Synthesis, characterization, and reactivity of lanthanide complexes with bulky silylallyl ligands

Timothy J. Woodman, Mark Schormann, Manfred Bochmann

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The synthesis of new lanthanide allyl complexes of enhanced stability and solubility in saturated hydrocarbons based on silyl-substituted allyl ligands is reported. Thus the potassium salt K(CH2CHCHSiMe3) (1) reacts with YCl3 in tetrahydrofuran to give the tris-allyl complex Y(CH2CHCHSiMe3)3 (2), while K(CH2CHCHSiMe2tBu) (3) affords Y(CH2CHCHSiMe2tBu)3(THF)1.5 (4). Slow re-crystallization of 4 from light petroleum in the presence of tert-butylcyanide led to multiple insertion to give the sec-amido complex Y{NHC(tBu)(CH)3SiMe2tBu}2{?2-NHC(tBu)CH=CHCH2SiMe2tBu)CH(CHCHSiMe2tBu)CtBuNH}(THF)·(CH3CH(Me)(CH2)2CH3) (5), which was crystallographically characterized. The reaction of ScCl3(THF)3 with two equivalents of Li{1,3-C3H3(SiMe3)2} in tetrahydrofuran gives the bis-allyl complex {1,3-C3H3(SiMe3)2}2Sc(µ-Cl)2Li(THF)2 (6), while the analogous reaction of K{1,3-C3H3(SiMe3)2} (7) with either LaCl3 or YCl3 in tetrahydrofuran affords the bis-allyl complexes MCl{1,3-C3H3(SiMe3)2}2(THF)x (8, M = La, x = 1; 9, M = Y, x = 0). An attempt to prepare the similar neodymium complex gave the mono-allyl complex NdI2{1,3-C3H3(SiMe3)2}(THF)1.25 (10). The reactions of 8 and 9 with triisobutyl aluminum in benzene-d6 show allyl exchange between lanthanide and aluminum. Complexes 8, 9, and 10 have been tested with a variety of activator systems as catalysts for the polymerization of 1,3-butadiene.
Original languageEnglish
Pages (from-to)283-293
Number of pages11
JournalIsrael Journal of Chemistry
Issue number4
Publication statusPublished - Jul 2003

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