Alkynyl Compounds of the Rare‐earth Metals

Abstract

AbstractConversion of the rare‐earth tetramethylaluminates [Ln(AlMe4)3] with phenylacetylene afforded the homoleptic alkynylaluminates [Ln{(μ‐C≡CPh)2AlMe2}3] [Ln = Ce (1), Er(2)]. The reaction of five equivalents of phenylacetylene with the yttrium aluminate [Y(AlMe4)3] afforded [Y{(μ‐C≡CPh)AlMe3}{(μ‐C≡CPh)2AlMe2}2] (3). The cationic yttrium complex [(TMTAC)2YMe2][AlMe4] (4) (TMTAC = 1, 3,5‐trimethyl‐1, 3,5triazacyclohexane) was reacted with phenylacetylene to give the product [(TMTAC)2Y(C≡CPh)2][Me2Al(C≡CPh)2] (5), in which two methyl groups of each, the cation and the anion, were substituted by phenylacetylide groups. Under the same conditions as for the synthesis of compound 5, the holmium analogue reveals different reactivity in forming a neutral alkynyl complex [(TMTAC)2Ho(C≡CPh)3] (6). The introduction of 1, 8‐diethynylanthracene to 4 leads to a structural very similar complex [(TMTAC)2Ho(μ‐1, 8‐diethynylanthracene)3] (7) and offers the same reactivity as observed for the synthesis of 6. All compounds were characterized by X‐ray diffraction experiments. Compounds 1–3 and 5 were also characterized by NMR and elemental analyses.