Oxidative addition of HSnR3 (R = Ph, nBu) to the square-planar iridium (I) compounds Ir(XR)(TFB)(PCy3) (XR = OMe, OEt, OiPr, OPh, SnPr) and Ir(C2Ph)L2(PCy3) (L2 = TFB, 2 CO)

The synthesis of the compounds Ir(OR)(TFB)(PCy3) (R = Et (2), ‘Pr (3), Ph (4); TFB = tetrafluorobenzobarrelene), Ir2(CO)6(PCy3)2 (5), Ir(SnPr)(TFB)(PCy3) (6), [Ir(/t-SnPr)(CO)-(PCy3)]2 (7), Ir(C2R)(TFB)(PCy3) (R = Ph (9), Cy (10), C02Me (11), SiMe3 (12)), and Ir(C2Ph)-(CO)2(PCy3) (13) is described. The complexes 2-4 and 6 react with HSnR'3 in a 1:2 molar ratio to give IrH2(SnR'3)(TFB)(PCy3) (R' = Ph (14), nBu (15)) and RXSnR'a (X = O, 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) k,b = 10.943(1) Á, c = 19.679(1) Á, a = 75.076(5)°, ß = 77.504(5)°, = 72.606(5)°, and Z = 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 AH* of 13.4 ± 0.9 (14) and 12.7 ± 0.7 (15) kcal/mol and for AS* of 3.0 ± 3.0 (14) and -1.6 ± 2.0 (15) eu, involves the relative positions of the diolefin atoms. The alkynyl derivative 9 reacts with HSnR'3 to afford IrH(C2Ph)(SnR'3)(TFB)(PCy3) (R' = Ph (19), nBu (20)). Under carbon monoxide atmosphere, 19 leads to IrH(C2Ph)(SnPh3)(CO)2(PCy3) (21) and tetrafluorobenzobarrelene. Compound 21, and the related derivative IrH(C2Ph)(SnnBu3)-(CO)2(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 irans-PhCH=CH(SnPh3) were obtained.We thank the DGICYT (Project PB92-0092, Programa de Promoción General del Conocimiento) and the E.U. (Project; Selective Processes and Catalysis involving Small Molecules). M.O. and E.O. thank the Diputación General de Aragón (DGA) for grants.Peer reviewe