Reactivity of Yttrium Carboxylates Toward Alkylaluminum Hydrides

Yttrocene-carboxylate complex [Cp*Y-2(OOCArMe)] (Cp*=C5Me5, Ar-Me=C6H2Me3-2,4,6) was synthesized as a spectroscopically versatile model system for investigating the reactivity of alkylaluminum hydrides towards rare-earth-metal carboxylates. Equimolar reactions with bis-neosilylaluminum hydride and dimethylaluminum hydride gave adduct complexes of the general formula [Cp*Y-2(-OOCArMe)(-H)AlR2] (R=CH2SiMe3, Me). The use of an excess of the respective aluminum hydride led to the formation of product mixtures, from which the yttrium-aluminum-hydride complex [{Cp*Y-2(-H)AlMe2(-H)AlMe2(-CH3)}(2)] could be isolated, which features a 12-membered-ring structure. The adduct complexes [Cp*Y-2(-OOCArMe)(-H)AlR2] display identical (1)J(Y,H) coupling constants of 24.5Hz for the bridging hydrido ligands and similar (YNMR)-Y-89 shifts of =-88.1ppm (R=CH2SiMe3) and =-86.3ppm (R=Me) in the (89)YDEPT45 NMR experiments.