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The reaction of dialane [LAl‐AlL] (1; L=dianion of 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene, dpp‐bian) with carbon dioxide results in two different products depending on solvent. In toluene at temperatures of about 0 °C, the reaction gives cycloadduct [L(CO2)Al‐Al(O2C)L] (2), whereas in diethyl ether, the reaction affords oxo‐bridged carbamato derivative [L(CO2)(Et2O)Al(μ‐O)AlL] (3). The DFT and QTAIM calculations provide reasonable explanations for the reversible formation of complex 2 in the course of two subsequent (2+4) cycloaddition reactions. Consecutive transition states with low activation barriers were revealed. Also, the DFT study demonstrated a crucial effect of diethyl ether coordination to aluminium on the reaction of dialane 1 with CO2. The optimized structures of key intermediates were obtained for the reactions in the presence of Et2O; calculated thermodynamic parameters unambiguously testify the irreversible formation of the product 3.

The reaction of ClGaH with a sodium salt of the dpp-Bian radical-anion (dpp-Bian)Na (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) affords paramagnetic gallane (dpp-Bian)Ga(Cl)H (1). Oxidation of (dpp-Bian)Ga-Ga(dpp-Bian) (2) with NO results in the dimeric oxide (dpp-Bian)Ga(μ-O)Ga(dpp-Bian) (3). A treatment of the oxide 3 with phenylsilane affords paramagnetic gallium hydrides (dpp-Bian)GaH (4) and (dpp-Bian)Ga{OSi(Ph)H}H (5) depending on the reagent's stoichiometry. The reaction of digallane 2 with benzaldehyde produces pinacolate (dpp-Bian)Ga(OCHPh) (6). In the presence of PhSiH, the reaction between digallane 2 and benzaldehyde (2: PhSiH: PhC(H)O = 1:4:4) affords compound 4. The newly prepared complexes 1, 3-6 consist of a spin-labeled diimine ligand-dpp-Bian radical-anion. The presence of the ligand-localized unpaired electron allows the use of the ESR spectroscopy for characterization of the gallium hydrides reported. The molecular structures of compounds 1, 3-6 have been determined by the single-crystal X-ray analysis.

The reactions of H2AlCl with [(dpp-Bian)­Na­(Et2O)n] and [(ArBIG-Bian)­Na­(THF)] produce respective aluminum hydrides supported by radical-anionic 1,2-bis­(arylimino)­acenaphthene ligands, [(dpp-Bian)­AlH2] (1) and [(ArBIG-Bian)­AlH2(THF)] (2) (dpp-Bian = 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene); ArBIG-Bian = 1,2-bis­[(2,6-dibenzhydryl-4-methylphenyl)­imino]­acenaphthene). The reaction of 1 with CO2 proceeds with reduction of both CO bonds and results in diolate [{(dpp-Bian)­Al­(μ-O2CH2)}2] (3). Complex 2 reacts with CO2 to carbonate [{(ArBIG-Bian)­Al­(μ-OCH2OCO2)}2] (4) that is a result of the insertion of CO2 into the Al–O bond in diolate species formed initially. Aluminum monohydrides [(dpp-Bian)­AlH­(X)] (X = Cl, 5; Me, 6) react with CO2 to form respective alumoxanes [{(dpp-Bian)­AlX}2(μ-O)] (X = Cl, 7 and X = Me, 8). Compounds 1–4, 7, and 8 have been characterized by ESR and IR spectroscopy, and their molecular structures have been determined by single-crystal X-ray analysis.

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