Yttrium Siloxide Complexes Bearing Terminal Methyl Ligands: Molecular Models for Ln−CH3 Terminated Silica Surfaces |
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| Authors: | Dr Nicole Dettenrieder Dr H Martin Dietrich Dr Cäcilia Maichle‐Mössmer Prof?Dr Reiner Anwander |
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| Institution: | Institute of Inorganic Chemistry, Eberhard Karls Universit?t Tübingen, Tübingen, Germany |
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| Abstract: | Surface organometallic chemistry (SOMC) on silica materials is a prominent approach for the generation of highly active heterogenized polymerization catalysts. Despite advanced methods of characterization, the elucidation of the catalytically active surface species remains a challenging task. Alkylated rare‐earth metal siloxide complexes can be regarded as molecular models of respective covalently bonded alkylated surface species, primarily used for 1,3‐diene polymerization. Here, we performed both salt metathesis reactions of Y(MMe4)3] (M = Al, Ga) with K{OSi(OtBu)3}] and alkylation reactions of Y{OSi(OtBu)3}3]2 with AlMe3. The obtained complexes Y(CH3)(AlMe2){OSi(OtBu)3}2](AlMe4)]2, Y(CH3)(AlMe2){OSi(OtBu)3}2]‐{OSi(OtBu)3}], Y{OSi(OtBu)3}3(μ‐Me)Y(μ‐Me)2Y{OSi(OtBu)3}2(AlMe4)], and Y(CH3)(GaMe4){OSi(OtBu)3}]2 represent rare examples of organoyttrium species with terminal methyl groups. The formation and purity of the mixed methyl/siloxy yttrium complexes could be enhanced by treating Y(MMe4)3] with K(MMe2){OSi(OtBu)3}2]n (M=Al: n=2; M=Ga: n=∞). Complexes K(MMe2){OSi(OtBu)3}2]n were obtained by addition of K{OSi(OtBu)3}] to Me2M{OSi(OtBu)3}]2. Deeper insight into the fluxional behavior of the mixed methyl/siloxy yttrium complexes in solution was gained by 1H and 13C NMR spectroscopic studies at variable temperature and 1H–89Y HSQC NMR spectroscopy. |
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| Keywords: | aluminum gallium methyl siloxy yttrium |
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