V. A. Antonovich

27Al NMR investigation of the products of the exchange reaction between lithium and sodium aluminum hydrides and MAlR4 tetraalkyl complexes

ConclusionsIn solution, the complexes MAlH3R (R=Me, Et) are unstable and disproportionate. The complexes MAlH2R2 and MAlHR3 are stable and the MAlHR3 complexes have a tendency to form associates.

Preparation of complex compounds of alumoxanes with alkyl and hydride derivatives of alkali metals

Conclusions1.Controlled reaction of NaAlR4 and NaAlR3H (R=Alk) with water (2∶1) leads to formation of disodiumhexaalkylalumoxanates Na2(R3A1OAlR3). Free alumoxane Et2A1OAlEt2 has been obtained by the reaction of Na2(Et3A1OAlEt3) with allyl bromide.2.Lithium, sodium, and potassium hydrides are attached to alumoxanes in ether and THF with formation of 1∶1 adducts; in aromatic hydrocarbons only NaH and KH react, forming monohydride complexes M(HR2AlOAlR2). Attachment of lithium and sodium hydrides to alumoxane is not complete and is a reversible process.3.Controlled hydrolysis or ammonolysis with methylamine MA1R2H2 (M is Li or Na) leads to the formationof equilibrial mixtures of lithium and sodium mono- and dihydride alumoxane or alumoxane complexes with detachment of MH.

Synthesis of aluminum hydride complex compounds containing the heptahydridodialuminate anion Al2H7

1. The reaction of alumohydrides of tetraalkylammonium cations with ethereal solutions of A1H3 leads to formation of heptahydridodialuminates of tetraalkylammonium cations, isolated as distinct compounds. 2 Complex compounds of NaAlH4 and LiAlH4 with dimethoxyethane form compounds containing the [Al2H7]− anion. 3. Some chemical properties of tetraalkylammonium heptahydridodialuminates have been investigated.

Synthesis of the complex aluminum hydrides M+Al2H7− (M+=Li, Na, K) and a study of their transformations

ConclusionsWhen lithium, sodium, and potassium aluminum hydrides react with an ether solution of AlH3 in the presence of crown ethers, complexes are formed that contain the Al2H7− anion.

27Al NMR study of disproportionation of aryloxy derivatives of alkali-metal aluminum hydrides in tetrahydrofuran

ConclusionsWe have used27Al NMR to study disproportionation processes in a series of aryloxy derivatives of alkali-metal aluminum hydrides, MAlH4−n(OArm), and have shown that an increase in steric hindrance in the aryl radical increases the stability of the alkali-metal aluminum hydride aryloxy derivatives.

Disproportionation of the alkynyl derivatives of alkali metal aluminum hydrides in electron-donor solvents

ConclusionsThe reaction of disproportionation of mixed hydride alkynyl complexes of aluminum in ether, THF, and hexametapol was studied by27Al NMR, and it was shown that the stability of MAlH(3−n)) (C≡CR)n, where M=Li, Na, K, and R=Ph, n-Bu decreases in the order: MAlH(C≡CR)3 < MAlH2(C≡CR)2 < MAlH3(C≡CR). The tendency of these complexes to disproportionate increases with an increase in the solvation of the cation.

Complexes of 1,1,1-tris(diethylalumino)hexane with electron-donor compounds

Conclusions1.Reaction of LiH and NaH with C5H11(AlEt2)3 gives the monohydride organoaluminum complexes M[C5H11C(AlEt2)3H].2.Reaction of KF with C5H11(AlEt2)3 affords the monofluoride organoaluminum complex K[C5H11(AlEt2)8F].3.Ether and pyridine give with C5H11C(AlEt2)3 complexes of compositions 1∶1, 1∶2, and 1∶3, but Et3N gives only the 1∶1 complex.

27Al NMR investigation of the dispropoetionation of amide and pyridine derivatives of sodium aluminum hydride in THF solutions

Conclusions1.The stable monohydride complexes NaAlHAm3, where Am=N(C2H5)2, NC5H10, and NC5H6, were detected by27Al NMR in the reactions of NaAlH4 with diethylamine, piperidine, and pyridine in THF solutions.2.The corresponding tri- and dihydride complexes NaAlH3Am and NaAlH2Am2 are unstable in solution and disproportionate partially or completely to NaAlH4 and NaAlHAm3.3.When diisopropylamine is reacted with NaAlH4 in THF, no more than 2 moles of the amine react, and the stable tri- and dihydride complexes NaAlH3N(i-C3H7)2 and NaAlH2[N(i-C3H7)2]2form.

Synthesis of binuclear organoaluminum complexes M[p-C5H11CH (AlR2)2X]

Conclusions1.By the action of LiH and NaH on C5H11CH(AlR2) (R=Et or i-Bu) the authors have obtained for the first time hydride binuclear organoaluminum complexes M[C5H11CH(A1R2)2H].2.By the action of KF on C5H11CH(AlR2)2 (R=Et or i-Bu) they have obtained for the first time binuclear organoaluminum complexes K[C5H11CH(AlR2)2F].

A study, using27Al methods, of the products obtained from the reaction of sodium and lithium aluminohydrides with alcohols and carbonyl compounds in tetrahydrofuran solution

Conclusions1.27A1 NMR methods have been used to show that the reaction of NaAlH4 with ethyl and isopropyl alcohols, acetaldehyde, acetone, ethyl acetate, and hexyl acetate in THF solution leads to the formation of NaAl(OR)4 through disproportionation of intermediate alkoxy derivatives.2.Methyl, tert-butyl, and nonyl alcohols react with NaAlH4, to form NaAl(OR)3H.3.Reaction of LiAlH4 with methyl and ethyl alcohols in THF solution leads to the formation of LiAlH2(OMe)2 and LiAl(OEt)3H.4.There was no evidence of disproportionation in the products resulting from the reaction of NaAlH4, with the monomethyl ester of ethyleneglycol.