Platinum and palladium complexes in arylation and silicone-forming reactions

Three new platinasilanols—(dcpe)Pt(SiR₂OH)(H) (where dcpe = 1,2-bis(dicyclohexylphosphino)ethane] and R = tBu, iPr, or mesityl)—have been synthesized by reacting (dcpe)PtH₂ with the corresponding hydrosilanol, HSiR₂OH. An X-ray crystal structure of (dcpe)Pt(SitBuOH)(H) was determined. Addition of McLi to the tBu derivative yields what appears to be the deprotonated platinasilanol. The tBu derivative can be converted into the platinasilatriflate by addition of triflic anhydride in the presence of 2,2,6,6-tetramethylpiperidine. The neutral platinum species does not catalyze the formation of a silanone with ditert-butylsilanol but does react in a stoichiometric fashion with diisopropylsilanol to give hexaisopropylcyclotrisiloxane.; The synthesis of [(dcpe)Pt(CH₂Cl₂)(Me)] +MeB(C₆F₅)₃− was accomplished by the reaction of (dcpe)PtMe₂ with B(C₆ F₅)₃ in CH₂Cl₂. This cation was found to catalytically convert HSitBu ₂OH into HSitBu₂OSi tBu₂OH and MeSitBU ₂OSitBU₂OH, which are trapping products indicative of a silanone intermediate (tBu ₂Si=O) being formed. [(dcpe)Pt(μ-H)₂Pt(dcpe)][2MeB(C ₆F₅)₃] is formed as the only phosphorus containing species in this reaction.; [(dcpe)Pt(μ-H)₂Pt(dcpe)][2MeB(C₆F₅) ₃] can also be formed from the reaction of [dcpePt(CH₂Cl ₂)(Me)]+MeB(C₆F₅)₃ − with H₂ gas. An X-ray crystal structure was determined for the dimer from a crystal grown in a mixture of wet CH₂Cl ₂ and pentane. The crystal grown, [(dcpe)Pt(μ-H)₂Pt(dcpe)][2[HOB(C ₆F₅)₃] is the first known example of a dicationic transition metal species with hydroxy-tris(pentafluorophenyl)borate as the anionic species. When a catalytic amount of [(dcpe)Pt(μ-H)₂Pt(dcpe)][2MeB(C ₆F₅)₃] is reacted with HSiiPr ₂OH, the cyclosiloxanes (iPr₂SiO) _{3, 4}, an insertion product HSiiPr ₂OSiiPr₂OH, and the condensation product HSiiPr₂OSi iPr₂H are formed. Formation of the insertion and cyclic products give strong evidence that a silanone intermediate was generated.; The complex [dcpePd]₂ was generated in situ by the reaction of (dcpe)PdCl₂ and N₂H₄. Ortho-, meta- and para-derivatives of chlorobenzene were reacted with [dcpePd]₂ to yield the corresponding dcpePd(Ar)Cl oxidative addition products. An X-ray crystal structure for (dcpe)Pd( o-tolyl)(Cl) is reported.; Bis(phosphino)ethane derivatives—R₂PCH₂CH ₂PR₂ (where R = Cy, iPr, or Ph)—have been prepared using a three step synthesis. First, two equivalents of the corresponding R₂PCl is reacted with HOCH₂CH ₂OH in the presence of a base to yield R₂POCH₂CH ₂OPR₂. W...