Aluminohydride complexes

One such reaction results in the isolation of a stable aluminohydride complex ... 

Hydride complexes, particularly those of the early transition metals, are often prepared from main group hydrides (Equations 3.115, 3.116, 3.117, 3.118, and 3.119 0-Borohydride and aluminohydride complexes are known and have been observed as intermediates in a few reactions that form transition metal hydrides. 

The Chemistry of Complex Aluminohydrides. Advanc. Inorg. Radio-chem. 8, 283 (1966). 

Hydrides, 23 607-631, 771 alkali metal, 23 608-610 alkaline-earth metal, 23 610-611 aluminohydrides, 23 621-624 complex, 23 613-621 covalent, 23 611-613 gallium, 22 355... 

Nuclear Quadrupole Resonance and Its Application in Inorganic Chemistry Masaji Kubo and Daiyu Nakamura The Chemistry of Complex Aluminohydrides E. C. Ashby... 

Treatment of an ethereal solution of 4-oxo-dihydro-l,3-diaza-anthracene (108) with lithium aluminum hydride reportedly resulted in the reduction of only the 1,2-carbon-nitrogen double bond with 4-oxo-l,2,3,4-tetrahydro-l,3-diazaanthracene (109) being the only product isolated.134 Apparently conditions were not sufficiently vigorous for the further reduction of the tautomeric form of 109, or possibly the formation of a complex with the aluminohydride pre-... 

The X-ray structural characterization of a series of mono-, di-, and poly-lanthanidocene aluminohydride and alane complexes by B.M. Bulychev and G.L. Soloveichik revealed a variety of coordination modes of the [A1H4] , [AIH3] and [A1H2]+ moieties [273-281]. Routinely, these complexes were synthesized by the reaction of a lanthanidocene chloride with LiAlH4 or A1H3. The nuclearity and All x coordination mode depend on the presence of additional Lewis bases, such as THF, diethyl ether, or triethylamine (Chart 7). Diene polymerization based on lanthanidocene aluminohydrides has not been reported. 

Chart 7 Aluminohydride and alane coordination modes in lanthanidocene complexes... 

Attempts have been made to isolate aluminohydride analogs in trivalent chemistry. Reaction of UCI3 with three equivalents of L1A1H4 yields a gray powder, proposed to be U(A1H4)3. The complex is reported to decompose at temperatures above —20 °C. 

The formula of the reagent is usually written as LiAlHi but interpreted as Li fAlH,]" or Li+A1H4. Thus in ether solution it exists as aggregates of solvated lithium ions and aluminohydride ions. The first step in the reaction with a ketone is transfer of a hydride ion to give the complex (1) since this has three more hydrogen... 

Insoluble MH hydrides react very slowly, they must be used in large excess and rearrangements often occur. In some cases, however, the addition of the hydride ion H- was observed, and the formation of anionic complexes of poor stability, CpjLnH-, was mentioned [14]. Nevertheless, an yttrium hydride could be structurally characterised [15]. Owing to the high electropositive character of the lanthanide atoms, the use of borohydride (or aluminohydrides) reagents leads to stable borohydrides (or to bimetallic Ln-Al complexes) [1]. The spontaneous elimination of the borane (or alane), which is commonly observed for the late transition metals, does not occur. 

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