Synthesis and study of transition metal silylene complexes and development of iridium chemistry featuring the tripodal anionic phosphine (PhB(CH(2)PPh(2))3-) ligand

This thesis describes the synthesis and study of several transition metal silylene complexes (LnM=SiR2) as well as the chemistry of iridium complexes featuring the tripodal anionic phosphine ligand PhB(CH 2PPh2)3- (herein abbreviated as [PhBP3]).;The first examples of neutral platinum silylene complexes of the type (R3P)2Pt=SiMes2 where R=iPr or Cy (cyclohexyl) were prepared by trapping photochemically generated Mes 2Si: with Pt(PR3)2.;The first iridium silylene complex, [fac-(Me3P) 3(H)2Ir=SiMes2][MeB(C6F5) 4], was formed via 1,2-H migration upon abstraction of Me- from fac-(Me3P)3(H)(Me)Ir-SiHMes 2. Zwitterionic analogs of this silylene complex were obtained via the reaction of [PhBP3]Ir(H)(&eegr;3-C8H 13) with secondary silanes (R2SiH2) to give [PhBP 3](H)2Ir=SiR2. The allyl complex also reacts with primary silanes (RSiH3) to give [PhBP3](H)2Ir=SiR( c-C8H15). The reaction of tertiary silanes (R3SiH) [PhBP3]Ir(H)(&eegr;3-C8 H13) provided the Ir(V) complexes [PhBP3]Ir(H) 3(SiR3).;The allyl complexes [PhBP3]Ir(H)(&eegr;3-C 8H13) (1) and [PhBP3]Ir(H)(&eegr; 3-C3H5) were synthesized from the reaction of [Li(TMED)][PhBP3] with the corresponding [(alkene)2IrCl] 2 complex. These allyl complexes serve as precursors to the dihalides [PhBP3]IrX2 (X=I, Cl). The 5-coordinate species [PhBP 3]IrMe2, [ClB(CH2PPh2)3]IrCl 2, and [PhBP3]Ir(CO)2 have also been isolated. The reaction of H2 with complex 1 yielded {[PhBP 3]IrH2}2 in benzene and [PhBP3]Ir(COE)H 2 in THF (where COE = cyclooctene). Allyl 1 reacted with PMePh2 to give [PhBP3]Ir(PMePh2)H2 (2) and 1,3-cyclooctadiene. The protonation of 2 with [H(OEt 2)]{B[3,5-C6H3(CF3)2] 4} gave the classical hydride complex {[PhBP3]Ir(PMePh 2)H3}{B[3,5-C6H3(CF3) 2]4}. Several C-H activation reactions have been observed; addition of PMe3 to 1 provided the cyclometallated product {PhB[(CH2PPh2)2(CH2PPh C6H4&sqbr0;&cubr0;Ir (H)(PMe3) and COE. Photolysis of 2 gave {PhB[(CH 2PPh2)2(CH2PPh C6H4&sqbr0;&cubr0;Ir (H)(PMePh2) (A) and [PhBP 3]Ir(H)(PMePhC6H4) ( B). The dihydride [PhBP3]Ir(COE)H2 catalyzes H/D exchange between COE and benzene-d6. Comparison of spectroscopic properties of related [PhBP3]Ir, Cp*Ir and TpMe2Ir complexes suggests that relative donating abilities follow the trend [PhBP3] ≥ Cp* > TpMe2 (where Cp* = pentamethylcyclopentadienyl, TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate), and structural comparisons indicate that [PhBP3] is the most sterically demanding ligand.