Reactivity of Yttrium Methyl Complexes: Hydrido Transfer Capability of Selected Alkylalanes

Abstract

The reactivity of alkylaluminum hydrides HAlMe2, HAl­(CH2SiMe3)2, and H2AlMes* (Mes* = C6H2 tBu3-2,4,6) toward yttrium methyl complexes was assessed. From the reaction with [Cp2YMe]2 the corresponding methylated alkylaluminum compounds could be isolated and characterized along with [Cp2Y­(thf)­(μ-H)]2, obtained upon workup in thf (Cp = C5H5 = cyclopentadienyl). Structurally characterized complexes Cp14Y6H3Cl and Cp15Y6H3 represent side-products of the transformation. The reactions of [YMe3] n and [(C5Me5)­YMe2]3 indicated occurrence of hydrido transfer for H2AlMes* and led to product mixtures for HAl­(CH2SiMe3)2. Following the reaction of HAlMe2 with these compounds as well as the half-sandwich derivatives (C5Me4R)­Y­(AlMe4)2 (R = Me, SiMe3) indicated reversible hydrido binding, leading ultimately to the formation of insoluble hydride clusters. The organoaluminum compounds [HAl­(CH2SiMe3)2]3, [(μ-H)­(Me)­AlMes*]2, and Me2AlMes* were analyzed by X-ray crystallography.

Rare‐Earth Metal Diimide Complexes via Alkylaluminate Templating, Including a Ceric Derivative

“…Most unfortunately, upscaling the 1‐La /PhSiH 3 reaction in a 1:2 ratio led to even more complicated mixtures. Nevertheless, the isolation of lanthanum hydride complex 5 clearly proves the feasibility of an imido/hydrido transformation, possibly involving a sequence of imido/amido and amido/hydrido transformations and subsequent ligand redistribution. Previously, the putative anilide hydride complex [LSc{H}{NAr(SiH 2 Ph)}] (Ar=C 6 H 3 i Pr 2 ‐2,6), formed via reaction of the terminal imide [LSc(NAr)(DMAP)] with PhSiH 3 but was only trackable by a subsequent reaction with a carbodiimide …”

Aluminum Complexes Bearing N-Protected 2-Amino- or 2-Imino-Functionalized Pyrrolyl Ligands: Synthesis, Structure, and Catalysis for Preparation of Pyrrolyl-End-Functionalized Polyesters

“…The bond length of Al1–N1 [1.840 (2) Å for 2 , 1.844(2) Å for 3 ] is significantly shorter than that of complex 1 [2.023(2) Å] mainly due to bond character (coordination bond in 1 vs covalent bond in 2 and 3 ). The bond distances of Al–C16 (3-C of the pyrrole ring) in complex 2 [2.051(2) Å] is shorter than that in complex 3 [2.070(2) Å], which is longer than the Al–C (Cp) [2.039(3) Å] found in THF·Li­(μ-TMP)­[μ-(C 5 H 4 )­Fe­(C 5 H 5 )]­Al­( i Bu) 2 (TMP = 2,2,6,6-tetramethylpiperidide) and Al–C (Mes*) [1.993 Å] found in Me 2 AlMes* (Mes* = 2,4,6- t Bu 3 C 6 H 2 ) . The distances of Al–C1 (methyl-Al for 2 , ethyl-Al for 3 ) in complex 2 [1.945(2) Å] are slightly shorter than that in complex 3 [1.953(3) Å].…”

Interconverting Lanthanum Hydride and Borohydride Catalysts for C=O Reduction and C−O Bond Cleavage

“…Thus, the lanthanum hydride species of 2 and 3 are reactive toward the C=O bond of ketones but not competent for reaction with esters. As is the case for many catalytic species, isolation of 2 and 3 in pure form was not possible, and the related YH 3 species has been assigned on the basis of mass balance in reactions trimethylyttrium and H 2 AlMes …”

“…[15] Further mechanistic insight was sought from in-situmonitored catalytic experiments.Second-order plots indicate that reaction rate is directly proportional to the concentration of HBpin and ester.T he pseudo-second-order rate constants (k obs )plotted vs. [1]reveal alinear relationship consistent with first-order dependence on catalyst concentration, giving the ternary-order rate constant k' obs = 1.95 AE 0.86 m À2 s À1 for the experimental rate law in Equation (1). Thus,t he lanthanum hydride species of 2 and 3 are reactive toward the C = Obond of ketones but not competent for reaction with esters.A si st he case for many catalytic species,isolation of 2 and 3 in pure form was not possible,and the related YH 3 species has been assigned on the basis of mass balance in reactions trimethylyttrium and H 2 AlMes.…”