| The interactions of the palladium(0) complex, [(μ-dcpe)Pd]2, where dcpe = 1,2-bis(dicyclohexylphosphino)ethane, with aryl and alkyl silanes has been investigated. The first mononuclear silyl palladium hydrides, (dcpe)Pd(H)SiR 3, have been observed by reacting [μ-(dcpe)Pd]2 with tertiary silanes. In solution, these silyl palladium hydrides display rich dissociative and associative equilibria. In addition, these complexes are fluxional in solution due to an intramolecular rotational interchange of the silicon and hydrogen positions. This degenerate isomerization displays pronounced temperature dependent isotope effects. The isotope effects can be successfully modeled with density functional calculations at the B3LYP/6-31G* level. This isomerization is consistent with the formation of an intermediate Si-H σ complex. Reaction of [μ-(dcpe)Pd]2 with a secondary silane, H2Si tBu2, gives the silyl palladium hydride, (dcpe)Pd(H)Si tBu2H. The Pd-H and the Si-H on this complex undergo rapid exchange at room temperature, confirming the presence of a Si-H σ complex.; The solution behavior of bissilyl palladium complexes was investigated. The complex, (dcpe)Pd(SiMe2H)2, was found to be fluxional for solution, giving secondary isotope effects consistent with the formation of a Si-Si σ complex.; The platinum analog to the silyl palladium hydrides, (dcpe)Pt(H)SiPh 3, was synthesized. No fluxional processes were detected in this compound or for (dcpe)Pt(H)SiEt3. A side product in the reaction of (dcpe)PtCl 2 with NaBH4, (dcpe)PtB3H7, was isolated and characterized.; The complex, (dcpe)Pd(CPh3)BF4, was synthesized through the reaction of [μ-(dcpe)Pd]2 with Ph3CBF 4. The trityl ligand binds η3 to the palladium, similar to an transition metal allyl complex. Comparisons were made to the density functional modeled benzylic palladium cation, which showed similar structural features.; [μ(dcpe)Pd]2 has been shown to be a catalyst for the hydrosilation of alkynes. The process was investigated, and it was determined that both α addition and cis hydrosilation occur. [(μ-dcpe)Pd] 2 has also been shown to successfully reduce chloroarenes. A variety of conditions were examined, and using HSiEt3 as a reductant proved to give complete reduction at room temperature within a day.; The solution behavior of a palladium(0) complex, Pd(dcpBiph)2 (where dcpBiph = ortho-(dicyclohexylphosphino)biphenyl), was investigated. At room temperature, this compound displays an equilibrium between two isomers, a symmetrical isomer and an asymmetrical isomer in which one of the biphenyl carbons is bound η1 to the palladium. The reactivity of Pd(dcpBiph)2 with aryl halides was investigated. Pd(dcpBiph)2 reacts with PhX (X = Cl, Br, I) to form the trans addition product, (dcpBiph)2Pd(Ph)X. The iodide analog further reacts to form the dimeric compound, (dcpBiph)2Pd2(Ph) 2I2. |
