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Carbon-carbon bond formation using yttrium(III) and the lanthanide elements

TitleCarbon-carbon bond formation using yttrium(III) and the lanthanide elements
Publication TypeJournal Article
Year of Publication2001
AuthorsFryzuk, MD, Jafarpour, L, Kerton, FM, Love, JB, Patrick, BO, Rettig, SJ
Date PublishedApr
Type of ArticleArticle
ISBN Number0276-7333

The synthesis and characterization of a series of yttrium and lanthanide complexes that incorporate the macrocyclic bis(amidophosphine) ligand PhP(CH2SiMe2NSiMe2CH2)(2)PPh, [P2N2], are described. The starting materials, {[P2N2]M}(2)(mu -Cl)(2), (M = Y, Sm, Ho, Yb, Lu), are prepared by the reaction of syn-Li-2(dioxane)[P2N2] with MCl3(THF)(3) in toluene. The reactivity of these complexes toward PhLi and other arylating agents is dependent on the size of the M3+ ion. M = Y and Ho undergo C-C bond formation reactions to give biphenyldiide compounds {[P2N2]M}(2){mu-eta (6):eta (6 ’)-(C6H5)(2)} and {[P2N2]Y}(2){mu-eta (6):eta (6 ’)-(C6H4-p-Ph)(2)} These have been structurally characterized and show the biphenyl dianion bridging two [P2N2]M fragments. These [P2N2]M fragments migrate over the bridging ligand’s pi -surface on the NMR time scale. M = Yb yields the paramagnetic monophenyl derivative [P2N2]Yb-(C6H5), where the Yb center is coordinatively unsaturated and resides in a distorted square-pyramidal environment. M = Lu results in a mixture of "ate" complexes of the formulation "[P2N2]LuPh . LiCl", as evidenced by Li-7 NMR. However, the biphenyl product {[P2N2]Lu}(2)-{mu-eta (6):eta (6 ’)-(C6H5)(2)} can be synthesized via a reductive route. The presence of THF was found to be deleterious to the coupling reaction; in this case, the THF adduct [P2N2]Y(C6H4-p-Me)-(THF) was isolated and structurally characterized. The mechanism for the C-C bond formation reaction is described based on the isolation of these yttrium and lanthanide complexes.

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