Reactivity of Yttrium Carboxylates Toward Alkylaluminum Hydrides

Abstract

Yttrocene-carboxylate complex [Cp*2Y(OOCAr(Me))] (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*2Y(μ-OOCAr(Me))(μ-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*2Y(μ-H)AlMe2(μ-H)AlMe2(μ-CH3)}2] could be isolated, which features a 12-membered-ring structure. The adduct complexes [Cp*2Y(μ-OOCAr(Me))(μ-H)AlR2] display identical (1)J(Y,H) coupling constants of 24.5 Hz for the bridging hydrido ligands and similar (89)Y NMR shifts of δ=-88.1 ppm (R=CH2SiMe3) and δ=-86.3 ppm (R=Me) in the (89)Y DEPT45 NMR experiments.

Molecular Main Group Metal Hydrides

“…760 44) assembled by way of bridging hydride and methyl moieties. 763 Multiple examples of hydride-bridged aluminum-metal complexes are known for the Group 4 metals. Most commonly, these species are generated by combining Group 4 metallocene fragments with aluminum hydrides.…”

“…Aluminum-yttrium heterobimetallic compounds 575 and 577 (Figure ) were prepared by the insertion of HAlR 2 into a Y–CH 3 bond. − The 1 H NMR spectrum of [(3,5- Me,tBu Tp)­Y­(κ 1 -HAlMe 3 ) 2 ] ( 575 ) shows a doublet (δ 5.05 ppm in toluene- d 8 ) with a large 89 Y– 1 H coupling constant of 30.8 Hz. The reaction of an yttrium carboxylate Cp* 2 Y­(O 2 CMes) with excess (5 equiv) of HAlMe 2 afforded the unusual 12-membered ring structure 576 (Figure ) assembled by way of bridging hydride and methyl moieties …”

Magnesium, zinc, aluminium and gallium hydride complexes of the transition metals

“… 92 This motif is not unique to 48 , and X-ray data has been collected on monomeric [Cp 2 Lu(μ-H)·AlH 3 ·NEt 3 ], 94 and dimeric [Cp*Y(Me)(μ-H)AlMe 2 (μ-H)] 2 . 95 Despite the coordinated Lewis acid, 47 displays reactivity consistent with a terminal hydride; deprotonation of 2,6-dimethylaniline gave complex 48 . Here, the imide linker supports an intramolecular Ln–H→Al interaction ( Fig.…”

“…Alanes react with yttrocene hydride or carboxylate complexes to form Y←H–Al adducts ( 55–56 ). 95 While investigating the salt metathesis of a β-diketiminato-supported Sc dichloride complex with LiAlH 4 , Piers and co-workers isolated the alane adduct, 57 . 107 In 57 , both metals are six coordinate, and this is the only time a (μ-H) 3 bridging motif seen in the absence of a late TM.…”

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

“…been synthesized according to Scheme 124 as a versatile model system for investigating the reactivity of alkylaluminum hydrides toward rare-earth metal carboxylates [110]. [110].…”