3486 Organometallics zyxwvu 1995, 14, 3486-3496 Oxidative Addition of HSnR3 (R zyxw = Ph, nB~) to the Square-Planar Iridium(1) Compounds Ir(XR) (TFB) (PCy3) zy (XR = OMe, OEt, OiPr, OPh, SnPr)and Ir(C2Ph)L2(PCys) (L2 = TFB, 2CO) Miguel A. Esteruelas," Fernando J. Lahoz, Montserrat OlivBn, Enrique Oiiate, and Luis A. Oro Departamento de Quimica Znorganica, Znstituto de Ciencia de Materiales de Aragbn, Universidad de Zaragoza, CSZC, 50009 Zaragoza, Spain Received February 17, zyxwv 1995@ The synthesis of the compounds Ir(OR)(TFB)(PCy3) (R = Et zyxw (2), 'Pr (3), Ph (4); TFB = tetrafluorobenzobarrelene), 1r2(CO)dPCy3)~ (5), Ir(S"Pr)(TFB)(PCyd (6), [Ir(p-S"Pr)(CO)- (PCy3)]2 (7), Ir(CzR)(TFB)(PCyd (R = Ph (9), Cy (lo), COzMe (ll), SiMe3 (12)), and Ir(CzPh)- (CO)z(PCy3) (13) is described. The complexes 2-4 and 6 react with HSnR3 in a 1:2 molar ratio to give I~Hz(S~R'~)(TFB)(PC~~) (R = Ph (14), "Bu (15)) and RXSnR3 (X = 0, S). The structure of 14 was determined by an X-ray investigation. Compound 14 crystallizes in the space group Pi (No. 2) with a = 10.923(1) zyxwv A, b = 10.943(1) A, zyxw c = 19.6790) A, a = 75.076(5)", ,8 = 77.504(5)", y = 72.606(5)", and 2 = 2. The coordination geometry around the iridium atom could be rationalized as being derived from a highly distorted octahedron with the triphenylstannyl group and the tricyclohexylphosphine ligand occupying pseudo-trans positions (Sn-Ir-P = 129.46(3)"). In solution 14 and 15 are fluxional. The fluxional process, with values for @ of 13.4 f 0.9 (14) and 12.7 f 0.7 (15) kcaymol and for AS* of 3.0 f 3.0 (14) and -1.6 f 2.0 (15) eu, involves the relative positions of the diolefin atoms. The alkynyl derivative 9 reacts with HSnR3 to afford IrH(CzPh)(SnR3)(TFB)(PCyd (R = Ph (19), "Bu (20)). Under carbon monoxide atmosphere, 19 leads to 1rH(C~Ph)(SnPhd(C0)dPCys) (21) and tetrafluorobenzobarrelene. Compound 21, and the related derivative IrH(CzPh)(SnnBu3)- (CO)z(PCy3) (22) can be also obtained by oxidative addition of the corresponding stannanes to 13. The complexes 14, 19, and 21 catalyze the addition of HSnPh3 to phenylacetylene, and from all experiments cis-PhCH=CH(SnPh3) and trans-PhCH=CH(SnPhs) were obtained. Introduction Vinylsilanes and vinylstannanes have been shown to be versatile intermediates in organic synthesis.l Vinyl- silanes are usually prepared by catalytic addition of silanes to alkynes. From a mechanistic point of view, the hydrosilylation reactions involve conventional oxi- dative addition, insertion, and reductive elimination steps.2 In this respect, the investigation of the oxidative addition of silanes to unsaturated transition metal complexes is of great interest and has received increas- ing attention in recent years.3 @Abstract published in Advance ACS Abstracts, June 15, 1995. (1) (a) Chan, T. H. Acc. Chem. Res. 1977, zyxwvutsrq 10, 442. (b) Hurdlike, P. F. in New Applications of Organometallic Reagents in Organic Syn- thesis; Seyferth, D., Ed.; Elsevier: Amsterdam, The Netherlands, 1976. (c) Cook, F.; Moerk, R.; Schwindeman, J.; Magnus, P. J. Org. Chem. 1980,45, 1406. (d) Negishi, E. Organometallics in Organic Synthesis, John Wiley and Sons: New York, 1980. (e) Neumann, W. P. Synthesis 1987,665. (D Fleming, I.; Dunogues, J.; Smithers, R. H. Org. React. 1989,37,57. (g) Kumar Das, V. G.; Chu C.-K. In The Chemistry ofthe Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; Wiley: New York, 1985; Vol. 3. (2) Chalk, A. J.; Harrod, J. F. J. Am. Chem. SOC. 1966, 87,16. (b) Schroeder, M.; Wrighton, M. S. J. Orgunomet. Chem. 1977,128, 345. (c) Dickers, H. M.; Haszeldine, R. N.; Mather, A. P.; Parish, R. V. J. Organomet. Chem. 1978,161,91. (d) Randolph, C. L.; Wrighton, M. S. J. Am. Chem. SOC. 1986, 108, 3366. (e) Seitz, F.; Wrighton, M. S. Angew. Chem., Int. Ed. Engl. 1988,27,289. (D Ojima, I.; Clos, N.; Donovan, R. J.; Ingallina, P. Organometallics 1990, 9, 3127. (g) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1991,10,462. (h) Duckett, S. B.; Perutz, R. N. Organometallics 1992, 12, 90. (i) Esteruelas, M. A.; Herrero, J.; Oro, L. A. Organometallics 1993,12, 2377. 0276-7333/95/2314-3486$09.00/0 The stereoselective formation of vinylstannanes by addition of alkyl- or arylstannanes to alkynes requires the presence of a transition metal ~atalyst.~ Although, at first glance, there should not be a great difference between the catalytic hydrosilylation and hydrostan- nation of alkynes, the applicability of catalyst precursors related to those used in hydrosilylation has been scarcely investigated in hydrostannation reactions. If these catalyst precursors were active as hydrostanna- tion catalysts, one would expect mechanistic similari- ties. However, the oxidative addition af alkyl- or arylstannanes to unsaturated transition metal com- plexes has received less attention than the oxidative addition of silane^.^ In addition, it should be noted that the comparison of physical and chemical properties for (3) (a) Tilley, T. D. In The Chemistry oforganic Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1989. (b) Schubert, U. Transition Met. Chem. 1991, 16, 136. (4) (a) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986,25, 508. (b) Mitchell, T. N.; Amamria, A,; Killing, H.; Rutschow, D. J. Organomet. Chem. 1986,304,257. (c) Kikukawa, K.; Umekawa, H.; Wada, F.; Matsuda, T. Chem. Lett. 1988, 881. (d) Zhang, H. X.; Guibe, F.; Balavoine, zyxwvut G. J. Org. Chem. 1990, 55, 1857. (e) Mitchell, T. N.; Schneider, U. J. Organomet. Chem. 1991,405, 195. (5) (a) Lappert, M. F.; Travers, N. F. J. Chem. SOC., Chem. Commun. 1968,1569. (b) Luo, X.-L.; Schulte, G. K.; Demou, P.; Crabtree, R. H. Inorg. Chem. 1990,29, 4268. (c) Cabeza, J. A.; Llamazares, A.; Riera, V.; Triki, S.; Ouahab, L. Organometallics 1992,11,3334. (d)Schubert, U.; Gilbert, S.; Mock, 9. Chem. Ber. 1992,125,835. (e) Seebald, S.; Mayer, B.; Schubert, U. J. Organomet. Chem. 1993,462,225. (D Clark, G. R.; Flower, K. R.; Rickard, C. E. F.; Roper, W. R.; Salter, D. M.; Wright, L. J. J. Organomet. Chem. 1993, 462,331. 0 1995 American Chemical Society