Thursday, 5 October 2006 - 1:05 PM
Great Hall (Christ Episcopal Church)
75

Synthesis, Characterization, and Reactivity of the Rhodium(I) Silyl Complexes trans-(PPh3)22- norbornene)RhSiR3 [SiR3 = SiMe2Ph, SiMe2Et, Si(OMe)2Me]

Jennifer Vreeland, Anthony Shaw, and Alan Cutler. Rensselaer Polytechnic Institute, Troy, NY

The Rhodium(I) silyl complex trans-(PPh3)22- norbornene)RhSiMe2Ph (1) was generated via three routes. Treatment of RhY(PPh3)3 (Y = Cl, OAc) with at least two equiv. of PhMe2SiH and norbornene (NBE) produced 1 and one equiv. of PhMe2SiY and norbornane (NBA). Optimally, RhH(PPh3)3 with three equiv of PhMe2SiH and NBE afforded 80% 1 plus one equiv of NBA; reactions with 10-20 equiv. each of PhMe2SiH and NBE quantitatively generated 1. Finally, (η3-cyclohexenyl)Rh(PPh3)2 plus at least one equiv of PhMe2SiH and NBE yielded 1:1 cyclohexene and 1. The reactivity of 1 reflects the high lability of its NBE and subsequent trapping of the 14-electron Rh(SiMe2Ph)(PPh3)2. Reactions of 1 with acetic acid, dihydrogen, and EtMe2SiH or Me(MeO)2SiH accordingly yield RhH(PPh3)3 plus PhMe2SiOAc or PhMe2SiH, or two new silyl complexes (PPh3)2(NBE)RhSiR3 [SiR3 = SiMe2Et, Si(OMe)2Me] plus PhMe2SiH. Either a deficiency of NBE or evaporation of solutions containing 1 initiates its degradation to a 3:1 mixture of (PPh3)2Rh-(η2-P,Si)-Si(MeR)C6H4PPh2 (R = Me, Ph) through loss of benzene or methane, respectively. The same product mixture results from treating (PPh3)2Rh-(η2-P,C)-C6H4PPh2 with PhMe2SiH. Results of recent studies on the reactivity of 1 towards styrene, fluorenone-acetophenone-acetone, and acetonitrile will be presented.


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