199607-96-0Relevant academic research and scientific papers
Solution structure and decomposition pathway of zwitterionic zirconium (IV) benzyl complexes
Gauvin, Régis M,Mazet,Kress, Jacky
, p. 1 - 8 (2007/10/03)
Reaction of the chelating diamido complexes Zr(ABAn)(CH2Ph)2 [ABA1 = N,N'-(SiMe3)2-2-amidobenzylamido, ABA2 = N,N'-(SiMePh2) (SiMe3)-2-amidobenzylamido] wit
Cationic aluminum alkyl complexes incorporating aminotroponiminate ligands
Korolev,Ihara,Guzei,Young Jr.,Jordan
, p. 8291 - 8309 (2007/10/03)
The synthesis, structures, and reactivity of cationic aluminum complexes containing the N,N'-diisopropylaminotroponiminate ligand (iPr2-ATI-) are described. The reaction of (iPr2-ATI)A1R2 (1a-e,g,h; R = H (a), Me (b), Et (c), Pr (d), iBu (e), Cy (g), CH2Ph (h)) with [Ph3C][B(C6F5)4] yields (iPr2-ATI)A1R+ species whose fate depends on the properties of the R ligand. 1a and 1b react with 0.5 equiv of [Ph3C]-[B(C6F5)4] to produce dinuclear monocationic complexes [{(iPr2-ATI)AIR}2(μ-R)][ (C6F5)4] (2a,b). The cation of 2b contains two (iPr2-ATI)AlMe+ units linked by an almost linear Al-Me-Al bridge; 2a is presumed to have an analogous structure. 2b does not react further with [Ph3C][B(C6F5)4]. However, 1a reacts with 1 equiv of [Ph3C][B(C6F5)4] to afford (iPr2-ATI)Al(C6F5) (μ-H)2B(C6F5)2 (3) and other products, presumably via C6F5- transfer and ligand redistribution of a [(iPr2-ATI)AlH] [(C6F5)4] intermediate. 1c-e react with 1 equiv of [Ph3C]-[B(C6F5)4] to yield stable base-free [(iPr2-ATI)AIR][B (C6F5)4] complexes (4c-e). 4c crystallizes from chlorobenzene as 4c(ClPh)·0.5PhCl, which has been characterized by X-ray crystallography. In the solid state the PhCl ligand of 4c(ClPh) is coordinated by a dative PhCl-Al bond and an ATI/Ph π-stacking interaction. 1g,h react with [Ph3C][B(C6F5)4] to yield (iPr2-ATI)Al(R)(C6F5)(5g,h) via C6F5- transfer of [(iPr2-ATI)A1R]-[ (BC6F5)4] intermediates. 1c,h react with B(C6F5)3 to yield [(iPr2-ATI)Al(R)](C6F5) (5c,h) via C6F5- transfer of [iPr2-ATI)A1R][RB (C6F5)3] intermediates. The reaction of 4c-e with MeCN or acetone yields [(iPr2-ATI)-Al(R)(L)][B (C6F5)4] adducts (L = MeCN (8c-e), acetone (9 c-e)), which undergo associative intermolecular L exchange. 9c-e undergo slow β-H transfer to afford the dinuclear dicationic alkoxide complex [{(iPr2 -ATI)Al(μ-OiPr)}2][B (C6F5)4]2 (10) and the corresponding olefin. 4c-e catalyze the head-to-tail dimerization of tert-butyl acetylene by an insertion/σ-bond metathesis mechanism involving [(iPr2-ATI)Al(C≡CtBu)]- [B(C6F5)4] (13) and [(iPr2-ATI)Al(CH =C(tBu)C≡Ct(Bu)] [B(C6F5)4] (14) intermediates. 13 crystallizes as the dinuclear dicationic complex [{(iPr2-ATI)Al (μ-C≡tBu)}2] [B(C6F5)4]2·5PhCl from chlorobenzene. 4e catalyzes the polymerization of propylene oxide and 2a catalyzes the polymerization of methyl methacrylate. 4c,e react with ethylene-d4 by β-H transfer to yield [(iPr2- ATI)AlCD2CD2H][B (C6F5)4 initially. Polyethylene is also produced in these reactions by an unidentified active species.
Controlled alkene and alkyne insertion reactivity of a cationic zirconium complex stabilized by an open diamide ligand
Horton, Andrew D.,De With, Jan
, p. 5424 - 5436 (2008/10/08)
The chemistry of electrophilic zirconium complexes stabilized by a sterically open diamide ligand has been studied. Treatment of Me2Si(NLiCMe3)2 with ZrCl4(THF)2 afforded {Me2Si(NCMe3)2}ZrCl2(THF) 2 (1), which, in solution, was in equilibrium with a dimeric zirconium dichloride species [{Me2Si(NCMe3)2}ZrCl2] 2(THF). Complex 1 was converted to dialkyl complexes {Me2Si(NCMe3)2}ZrR2 (R = CH2Ph, 4; CH2CMe3, 5) using MgBz2(dioxane)0.5 and LiCH2CMe3, respectively, but dimethylation was unsuccessful. Alkyl abstraction from 4 using B(C6F5)3 cleanly afforded {Me2Si(NCMe3)2}Zr(CH2Ph){η 6-PhCH2B(C6F5)3} (6), in which the anion strongly coordinates to the benzylzirconium cation via the aromatic ring. Protonolysis of 4 using [PhMe2NH][B(C6F5)4] afforded the Lewis-base adduct [{Me2Si(NCMe3)2}Zr{CH2Ph)(NMe 2Ph)]+ (7), whereas [Ph3C][B(C6F5)4] gave 1 equiv of Ph3CCH2Ph and a mixture of two cationic species, 9a/b, proposed to be monomeric and dimeric benzylzirconium cations. Reaction of 4 with 0.5 equiv of the trityl reagent afforded the dizirconium complex [{Me2Si(NCMe3)2}2Zr 2(CH2Ph)3]+. Cations 6, 7, and 9a/b cleanly and rapidly reacted with 2-butyne to afford the single insertion product, [{Me2Si(NCMe3)2}Zr{η1,η 6C(Me)=C(Me)CH2Ph]+, stabilized by a chelating π-coordination of the benzene ring of the hydrocarbyl ligand. Structurally similar insertion products were obtained from the reaction of 9a with a range of alkenes, [{Me2Si(NCMe3)2}Zr{η1,η 6-CH2CH(R)CH2Ph]+ (R = H, Me, n-Bu, CH2Ph). Benzylborate adduct 6 also underwent single alkene insertion giving {Me2Si(NCMe3)2}Zr{η1-CH 2CH(R)CH2Ph}{η6-PhCH2B(C 6F5)3} (R = H, Me), stabilized by anion coordination to zirconium. The dramatic effects of anion, Lewis base, solvent, and substrate variation on the rate of insertion have been rationalized in terms of the facility of anion or base dissociation from the benzylzirconium cation.
