (KBr) cm-1: νOsH 2005 (w); νOCO 1673, 1634 (s). 1H NMR (CD3C6D5, 25 °C) δ: 8.93 (s, 2H, HC=O), 8.05-6.97 (m, 20H, Ph), 4.02-3.10 (m, 16H, CH2), 1.19, 1.13, 1.04 (t, 24H, CH3), -11.73 (m, 1H, OsH). 31P{1H} NMR (CD3C6D5, 25 °C) δ: AB2C, δA = 128.2, δB 125.5, δC 122.9, J31PA31PB = 21.2, J31PA31PC = 13.4, J31PB31PC = 27.9. 119Sn NMR (CD3C6D5, 25 °C) δ: -451 (m, br). Anal. Calcd for C42H64O13OsP4Sn: C, 41.70; H, 5.33. Found: C, 41.84; H, 5.29. Crystal Structure Determination of OsH[Sn(OH){OC(H)dO}2][PPh(OEt)2]4 (10b). Crystallographic data were collected on a Bruker Smart 1000 CCD diffractometer at CACTI (Universidade de Vigo) using graphite-monochromated Mo KR radiation (λ = 0.71073 A˚) and were corrected for Lorentz and polarization effects. The software SMART13 was used for collecting frames of data, indexing reflections, and the determination of lattice parameters, SAINT14 for integration of intensity of reflections and scaling, and SADABS15 for empirical absorption correction. The structure was solved and refined with the Oscail program16 by direct methods and refined by full-matrix leastsquares based on F2.17 Non-hydrogen atoms were refined with anisotropic displacement parameters. The hydrogen atom (13) SMART Version 5.054, Instrument control and data collection software; Bruker Analytical X-ray Systems Inc.: Madison, WI, 1997. (14) SAINT Version 6.01, Data integration software package; Bruker Analytical X-ray Systems Inc.: Madison, WI, 1997. (15) Sheldrick, G. M. SADABS, An empirical absorption correction program for area detector data; University of G€ottingen: Germany, 1996. (16) McArdle, P. J. Appl. Crystallogr. 1995, 28, 65–65. (17) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.

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bonded to the metal atom was found in the final density map and refined with isotropic displacement parameters. The hydrogen atom bonded to the oxygen atom at the hydroxyl group was included in idealized position, allowing the possible intermolecular interactions with the symmetry related (-x, -y, 2-z) hydroxyl groups. This H-atom was also refined with isotropic displacement parameters. Other hydrogen atoms were included in idealized positions and refined with isotropic displacement parameters. Details of crystal data and structural refinement are given in Table 1.

Results and Discussion Depending on the nature of both the central metal and experimental conditions, the reaction of dihydride MH2P4 [M = Fe, Ru, Os; P = P(OEt)3, PPh(OEt)2] with SnCl2 gives either hydride-trichlorostannyl MH(SnCl3)P4 (1, 2) or bis(trichlorostannyl) M(SnCl3)2P4 (3, 4) derivatives, as shown in eqs 1-3.

P = P(OEt)3 (a), PPh(OEt)2 (b).

P = P(OEt)3.

P = P(OEt)3 (a), PPh(OEt)2 (b). Iron dihydride FeH2P4 reacts with SnCl2 in CH2Cl2 to give the hydride-trichlorostannyl complex FeH(SnCl3)P4 (1) in good yield. The formation of complex 1 may involve the insertion of SnCl2 into the Fe-H bond to give a hydridebis(chloro)stannyl [Fe]-SnHCl2 intermediate, which, by halide exchange, may then give the final [Fe]-SnCl3 derivative 1. However, a first reaction of the dihydride FeH2P4 with SnCl2, giving the chloro-hydride complex FeHClP4, is also plausible, and the subsequent insertion of SnCl2 into the Fe-Cl bond can yield the final trichlorostannyl derivative 1. The rection of dihydride FeH2P4 with SnCl2 was also carried out in refluxing 1,2-dichloroethane for several hours, but exclusively monostannyl complex 1 was isolated. In refluxing ethanol, too, the reaction of FeH2P4 with SnCl2 3 2H2O yielded the derivative FeH(SnCl3)P4 (1), and longer reaction times did not give any evidence of the insertion of two SnCl2 groups with the formation of a bis(stannyl) derivative Fe(SnCl3)2P4; only some decomposition was observed. We also studied the reaction of nonclassical hydride [FeH(η2-H2)P4]BPh4 with SnCl2 3 2H2O and observed that,

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also in this case, the reaction proceeded to give the hydridetrichlorostannyl FeH(SnCl3)P4 (1) derivative (eq 4).

The formation of stannyl complex 1 may be explained by taking into account the lability of the η2-H2 ligand in the hydride precursor,12a which may be substituted by one chloride to give the FeHClP4 intermediate. Insertion of SnCl2 into the Fe-Cl bond of this species yielded the final trichlorostannyl derivative. In contrast with iron, ruthenium dihydride RuH2[P(OEt)3]4 reacted with an excess of SnCl2 to give the bis(trichlorostannyl) derivative Ru(SnCl3)2P4 (3) in good yield (eq 2). The reaction was also studied with a Ru:Sn ratio lower than 2, in an attempt to prepare the hydride-trichlorostannyl complex RuH(SnCl3)P4. Although the NMR spectra of the reaction mixture indicated that this species was the first complex formed, it was never isolated in pure form owing to its fast reaction with SnCl2. Even with one equivalent of SnCl2, the isolated product contained bis(stannyl) Ru(SnCl3)2P4 (3) and the starting dihydride RuH2P4 as the main compounds, with only traces of the monostannyl RuH(SnCl3)P4 derivative. Insertion of SnCl2 into both Ru-H bonds, followed by the exchange of H- with Cl-, may explain the formation of bis(trichlorostannyl) derivative 3. However, the second insertion is probably faster than the first, thus preventing separation of the monostannyl RuH(SnCl3)P4 derivative. The reaction of osmium dihydride OsH2P4 with SnCl2 3 2H2O is very slow at room temperature, but in refluxing ethanol proceeded to give first the hydride-trichlorostannyl OsH(SnCl3)P4 (2) and then the bis(stannyl) Os(SnCl3)2P4 (4) derivatives (eq 3). The reagents ratio and reaction time are crucial in controlling the reaction and preparing both mono(stannyl) 2 and bis(stannyl) 4 in pure form. Unappropriate reaction conditions gave mixtures of 2 and 4, which were difficult to separate. The easy formation of bis(trichlorostannyl) species with both Ru (3) and Os (4), in contrast with the monoinsertion observed with Fe, suggests that steric factors prevent the second insertion of SnCl2 in the FeH2P4 precursor to give bis(trichlorostannyl) derivatives. It is worth noting that iron triad dihydrides MH2P4 are known to undergo insertion into the M-H bond of several unsaturated molecules, including aryldiazonium cations,11d,18 terminal alkynes,19 and heteroallenes.20 The reaction with SnCl2 highlights how even a carbene-like stannylene species1b can be inserted into the M-H bond, giving both mono- and bis(trichlorostannyl) derivatives. (18) (a) Albertin, G.; Antoniutti, S.; Pelizzi, G.; Vitali, F.; Bordignon, E. J. Am. Chem. Soc. 1986, 108, 6627–6634. (b) Albertin, G.; Antoniutti, S.; Pelizzi, G.; Vitali, F.; Bordignon, E. Inorg. Chem. 1988, 27, 829–835. (19) (a) Albertin, G.; Amendola, P.; Antoniutti, S.; Ianelli, S.; Pelizzi, G.; Bordignon, E. Organometallics 1991, 10, 2876–2883. (b) Albertin, G.; Antoniutti, S.; Del Ministro, E.; Bordignon, E. J. Chem. Soc., Dalton Trans. 1992, 3203–3208. (c) Albertin, G.; Antoniutti, S.; Bordignon, E. J. Chem. Soc., Dalton Trans. 1995, 719–725. (20) (a) Albertin, G.; Antoniutti, S.; Bordignon, E. Gazz. Chim. Ital. 1994, 124, 355–365. (b) Albertin, G.; Antoniutti, S.; Del Ministro, E.; Bordignon, E. J. Chem. Soc., Dalton Trans. 1994, 1769–1775.

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Both mono(trichlorostannyl) MH(SnCl3)P4 and bis(trichlorostannyl) complexes M(SnCl3)2P4 react with NaBH4 in ethanol at 0 °C to give the corresponding trihydridestannyl derivatives MH(SnH3)P4 (5, 6) and M(SnH3)2P4 (7, 8), which were isolated as pale yellow or white solids and characterized (eqs 5 and 6).

M = Fe (5), Os (6); P = P(OEt)3 (a), PPh(OEt)2 (b).

M=Ru (7), Os (8); P=P(OEt)3 (a), PPh(OEt)2 (b). NaBH4 as a reagent to prepare tin trihydride complexes turns out to be an interesting synthetic method in tin chemistry, and we had previously used it to synthesize several [M]-SnH3 derivatives.7 In the present case, this route yielded hydride-trihydridestannyl derivatives [M]-(H)(SnH3) and the unprecedented complexes containing two trihydridestannyl groups bonded to the same metal center. Bis(trichlorostannyl) and bis(triorganostannyl) complexes have been described for several central metals, including Ti,21 Cr,22 Ir and Co,23 Mo,24 Ru,25 Os,26 and Pt,27 but none containing two trihydridestannyls as ligands have been described. In addition, it may be noted that previous results, from our and other groups,28 have shown that both half-sandwich M(Cp)P(PPh3), M(Tp)P(PPh3)7a,c (M = Ru, OS; P = phosphites) and Os(κ2S2CNMe2)(CO)(PPh3)28 fragments can stabilize the tin-trihydride group. Results on the reactivity of dihydride MH2P4 with SnCl2 followed by reaction with NaBH4 highlighted the fact that the [MHP4] and MP4 fragments containing phosphite as supporting ligands can also stabilize the tin-trihydride ligand. Hydride-trichlorostannyl [M]-H(SnCl3) (1, 2) and bis(trichlorostannyl) complexes [M]-(SnCl3)2 (3, 4) were separated as yellow solids stable in air and in solutions of common organic solvents, where they behave as nonelectrolytes.29 Conversely, the related hydride-trihydridestannyl [M]-H(SnH3) (21) Ellis, J. E.; Blackburn, D. W.; Yuen, P.; Jang, M. J. Am. Chem. Soc. 1993, 115, 11616–11617. (22) Khaleel, A.; Klabunde, K. J.; Johnson, A. J. Organomet. Chem. 1999, 572, 11–20. (23) (a) Esteruelas, M. A.; Lahoz, F. J.; Olivan, M.; O~ nate, E.; Oro, L. A. Organometallics 1994, 13, 4246–4257. (b) Allen, J. M.; Brennessel, W. W.; Buss, C. E.; Ellis, J. E.; Minyaev, M. E.; Pink, M.; Warnock, G. F.; Winzenburg, M. L.; Young, V. G., Jr. Inorg. Chem. 2001, 40, 5279–5284. (24) Szymanska-Buzar, T.; Gowiak, T. J. Organomet. Chem. 1999, 575, 98–107. (25) (a) Aarnts, M. P.; Wilms, M. P.; Peelen, K.; Fraanje, J.; Goubitz, K.; Hartl, F.; Stufkens, D. J.; Baerends, E. J.; Vlcek, A., Jr. Inorg. Chem. 1996, 35, 5468–5477. (b) Weinstein, J. A.; van Slageren, J.; Stufkens, D. J.; Zalis, S.; George, M. W. J. Chem. Soc., Dalton Trans. 2001, 2587–2592. (26) Esteruelas, M. A.; Lled os, A.; Maresca, O.; Olivan, M.; O~ nate, E.; Tajada, M. A. Organometallics 2004, 23, 1453–1456. (27) Albinati, A.; Pregosin, P. S.; R€ uegger, H. Inorg. Chem. 1984, 23, 3223–3229. (28) M€ ohlen, M. M.; Rickard, C. E. F.; Roper, W. R.; Whittell, R. G.; Wright, L. J. Inorg. Chim. Acta 2007, 360, 1287–1297. (29) Geary, W. J. Coord. Chem. Rev. 1971, 7, 81–122.

Figure 1. ORTEP view of compound 10b drawn at the 30% probability level. Big atoms bonded to phosphorus atoms represent ethoxy groups. Phenyl groups are represented as small spheres.

(5, 6) and bis(trihydridestannyl) complexes [M]-(SnH3)2 (7, 8) are white or pale yellow solids relatively stable in solutions of hydrocarbons, in which they slowly decompose even at low temperature, thus preventing the production of crystals for X-ray analysis. However, the formulation of stannyl complexes 1-8 is supported by analytical and spectroscopic data (IR and 1H, 31P, 13 C, 119Sn NMR) and X-ray crystal structure determination of the reaction product of trihydridestannyl compounds with CO2, the complex OsH[Sn(OH){OC(H)dO}2][PPh(OEt)2]4 (10b) (see Figure 1). The IR spectra of complexes MH(SnCl3)P4 (1, 2) show a medium-intensity band at 1975-1728 cm-1, attributed to νMH of the hydride ligand. Its presence was confirmed by 1H NMR spectra, which show the characteristic low-frequency signal of the hydride as a multiplet between -11.73 and -10.33 ppm (Figure S3). In the temperature range þ20 to -80 °C, the 31P{1H} NMR is either an AB2C or ABC2 multiplet with the characteristic satellites due to coupling with the 117 Sn and 119Sn nuclei of the stannyl group (Figure S1, S4). The spectra can be simulated with the parameters reported in the Experimental Section and suggest the mutually cis position of the hydride and SnCl3 ligands, as in geometry I. The 119Sn NMR spectra appear as a complicated multiplet, at -163.1 to -220.0 ppm for iron (Figure S2) and -435.9 to -456.6 ppm for osmium, due to coupling with the phosphorus nuclei, which was simulated with either an ABC2M or AB2CM model (M = 119 Sn), fitting the proposed formulation for the complexes. 31 P{1H} NMR analysis of bis(trichlorostannyl) complexes M(SnCl3)2P4 (3, 4) showed symmetric AA0 B2 spectra (Figure S6) with the characteristic 117Sn and 119Sn satellites, which were simulated with the parameters reported in the Experimental Section and support the mutually cis arrangement of the two stannyl groups. The related 119Sn NMR spectra were also recorded and appear as symmetric multiplets (Figure S5), between -349 and -423 ppm, which were simulated with an AA0 B2MM0 model (M = M0 = Sn). The good fit between calculated and experimental data support the proposed formulation for bis(trichlorostannyl) complexes. The IR spectra of hydride-trihydridestannyl complexes MH(SnH3)P4 (5, 6) show a medium-intensity band at 1976-1901 cm-1, attributed to the νMH of the hydride

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ligand, and two bands of strong intensity between 1762 and 1735 cm-1, due to the νSnH of the trihydridestannyl group. 1H and 119Sn NMR spectra were diagnostic for the presence of both H- and SnH3 ligands. In the low-frequency region, the proton spectra show a multiplet at -11.39 to -13.9 ppm (Figures S8, S11), with the 117Sn and 119Sn satellites, attributed to the hydride ligand. Another multiplet is also present, with the characteristic tin satellites, between 3.84 and 2.55 ppm (Figure S10), and was attributed to the SnH3 group. The proton- and phosphoruscoupled 119Sn spectra appear as very complicated multiplets due to coupling with four hydride and four inequivalent phosphorus nuclei. The related proton-decoupled 119Sn{1H} NMR spectra appear as less complicated patterns (Figure S7), and as the 31 P{1H} spectra are ABC2 or AB2C multiplets (Figure S9), the 119 Sn{1H} ones could be simulated with an AB2CM or ABC2M model (M = 119Sn) with the parameters reported in the Experimental Section. The two proton multiplets attributed to the hydride (-11.31 to -13.9 ppm) and SnH3 (3.842.55 ppm) groups were also simulated with an AB2CXY3 model [X = H-; Y3 = H3Sn], matching the proposed formulation for hydride-trihydridestannyl complexes, the geometry of which (III) contains the hydride and stannyl groups in a mutually cis position. The IR spectra of bis(trihydridestannyl) complexes M(SnH3)2P4 (7, 8) show two strong-intensity bands at 17591721 cm-1, attributed to the νSnH of the SnH3 group. The proton NMR spectra confirm the presence of the trihydridestannyl ligand, showing a multiplet at 3.64-3.20 ppm, with the characteristic 117Sn and 119Sn satellites, attributed to the tin hydrogen atoms of SnH3. 31P{1H} NMR spectra appear as a symmetric multiplet (Figure S12) with the tin satellites, which was simulated with an AA0 B2 model, fitting the mutually cis position of the two SnH3 ligands. The proton- and phosphorus-coupled 119Sn NMR spectra were also symmetric multiplets (Figure S13), due to coupling with six hydride and four phosphorus nuclei, and were simulated with an AA0 B2MY3M0 Y30 model (M=M0 =119Sn; Y = Y0 = 1 H). The good fit between calculated and experimental spectra supports the presence of two SnH3 groups bonded to the same metal center in a mutually cis position (IV). Note that the tin-hydride signal at 3.64-3.20 ppm in the proton NMR spectrum may be simulated with an AA0 B2Y3Y30 model with the parameters reported in the Experimental Section, further supporting the proposed formulation for bis(trihydridestannyl) complexes. Reactivity with CO2. The reactivity of trihydridestannyl complexes 5-8 toward carbon dioxide was studied, and results are shown in eq 7.

M = Fe (9), Os (10); P = P(OEt)3 (a), PPh(OEt)2 (b). Hydride-trihydridestannyl complexes MH(SnH3)P4 react with CO2 in mild conditions (1 atm, 25 °C) to give, after workup, white solids characterized as hydroxobis(formate)stannyl derivatives MH[Sn(OH){OC(H)dO}2]P4 (9, 10). The related bis(trihydridestannyl) complexes M(SnH3)2P4

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also reacted with CO2 (1 atm), but in this case only intractable oils, containing a mixture of products, were obtained. The formation of compounds 9 and 10 is not surprising, in light of the results previously obtained in our laboratory,7 and may be explained as due to the insertion of two CO2 molecules into two Sn-H bonds to give the bis(formate) intermediate MH[SnH{OC(H)dO}2]P4 [A] (eq 8).

[M] = MP4. Hydrolysis of the Sn-H bond by traces of water present in the solvent gives the final hydroxostannyl complexes 9 and 10.30 Instead, carbon dioxide is not inserted into the metalhydride bond, and the H- ligand is found intact in the final complex. This result highlights the fact that the two types of hydride ligand in the complex, the classical M-H and the unconventional M-Sn-H, show different behavior toward CO2 insertion, since tin hydride is the only one able to functionalize the CO2 molecule. Comparison of our results with those previously obtained on the reactivity of trihydridestannyl with CO27 shows that, although hydroxostannyl derivatives 9 and 10 were separated as monomeric species, the related tin formate osmium [Os{Sn[OC(H)dO]2(μ-OH)}(Tp)(PPh3)P]2 [Tp = tris(pyrazolyl)borate; P = phosphite] and rhenium derivatives [Re{Sn[OC(H)dO]2(μ-OH)}(CO)2P3]2 were separated as dimeric ones, in which two octahedrally coordinated metal units are joined by a bridging tetraformatebis(μ-hydroxo)ditin moiety. The absence of dimerization is unexpected in our tetrakis(phosphite) complexes and is tentatively explained on the basis of the steric requirements of the MP4 units, which prevent the formation of the μ-hydroxo ditin unit (see X-ray section). New formate complexes MH[Sn(OH){OC(H)dO}2]P4 (9, 10) were isolated as white solids stable in air and in solutions of common organic solvents, in which they behave as nonelectrolytes.29 Analytical and spectroscopic data (IR, 1H, 31 P, 13C, 119Sn NMR) support their proposed formulations, which were further confirmed by X-ray crystal structure determination of OsH[Sn(OH){OC(H)dO}2][PPh(OEt)2]4 (10b) (the ORTEP diagram33 is shown in Figure 1). Selected bond distances and angles are given in Table 2. The structure of the complex consists of an osmium atom coordinated by four PPh(OEt)2 phosphonite ligands, one hydride ligand, and one hydroxobis(formate)stannyl ligand. (30) The formation of hydroxostannyl complexes such as 9 and 10 is not surprising and is due to the oxophilic nature of tin compounds, which can react with water to give O and OH bridges in ring and cage compounds (see refs 31, 32). (31) (a) Riviere, P.; Riviere-Baudet, M.; Satge, J., In Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon Press: Oxford, U.K., 1982; Chapter 10. (b) Davies, A. G.; Smith, P. J. In Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon Press: Oxford, U.K., 1982; Chapter 11. (32) (a) Roesky, H. W.; Singh, S.; Jancik, V.; Chandrasekhar, V. Acc. Chem. Res. 2004, 37, 969–981. (b) Shea, K. J.; Loy, D. A. Acc. Chem. Res. 2001, 34, 707. (33) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565–566.

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Table 2. Selected Bond Lengths [A˚] and Angles [deg] for 10b Os-H(0) Os-P(2) Os-P(4) Sn-O(5) Sn-O(3) C(1)-O(2) C(2)-O(4) P(1)-Os-P(2) P(1)-Os-P(4) P(2)-Os-P(4) H(0)-Os-P(2) H(0)-Os-P(1) H(0)-Os-Sn P(2)-Os-Sn P(4)-Os-Sn O(5)-Sn-O(3) O(5)-Sn-Os O(3)-Sn-Os

1.48(6) 2.2800(16) 2.3079(16) 1.977(4) 2.089(5) 1.204(9) 1.110(11) 98.41(6) 107.10(6) 91.63(6) 98(2) 158(2) 80(2) 177.00(4) 85.82(4) 96.6(3) 128.39(17) 115.26(14)

Os-P(1) Os-P(3) Os-Sn Sn-O(1) O(1)-C(1) O(3)-C(2)

2.3331(16) 2.3110(16) 2.6249(5) 2.062(5) 1.165(10) 1.251(13)

P(1)-Os-P(3) P(2)-Os-P(3) P(3)-Os-P(4) H(0)-Os-P(4) H(0)-Os-P(3) P(1)-Os-Sn P(3)-Os-Sn O(5)-Sn-O(1) O(1)-Sn-O(3) O(1)-Sn-Os

97.30(6) 92.79(6) 154.27(6) 87(2) 68(2) 83.87(4) 88.84(5) 96.1(2) 91.9(2) 120.60(16)

Table 3. Hydrogen Bond Parametersa D-H 3 3 3 A

d(D-H) [A˚]

O(5)-H(5) 3 3 3 O(50 ) 0.66 a Symm. op.0 : -x, -y, 2-z.

d(H 3 3 3 A) [A˚]

d(D 3 3 3 A) [A˚]

(DHA) [deg]

2.29

2.840(8)

143.0

There is an important interaction between asymmetric units in the cell, involving the oxygen atoms of the hydroxyl group, at only 2.782(9) A˚ to the symmetry-related (-x, -y, 2-z) hydroxyl group of the neighbor molecule (see Figure 2). A similar situation was found for the seven-coordinated dihydride osmium complex with the hydroxyldiphenyltin ligand, Sn(OH)Ph2.34 The hydrogen bond in 10b substitutes a bond between the neighbor hydroxyl group and the tin atom, as found in the related dimeric compounds [Ru[Sn{OC(H)dO}2(μ-OH)](Cp){P(OEt)3}(PPh3)]27c and [Re{Sn[OC (H)dO]2(μ-OH)}(CO)2{P(OEt)3}3]2.7b The important steric requirements of the ancillary ligands PPh(OEt)2 on the osmium atom probably play an important role in this case. The coordination polyhedron around the osmium metal could be defined as a distorted octahedron, with the hydride and stannyl ligand in cis positions. This relative disposition was also found for the complex [OsH(SnPh3)(CO)4].35 The Os-Sn bond, 2.6249(5) A˚, falls in the range observed for the 55 examples of compounds containing a terminal Os-SnR3 bond reported in the CCDC database (2.59-2.74 A˚, average 2.67 A˚) (CSD version 5.30, updated September, 2009),36 but no data are available for terminal Os-Sn(OR)3 bonds. The Os-Sn bond in 10b is slightly longer than that found [2.5901 (4) A˚] for the complex [Os{Sn(OC(O)CH2)3N}(η2-S2CNMe2)(CO)(PPh3)2], where the tin atom is pentacoordinated.37 The Os-P bond lengths range from 2.280(2) to 2.333(2) A˚, and they are, in practice, the same values as those found for the cation [OsH(PhNdNH){PPh(OEt)2}4]+.38 The different values of the Os-P bond lengths allowed us to estimate the trans influence of the ligands: the Os-P bond trans to the stannyl ligand is shorter, at 2.28 A˚, and the Os-P bond trans to the hydride ligand is longer, at 2.33 A˚; the (34) Esteruelas, M. A.; Lled os, A.; Olivan, M.; O~ nate, E.; Tajada, M. A.; Ujaque, G. Organometallics 2003, 22, 3753–3765. (35) Adams, R. D.; Captain, B.; Zhu, L. Organometallics 2006, 25, 4183–4187. (36) Allen, F. H. Acta Crystallogr. 2002, B58, 380–388. (37) Clark, A. M.; Rickard, C. E. F.; Roper, W. R.; Woodman, T. J.; Wright, L. J. Organometallics 2000, 19, 1766–1774. (38) Albertin, G.; Antoniutti, S.; Bedin, M.; Castro, J.; Garcı´ a-Fontan, S. Inorg. Chem. 2006, 45, 3816–3825.

Figure 2. ORTEP view of the supramolecular arrangement of compound 10b (symm. op.0 : -x, -y, 2-z).

mutually trans Os-P bond is midway and has the same value (on average, 2.31 A˚). The hydride ligand was located and refined crystallographically, but its geometrical parameters are not precise, due to the well-known limitations of the X-ray technique for hydride ligands coordinated to a third-row transition metal. In fact, the distance, 1.48(6) A˚, is very short when compared with those found, for example, in [OsH(SnPh3)(CO)4]35 or in the cation [OsH(PhNdNH){PPh(OEt)2}4]+.38 However at least 57 osmium compounds with terminal hydrides can be found in the CCDC database36 with shorter values, but do not require further comment here. Angles dealing with this ligand should also be mentioned with prudence. Angles around the osmium atom show good fits with an octahedral distribution (see Table 2), but an important source of polyhedron distortion comes from the bending of the axis P-Re-P, with an angle value of 154.27(6)°. This distortion has previously been found in hydride osmium complexes.38,39 However, the other axis (the third one includes the hydride ligand) is linear in practice, with a POs-Sn angle of 177.00(4)°. In fact, it is mainly the phosphonite labeled as P(4) that is out of the regular position, like the hydride atom. The P(1)-Os-P(3) angle is about 7° larger than the theoretical 90°, 97.30(6)°, but the P(1)-Os-P(4) angle is more than 17° larger, 107.10(6)°. This distortion means that the equatorial plane formed by three phosphorus and the tin donor atoms are highly distorted, with a rms deviation of 0.230 A˚. The osmium atom is displaced from this plane by 0.2751(8) A˚ toward the fourth phosphorus atom. Substituents of both trans phosphonites are in a staggered conformation, and in P(4), the phenyl ring is situated in the same direction as the hydride ligand (see Figure 3, left). Torsion angles confirming the staggered conformation are C (31)-P(3)-P(4)-C(41), -177.7(4)°; O(31)-P(3)-P(4)-O (41), 159.4(3)°; and O(32)-P(3)-P(4)-O(42), -172.2(3)°. This disposition contrasts with that found for the triphenylphosphine ligands in [Os(SnR3)(η2-S2CNMe2)(CO)(PPh3)2]37 and also with the other axis in the molecule, where we find the stannyl ligand trans to a phosphonite ligand. Now, in this Sn-Os-P axis, the substituents of both tetrahedral phosphorus and tin atoms are eclipsed, as demonstrated by dihedral angles O(1)-Sn-P(2)-O(22), -19.3(3)°; O(5)-Sn-P(2)-C (21), -8.7(4)°; and O(3)-Sn-P(2)-O(21), -4.5(3)° (see Figure 3, right). The tin atom turns out to be tetracoordinated, with angles around it ranging from 91.9(2)° to 128.4(2)°. Angular (39) (a) Schlaf, M.; Lough, A. J.; Maltby, P. A.; Morris, R. H. Organometallics 1996, 15, 2270–2278. (b) Rocchini, E.; Rigo, P.; Mezzetti, A.; Stephan, T.; Morris, R. H.; Lough, A. J.; Forde, C. E.; Fong, T. P.; Drouin, S. D. J. Chem. Soc., Dalton Trans. 2000, 3591–3602.

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Figure 3. ORTEP view of the compound nearly along the Sn-Os-P(2) axis. Left: only substituents on the P-Os-P axis are shown. Right: only substituents on the Sn-Os-P axis are shown.

distortions away from tetrahedral geometry in tin are apparent, the three Os-Sn-O angles being 128.4(2)°, 120.6(2)°, and 115.3(2)°. The largest angle is associated with the hydroxyl group. The O-Sn-O angles are 96.1(2)°, 96.6(3)°, and 91.9 (2)°. The last one, about 4° smaller than the others, is associated with both formyl groups. The Sn-O bond lengths range from 1.977(4) A˚, for that corresponding to the hydroxyl group, to an average of 2.075 (5) A˚, for those corresponding to the formyl groups. For the best of our knowledge, no crystallographic data for transition metal complexes with a terminal Sn(OR)3 ligand are available, but the above distances are, on average, slightly shorter than those found for the complex [Os{Sn(OC(O) CH2)3N}(η2-S2CNMe2)(CO)(PPh3)2]37 or the related dimeric compounds [Ru[Sn{OC(H)dO}2(μ-OH)](Cp){P(OEt)3}(PPh 3 )]2 7c and [Re{Sn[OC(H)dO] 2 (μ-OH)}(CO) 2 {P (OEt)3}3]2,7b where the tin atom is pentacoordinated. The IR spectra of tin formate complexes MH[Sn(OH){OC (H)dO}2]P4 (9, 10) show two medium-intensity bands at 1673-1614 cm-1, attributed to the νOCOasym of the two η1formate OC(H)dO groups.40,41 In the spectrum of osmium complex 10b, a weak band at 2005 cm-1 also appears, due to the νOsH of the hydride ligand. The 1H NMR spectra confirm the presence of the hydride, showing the characteristic multiplet in the low-frequency region, between -11 and -14 ppm. The multiplicity of signals is due to coupling with the phosphorus nuclei of phosphites, as shown by phosphorus-decoupled 1 H spectra, which appear as singlets with the characteristic 119Sn and 117Sn satellites. As the 31P NMR spectra are AB2C multiplets, hydride signals may also be simulated (10a) with an (40) (a) Pandey, K. K. Coord. Chem. Rev. 1995, 140, 37–114. (b) Jessop, P. G.; Hsiao, Y.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1996, 119, 344–355. (c) Leitner, W. Coord. Chem. Rev. 1996, 153, 257–284. (d) Yin, X.; Moss, J. R. Coord. Chem. Rev. 1999, 181, 27–59. (e) Jessop, P. G.; Joo, F.; Tai, C.-C. Coord. Chem. Rev. 2004, 248, 2425–2442. (41) (a) Whittlesey, M. K.; Perutz, R. N.; Moore, M. H. Organometallics 1996, 25, 5166–5169. (b) Field, L. D.; Lawrenz, E. T.; Shaw, W. J.; Turner, P. Inorg. Chem. 2000, 39, 5632–5638, and references therein..

AB2CX model (X = 1H) with the parameters reported in the Experimental Section. In the 1H NMR spectra, a signal at 9.30-8.78 ppm is also present, which was attributed to the formate OC(H)dO hydrogen atom. In a HMQC experiment, this signal was correlated with a singlet at 165.5 ppm (10a) of the formate carbon atom in the 13C NMR spectrum, fitting the proposed attribution. The 119Sn NMR spectra of complexes 9 and 10 appear as quite complicated multiplets between -275 and -451 ppm due to coupling with the phosphorus nuclei and the hydride. In the case of complex 10a, as the 31P spectrum shows an AB2C pattern, the 119Sn multiplet was simulated with an AB2CXM model (X = 1H, M = 119Sn) with the parameters reported in the Experimental Section. The good fit between experimental and calculated spectra supports the proposed formulation for the complex, with the hydride and stannyl ligands in a mutually cis position (V), as found in the solid state. Conclusions. This paper demonstrates that both M-H bonds of dihydride complexes MH2P4 (M=Fe, Ru, Os) may undergo insertion of SnCl2, giving both hydride-trichlorostannyl MH (SnCl3)P4 and bis(trichlorostannyl) M(SnCl3)2P4 derivatives. Reaction with NaBH4 of these compounds allowed synthesis of both hydride-trihydridestannyl MH(SnH3)P4 and the first bis(trihydridestannyl) derivatives M(SnH3)2P4. Among the properties shown by the [M]-SnH3 fragment there is the insertion of CO2 into the Sn-H bonds, yielding the mononuclear hydroxobis(formate) derivative OsH[Sn(OH){OC(H)dO}2] [PPh(OEt)2]4, the crystal structure and spectroscopic characterization of which are also discussed.

Acknowledgment. The financial support of MIUR (Rome)-PRIN 2007 is gratefully acknowledged. We thank Mrs. Daniela Baldan, from the Universit a Ca’ Foscari Venezia (Italy), for her technical assistance. Supporting Information Available: Crystallographic data for compound 10b (cif) and spectroscopic NMR data for selected compounds (Figures S1-S13, pdf). This material is available free of charge via the Internet at http://pubs.acs.org.