Rare-earth Metal And Lithium Complexes Incorporating 1-alkyl-3-imino Indolyl Or Neutral Pyrrole Ligands: Synthesis, Structure And Reactivity

The dissertation presents the synthesis,structure and reactivity of rare-earth metal and lithium complexes incorporating 1-alkyl-3-imino indolyl or neutral pyrrole ligands,which consists of four parts:1.Synthesis and characterization of rare-earth metal complexes incorporating1-alkyl-3-imino indolyl ligands A series of 1-alkyl-3-imino-functionalized indolyl ligands 1-R-3-?R'N=CH?C₈H₅N[R=Bn,R'=2,6-iPr₂C₆H₃?la?;R=Bn,R'=2,6-Me₂C₆H₃?1b?;R=Bn,R'=tBu?1c?;R=CH₂OCH₃,R'=2,6-iPr₂C₆H₃?3?;R=CH₃,R'=2,6-iPr₂C₆H₃?2?;R=2-CH₂C₆H₄N,R'= 2,6-iPr₂C₆H₃?4b?]were prepared via the reactions of 1-alkyl-3-indolyl aldehydes with corresponding amines.The C-H ?-bond metathesis followed by alkane elimination reactions between RE?CH₂SiMe₃?₃?thf?x and the ligands afforded the carbon ?-bonded indolyl-ligated rare earth metal complexes.Rare-earth metal dialkyl complexes[1-Bn-3-?2,6-'Pr₂C₆H₃N=CH?-C₈H₄N]RE?CH₂SiMe₃?₂?thf?2[RE=Y?6a?,Er?6b?,Yb?6c?]were obtained by the reactions of RE?CH₂SiMe₃?₃?thf?2 with 1 equiv of ligand la in toluene.Reactions of RE?CH₂SiMe₃?₃?thf?2 with 2 equiv of ligands la or 2 gave rare-earth metal monoalkyl complexes[1-R-3-?2,6-iPr₂C₆H₃N=CH?-C₈H₄N]2RECH₂SiMe₃[R=Bn,RE=Y?7a?,Er?7b?,Dy?7c?,Sm?7d?;R=Me,RE=Y?9a?,Er?9b?,Dy?9c?,Yb?9d?].Reactions of RE?CH₂SiMe₃?₃?thf?2 with ligand lc gave the homoleptic rare-earth metal complexes[1-Bn-3-?'BuN=CH?-C₈H₄N]3RE[RE=Y?8a?,Er?8b?].2.The catalytic activity of the rare-earth metal complexes supported by1-alkyl-3-imino indolyl ligands in the polymerization of isoprene?1?In the presence of cocatalyst borate and AIR3,the rare-earth metal dialkyl complexes incorporating 1-Bn-3-imino indolyl ligand?6a,6b?initiated the polymerization of isoprene.The catalytic activity and 1,4-selectivity of the ternary system highly depended on the solvents,which was used in the polymerization reaction.In comparing with CH₂Cl2,the polymerization reaction proceeded in C₆H₅CH₃ or C₆H₅Cl exhibited high activity?100%conversion of 1000 equiv of isoprene in 40 min?with low 1,4-selectivity?67%?.The kinds of alkylaluminium also have a great influence on the catalytic activity and 1,4-selectivity of the ternary system with the trend of AliBu3>AlEt3>AlMe₃.When[PhNMe₂H][B?C₆F₅?₄]was used in the polymerization,1,4-selectivity was comparable to that of[Ph3C][B?C₆F₅?₄],but the catalytic activity declined.?2?In combination with cocatalyst,the novel rare-earth metal monoalkyl complexes supported by 1-alkyl-3-imino indolyl ligands?7a-7c,9a-9c?initiated the polymerization of isoprene with a high activity?90%conversion of 1000 equiv of isoprence in 25 min?with a high regio-and stereoselectivity?1,4-cis polymers up to 99%?.The kinds of solvents which was used in the polymerization reaction strongly effected the 1,4-cis selectivity of the ternary system with the trend of C₆HsCl?99%?>CH₂Cl2?98%?>C₆H₅CH₃?87%?.The[AIR3]/[RE]ratio affected the molecular weight of the polymers.Increasing the[AliBu3]/[RE]ratio significantly reduced the molecular weight of the polymers and broadened the molecular weight distribution.The catalytic activity of the system increased with an increasing of the ionic radii of central rare-earth metal ions.The ligand also affected the catalytic activity of the system.Complexes 7a-7c,which bearing more bulky ligand,exhibited higher activity than those of complexes 9a-9c.Ytterbium analogue 9d showed no activity for the isoprene polymerization under the same conditions.3.Lithium complexes supported by 1-alkyl-3-imino-2-indolyl ligands:synthesis,characterization and reactivityTreatment of 1-alkyl-3-imino functionalized indolyl ligands 1-R-3-?R'N=CH?C₈H₅N[R = Bn,R' = 2,6-iPr₂C₆H₃?la?;R = Bn R'= tBu?lc?;R =CH₂OCH₃,R'= 2,6-iPr₂C₆H₃?3?]with TMSCH₂Li in non-coordinating solvents produced carbon a-bonded indolyl lithium complexes[1-Bn-3-?2,6-iPr₂C₆H₃N=CH?-C₈H₄NLi]2?10?,[1-Bn-3-?tBuN=CH?C₈H₄NLi]3?12?and[1-CH₃OCH₂-3-?2,6-iPr₂C₆H₃N=CH?-C₈H₄NLi]2?13?.THF coordinated complex[1-Bn-3-?2,6-iPr₂C₆H₃N=CH?-C₈H₄NLiTHF]2?11?was obtained by the reaction of la with 1 equiv nBuLi in THF.Compounds 11 and 13 crystallized as dimers with the carbanionic sp2 carbon atoms of indolyl coordinated to lithium in ?2-?1:?1 manner,while compound 12 crystallized as trimer with carbanionic atoms coordinated to lithium in ?2-?1:?1 and ?3-?1:?1:?1 manners.Complex 10 with the polarized C-Li a bond played a part of nucleophilic substrate and reacted with the ligand la in 1,4-addition manner afforded lithium amide complex 1-Bn-3-?2,6-iPr₂C₆H₃N=CH?-2-[1'-Bn-3'-?2,6-iPr₂C₆H₃NCH?C₈H₅N]C₈H₅NLiTHF?14?.Complex 14 can also be obtained by the reaction of la with 0.5 equiv nBuLi in THF.Similarly,ligand lc reacted with 0.5 equiv nBuLi in THF or Et2O produced lithium amide complexes 1-Bn-3-tBuN=CH-2-?1'-Bn-3'-tBuNCHC₈H₅N?C₈H₅NLiTHF?15a?and 1-Bn-3-tBuN=CH-2-?1'-Bn-3'-tBuNCHC₈H₅N?C₈H₅NLiEt20?15b?respectively:4.Synthesis and characterization of rare earth metal alkyl and chloride complex incorporating neutral pyrrole ligand Reaction of neutral pyrrole ligand 1-?2-NMe₂C₆H₄?-2-?2,5-Me₂C₄H₂N?-C₆H₄NH?19?with Yb?CH₂TMS?3?thf?2 afforded ytterbium dialkyl complex[?5:?1:?1-1-?2-NMe₂C₆H₄?-2-?2,5-Me₂C₄H₂N?-C₆H₄]NYb?CH₂TMS?2?22?and the pyrrole moiety coordinate to metal center in the ?5 manner.Yttrium dichloride complex[?5:?1:?1-1-?2-NMe₂C₆H₄?-2-?2,5-Me₂C₄H₂N?-C₆H₄]NYCl??2-Cl?2Li?thf?2?23?was obtained by the reaction of organolithium complex[?5:?1:?1-1-?2-NMe₂C₆H₄?-2-?2,5-Me₂C₄H₂N?-C₆H₄]NLi?20?with YC13 in THF.The chloride bridged moiety in complex 22 was destroyed by addition of LiCH₂C₆H₄-o-NMe₂ with producing yttrium monochloride complex[?5:?1:?1-1-?2-NMe₂C₆H₄?-2-?2,5-Me₂C₄H₂N?-C₆H₄]NY[CH₂C₆H₄-o-NMe₂]Cl?24?.